HYPOTHESIS AND THEORY article

Front. Neurosci., 08 February 2024

Sec. Neurodegeneration

Volume 18 - 2024 | https://doi.org/10.3389/fnins.2024.1276714

Grid cells: the missing link in understanding Parkinson’s disease?

  • SANA Hospital Leipzig County, Borna, Germany

Abstract

The mechanisms underlying Parkinson’s disease (PD) are complex and not fully understood, and the box-and-arrow model among other current models present significant challenges. This paper explores the potential role of the allocentric brain and especially its grid cells in several PD motor symptoms, including bradykinesia, kinesia paradoxa, freezing of gait, the bottleneck phenomenon, and their dependency on cueing. It is argued that central hubs, like the locus coeruleus and the pedunculopontine nucleus, often narrowly interpreted in the context of PD, play an equally important role in governing the allocentric brain as the basal ganglia. Consequently, the motor and secondary motor (e.g., spatially related) symptoms of PD linked with dopamine depletion may be more closely tied to erroneous computation by grid cells than to the basal ganglia alone. Because grid cells and their associated central hubs introduce both spatial and temporal information to the brain influencing velocity perception they may cause bradykinesia or hyperkinesia as well. In summary, PD motor symptoms may primarily be an allocentric disturbance resulting from virtual faulty computation by grid cells revealed by dopamine depletion in PD.

Introduction

“Grid cells are such a beautiful and unique phenomenon in the nervous system that it is tempting to regard them as a crucial element of its design” (Kropff and Treves, 2008).

The existing model of the basal ganglia (BG) and dopamine depletion (DD) in Parkinson’s disease (PD) goes back to the late 1950s (Carlsson et al., 1957; Carlsson and Waldeck, 1958; Ehringer and Hornykiewicz, 1960; Birkmayer and Hornykiewicz, 1961; Hornykiewicz, 1962; Bernheimer and Hornykiewicz, 1965; Carlsson, 1971; Yeragani et al., 2010). This model was further refined in the 1980s and early 1990s with the formulation of the direct and indirect striatal output pathways and the “box-and-arrow” model (Penney and Young, 1986; Albin et al., 1989; DeLong, 1990; Nambu et al., 2002; Plotkin and Goldberg, 2018). Although this “has led to groundbreaking strategies to treat motor disorders” (Plotkin and Goldberg, 2018), it “fails to explain certain clinical findings and leaves a number of paradoxes” (Brown and Marsden, 1998, p. 1801), leaving us “far from a comprehensive mechanistic understanding of the pathophysiology of PD” (Wichmann et al., 2011). Furthermore, neurocomputational models (Gurney et al., 2001a,b; Fiore et al., 2016; Suryanarayana et al., 2019; Hjorth et al., 2020) and also trials with respect to deep brain stimulation (DBS) have demonstrated that current concepts of basal ganglia pathophysiology have reached “the point where total rejection, rather than continual attempts at modification, is necessary” (Montgomery, 2011, p. 14). Numerous critical reviews on this topic underline these limitations (Marsden and Obeso, 1994; Mink, 1996; Nambu, 2008; Wichmann et al., 2011; Plotkin and Goldberg, 2018).

The BG pathway refers to medium spiny neurons (MSN), which form clustered cell groups. These groups are activated not only by active and passive manipulation of one body part, but also by their cutaneous stimulation (Crutcher and DeLong, 1984; Alexander and DeLong, 1985; Carelli and West, 1991; Coffey et al., 2016, 2017) are referred to as single body parts (SBP). These SBP deliver a body-referenced frame that primarily “encodes action space” (Klaus et al., 2017) from the egocentric view.

However, as movement is generally goal-directed, originating from a starting point and progressing toward an endpoint, and often involving the late-stage positioning of a potential target, it relates to the external environment/space (Redgrave et al., 2010; Penner and Mizumori, 2012; Elliott et al., 2017; Grieves and Jeffery, 2017; Pernia-Andrade et al., 2021). It is therefore essential to consider not only the animal’s perspective of the goal’s position, but also the goal’s representation relative to external contextual features (the allocentric frame; Neely et al., 2008; Chersi and Burgess, 2015).

By applying the allocentric properties of grid cells to parkinsonian symptoms in connection with dopamine depletion (DD), we can gain new insights into the pivotal role of the allocentric brain not just in PD, but also in the inception of movement.

What we know

The allocentric space model

An individual’s objective position and the location of desirable goals are deduced from external landmarks and determined within the hippocampal place cells (O'Keefe and Dostrovsky, 1971). In turn, the computation of allocentric movement, necessary to navigate between landmarks, depends on grid cells (GCs) in the medial entorhinal cortex (mEC)—mainly within layer II in particular (Fyhn et al., 2004; Hafting et al., 2005; Moser et al., 2008; Boccara et al., 2010) (see Figure 1). The mEC consists of about two thirds reelin-positive stellate cells (SC), which supply the dentate gyrus and the hippocampus, also called “ocean cells,” surrounding about one third so-called pyramid cells (PC) or “island cells” projecting to mEC layer I and the contralateral EC. Both SC and PC are influenced by inhibitory microcircuits of different interneurons (Gatome et al., 2010; Witter et al., 2017; Naumann et al., 2018; Tukker et al., 2022) and can function as grid cells with an emphasis on pyramid cells (Tang et al., 2014; Rowland et al., 2018). Grid cells again receive significant dopaminergic innervation (Fallon et al., 1978; Akil and Lewis, 1993; Li et al., 2015).

Figure 1

Grid cell generate the external spatial allocentric reference overlaying the animal’s surrounding floor with a two-dimensional hexagonal pattern/carpet (the grid fields) formed by isosceles triangles (Hafting et al., 2005; Burak, 2014; Moser et al., 2014; Knierim, 2015; Vago and Ujfalussy, 2018; Mosheiff and Burak, 2019) (see Figure 2A). The emergence and maintenance of GCs and grid fields rely on exploratory movement, which is anchored to external landmarks and borders (Hafting et al., 2005; Savelli et al., 2008; Couey et al., 2013; Pastoll et al., 2013; Stensola et al., 2015). This movement again generates a self-organizing internal spiking within GCs based on local network dynamics (LFP, described in more detail below). For this, similar to striatal SBP, GCs receive spatial information in the form of copies of multimodal sensory input from external landmarks through self-motion data. This data originate from “vestibular, proprioceptive, visual (optic flow) and motor (motor-efference copy) systems” (Jeffery, 2007; Mohedano-Moriano et al., 2008; Barry and Burgess, 2014, p R332; Perez-Escobar et al., 2016; Nadasdy et al., 2017; Campbell et al., 2018), most visual cues being particularly relevant (Maaswinkel and Whishaw, 1999; Chen et al., 2013; Kinkhabwala et al., 2020). GCs are grouped into modules that share the same scale/period (for distance computing) and orientation (relative to external references), but have different phases (relative positioning of grid fields). These modules present a dorso–ventral gradient within the mEC, with exponentially larger scaling for the ventral modules (Barry et al., 2007; Brun et al., 2008; Stensola et al., 2012; Bant et al., 2020).

Figure 2

Entorhinal theta phase precession and velocity integration

Within the hippocampal-entorhinal (HF/EC) formation, there is a prominent theta oscillation ranging from approximately 6–11 Hz, known as the “local field potential” (LFP) (Vanderwolf, 1969; Eggink et al., 2014). This oscillation is largely driven by the medial septum (the diagonal band of Broca, MSDB), but underlies the spatial periodicity and internal spiking properties of GCs as well (Burgess et al., 2007; Fyhn et al., 2007; Brandon et al., 2011; Barry et al., 2012; Pilly and Grossberg, 2013; Shay et al., 2016; Jacob et al., 2017; Tsanov, 2017; Joshi and Somogyi, 2020). On the other side active movement stimulates GCs’ internal spiking, which increases in frequency and aligns with the LFP frequency as the vertex of the grid field is approached (Burgess et al., 2007; Giocomo and Hasselmo, 2008; Shay et al., 2016; Gu and Yakel, 2017) such that internal spikes, originating from the peak of the sine wave, descend the wave arriving the slack of the LFP sine wave by reaching the vertex of the grid field, with the leading spike’s phase delivering mostly spatial information (Reifenstein et al., 2012) (see Figure 2A).

This precession of spikes related to the LFP (i.e., relative to the sum of nearby firing cells) is termed “theta phase precession” (TPP) initially described in place cells (O'Keefe and Recce, 1993; Skaggs et al., 1996) later in GCs as well (Hafting et al., 2008) and again later within the ventral striatum (van der Meer and Redish, 2011; Malhotra et al., 2012). As GCs’ scales compute distances, their TPP signifies distances traveled in a given time that establishes the quality of speed and therefore time, velocity, and acceleration in GC computation (Burgess et al., 2007; Zilli, 2012; Kropff et al., 2021). In this regard, the allocentric computation of GCs introduces the concept of time into the brain (Kropff et al., 2015; Heys and Dombeck, 2018; Alexander et al., 2020; Carvalho et al., 2020; Heys et al., 2020; Ridler et al., 2020) (see Figure 2B). This is complemented by the MSDB’s parvalbumin-positive cells modulating the entorhinal LFP’s speed information (Lepperod et al., 2021) and its glutamatergic circuit that controls the initiation and velocity of locomotion (Fuhrmann et al., 2015; Justus et al., 2017). I argue that the nature of GC’s theta phase precession (TPP) misgauged in dopamine depletion accounts for bradykinesia generating the slowdown of movement (see Figure 2).

The link between the striatum and the hippocampal formation

To translate goal-directed allocentric components into striatal egocentric self-motion computation and vice versa, the striatum and the HF/EC are effectively linked (Finch et al., 1995; Totterdell and Meredith, 1997; Devan and White, 1999; Hartley et al., 2003; Johnson et al., 2007; Lex and Hauber, 2010; van der Meer et al., 2010; Ghiglieri et al., 2011; Verschure et al., 2014; Stoianov et al., 2018). Constant switching takes place between them (Bohbot et al., 2004; Burgess, 2006; Harris et al., 2012; Colombo et al., 2017), a process that appears to be dopamine-dependent (Penner and Mizumori, 2012) and is driven by the locus coeruleus (LC), the structure to be impaired in PD first (Hornykiewicz and Kish, 1987; German et al., 1992; Braak et al., 2003; Zarow et al., 2003; Braak and Del Tredici, 2017; Vermeiren and De Deyn, 2017; Nahimi et al., 2018; Oertel et al., 2019; Giorgi et al., 2020; Zhou et al., 2021) (see Figure 3). Damage to connecting fibers between the striatum and the HF/EC, the striato-HF/EC loop, disrupts precise navigation in open environments (Devan et al., 1996; Gorny et al., 2002) and the deactivation of one side tends to increase the compensatory use of the other (Packard and McGaugh, 1996; Igloi et al., 2009; Sodums and Bohbot, 2020) with the LC playing a crucial role in creating spatial representations especially sensitive to environmental novelty (Harris et al., 2012; Takeuchi et al., 2016; Ruggiero et al., 2018; Zhong and Moffat, 2018).

Figure 3

For both the striatum and the HF/EC, dopamine is supplied from mesencephalic structures—which undergo loss of dopaminergic neurons in PD (Bogerts et al., 1983; Akil and Lewis, 1993; Jin et al., 2019). Whereas the dorsal striatum is primarily supplied by the substantia nigra pars compacta (SNpc), HF/EC mainly receives dopamine from the ventral tegmental area (VTA) (Scatton et al., 1980; Oades and Halliday, 1987; Gasbarri et al., 1997; Rosen et al., 2015) (see Figure 3). Although dopamine depletion is comparable in early PD, the VTA dopamine supply exhibits higher inter-subject variability (Caminiti et al., 2017; Bortz and Grace, 2018).

Altered somatotopy disrupts body representation

The striatal side of the striato-HF/EC loop with its ontogenetic optimized sensorimotor SBPs undergoes an up to 16-fold decrease in PD (Cho et al., 2002). This results in SBPs becoming responsible for not one but as many as three or five body parts, becoming fragmented, existing in clusters or isolated cells outside their diminished former clusters (“satellite potentials”) (Cho et al., 2002; Obeso et al., 2008a; Bronfeld and Bar-Gad, 2011; Coffey et al., 2016). There was the argument that these (striatal) “distorted internal body representations… may contribute to bradykinesia, impaired movement scaling, and the strong reliance on visual feedback” (Contreras-Vidal and Gold, 2004, p 505) that seems to be much more attributable to the other side of the striato-HF/EC loop: the GCs with (1) their (distance) scaling properties, (2) their reference to time and velocity (Kropff et al., 2015; Heys and Dombeck, 2018; Carvalho et al., 2020; Heys et al., 2020), and (3) their ligation to external landmarks/cues, with visual cues being the most influential (Maaswinkel and Whishaw, 1999; Hardcastle et al., 2015; Stensola et al., 2015; Chen et al., 2016; Perez-Escobar et al., 2016; Campbell et al., 2018; Keinath et al., 2018; Mosheiff and Burak, 2019; Kinkhabwala et al., 2020).

Compared to the striatal system, the ontogenetically young GC system is highly malleable in its physiological state already (Barry et al., 2007; Langston et al., 2010; Wills et al., 2010; Stensola et al., 2012; Krupic et al., 2015; Latuske et al., 2015; Dunn et al., 2017; Ismakov et al., 2017). Thus, disruptive shifts occur in GCs, with half of grid cells changing to multiple distance and time computations (Kraus et al., 2015), compressing (Raudies and Hasselmo, 2015), skipping (Deshmukh et al., 2010), or even getting lost their grid fields. Even partial inactivation may be enough to disturb allocentric computing, necessitating complete spatial allocentric remapping (Miao et al., 2015; Rueckemann et al., 2016; Savelli et al., 2017). It is only their robust redundancy and the pooling of all information that allow the complete spatial function of GCs (Reifenstein et al., 2012). The recent discovery of an aperiodic 3D GC pattern in flying bats (Ginosar et al., 2021) implies that there are far more inconsistencies in the real 3D world than in the 2D lattice mazes that shape our current understanding of GCs.

Hypotheses: dopamine-depleted grid cells evoke Parkinson’s symptoms

We are all too familiar with the debilitating symptoms of PD, yet how they manifest within the framework of the BG-focused box-and-arrow model remains a mystery (Mink, 1996; Brown and Marsden, 1998; Montgomery, 2011). In contrast, when considering the allocentric brain with its grid cells in particular, PD symptoms seem to be self-explanatory, as will be shown below.

“Conceptual hypometria” as a fundamental symptom in PD

Hypometria may not be the first symptom we bear in mind when discussing PD, but it serves to introduce some key ideas. Just think of clinical signs of hypometria in PD patients, including perceiving distances as shorter (Demirci et al., 1997; Kabasakalian et al., 2013), failing to reach far enough when trying to grasp objects (Klockgether and Dichgans, 1994; Kulkarni et al., 2013; Ryckewaert et al., 2015), underestimating the sizes of objects and openings (Harris et al., 2003; Young et al., 2010; Smith et al., 2011; Laudate et al., 2013), and an impaired ability to perceive large spatial configurations (Barrett et al., 2001; Bernardinis et al., 2018). Therefore, it has been argued that in PD “the sensorimotor apparatus is ‘set smaller’” (Demirci et al., 1997) in line with a constriction of the “perception of extrapersonal space” or a virtual compressed space (Lee et al., 1998, 2001b; Davidsdottir et al., 2008). This has led to the postulation of not only a virtual egocentric but allocentric hypometria in PD, termed “conceptual hypometria” (Skidmore et al., 2009; Kabasakalian et al., 2013).

Given that GCs represent external space virtually, their dwindling in the context of dopamine depletion (DD) (see above for mEC dopamine receptors; Fallon et al., 1978; Akil and Lewis, 1993; Li et al., 2015) would first and foremost weaken the large spatial allocentric representation because ventral GCs, which represent large spatial scaling, are sparse (Brun et al., 2008; Burgess, 2008; Jeewajee et al., 2008), have a lower signal-to-noise ratio (Bant et al., 2020), and occasionally get lost or switched off (Campbell et al., 2018) in their physiological status already limiting large grid field computations, but favoring smaller ones.

Furthermore, if the mechanisms of TPP (see above), which normally record the time spent crossing a grid field, are detached from other consistent information or even become inverted in DD, they may signal premature or mistaken spiking. In particular, as the leading GC’s spike yields a clear signature of TPP (Reifenstein et al., 2012), the system might become more volatile with its disinhibition, generating an “already reached” or “closer than” signal and thus restricting the virtual space and impacting the forward planning of velocity (see Figure 4).

Figure 4

All in all, this supports the idea of a downsized allocentric virtual space, in the sense of “conceptual hypometria.” Note that GC function also deteriorates under social conditions due to an increased GC firing rate (Xu et al., 2022), which is not further elaborated on in this paper.

Bradykinesia

Bradykinesia, one of the primary and most debilitating motor symptoms of PD, is characterized by a marked slowness of movement (Marsden, 1989). This symptom has been postulated to arise from the inhibition of the primary motor cortex, a consequence of the overstimulation of the globus pallidus internus (GPi) (Berardelli et al., 2001; Spiegel et al., 2007; Moccia et al., 2014). However, the validity of this model is challenged by the fact that GPi inactivation improves not just bradykinesia, but also its antithesis, L-dopa-induced dyskinesia (LID, see below) (Laitinen et al., 1992; Brown and Marsden, 1998). Consequently, doubt persists regarding this explanation and the model in general (Obeso et al., 2008b; Bologna et al., 2020).

As described above, the concept of time is conveyed to the brain via GCs’ TPP (Harris et al., 2002; Sargolini et al., 2006; Burgess, 2008; Hafting et al., 2008; Climer et al., 2013; Eichenbaum, 2014; Kraus et al., 2015; Kropff et al., 2015; Schlesiger et al., 2015; Hardcastle et al., 2017; Heys and Dombeck, 2018; Tsao et al., 2018; Ye et al., 2018; Jacob et al., 2019; Carvalho et al., 2020; Heys et al., 2020). As an animal moves faster or even accelerates its movement, the internal firing/spiking of grid cells occurs earlier in their physiological state. However, when faced with an errant virtual hypometria (see above), the GCs signal as if the animal has moved a greater distance than it actually has what would compute a demand note to slow down or even to stop movement altogether. Bradykinesia could therefore be a secondary effect of “conceptual hypometria” (see above and Figure 4), arguing for limb movements as well as for whole body motion (see below for limitations).

Furthermore, to introduce time into the brain, there are discrete “speed cells” found in GC formation—mainly fast-spiking interneurons, which constitute about 15% of layer II mEC cells (Couey et al., 2013; Buetfering et al., 2014; Kropff et al., 2015). These speed cells are driven externally by neurons from the pedunculopontine nucleus (PPN) and are highly correlated with future speed (Rolland et al., 2009; Ryczko et al., 2013; Ryczko and Dubuc, 2017), the PPN again modulating neurons in the MSDB (Justus et al., 2017; Carvalho et al., 2020). The PPN and MSDB are, in turn, both influenced by the LC and dopamine, with the MSDB containing cells that fluctuate as a function of running speed (Zhou et al., 1999; see Figure 3).

In dopamine-deficient conditions, grid and speed cells may lose their anticipatory internal spiking functions. This suggests that grid cells (GCs) have a harder time calculating the upcoming grid field, which is essential for transitioning from the current position to the next, or as Tukker and coworkers write, that changing properties of the grids in altered or novel environments might limit their representational capacity (Tukker et al., 2022), not to mention turbulences caused by dopamine deficiency (DD) of the weakened grid cells themselves, or their decoupling from the striatal egocentric counterpart (see for GC’s malleability above), negatively affecting their accelerating and computational properties promoting bradykinesia.

At the same time, speed cells may become disconnected from future movement (Kropff et al., 2015; Ye et al., 2018). Coupled with the potentially inaccurate activity of the fusimotor system, which acts as a “forward sensory model” too (Dimitriou and Edin, 2010), this can lead to a decrease in movement speed, resulting in bradykinesia.

Kinesia paradoxa

Kinesia paradoxa (KP) refers to the abrupt shift from bradykinetic to normal velocity, typically brought about by an external cue (Glickstein and Stein, 1991; Distler et al., 2016; Duysens and Nonnekes, 2021). As GCs are thought to generate multiple speed computations (Jeewajee et al., 2008; Kraus et al., 2015; Hinman et al., 2016) for example by skipping theta cycles (Deshmukh et al., 2010; Kraus et al., 2015), see above, the phenomenon of KP can also be comprehended from the GC’s perspective. Skipping from slow to “normal velocity” is probably facilitated by the noradrenergic LC, which allows for “rapid behavioral adaptation to changing environmental and (unpredicted) imperatives” (Aston-Jones and Bloom, 1981; Bouret and Sara, 2005), additionally supported by the PPN (Carvalho et al., 2020), which plays a role in escape responses (Caggiano et al., 2018) and drives both grid and speed cells.

Sequence effect

The sequence effect (SE) is a clinical term denoting the progressive shortening of step length observed during repetitive movements influencing handwriting, gait, and speech (Benecke et al., 1987; Agostino et al., 1992; Iansek et al., 2006; Wu et al., 2016). The SE does not improve with dopamine supply (Kang et al., 2010; Lee et al., 2015; Bologna et al., 2020), but tends to occur less frequently in advanced PD (Bologna et al., 2016) and responds positively to visual cues (Iansek et al., 2006; Tinaz et al., 2016). From an allocentric standpoint, this phenomenon could be seen as a form of self-perpetuating hypometria, possibly resulting from the continuous depletion of larger and more susceptible GCs or from a self-reinforcing mechanism focusing on smaller dimensions (this will be further discussed below).

Festination

Festination, another fascinating parkinsonian paradox, refers to “a progressive shortening of step length, in that case accompanied by a compensatory increase in cadence” (Iansek et al., 2006; Nonnekes et al., 2019a), affecting handwriting and speech (Martin et al., 1994; Giladi et al., 2001; Moreau et al., 2007; Nutt et al., 2011) as well. Festination essentially embodies GCs’ characteristics by reducing amplitudes and generating faster speed computations (Jeewajee et al., 2008; Kraus et al., 2015; Hinman et al., 2016). In simpler terms, it equates to pacing in smaller grid fields with compensatory acceleration for the increased cadence (Jeewajee et al., 2008; Kraus et al., 2015; Hinman et al., 2016; Kropff et al., 2021) – the last contradicting being brady-kinetic observed such as in freezing episodes and trembling (see below).

Micrographia

Micrographia is defined as an “obvious reduction in the size of letters” in handwriting. This symptom is observed in up to three quarters of PD patients (Jarzebska, 2006; Wagle Shukla et al., 2012), with about two thirds exhibiting a waning amplitude (Zham et al., 2019) known as progressive micrographia. This pattern is strikingly similar to the SE, as opposed to continuous micrographia (Kinnier Wilson, 1925; Inzelberg et al., 2016; Wu et al., 2016), which appears more hypometric. Importantly, micrographia can be improved with visual cues such as markers or lines (McLennan et al., 1972; Oliveira et al., 1997; Bryant et al., 2010).

An early study on micrographia argued that it “seems to be a compression of words into insufficient space” (McLennan et al., 1972), thus drawing an early connection to the concept of external (virtual hypometric) space. Hypothetically, if the first letters written are related to the external space, the following ones could lose their external spacing for two reasons. Firstly, writing is predominantly an egocentric activity that can overlook its allocentric calibration. Secondly, due to the enlarged SBPs, continuous calibration to a virtual oversized writing gesture occurs, in comparison to an egocentrically represented previous letter (this effect is more pronounced in progressive micrographia).

Cueing in PD

The utilization of external cues has long been recognized as a powerful tool to improve PD motor symptoms (Martin, 1967; Thaut et al., 1996; Burleigh-Jacobs et al., 1997; Lim et al., 2005; Nieuwboer, 2008; Delval et al., 2014; McCandless et al., 2016; Ginis et al., 2018; Nonnekes et al., 2019b). Flowers argued that “it seems as if the Parkinsonian subject does not seem to ‘know’ where his hand is in space nor in relation to other objects, and so must continuously monitor visually both his own movement and the external world to maintain control” (Flowers, 1976; p. 305). This observation anticipates the underlying egocentric and allocentric structures. When considering cueing and visual guiding in PD, classical PD models offer little insight, but there is evidence pointing to the GC’s significant dependency on external cues (Hardcastle et al., 2015; Chen et al., 2016; Perez-Escobar et al., 2016; Campbell et al., 2018; Mosheiff and Burak, 2019; Dannenberg et al., 2020). This is especially true for visually driven cues (Maaswinkel and Whishaw, 1999; Chen et al., 2013; Kinkhabwala et al., 2020), such as transverse bars, a laser beam, or a companion’s foot, which can enhance movement speed and accuracy, and thereby alleviate freezing of gait (FOG, see below) (Georgiou et al., 1994; Nonnekes et al., 2015; Ginis et al., 2018).

For visual cueing, the mEC not only receives robust input from visuospatial regions (Burwell and Amaral, 1998) but also direct visual input from “intrinsic mEC visual cue cells” (Kinkhabwala et al., 2020), object-vector (OV) cells responding to visual contrasts (Killian et al., 2012; Casali et al., 2018; Andersson et al., 2021), and cells responsible for gaze position (Meister and Buffalo, 2018). The latter could be the allocentric counterpart of or be reinforced by visual streaming via the (egocentric) oculomotor loop (Alexander et al., 1986; Fooken and Spering, 2020).

Freezing of gait

One of the most debilitating symptoms of PD is freezing of gait (FOG), which is characterized by a sudden, transient inability to initiate effective steps, whether when beginning to move (“start hesitation”), turning, or continuing to move (Rahman et al., 2008; Lebold and Almeida, 2010; Vercruysse et al., 2014; Matar et al., 2019). It often occurs when adapting to new forms of locomotion, encountering specific obstacles, or managing a spatial constriction through visual or proprioceptive input (Giladi and Nieuwboer, 2008; Almeida and Lebold, 2010; Nutt et al., 2011; Matar et al., 2019). FOG is notably associated with spatial references, particularly the grid field’s faced floor as occurs when “stepping from one type of surface to another” (Freezing; Parkinson’s Foundation, n.d.).

It has previously been suggested that a “disruption of the representation of external space” contributes to FOG (Lee et al., 2001a; Almeida and Lebold, 2010), pointing again to the role of the allocentric brain. Without sufficient computing the current and the subsequent grid field to facilitate the transition from one to the next—a mechanism seen in place cells (Souza and Tort, 2017)—one might feel “lost in space” or as if “stepping into the void.” FOG is often paradoxically paired with an increased cadence and uncoordinated trembling of the knees (Hausdorff et al., 2003; Schaafsma et al., 2003; Iansek et al., 2006; Jacobs et al., 2009; Nutt et al., 2011), which contradicts the notion of being purely hypo-or bradykinetic. These expressions align with the clinical manifestations of FOG (Nakamura et al., 1978; Hausdorff et al., 2003; Plotnik et al., 2005; Okuma, 2006; Plotnik and Hausdorff, 2008; Jacobs et al., 2009; Almeida and Lebold, 2010; Rehman et al., 2019).

Turning—a movement that often triggers freezing (Schaafsma et al., 2003; Spildooren et al., 2010; Mancini et al., 2017; Park et al., 2020)—relies on GCs maintaining consistent interaction with the floor (see GC phases) and on conjunctive cells, a fusion of grid and head direction cells, computing turning properties (Sargolini et al., 2006; Keinath, 2016). Internal disturbances of grid and conjunctive cells may disrupt their rotational properties, being “lost in space” or tethering them more closely to environmental borders (see below for the bottleneck phenomenon) (Krupic et al., 2015; Stensola et al., 2015) and thereby precluding turning. Overall, freezing may result from an overload of movement computation in a disturbed allocentric virtual computation (Tukker et al., 2022), particularly during turning when the linearity of grid fields is abandoned.

Freezing of gait typically lasts a matter of seconds or even minutes, aligning with the observation that dramatic GC disruption can even persist for weeks in healthy rats (Savelli et al., 2017). FOG is likely to persist until compensation strategies, such as cueing, are initiated (see above) (Lee et al., 2001a; Schaafsma et al., 2003; Lim et al., 2005; Nieuwboer, 2008; Ginis et al., 2018; Nonnekes et al., 2019b), helping to reconcile and surpass the GC’s ambiguity level (Carpenter and Barry, 2016; Savelli et al., 2017).

Remarkably, there have been reports of patients who were able to ride a bicycle directly out of a FOG episode (while standing on the floor) (Snijders et al., 2011; Kikuchi et al., 2014). This lends support to the idea that FOG is not simply a manifestation of bradykinesia, but that moving away from the disconcerting tessellating floor could resolve the computational deadlock (Freezing; Parkinson’s Foundation, n.d.). Further highlighting the allocentric brain’s responsiveness to cueing (see above), festination can be improved with spatial cues, especially visual ones (Martin et al., 1994; Nonnekes et al., 2019a).

The anatomic structure most commonly associated with FOG is the pedunculopontine nucleus (PPN) (Lewis and Barker, 2009; Virmani et al., 2019; Craig et al., 2020) that—from the allocentric view—drives mEC speed cells (see above and Figure 4), projects strongly via the MSDB to control the initiation of locomotion (Fuhrmann et al., 2015), and determines locomotor speed and gait selection (Caggiano et al., 2018; Carvalho et al., 2020).

The bottleneck phenomenon

Here I discuss a special form of FOG, the bottleneck phenomenon (BNP), which is characterized by a halt or freeze before entering narrow spaces or passageways, or even when navigating close to the edge of a table (Cowie et al., 2012; Gomez-Jordana et al., 2018; Matar et al., 2019). BNP has previously been framed as a perceptual or visuomotor disturbance (Almeida and Lebold, 2010; Cowie et al., 2012; Sidaway et al., 2018).

For an allocentric explanation of BNP, boundary vector cells (BVC)—the ontogenetically oldest allocentric cells (Bicanski and Burgess, 2020)—have to be introduced. BVCs not only provide the intrinsic allocentric framework for native GC metric formation, but also support the continuous stabilization and error correction of GCs (Lever et al., 2009; Bjerknes et al., 2014; Hartley and Lever, 2014; Hardcastle et al., 2015; Stensola et al., 2015; Giocomo, 2016; Stensola and Moser, 2016; Savelli et al., 2017). This is important because when an animal enters a non-familiar environment, it must instantly self-organize a new grid pattern (Hafting et al., 2005; Fuhs and Touretzky, 2006; Barry et al., 2012; Giocomo, 2016; Nadasdy et al., 2017; Stangl et al., 2018) dependent on external landmarks and borders, with the GC system exhibiting the greatest flexibility (Barry et al., 2007; Langston et al., 2010; Wills et al., 2010; Stensola et al., 2012; Krupic et al., 2015; Latuske et al., 2015; Dunn et al., 2017; Ismakov et al., 2017; Keinath et al., 2018). BVC cells respond at specific distances and angles from between one and four boundaries, albeit with gaps between them (Barry et al., 2006; Savelli et al., 2008; Solstad et al., 2008; Lever et al., 2009; Stewart et al., 2014; Bicanski and Burgess, 2020). Especially in the mEC, there are border cells (BC) (Solstad et al., 2008) that respond to proximate boundaries (within “whisker’s range”) that immediately block an animal’s path (Hoydal et al., 2019). There are also retrosplenial BCs linked to the mEC that fire “prospective to the animal’s next motion” (van Wijngaarden et al., 2020).

If these cells are disinhibited by deteriorating GCs (Krupic et al., 2015), they virtually generate a stop/freeze signal when standing close to a border. This happens not only in response to borders, but also to doorways enclosed by edges because grid fields are inherently distorted at the edges of the environment (Stensola et al., 2015; Hagglund et al., 2019) bringing BVC and BC to the fore (see Figure 5).

Another potential trigger for the BNP could be the requirement to encode the geometric layout of the subsequent room when leaving the room through a doorway (see Figure 5C). This task may be skipped due to the instability of grid field computations across connected enclosures’ borders (Derdikman et al., 2009; Carpenter et al., 2015; Krupic et al., 2016; He and Brown, 2019). This instability is further compounded by the novelty beyond the bottleneck, which again enlarges and dysregulates grid fields, leading to a brief reduction in spatial stability (Hafting et al., 2005) even in healthy subjects (Figures 5A,B).

Figure 5

Resting tremor (tremor-at-rest)

Resting tremor (RT), which affects about three-quarters of PD patients, is characterized by an agonist–antagonist motor action in an alert resting position with a frequency of about 4–6 Hz (Milanov, 2001; Hallett, 2012; Zach et al., 2015; Bhatia et al., 2018). Often manifesting a pill-roll component in the distal part of the limb, it is a highly specific sign of idiopathic PD. However, its origin, particularly in relation to the BG, “remains a mystery” (Obeso et al., 2014, p. 524); (Deuschl et al., 2000; Hallett, 2012). Above all, no central pacemakers have been found for PD tremor; instead, there are only cerebral “followers” (Zirh et al., 1998; Hallett, 2014). The independent oscillations of tremulous limbs suggest that individual body parts or even single muscles may each have separate tremor generators (O'Suilleabhain and Matsumoto, 1998; Hurtado et al., 2000; Raethjen et al., 2000; Hallett, 2012; Pedrosa et al., 2012).

To explore potential routes, a resting animal or limb needs reliable information about its actual position (Bush et al., 2015; Olafsdottir et al., 2018). If this information is disrupted, such as by the (egocentric) fusimotor disruption, discussed below, or any other kind of computational spatial feedback and if the allocentric brain is unable to store this information during rest due to DD, the GCs’ continuous dynamic error correction system, which again depends on ongoing movement, could lead the spatially related distal limb to seek spatial information through a (searching) movement. This could be exacerbated by unstable egocentric information arising from enlarged striatal SBP, and more so by detached feedback from the hippocampal place cells for GCs’ forward planning during immobility (Olafsdottir et al., 2016, 2017; Zhang and Liu, 2023) or even self-reliant replay (O'Neill et al., 2017).

The antagonistic rhythmicity of tremor could result from striking the virtual edge of the enlarged SBPs, as per the fusimotor “resonance hypothesis” associated with desynchronized long-loop reflexes in PD (Eklund et al., 1982; Zirh et al., 1998). Conversely, it could arise from attaining sufficient positional information and then being deflected from the edges of the associated grid field, possibly in a looser relationship with the LFP. Both peripheral perspectives support the concept of separate body part tremor generation and brain tremor hubs merely acting as “followers.” With the loss of GCs’ stable circular hexagonality, limbs—particularly distal ones responsible for interacting with the proximate, allocentric computed world—may be deflected in their positional scanning, achieving the rotating “pill roll” component.

Rigidity

Rigidity, a cardinal feature of PD, is present in up to 90% of cases and serves as a primary component of the assessment of dopamine and surgical PD treatment (Andrews and Burke, 1973; Mutch et al., 1986; Powell et al., 2012; Postuma et al., 2015; Powell et al., 2016). Parkinsonian rigidity is characterized by an intrinsically increased muscle tone with clinically uniform resistance to externally imposed joint movement in antagonist muscles throughout the range of motion. Abnormal responses to muscle stretch and long-loop latencies/reflexes have been discussed (Berardelli et al., 1983; Delwaide and Schoenen, 1985; Xia et al., 2011; Pasquereau et al., 2016; Powell et al., 2016).

Alternatively, one could revisit the inconsistent computation of SBP, the “conceptual hypometria” signaling a position beyond the real one, decelerating further movement. That would provide an allocentric explanation for the central proprioceptive disturbances, which are often posited as the actual pathogenesis of PD (Abbruzzese and Berardelli, 2003; Contreras-Vidal and Gold, 2004; Jacobs and Horak, 2006; Fiorio et al., 2007; Rand et al., 2010; Lee et al., 2013). In addition there is also peripheral fusimotor activity of the muscle spindle (Radovanovic et al., 2015), the afferent spinal dorsal horn (Skoog and Noga, 1995; Garraway and Hochman, 2001; Milla-Cruz et al., 2020), and its efferent paths along the ventral horn (Yoshida and Tanaka, 1988; Weil-Fugazza and Godefroy, 1993; Barriere et al., 2004; Han et al., 2007; Zhu et al., 2007; Schwarz and Peever, 2011; Clemens et al., 2012; Sharples, 2017; Rivera-Oliver et al., 2019), all of which are disturbed in DD. This apparatus is controlled by the CNS (Ellaway et al., 2015; Macefield and Knellwolf, 2018), with fusimotor activity operating as a “forward sensory model” (Dimitriou and Edin, 2010). Without this—or a determined virtual position to cipher forward motion (Bush et al., 2015; Olafsdottir et al., 2018)—its continuous recalculation could drive the system toward computational overcompensation, resulting in rigidity.

Often, passive turning of an extremity yields cogwheel-like jerks commonly referred to as “cogwheel” rigidity (Ghiglione et al., 2005). This rhythmic unclenching from rigidity may be due to the enlarged and consequently virtually unsubsumable SBPs or their disturbed allocentric link, causing the rigid calibration of tested body parts to break apart and slip into the unknown. The rhythmicity of the “cogwheel” could emerge based on the extent of the virtual egocentric or even ego-allocentric intangible dimensions, or the time delay for allocentric adjustment via the striato-HF/EC loop with a delayed position signal in GCs would prematurely hit the LFP, eliciting a spatial rebound signal and again forcing rigidity. This aligns with the notion of a spatial threshold (ST), the point at which the stretch reflexes and other proprioceptive reflexes activate, modulated by the “corticospinal set” which has been observed to be either hypo-sensitive or even inversely sensitive in PD (Mullick et al., 2013).

L-dopa induced dyskinesia

“Dyskinesia are involuntary hyperkinetic movements presenting mostly as chorea or choreoathetoid form, but rare ballistic, dystonic or stereotypical variants have been described as well” (McFarthing et al., 2019, p. 449). While these movements develop as a function of disease duration, dopaminergic treatment significantly escalates the probability of their occurrence (Katzenschlager et al., 2008; Nadjar et al., 2009; Nutt et al., 2010; Cilia et al., 2014; Espay et al., 2018; Ryan et al., 2018), largely contingent on plasma L-dopa concentrations. However, LID presents a key paradox in the box-and-arrow model: although therapeutic inactivation of the GPi is thought to trigger dyskinesia, it also alleviates it (Inase et al., 1996; Brown and Marsden, 1998; Desmurget and Turner, 2008; Nambu et al., 2015). LID-associated abnormal neuronal activity has been detected not only in the striatum, but also in the primary somatosensory (Alam et al., 2017) and the primary motor cortex (Halje et al., 2012; Swann et al., 2016).

Reflecting the up to 16-fold enlarged, clustered, fragmented, and at least partially overlapping striatal single body parts (SBP) in PD, along with satellite potentials within remote somatotopic clusters (Cho et al., 2002) and with “neurons that were previously deemed ‘unrelated’ [to movement and that] might now demonstrate movement-related activity” (Bronfeld and Bar-Gad, 2011), LID could signify a disruption of established sensorimotor pathways. Such disruptions disturb their spatial and, therefore, choreographic chronology, promoting chaotic, possibly bizarre movements, deviating from the well-trodden path amplified by a dopamine surplus. In this “unleashed SBP theory,” hyperkinesia in LID is no longer interpreted as an acceleration of movement per se, but rather as a secondary effect of chaotic or unmanaged somatotopic displacement activity. This theory underscores that “dyskinesia” and “hyperkinesia” in PD are not merely the antithesis of being “hypokinetic,” but rather a by-product or the other side of the parkinsonian spatial coin. Therefore, the therapeutic effect of GPi-DBS on LID would not be surprising.

Broadening the perspective to the allocentric brain, the SBP could be unleashed from the otherwise stabilizing or balancing mEC due to a dopamine surplus suppressing the mEC (Mayne et al., 2013; Jin et al., 2019) or the LC’s dyskinesia-limiting possibilities (Cedarbaum and Aghajanian, 1977; Miguelez et al., 2011) (see Figure 6). Apart from peak dose dyskinesia, there is lower body predominant diphasic dyskinesia (Manson et al., 2012; Verhagen Metman and Espay, 2017; Espay et al., 2018) occurring just below the therapeutic L-Dopa level. This could meet the criteria for being below the LC’s dyskinesia-limiting possibilities (Miguelez et al., 2011) as well (see Figure 6).

Figure 6

Limitations

Aside from the hypotheses mentioned, there is, to the best of my knowledge, a dearth of literature discussing the potential role of mEC’s GCs in Parkinson’s disease. Recently, two papers stressed the early involvement of the allocentric brain in PD (Fernandez-Baizan et al., 2020), particularly the mEC (Pieperhoff et al., 2022). Furthermore, evidence suggesting the involvement of EC layer II in parkinsonian symptoms in postencephalitic patients is scant (Hof et al., 1992).

Allocentric “studies have mainly been conducted in simple laboratory settings in which animals explore small, two-dimensional (i.e., flat) arenas” so that “data on the issue of grid cell encoding in 3D are scarce” (Jeffery et al., 2015; Casali et al., 2019; Grieves et al., 2021; Xu et al., 2022). The existence of 3D GCs has been demonstrated in flying bats (Yartsev and Ulanovsky, 2013; Ginosar et al., 2021), and others have identified preliminary 3D grid codes at least in the left human entorhinal cortex (Kim and Maguire, 2019). This study presumes not only the three-dimensionality of GCs and their continuous interactions with striatal SBP, but also its influence on limbs acting in the proximal space liaising the egocentric and allocentric world. However, in the typical allocentric laboratory experiment, foraging—which often concludes with grabbing using the paw or picking up with the snout—demonstrates how the most distant organs complete the link between allocentric guidance and the egocentric world (Heath et al., 2007; Neely et al., 2008). Although allocentric research has already shown hippocampal theta activity accompanying isolated limb movements (Vanderwolf, 1969), there is a gap in the further exploration of this topic.

The hypothesis of translating allocentric whole-body computation to that of the distal body parts involved in goal-directed movements remains largely untested. The extent to which allocentric cells, responsible for completing tasks egocentrically, are present among the many unclassified cells in the mEC remains unknown (Diehl et al., 2017; Miao et al., 2017).

Conclusion

This paper hypothesizes and illustrates the intriguing association between allocentric properties and PD motor and secondary, spatially related, symptoms in dopamine depletion, with several examples cited throughout. The common thread among these hypotheses is the ambition to surpass the constraints of the box-and-arrow model and the narrow scope of basal ganglia-centric perspectives in PD. Much like other prevailing PD models, these have reached “the point where (their) total rejection, rather than continual attempts at (their) modification, is necessary” (Montgomery, 2011, p. 14). The compelling notion that the allocentric brain influences PD motor symptoms has the potential to substantially shape not only research into movement and movement disorders, but also the broader field of neuroscience.

Statements

Data availability statement

The original contributions presented in the study are included in the article/supplementary material; further inquiries can be directed to the corresponding author.

Author contributions

AR: Writing – original draft.

Funding

The author declares that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

  • 1

    AbbruzzeseG.BerardelliA. (2003). Sensorimotor integration in movement disorders. Mov. Disord.18, 231240. doi: 10.1002/mds.10327

  • 2

    AgostinoR.BerardelliA.FormicaA.AccorneroN.ManfrediM. (1992). Sequential arm movements in patients with Parkinson's disease, Huntington's disease and dystonia. Brain115, 14811495. doi: 10.1093/brain/115.5.1481

  • 3

    AkilM.LewisD. A. (1993). The dopaminergic innervation of monkey entorhinal cortex. Cereb. Cortex3, 533550. doi: 10.1093/cercor/3.6.533

  • 4

    AlamM.RumpelR.JinX.von WrangelC.TschirnerS. K.KraussJ. K.et al. (2017). Altered somatosensory cortex neuronal activity in a rat model of Parkinson's disease and levodopa-induced dyskinesias. Exp. Neurol.294, 1931. doi: 10.1016/j.expneurol.2017.04.011

  • 5

    AlbinR. L.YoungA. B.PenneyJ. B. (1989). The functional anatomy of basal ganglia disorders. Trends Neurosci.12, 366375. doi: 10.1016/0166-2236(89)90074-X

  • 6

    AlexanderG. E.DeLongM. R. (1985). Microstimulation of the primate neostriatum. II. Somatotopic organization of striatal microexcitable zones and their relation to neuronal response properties. J. Neurophysiol.53, 14171430. doi: 10.1152/jn.1985.53.6.1417

  • 7

    AlexanderG. E.DeLongM. R.StrickP. L. (1986). Parallel organization of functionally segregated circuits linking basal ganglia and cortex. Annu. Rev. Neurosci.9, 357381. doi: 10.1146/annurev.ne.09.030186.002041

  • 8

    AlexanderA. S.RobinsonJ. C.DannenbergH.KinskyN. R.LevyS. J.MauW.et al. (2020). Neurophysiological coding of space and time in the hippocampus, entorhinal cortex, and retrosplenial cortex. Brain Neurosci. Adv.4:2398212820972871. doi: 10.1177/2398212820972871

  • 9

    AlmeidaQ. J.LeboldC. A. (2010). Freezing of gait in Parkinson's disease: a perceptual cause for a motor impairment?J. Neurol. Neurosurg. Psychiatry81, 513518. doi: 10.1136/jnnp.2008.160580

  • 10

    AnderssonS. O.MoserE. I.MoserM. B. (2021). Visual stimulus features that elicit activity in object-vector cells. Commun. Biol.4:1219. doi: 10.1038/s42003-021-02727-5

  • 11

    AndrewsC. J.BurkeD. (1973). Quantitative study of the effect of L-dopa and phenoxybenzamine on the rigidity of Parkinson's disease. J. Neurol. Neurosurg. Psychiatry36, 321328. doi: 10.1136/jnnp.36.3.321

  • 12

    Aston-JonesG.BloomF. E. (1981). Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle. J. Neurosci.1, 876886. doi: 10.1523/JNEUROSCI.01-08-00876.1981

  • 13

    BantJ. S.HardcastleK.OckoS. A.GiocomoL. M. (2020). Topography in the bursting dynamics of entorhinal neurons. Cell Rep.30, 23492359. doi: 10.1016/j.celrep.2020.01.057

  • 14

    BarrettA. M.CrucianG. P.SchwartzR.NallamshettyH.HeilmanK. M. (2001). Seeing trees but not the forest: limited perception of large configurations in PD. Neurology56, 724729. doi: 10.1212/wnl.56.6.724

  • 15

    BarriereG.MellenN.CazaletsJ. R. (2004). Neuromodulation of the locomotor network by dopamine in the isolated spinal cord of newborn rat. Eur. J. Neurosci.19, 13251335. doi: 10.1111/j.1460-9568.2004.03210.x

  • 16

    BarryC.BurgessN. (2014). Neural mechanisms of self-location. Curr. Biol.24, R330R339. doi: 10.1016/j.cub.2014.02.049

  • 17

    BarryC.GinzbergL. L.O'KeefeJ.BurgessN. (2012). Grid cell firing patterns signal environmental novelty by expansion. Proc. Natl. Acad. Sci. U.S.A.109, 1768717692. doi: 10.1073/pnas.1209918109

  • 18

    BarryC.HaymanR.BurgessN.JefferyK. J. (2007). Experience-dependent rescaling of entorhinal grids. Nat. Neurosci.10, 682684. doi: 10.1038/nn1905

  • 19

    BarryC.LeverC.HaymanR.HartleyT.BurtonS.O'KeefeJ.et al. (2006). The boundary vector cell model of place cell firing and spatial memory. Rev. Neurosci.17, 7197. doi: 10.1515/REVNEURO.2006.17.1-2.71

  • 20

    BeneckeR.RothwellJ. C.DickJ. P.DayB. L.MarsdenC. D. (1987). Disturbance of sequential movements in patients with Parkinson's disease. Brain110, 361379. doi: 10.1093/brain/110.2.361

  • 21

    BerardelliA.RothwellJ. C.ThompsonP. D.HallettM. (2001). Pathophysiology of bradykinesia in Parkinson's disease. Brain124, 21312146. doi: 10.1093/brain/124.11.2131

  • 22

    BerardelliA.SabraA. F.HallettM. (1983). Physiological mechanisms of rigidity in Parkinson's disease. J. Neurol. Neurosurg. Psychiatry46, 4553. doi: 10.1136/jnnp.46.1.45

  • 23

    BernardinisM.AtashzarS. F.JogM.PatelR. V. (2018). Visual displacement perception in Parkinson's disease analyzed using a computer-generated graphical tool. Conf. Proc. IEEE Eng. Med. Biol. Soc.2018, 27482751. doi: 10.1109/EMBC.2018.8512754

  • 24

    BernheimerH.HornykiewiczO. (1965). Decreased homovanillic acid concentration in the brain in parkinsonian subjects as an expression of a disorder of central dopamine metabolism. Klin. Wochenschr.43, 711715. doi: 10.1007/BF01707066

  • 25

    BhatiaK. P.BainP.BajajN.ElbleR. J.HallettM.LouisE. D.et al. (2018). Consensus statement on the classification of tremors. From the task force on tremor of the International Parkinson and Movement Disorder Society. Mov. Disord.33, 7587. doi: 10.1002/mds.27121

  • 26

    BicanskiA.BurgessN. (2020). Neuronal vector coding in spatial cognition. Nat. Rev. Neurosci.21, 453470. doi: 10.1038/s41583-020-0336-9

  • 27

    BirkmayerW.HornykiewiczO. (1961). The L-3, 4-dioxyphenylalanine (DOPA)-effect in Parkinson-akinesia. Wien. Klin. Wochenschr.73, 787788. PMID:

  • 28

    BjerknesT. L.MoserE. I.MoserM. B. (2014). Representation of geometric borders in the developing rat. Neuron82, 7178. doi: 10.1016/j.neuron.2014.02.014

  • 29

    BoccaraC. N.SargoliniF.ThoresenV. H.SolstadT.WitterM. P.MoserE. I.et al. (2010). Grid cells in pre- and parasubiculum. Nat. Neurosci.13, 987994. doi: 10.1038/nn.2602

  • 30

    BogertsB.HantschJ.HerzerM. (1983). A morphometric study of the dopamine-containing cell groups in the mesencephalon of normals, Parkinson patients, and schizophrenics. Biol. Psychiatry18, 951969. PMID:

  • 31

    BohbotV. D.IariaG.PetridesM. (2004). Hippocampal function and spatial memory: evidence from functional neuroimaging in healthy participants and performance of patients with medial temporal lobe resections. Neuropsychology18, 418425. doi: 10.1037/0894-4105.18.3.418

  • 32

    BolognaM.LeodoriG.StirpeP.PaparellaG.ColellaD.BelvisiD.et al. (2016). Bradykinesia in early and advanced Parkinson's disease. J. Neurol. Sci.369, 286291. doi: 10.1016/j.jns.2016.08.028

  • 33

    BolognaM.PaparellaG.FasanoA.HallettM.BerardelliA. (2020). Evolving concepts on bradykinesia. Brain143, 727750. doi: 10.1093/brain/awz344

  • 34

    BortzD. M.GraceA. A. (2018). Medial septum differentially regulates dopamine neuron activity in the rat ventral tegmental area and substantia nigra via distinct pathways. Neuropsychopharmacology43, 20932100. doi: 10.1038/s41386-018-0048-2

  • 35

    BouretS.SaraS. J. (2005). Network reset: a simplified overarching theory of locus coeruleus noradrenaline function. Trends Neurosci.28, 574582. doi: 10.1016/j.tins.2005.09.002

  • 36

    BraakH.Del TrediciK. (2017). Neuropathological staging of brain pathology in sporadic Parkinson's disease: separating the wheat from the chaff. J. Parkinsons Dis.7, S71S85. doi: 10.3233/JPD-179001

  • 37

    BraakH.Del TrediciK.RubU.de VosR. A.Jansen SteurE. N.BraakE. (2003). Staging of brain pathology related to sporadic Parkinson's disease. Neurobiol. Aging24, 197211. doi: 10.1016/s0197-4580(02)00065-9

  • 38

    BrandonM. P.BogaardA. R.LibbyC. P.ConnerneyM. A.GuptaK.HasselmoM. E. (2011). Reduction of theta rhythm dissociates grid cell spatial periodicity from directional tuning. Science332, 595599. doi: 10.1126/science.1201652

  • 39

    BronfeldM.Bar-GadI. (2011). Loss of specificity in basal ganglia related movement disorders. Front. Syst. Neurosci.5:38. doi: 10.3389/fnsys.2011.00038

  • 40

    BrownP.MarsdenC. D. (1998). What do the basal ganglia do?Lancet351, 18011804. doi: 10.1016/S0140-6736(97)11225-9

  • 41

    BrunV. H.SolstadT.KjelstrupK. B.FyhnM.WitterM. P.MoserE. I.et al. (2008). Progressive increase in grid scale from dorsal to ventral medial entorhinal cortex. Hippocampus18, 12001212. doi: 10.1002/hipo.20504

  • 42

    BryantM. S.RintalaD. H.LaiE. C.ProtasE. J. (2010). An investigation of two interventions for micrographia in individuals with Parkinson's disease. Clin. Rehabil.24, 10211026. doi: 10.1177/0269215510371420

  • 43

    BuetferingC.AllenK.MonyerH. (2014). Parvalbumin interneurons provide grid cell-driven recurrent inhibition in the medial entorhinal cortex. Nat. Neurosci.17, 710718. doi: 10.1038/nn.3696

  • 44

    BurakY. (2014). Spatial coding and attractor dynamics of grid cells in the entorhinal cortex. Curr. Opin. Neurobiol.25, 169175. doi: 10.1016/j.conb.2014.01.013

  • 45

    BurgessN. (2006). Spatial memory: how egocentric and allocentric combine. Trends Cogn. Sci.10, 551557. doi: 10.1016/j.tics.2006.10.005

  • 46

    BurgessN. (2008). Grid cells and theta as oscillatory interference: theory and predictions. Hippocampus18, 11571174. doi: 10.1002/hipo.20518

  • 47

    BurgessN.BarryC.O'KeefeJ. (2007). An oscillatory interference model of grid cell firing. Hippocampus17, 801812. doi: 10.1002/hipo.20327

  • 48

    Burleigh-JacobsA.HorakF. B.NuttJ. G.ObesoJ. A. (1997). Step initiation in Parkinson's disease: influence of levodopa and external sensory triggers. Mov. Disord.12, 206215. doi: 10.1002/mds.870120211

  • 49

    BurwellR. D.AmaralD. G. (1998). Cortical afferents of the perirhinal, postrhinal, and entorhinal cortices of the rat. J. Comp. Neurol.398, 179205. doi: 10.1002/(sici)1096-9861(19980824)398:2<179::aid-cne3>3.0.co;2-y

  • 50

    BushD.BarryC.MansonD.BurgessN. (2015). Using grid cells for navigation. Neuron87, 507520. doi: 10.1016/j.neuron.2015.07.006

  • 51

    CaggianoV.LeirasR.Goni-ErroH.MasiniD.BellarditaC.BouvierJ.et al. (2018). Midbrain circuits that set locomotor speed and gait selection. Nature553, 455460. doi: 10.1038/nature25448

  • 52

    CaminitiS. P.PresottoL.BaronciniD.GaribottoV.MorescoR. M.GianolliL.et al. (2017). Axonal damage and loss of connectivity in nigrostriatal and mesolimbic dopamine pathways in early Parkinson's disease. Neuroimage Clin14, 734740. doi: 10.1016/j.nicl.2017.03.011

  • 53

    CampbellM. G.OckoS. A.MalloryC. S.LowI. I. C.GanguliS.GiocomoL. M. (2018). Principles governing the integration of landmark and self-motion cues in entorhinal cortical codes for navigation. Nat. Neurosci.21, 10961106. doi: 10.1038/s41593-018-0189-y

  • 54

    CarelliR. M.WestM. O. (1991). Representation of the body by single neurons in the dorsolateral striatum of the awake, unrestrained rat. J. Comp. Neurol.309, 231249. doi: 10.1002/cne.903090205

  • 55

    CarlssonA. (1971). Basic concepts underlying recent developments in the field of Parkinson's disease. Contemp. Neurol. Ser.8, 131. PMID:

  • 56

    CarlssonA.LindqvistM.MagnussonT. (1957). 3, 4-Dihydroxyphenylalanine and 5-hydroxytryptophan as reserpine antagonists. Nature180:1200. doi: 10.1038/1801200a0

  • 57

    CarlssonA.WaldeckB. (1958). A fluorimetric method for the determination of dopamine (3-hydroxytyramine). Acta Physiol. Scand.44, 293298. doi: 10.1111/j.1748-1716.1958.tb01628.x

  • 58

    CarpenterF.BarryC. (2016). Distorted grids as a spatial label and metric. Trends Cogn. Sci.20, 164167. doi: 10.1016/j.tics.2015.12.004

  • 59

    CarpenterF.MansonD.JefferyK.BurgessN.BarryC. (2015). Grid cells form a global representation of connected environments. Curr. Biol.25, 11761182. doi: 10.1016/j.cub.2015.02.037

  • 60

    CarvalhoM. M.TankeN.KropffE.WitterM. P.MoserM. B.MoserE. I. (2020). A brainstem locomotor circuit drives the activity of speed cells in the medial entorhinal cortex. Cell Rep.32:108123. doi: 10.1016/j.celrep.2020.108123

  • 61

    CasaliG.BushD.JefferyK. (2019). Altered neural odometry in the vertical dimension. Proc. Natl. Acad. Sci. USA116, 46314636. doi: 10.1073/pnas.1811867116

  • 62

    CasaliG.ShipleyS.DowellC.HaymanR.BarryC. (2018). Entorhinal neurons exhibit Cue locking in rodent VR. Front. Cell. Neurosci.12:512. doi: 10.3389/fncel.2018.00512

  • 63

    CedarbaumJ. M.AghajanianG. K. (1977). Catecholamine receptors on locus coeruleus neurons: pharmacological characterization. Eur. J. Pharmacol.44, 375385. doi: 10.1016/0014-2999(77)90312-0

  • 64

    ChenG.KingJ. A.BurgessN.O'KeefeJ. (2013). How vision and movement combine in the hippocampal place code. Proc. Natl. Acad. Sci. USA110, 378383. doi: 10.1073/pnas.1215834110

  • 65

    ChenG.MansonD.CacucciF.WillsT. J. (2016). Absence of visual input results in the disruption of grid cell firing in the mouse. Curr. Biol.26, 23352342. doi: 10.1016/j.cub.2016.06.043

  • 66

    ChersiF.BurgessN. (2015). The cognitive architecture of spatial navigation: hippocampal and striatal contributions. Neuron88, 6477. doi: 10.1016/j.neuron.2015.09.021

  • 67

    ChoJ.DukeD.ManzinoL.SonsallaP. K.WestM. O. (2002). Dopamine depletion causes fragmented clustering of neurons in the sensorimotor striatum: evidence of lasting reorganization of corticostriatal input. J. Comp. Neurol.452, 2437. doi: 10.1002/cne.10349

  • 68

    CiliaR.AkpaluA.SarfoF. S.ChamM.AmboniM.CeredaE.et al. (2014). The modern pre-levodopa era of Parkinson's disease: insights into motor complications from sub-Saharan Africa. Brain137, 27312742. doi: 10.1093/brain/awu195

  • 69

    ClemensS.Belin-RauscentA.SimmersJ.CombesD. (2012). Opposing modulatory effects of D1- and D2-like receptor activation on a spinal central pattern generator. J. Neurophysiol.107, 22502259. doi: 10.1152/jn.00366.2011

  • 70

    ClimerJ. R.NewmanE. L.HasselmoM. E. (2013). Phase coding by grid cells in unconstrained environments: two-dimensional phase precession. Eur. J. Neurosci.38, 25262541. doi: 10.1111/ejn.12256

  • 71

    CoffeyK. R.NaderM.BawaJ.WestM. O. (2017). Homogeneous processing in the striatal direct and indirect pathways: single body part sensitive type IIb neurons may express either dopamine receptor D1 or D2. Eur. J. Neurosci.46, 23802391. doi: 10.1111/ejn.13690

  • 72

    CoffeyK. R.NaderM.WestM. O. (2016). Single body parts are processed by individual neurons in the mouse dorsolateral striatum. Brain Res.1636, 200207. doi: 10.1016/j.brainres.2016.01.031

  • 73

    ColomboD.SerinoS.TuenaC.PedroliE.DakanalisA.CipressoP.et al. (2017). Egocentric and allocentric spatial reference frames in aging: a systematic review. Neurosci. Biobehav. Rev.80, 605621. doi: 10.1016/j.neubiorev.2017.07.012

  • 74

    Contreras-VidalJ. L.GoldD. R. (2004). Dynamic estimation of hand position is abnormal in Parkinson's disease. Parkinsonism Relat. Disord.10, 501506. doi: 10.1016/j.parkreldis.2004.06.002

  • 75

    CoueyJ. J.WitoelarA.ZhangS. J.ZhengK.YeJ.DunnB.et al. (2013). Recurrent inhibitory circuitry as a mechanism for grid formation. Nat. Neurosci.16, 318324. doi: 10.1038/nn.3310

  • 76

    CowieD.LimousinP.PetersA.HarizM.DayB. L. (2012). Doorway-provoked freezing of gait in Parkinson's disease. Mov. Disord.27, 492499. doi: 10.1002/mds.23990

  • 77

    CraigC. E.JenkinsonN. J.BrittainJ. S.GrotheM. J.RochesterL.SilverdaleM.et al. (2020). Pedunculopontine nucleus microstructure predicts postural and gait symptoms in Parkinson's disease. Mov. Disord.35, 11991207. doi: 10.1002/mds.28051

  • 78

    CrutcherM. D.DeLongM. R. (1984). Single cell studies of the primate putamen. II. Relations to direction of movement and pattern of muscular activity. Exp. Brain Res.53, 244258. doi: 10.1007/BF00238154

  • 79

    DannenbergH.LazaroH.NambiarP.HoylandA.HasselmoM. E. (2020). Effects of visual inputs on neural dynamics for coding of location and running speed in medial entorhinal cortex. elife9, 134. doi: 10.7554/eLife.62500

  • 80

    DavidsdottirS.WagenaarR.YoungD.Cronin-GolombA. (2008). Impact of optic flow perception and egocentric coordinates on veering in Parkinson's disease. Brain131, 28822893. doi: 10.1093/brain/awn237

  • 81

    DeLongM. R. (1990). Primate models of movement disorders of basal ganglia origin. Trends Neurosci.13, 281285. doi: 10.1016/0166-2236(90)90110-V

  • 82

    DelvalA.MoreauC.BleuseS.TardC.RyckewaertG.DevosD.et al. (2014). Auditory cueing of gait initiation in Parkinson's disease patients with freezing of gait. Clin. Neurophysiol.125, 16751681. doi: 10.1016/j.clinph.2013.12.101

  • 83

    DelwaideP. J.SchoenenJ. (1985). Clinical neurophysiology in the evaluation and physiopathology of Parkinson's disease. Rev. Neurol. (Paris)141, 759773.

  • 84

    DemirciM.GrillS.McShaneL.HallettM. (1997). A mismatch between kinesthetic and visual perception in Parkinson's disease. Ann. Neurol.41, 781788. doi: 10.1002/ana.410410614

  • 85

    DerdikmanD.WhitlockJ. R.TsaoA.FyhnM.HaftingT.MoserM. B.et al. (2009). Fragmentation of grid cell maps in a multicompartment environment. Nat. Neurosci.12, 13251332. doi: 10.1038/nn.2396

  • 86

    DeshmukhS. S.YoganarasimhaD.VoicuH.KnierimJ. J. (2010). Theta modulation in the medial and the lateral entorhinal cortices. J. Neurophysiol.104, 9941006. doi: 10.1152/jn.01141.2009

  • 87

    DesmurgetM.TurnerR. S. (2008). Testing basal ganglia motor functions through reversible inactivations in the posterior internal globus pallidus. J. Neurophysiol.99, 10571076. doi: 10.1152/jn.01010.2007

  • 88

    DeuschlG.RaethjenJ.BaronR.LindemannM.WilmsH.KrackP. (2000). The pathophysiology of parkinsonian tremor: a review. J. Neurol.247, V33V48. doi: 10.1007/pl00007781

  • 89

    DevanB. D.GoadE. H.PetriH. L. (1996). Dissociation of hippocampal and striatal contributions to spatial navigation in the water maze. Neurobiol. Learn. Mem.66, 305323. doi: 10.1006/nlme.1996.0072

  • 90

    DevanB. D.WhiteN. M. (1999). Parallel information processing in the dorsal striatum: relation to hippocampal function. J. Neurosci.19, 27892798. doi: 10.1523/JNEUROSCI.19-07-02789.1999

  • 91

    DiehlG. W.HonO. J.LeutgebS.LeutgebJ. K. (2017). Grid and nongrid cells in medial entorhinal cortex represent spatial location and environmental features with complementary coding schemes. Neuron94, 8392.e6. doi: 10.1016/j.neuron.2017.03.004

  • 92

    DimitriouM.EdinB. B. (2010). Human muscle spindles act as forward sensory models. Curr. Biol.20, 17631767. doi: 10.1016/j.cub.2010.08.049

  • 93

    DistlerM.SchlachetzkiJ. C.KohlZ.WinklerJ.SchenkT. (2016). Paradoxical kinesia in Parkinson's disease revisited: anticipation of temporal constraints is critical. Neuropsychologia86, 3844. doi: 10.1016/j.neuropsychologia.2016.04.012

  • 94

    DunnB.WennbergD.HuangZ.RoudiY. (2017). Grid cells show field-to-field variability and this explains the aperiodic response of inhibitory interneurons. arXiv [Preprint].

  • 95

    DuysensJ.NonnekesJ. (2021). Parkinson's Kinesia Paradoxa is not a paradox. Mov. Disord.36, 11151118. doi: 10.1002/mds.28550

  • 96

    EgginkH.MertensP.StormE.GiocomoL. M. (2014). Hyperpolarization-activated cyclic nucleotide-gated 1 independent grid cell-phase precession in mice. Hippocampus24, 249256. doi: 10.1002/hipo.22231

  • 97

    EhringerH.HornykiewiczO. (1960). Distribution of noradrenaline and dopamine (3-hydroxytyramine) in the human brain and their behavior in diseases of the extrapyramidal system. Klin. Wochenschr.38, 12361239. doi: 10.1007/BF01485901

  • 98

    EichenbaumH. (2014). Time cells in the hippocampus: a new dimension for mapping memories. Nat. Rev. Neurosci.15, 732744. doi: 10.1038/nrn3827

  • 99

    EklundG.HagbarthK. E.HagglundJ. V.WallinE. U. (1982). The 'late' reflex responses to muscle stretch: the 'resonance hypothesis' versus the 'long-loop hypothesis'. J. Physiol.326, 7990. doi: 10.1113/jphysiol.1982.sp014178

  • 100

    EllawayP. H.TaylorA.DurbabaR. (2015). Muscle spindle and fusimotor activity in locomotion. J. Anat.227, 157166. doi: 10.1111/joa.12299

  • 101

    ElliottD.LyonsJ.HayesS. J.BurkittJ. J.RobertsJ. W.GriersonL. E.et al. (2017). The multiple process model of goal-directed reaching revisited. Neurosci. Biobehav. Rev.72, 95110. doi: 10.1016/j.neubiorev.2016.11.016

  • 102

    EspayA. J.MorganteF.MerolaA.FasanoA.MarsiliL.FoxS. H.et al. (2018). Levodopa-induced dyskinesia in Parkinson disease: current and evolving concepts. Ann. Neurol.84, 797811. doi: 10.1002/ana.25364

  • 103

    FallonJ. H.KoziellD. A.MooreR. Y. (1978). Catecholamine innervation of the basal forebrain. II. Amygdala, suprarhinal cortex and entorhinal cortex. J. Comp. Neurol.180, 509531. doi: 10.1002/cne.901800308

  • 104

    Fernandez-BaizanC.Paula FernandezG. M.Diaz-CaceresE.Menendez-GonzalezM.AriasJ. L.MendezM. (2020). Patients with Parkinson's disease show alteration in their visuospatial abilities and in their egocentric and Allocentric spatial orientation measured by card placing tests. J. Parkinsons Dis.10, 18071816. doi: 10.3233/JPD-202122

  • 105

    FinchD. M.GiggJ.TanA. M.KosoyanO. P. (1995). Neurophysiology and neuropharmacology of projections from entorhinal cortex to striatum in the rat. Brain Res.670, 233247. doi: 10.1016/0006-8993(94)01279-q

  • 106

    FioreV. G.RigoliF.StennerM. P.ZaehleT.HirthF.HeinzeH. J.et al. (2016). Changing pattern in the basal ganglia: motor switching under reduced dopaminergic drive. Sci. Rep.6:23327. doi: 10.1038/srep23327

  • 107

    FiorioM.StanzaniC.RothwellJ. C.BhatiaK. P.MorettoG.FiaschiA.et al. (2007). Defective temporal discrimination of passive movements in Parkinson's disease. Neurosci. Lett.417, 312315. doi: 10.1016/j.neulet.2007.02.050

  • 108

    FlorescoS. B.WestA. R.AshB.MooreH.GraceA. A. (2003). Afferent modulation of dopamine neuron firing differentially regulates tonic and phasic dopamine transmission. Nat. Neurosci.6, 968973. doi: 10.1038/nn1103

  • 109

    FlowersK. A. (1976). Visual "closed-loop" and "open-loop" characteristics of voluntary movement in patients with parkinsonism and intention tremor. Brain99, 269310. doi: 10.1093/brain/99.2.269

  • 110

    FookenJ.SperingM. (2020). Eye movements as a readout of sensorimotor decision processes. J. Neurophysiol.123, 14391447. doi: 10.1152/jn.00622.2019

  • 111

    FuhrmannF.JustusD.SosulinaL.KanekoH.BeutelT.FriedrichsD.et al. (2015). Locomotion, Theta oscillations, and the speed-correlated firing of hippocampal neurons are controlled by a medial septal glutamatergic circuit. Neuron86, 12531264. doi: 10.1016/j.neuron.2015.05.001

  • 112

    FuhsM. C.TouretzkyD. S. (2006). A spin glass model of path integration in rat medial entorhinal cortex. J. Neurosci.26, 42664276. doi: 10.1523/JNEUROSCI.4353-05.2006

  • 113

    FyhnM.HaftingT.TrevesA.MoserM. B.MoserE. I. (2007). Hippocampal remapping and grid realignment in entorhinal cortex. Nature446, 190194. doi: 10.1038/nature05601

  • 114

    FyhnM.MoldenS.WitterM. P.MoserE. I.MoserM. B. (2004). Spatial representation in the entorhinal cortex. Science305, 12581264. doi: 10.1126/science.1099901

  • 115

    GarrawayS. M.HochmanS. (2001). Modulatory actions of serotonin, norepinephrine, dopamine, and acetylcholine in spinal cord deep dorsal horn neurons. J. Neurophysiol.86, 21832194. doi: 10.1152/jn.2001.86.5.2183

  • 116

    GasbarriA.SulliA.PackardM. G. (1997). The dopaminergic mesencephalic projections to the hippocampal formation in the rat. Prog. Neuropsychopharmacol. Biol.Psychiatry21, 122. doi: 10.1016/S0278-5846(96)00157-1

  • 117

    GatomeC. W.SlomiankaL.LippH. P.AmreinI. (2010). Number estimates of neuronal phenotypes in layer II of the medial entorhinal cortex of rat and mouse. Neuroscience170, 156165. doi: 10.1016/j.neuroscience.2010.06.048

  • 118

    GeorgiouN.BradshawJ. L.IansekR.PhillipsJ. G.MattingleyJ. B.BradshawJ. A. (1994). Reduction in external cues and movement sequencing in Parkinson's disease. J. Neurol. Neurosurg. Psychiatry57, 368370. doi: 10.1136/jnnp.57.3.368

  • 119

    GermanD. C.ManayeK. F.WhiteC. L.3rdWoodwardD. J.McIntireD. D.SmithW. K.et al. (1992). Disease-specific patterns of locus coeruleus cell loss. Ann. Neurol.32, 667676. doi: 10.1002/ana.410320510

  • 120

    GhiglieriV.SgobioC.CostaC.PicconiB.CalabresiP. (2011). Striatum-hippocampus balance: from physiological behavior to interneuronal pathology. Prog. Neurobiol.94, 102114. doi: 10.1016/j.pneurobio.2011.04.005

  • 121

    GhiglioneP.MutaniR.ChioA. (2005). Cogwheel rigidity. Arch. Neurol.62, 828830. doi: 10.1001/archneur.62.5.828

  • 122

    GiladiN.NieuwboerA. (2008). Understanding and treating freezing of gait in parkinsonism, proposed working definition, and setting the stage. Mov. Disord.23, S423S425. doi: 10.1002/mds.21927

  • 123

    GiladiN.ShabtaiH.RozenbergE.ShabtaiE. (2001). Gait festination in Parkinson's disease. Parkinsonism Relat. Disord.7, 135138. doi: 10.1016/s1353-8020(00)00030-4

  • 124

    GinisP.NackaertsE.NieuwboerA.HeremansE. (2018). Cueing for people with Parkinson's disease with freezing of gait: a narrative review of the state-of-the-art and novel perspectives. Ann. Phys. Rehabil. Med.61, 407413. doi: 10.1016/j.rehab.2017.08.002

  • 125

    GinosarG.AljadeffJ.BurakY.SompolinskyH.LasL.UlanovskyN. (2021). Locally ordered representation of 3D space in the entorhinal cortex. Nature596, 404409. doi: 10.1038/s41586-021-03783-x

  • 126

    GiocomoL. M. (2016). Environmental boundaries as a mechanism for correcting and anchoring spatial maps. J. Physiol.594, 65016511. doi: 10.1113/JP270624

  • 127

    GiocomoL. M.HasselmoM. E. (2008). Time constants of h current in layer ii stellate cells differ along the dorsal to ventral axis of medial entorhinal cortex. J. Neurosci.28, 94149425. doi: 10.1523/JNEUROSCI.3196-08.2008

  • 128

    GiorgiF. S.BiagioniF.GalganiA.PaveseN.LazzeriG.FornaiF. (2020). Locus coeruleus modulates neuroinflammation in parkinsonism and dementia. Int. J. Mol. Sci.21, 121. doi: 10.3390/ijms21228630

  • 129

    GlicksteinM.SteinJ. (1991). Paradoxical movement in Parkinson's disease. Trends Neurosci.14, 480482. doi: 10.1016/0166-2236(91)90055-y

  • 130

    Gomez-JordanaL. I.StaffordJ.PeperC. L. E.CraigC. M. (2018). Crossing virtual doors: a new method to study gait impairments and freezing of gait in Parkinson's disease. Parkinsons Dis.2018:2957427. doi: 10.1155/2018/2957427

  • 131

    GornyJ. H.GornyB.WallaceD. G.WhishawI. Q. (2002). Fimbria-fornix lesions disrupt the dead reckoning (homing) component of exploratory behavior in mice. Learn. Mem.9, 387394. doi: 10.1101/lm.53002

  • 132

    GrievesR. M.Jedidi-AyoubS.MishchanchukK.LiuA.RenaudineauS.DuvelleE.et al. (2021). Irregular distribution of grid cell firing fields in rats exploring a 3D volumetric space. Nat. Neurosci.24, 15671573. doi: 10.1038/s41593-021-00907-4

  • 133

    GrievesR. M.JefferyK. J. (2017). The representation of space in the brain. Behav. Process.135, 113131. doi: 10.1016/j.beproc.2016.12.012

  • 134

    GuZ.YakelJ. L. (2017). Inducing theta oscillations in the entorhinal hippocampal network in vitro. Brain Struct. Funct.222, 943955. doi: 10.1007/s00429-016-1256-3

  • 135

    GurneyK.PrescottT. J.RedgraveP. (2001a). A computational model of action selection in the basal ganglia. I. A new functional anatomy. Biol. Cybern.84, 401410. doi: 10.1007/PL00007984

  • 136

    GurneyK.PrescottT. J.RedgraveP. (2001b). A computational model of action selection in the basal ganglia. II. Analysis and simulation of behaviour. Biol. Cybern.84, 411423. doi: 10.1007/PL00007985

  • 137

    HaftingT.FyhnM.BonnevieT.MoserM. B.MoserE. I. (2008). Hippocampus-independent phase precession in entorhinal grid cells. Nature453, 12481252. doi: 10.1038/nature06957

  • 138

    HaftingT.FyhnM.MoldenS.MoserM. B.MoserE. I. (2005). Microstructure of a spatial map in the entorhinal cortex. Nature436, 801806. doi: 10.1038/nature03721

  • 139

    HagglundM.MorreaunetM.MoserM. B.MoserE. I. (2019). Grid-cell distortion along geometric Borders. Curr. Biol.29, 10471054. doi: 10.1016/j.cub.2019.01.074

  • 140

    HaljeP.TamteM.RichterU.MohammedM.CenciM. A.PeterssonP. (2012). Levodopa-induced dyskinesia is strongly associated with resonant cortical oscillations. J. Neurosci.32, 1654116551. doi: 10.1523/JNEUROSCI.3047-12.2012

  • 141

    HallettM. (2012). Parkinson's disease tremor: pathophysiology. Parkinsonism Relat. Disord.18, S85S86. doi: 10.1016/S1353-8020(11)70027-X

  • 142

    HallettM. (2014). Tremor: pathophysiology. Parkinsonism Relat. Disord.20, S118S122. doi: 10.1016/S1353-8020(13)70029-4

  • 143

    HanP.NakanishiS. T.TranM. A.WhelanP. J. (2007). Dopaminergic modulation of spinal neuronal excitability. J. Neurosci.27, 1319213204. doi: 10.1523/JNEUROSCI.1279-07.2007

  • 144

    HardcastleK.GanguliS.GiocomoL. M. (2015). Environmental boundaries as an error correction mechanism for grid cells. Neuron86, 827839. doi: 10.1016/j.neuron.2015.03.039

  • 145

    HardcastleK.MaheswaranathanN.GanguliS.GiocomoL. M. (2017). A multiplexed, heterogeneous, and adaptive code for navigation in medial entorhinal cortex. Neuron94, 375387.e7. doi: 10.1016/j.neuron.2017.03.025

  • 146

    HarrisJ. P.AtkinsonE. A.LeeA. C.NithiK.FowlerM. S. (2003). Hemispace differences in the visual perception of size in left hemi Parkinson's disease. Neuropsychologia41, 795807. doi: 10.1016/S0028-3932(02)00285-3

  • 147

    HarrisK. D.HenzeD. A.HiraseH.LeinekugelX.DragoiG.CzurkoA.et al. (2002). Spike train dynamics predicts theta-related phase precession in hippocampal pyramidal cells. Nature417, 738741. doi: 10.1038/nature00808

  • 148

    HarrisM. A.WienerJ. M.WolbersT. (2012). Aging specifically impairs switching to an allocentric navigational strategy. Front. Aging Neurosci.4:29. doi: 10.3389/fnagi.2012.00029

  • 149

    HartleyT.LeverC. (2014). Know your limits: the role of boundaries in the development of spatial representation. Neuron82, 13. doi: 10.1016/j.neuron.2014.03.017

  • 150

    HartleyT.MaguireE. A.SpiersH. J.BurgessN. (2003). The well-worn route and the path less traveled: distinct neural bases of route following and wayfinding in humans. Neuron37, 877888. doi: 10.1016/s0896-6273(03)00095-3

  • 151

    HausdorffJ. M.BalashJ.GiladiN. (2003). Time series analysis of leg movements during freezing of gait in Parkinson’s disease: akinesia, rhyme or reason?Phys. A321, 565570. doi: 10.1016/S0378-4371(02)01744-2

  • 152

    HeQ.BrownT. I. (2019). Environmental barriers disrupt grid-like representations in humans during navigation. Curr. Biol.29, 27182722. doi: 10.1016/j.cub.2019.06.072

  • 153

    HeathM.NeelyK.BinstedG. (2007). Allocentric visual cues influence online limb adjustments. Mot. Control.11, 5470. PMID:

  • 154

    HeysJ. G.DombeckD. A. (2018). Evidence for a subcircuit in medial entorhinal cortex representing elapsed time during immobility. Nat. Neurosci.21, 15741582. doi: 10.1038/s41593-018-0252-8

  • 155

    HeysJ. G.WuZ.Allegra MascaroA. L.DombeckD. A. (2020). Inactivation of the medial entorhinal cortex selectively disrupts learning of interval timing. Cell Rep.32:108163. doi: 10.1016/j.celrep.2020.108163

  • 156

    HinmanJ. R.BrandonM. P.ClimerJ. R.ChapmanG. W.HasselmoM. E. (2016). Multiple running speed signals in medial entorhinal cortex. Neuron91, 666679. doi: 10.1016/j.neuron.2016.06.027

  • 157

    HjorthJ. J. J.KozlovA.CarannanteI.Frost NylenJ.LindroosR.JohanssonY.et al. (2020). The microcircuits of striatum in silico. Proc. Natl. Acad. Sci. USA117, 95549565. doi: 10.1073/pnas.2000671117

  • 158

    HofP. R.CharpiotA.DelacourteA.BueeL.PurohitD.PerlD. P.et al. (1992). Distribution of neurofibrillary tangles and senile plaques in the cerebral cortex in postencephalitic parkinsonism. Neurosci. Lett.139, 1014. doi: 10.1016/0304-3940(92)90846-y

  • 159

    HornykiewiczO. (1962). Dopamine (3-hydroxytyramine) in the central nervous system and its relation to the Parkinson syndrome in man. Dtsch. Med. Wochenschr.87, 18071810. doi: 10.1055/s-0028-1114024

  • 160

    HornykiewiczO.KishS. J. (1987). Biochemical pathophysiology of Parkinson's disease. Adv. Neurol.45, 1934. PMID:

  • 161

    HoydalO. A.SkytoenE. R.AnderssonS. O.MoserM. B.MoserE. I. (2019). Object-vector coding in the medial entorhinal cortex. Nature568, 400404. doi: 10.1038/s41586-019-1077-7

  • 162

    HurtadoJ. M.LachauxJ. P.BeckleyD. J.GrayC. M.SigvardtK. A. (2000). Inter- and intralimb oscillator coupling in parkinsonian tremor. Mov. Disord.15, 683691. doi: 10.1002/1531-8257(200007)15:4<683::aid-mds1013>3.0.co;2-#

  • 163

    IansekR.HuxhamF.McGinleyJ. (2006). The sequence effect and gait festination in Parkinson disease: contributors to freezing of gait?Mov. Disord.21, 14191424. doi: 10.1002/mds.20998

  • 164

    IgloiK.ZaouiM.BerthozA.Rondi-ReigL. (2009). Sequential egocentric strategy is acquired as early as allocentric strategy: parallel acquisition of these two navigation strategies. Hippocampus19, 11991211. doi: 10.1002/hipo.20595

  • 165

    InaseM.BufordJ. A.AndersonM. E. (1996). Changes in the control of arm position, movement, and thalamic discharge during local inactivation in the globus pallidus of the monkey. J. Neurophysiol.75, 10871104. doi: 10.1152/jn.1996.75.3.1087

  • 166

    InzelbergR.PlotnikM.HarpazN. K.FlashT. (2016). Micrographia, much beyond the writer's hand. Parkinsonism Relat. Disord.26, 19. doi: 10.1016/j.parkreldis.2016.03.003

  • 167

    IsmakovR.BarakO.JefferyK.DerdikmanD. (2017). Grid cells encode local positional information. Curr. Biol.27, 23372343. doi: 10.1016/j.cub.2017.06.034

  • 168

    JacobP. Y.CapitanoF.PoucetB.SaveE.SargoliniF. (2019). Path integration maintains spatial periodicity of grid cell firing in a 1D circular track. Nat. Commun.10:840. doi: 10.1038/s41467-019-08795-w

  • 169

    JacobP. Y.Gordillo-SalasM.FacchiniJ.PoucetB.SaveE.SargoliniF. (2017). Medial entorhinal cortex and medial septum contribute to self-motion-based linear distance estimation. Brain Struct. Funct.222, 27272742. doi: 10.1007/s00429-017-1368-4

  • 170

    JacobsJ. V.HorakF. B. (2006). Abnormal proprioceptive-motor integration contributes to hypometric postural responses of subjects with Parkinson's disease. Neuroscience141, 9991009. doi: 10.1016/j.neuroscience.2006.04.014

  • 171

    JacobsJ. V.NuttJ. G.Carlson-KuhtaP.StephensM.HorakF. B. (2009). Knee trembling during freezing of gait represents multiple anticipatory postural adjustments. Exp. Neurol.215, 334341. doi: 10.1016/j.expneurol.2008.10.019

  • 172

    JarzebskaE. (2006). Evaluation of effectiveness of the micrographia's therapy in Parkinson's disease patients. Pol. Merkur. Lekarski20, 688690. PMID:

  • 173

    JeewajeeA.BarryC.O'KeefeJ.BurgessN. (2008). Grid cells and theta as oscillatory interference: electrophysiological data from freely moving rats. Hippocampus18, 11751185. doi: 10.1002/hipo.20510

  • 174

    JefferyK. J. (2007). Integration of the sensory inputs to place cells: what, where, why, and how?Hippocampus17, 775785. doi: 10.1002/hipo.20322

  • 175

    JefferyK. J.WilsonJ. J.CasaliG.HaymanR. M. (2015). Neural encoding of large-scale three-dimensional space-properties and constraints. Front. Psychol.6:927. doi: 10.3389/fpsyg.2015.00927

  • 176

    JinX.ChenQ.SongY.ZhengJ.XiaoK.ShaoS.et al. (2019). Dopamine D2 receptors regulate the action potential threshold by modulating T-type calcium channels in stellate cells of the medial entorhinal cortex. J. Physiol.597, 33633387. doi: 10.1113/JP277976

  • 177

    JohnsonA.van der MeerM. A.RedishA. D. (2007). Integrating hippocampus and striatum in decision-making. Curr. Opin. Neurobiol.17, 692697. doi: 10.1016/j.conb.2008.01.003

  • 178

    JoshiA.SomogyiP. (2020). Changing phase relationship of the stepping rhythm to neuronal oscillatory theta activity in the septo-hippocampal network of mice. Brain Struct. Funct.225, 871879. doi: 10.1007/s00429-020-02031-8

  • 179

    JustusD.DaluggeD.BotheS.FuhrmannF.HannesC.KanekoH.et al. (2017). Glutamatergic synaptic integration of locomotion speed via septoentorhinal projections. Nat. Neurosci.20, 1619. doi: 10.1038/nn.4447

  • 180

    KabasakalianA.KesayanT.WilliamsonJ. B.SkidmoreF. M.FalchookA. D.HarciarekM.et al. (2013). Hypometric allocentric and egocentric distance estimates in Parkinson disease. Cogn. Behav. Neurol.26, 133139. doi: 10.1097/WNN.0000000000000007

  • 181

    KangS. Y.WasakaT.ShamimE. A.AuhS.UekiY.LopezG. J.et al. (2010). Characteristics of the sequence effect in Parkinson's disease. Mov. Disord.25, 21482155. doi: 10.1002/mds.23251

  • 182

    KatzenschlagerR.HeadJ.SchragA.Ben-ShlomoY.EvansA.LeesA. J.et al. (2008). Fourteen-year final report of the randomized PDRG-UK trial comparing three initial treatments in PD. Neurology71, 474480. doi: 10.1212/01.wnl.0000310812.43352.66

  • 183

    KeinathA. T. (2016). The preferred directions of conjunctive grid X Head direction cells in the medial entorhinal cortex are periodically organized. PLoS One11:e0152041. doi: 10.1371/journal.pone.0152041

  • 184

    KeinathA. T.EpsteinR. A.BalasubramanianV. (2018). Environmental deformations dynamically shift the grid cell spatial metric. elife7, 122. doi: 10.7554/eLife.38169

  • 185

    KikuchiA.BabaT.HasegawaT.SugenoN.KonnoM.MiuraE.et al. (2014). Improvement of freezing of gait in patients with Parkinson's disease by imagining bicycling. Case Rep. Neurol.6, 9295. doi: 10.1159/000362119

  • 186

    KillianN. J.JutrasM. J.BuffaloE. A. (2012). A map of visual space in the primate entorhinal cortex. Nature491, 761764. doi: 10.1038/nature11587

  • 187

    KimM.MaguireE. A. (2019). Can we study 3D grid codes non-invasively in the human brain? Methodological considerations and fMRI findings. NeuroImage186, 667678. doi: 10.1016/j.neuroimage.2018.11.041

  • 188

    KinkhabwalaA. A.GuY.AronovD.TankD. W. (2020). Visual cue-related activity of cells in the medial entorhinal cortex during navigation in virtual reality. elife9, 124. doi: 10.7554/eLife.43140

  • 189

    Kinnier WilsonS. A. (1925). The Croonian lectures on some disorders of motility and of muscle tone, with special reference to the corpus striatum. Lancet206, 110. doi: 10.1016/S0140-6736(01)20638-2

  • 190

    KlausA.MartinsG. J.PaixaoV. B.ZhouP.PaninskiL.CostaR. M. (2017). The spatiotemporal Organization of the Striatum Encodes Action Space. Neuron95, 11711180.e.1177. doi: 10.1016/j.neuron.2017.08.015

  • 191

    KlockgetherT.DichgansJ. (1994). Visual control of arm movement in Parkinson's disease. Mov. Disord.9, 4856. doi: 10.1002/mds.870090108

  • 192

    KnierimJ. J. (2015). From the GPS to HM: place cells, grid cells, and memory. Hippocampus25, 719725. doi: 10.1002/hipo.22453

  • 193

    KrausB. J.BrandonM. P.RobinsonR. J.ConnerneyM. A.HasselmoM. E.EichenbaumH. (2015). During running in place, grid cells integrate elapsed time and distance run. Neuron88, 578589. doi: 10.1016/j.neuron.2015.09.031

  • 194

    KropffE.CarmichaelJ. E.MoserM. B.MoserE. I. (2015). Speed cells in the medial entorhinal cortex. Nature523, 419424. doi: 10.1038/nature14622

  • 195

    KropffE.CarmichaelJ. E.MoserE. I.MoserM. B. (2021). Frequency of theta rhythm is controlled by acceleration, but not speed, in running rats. Neuron109, 10291039.e.1028. doi: 10.1016/j.neuron.2021.01.017

  • 196

    KropffE.TrevesA. (2008). The emergence of grid cells: intelligent design or just adaptation?Hippocampus18, 12561269. doi: 10.1002/hipo.20520

  • 197

    KrupicJ.BauzaM.BurtonS.BarryC.O'KeefeJ. (2015). Grid cell symmetry is shaped by environmental geometry. Nature518, 232235. doi: 10.1038/nature14153

  • 198

    KrupicJ.BauzaM.BurtonS.O'KeefeJ. (2016). Framing the grid: effect of boundaries on grid cells and navigation. J. Physiol.594, 64896499. doi: 10.1113/JP270607

  • 199

    KulkarniO.LafaverK.TarsyD. (2013). The "floating door sign" in Parkinson's disease. Parkinsonism Relat. Disord.19, 825826. doi: 10.1016/j.parkreldis.2013.04.013

  • 200

    LaitinenL. V.BergenheimA. T.HarizM. I. (1992). Leksell's posteroventral pallidotomy in the treatment of Parkinson's disease. J. Neurosurg.76, 5361. doi: 10.3171/jns.1992.76.1.0053

  • 201

    LangstonR. F.AingeJ. A.CoueyJ. J.CantoC. B.BjerknesT. L.WitterM. P.et al. (2010). Development of the spatial representation system in the rat. Science328, 15761580. doi: 10.1126/science.1188210

  • 202

    LatuskeP.ToaderO.AllenK. (2015). Interspike intervals reveal functionally distinct cell populations in the medial entorhinal cortex. J. Neurosci.35, 1096310976. doi: 10.1523/JNEUROSCI.0276-15.2015

  • 203

    LaudateT. M.NeargarderS.Cronin-GolombA. (2013). Line bisection in Parkinson's disease: investigation of contributions of visual field, retinal vision, and scanning patterns to visuospatial function. Behav. Neurosci.127, 151163. doi: 10.1037/a0031618

  • 204

    LeboldC. A.AlmeidaQ. J. (2010). Evaluating the contributions of dynamic flow to freezing of gait in Parkinson's disease. Parkinsons Dis.2010:732508. doi: 10.4061/2010/732508

  • 205

    LeeA. C.HarrisJ. P.AtkinsonE. A.FowlerM. S. (2001a). Disruption of estimation of body-scaled aperture width in Hemiparkinson's disease. Neuropsychologia39, 10971104. doi: 10.1016/S0028-3932(01)00032-X

  • 206

    LeeA. C.HarrisJ. P.AtkinsonE. A.FowlerM. S. (2001b). Evidence from a line bisection task for visuospatial neglect in left hemiparkinson's disease. Vis. Res.41, 26772686. doi: 10.1016/S0042-6989(01)00129-8

  • 207

    LeeA. C.HarrisJ. P.CalvertJ. E. (1998). Impairments of mental rotation in Parkinson's disease. Neuropsychologia36, 109114. doi: 10.1016/S0028-3932(97)00017-1

  • 208

    LeeD.HenriquesD. Y.SniderJ.SongD.PoiznerH. (2013). Reaching to proprioceptively defined targets in Parkinson's disease: effects of deep brain stimulation therapy. Neuroscience244, 99112. doi: 10.1016/j.neuroscience.2013.04.009

  • 209

    LeeM. J.KimS. L.LyooC. H.RinneJ. O.LeeM. S. (2015). Impact of regional striatal dopaminergic function on kinematic parameters of Parkinson's disease. J. Neural Transm. (Vienna)122, 669677. doi: 10.1007/s00702-014-1296-x

  • 210

    LepperodM. E.ChristensenA. C.LensjoK. K.BuccinoA. P.YuJ.FyhnM.et al. (2021). Optogenetic pacing of medial septum parvalbumin-positive cells disrupts temporal but not spatial firing in grid cells. Sci. Adv.7, 118. doi: 10.1126/sciadv.abd5684

  • 211

    LeverC.BurtonS.JeewajeeA.O'KeefeJ.BurgessN. (2009). Boundary vector cells in the subiculum of the hippocampal formation. J. Neurosci.29, 97719777. doi: 10.1523/JNEUROSCI.1319-09.2009

  • 212

    LewisS. J.BarkerR. A. (2009). A pathophysiological model of freezing of gait in Parkinson's disease. Parkinsonism Relat. Disord.15, 333338. doi: 10.1016/j.parkreldis.2008.08.006

  • 213

    LexB.HauberW. (2010). Disconnection of the entorhinal cortex and dorsomedial striatum impairs the sensitivity to instrumental contingency degradation. Neuropsychopharmacology35, 17881796. doi: 10.1038/npp.2010.46

  • 214

    LiH. B.LinL.YangL. Y.XieC. (2015). Dopaminergic facilitation of GABAergic transmission in layer III of rat medial entorhinal cortex. Chin. J. Phys.58, 4654. doi: 10.4077/CJP.2015.BAC241

  • 215

    LimI.van WegenE.de GoedeC.DeutekomM.NieuwboerA.WillemsA.et al. (2005). Effects of external rhythmical cueing on gait in patients with Parkinson's disease: a systematic review. Clin. Rehabil.19, 695713. doi: 10.1191/0269215505cr906oa

  • 216

    MaaswinkelH.WhishawI. Q. (1999). Homing with locale, taxon, and dead reckoning strategies by foraging rats: sensory hierarchy in spatial navigation. Behav. Brain Res.99, 143152. doi: 10.1016/S0166-4328(98)00100-4

  • 217

    MacefieldV. G.KnellwolfT. P. (2018). Functional properties of human muscle spindles. J. Neurophysiol.120, 452467. doi: 10.1152/jn.00071.2018

  • 218

    MalhotraS.CrossR. W.van der MeerM. A. (2012). Theta phase precession beyond the hippocampus. Rev. Neurosci.23, 3965. doi: 10.1515/revneuro-2011-0064

  • 219

    ManciniM.SmuldersK.CohenR. G.HorakF. B.GiladiN.NuttJ. G. (2017). The clinical significance of freezing while turning in Parkinson's disease. Neuroscience343, 222228. doi: 10.1016/j.neuroscience.2016.11.045

  • 220

    MansonA.StirpeP.SchragA. (2012). Levodopa-induced-dyskinesias clinical features, incidence, risk factors, management and impact on quality of life. J. Parkinsons Dis.2, 189198. doi: 10.3233/JPD-2012-120103

  • 221

    MarsdenC. D. (1989). Slowness of movement in Parkinson's disease. Mov. Disord.4, S26S37. doi: 10.1002/mds.870040505

  • 222

    MarsdenC. D.ObesoJ. A. (1994). The functions of the basal ganglia and the paradox of stereotaxic surgery in Parkinson's disease. Brain117, 877897. doi: 10.1093/brain/117.4.877

  • 223

    MartinJ. P. (1967). The Basal Ganglia and Posture. Philadelphia: Lippincott.

  • 224

    MartinK. E.PhillipsJ. G.IansekR.BradshawJ. L. (1994). Inaccuracy and instability of sequential movements in Parkinson's disease. Exp. Brain Res.102, 131140. doi: 10.1007/BF00232445

  • 225

    MatarE.ShineJ. M.GilatM.Ehgoetz MartensK. A.WardP. B.FrankM. J.et al. (2019). Identifying the neural correlates of doorway freezing in Parkinson's disease. Hum. Brain Mapp.40, 20552064. doi: 10.1002/hbm.24506

  • 226

    MathisA.HerzA. V.StemmlerM. B. (2013). Multiscale codes in the nervous system: the problem of noise correlations and the ambiguity of periodic scales. Phys. Rev. E Stat. Nonlinear Soft Matter Phys.88:022713. doi: 10.1103/PhysRevE.88.022713

  • 227

    MayneE. W.CraigM. T.McBainC. J.PaulsenO. (2013). Dopamine suppresses persistent network activity via D (1) -like dopamine receptors in rat medial entorhinal cortex. Eur. J. Neurosci.37, 12421247. doi: 10.1111/ejn.12125

  • 228

    McCandlessP. J.EvansB. J.JanssenJ.SelfeJ.ChurchillA.RichardsJ. (2016). Effect of three cueing devices for people with Parkinson's disease with gait initiation difficulties. Gait Posture44, 711. doi: 10.1016/j.gaitpost.2015.11.006

  • 229

    McFarthingK.PrakashN.SimuniT. (2019). Clinical trial highlights-dyskinesia. J. Parkinsons Dis.9, 449465. doi: 10.3233/JPD-199002

  • 230

    McLennanJ. E.NakanoK.TylerH. R.SchwabR. S. (1972). Micrographia in Parkinson's disease. J. Neurol. Sci.15, 141152. doi: 10.1016/0022-510x(72)90002-0

  • 231

    MeisterM. L. R.BuffaloE. A. (2018). Neurons in primate entorhinal cortex represent gaze position in multiple spatial reference frames. J. Neurosci.38, 24302441. doi: 10.1523/JNEUROSCI.2432-17.2018

  • 232

    Mena-SegoviaJ.BolamJ. P. (2017). Rethinking the Pedunculopontine nucleus: from cellular organization to function. Neuron94, 718. doi: 10.1016/j.neuron.2017.02.027

  • 233

    Mena-SegoviaJ.BolamJ. P.MagillP. J. (2004). Pedunculopontine nucleus and basal ganglia: distant relatives or part of the same family?Trends Neurosci.27, 585588. doi: 10.1016/j.tins.2004.07.009

  • 234

    MiaoC.CaoQ.ItoH. T.YamahachiH.WitterM. P.MoserM. B.et al. (2015). Hippocampal remapping after partial inactivation of the medial entorhinal cortex. Neuron88, 590603. doi: 10.1016/j.neuron.2015.09.051

  • 235

    MiaoC.CaoQ.MoserM. B.MoserE. I. (2017). Parvalbumin and somatostatin interneurons control different space-coding networks in the medial entorhinal cortex. Cell171, 507521.e17. doi: 10.1016/j.cell.2017.08.050

  • 236

    MiguelezC.AristietaA.CenciM. A.UgedoL. (2011). The locus coeruleus is directly implicated in L-DOPA-induced dyskinesia in parkinsonian rats: an electrophysiological and behavioural study. PLoS One6:e24679. doi: 10.1371/journal.pone.0024679

  • 237

    MilanovI. (2001). Electromyographic differentiation of tremors. Clin. Neurophysiol.112, 16261632. doi: 10.1016/S1388-2457(01)00629-0

  • 238

    Milla-CruzJ. J.Mena-AvilaE.CalvoJ. R.HochmanS.VillalonC. M.QuevedoJ. N. (2020). The activation of D2 and D3 receptor subtypes inhibits pathways mediating primary afferent depolarization (PAD) in the mouse spinal cord. Neurosci. Lett.736:135257. doi: 10.1016/j.neulet.2020.135257

  • 239

    MinkJ. W. (1996). The basal ganglia: focused selection and inhibition of competing motor programs. Prog. Neurobiol.50, 381425. doi: 10.1016/S0301-0082(96)00042-1

  • 240

    MocciaM.PappataS.PicilloM.ErroR.CodaA. R.LongoK.et al. (2014). Dopamine transporter availability in motor subtypes of de novo drug-naive Parkinson's disease. J. Neurol.261, 21122118. doi: 10.1007/s00415-014-7459-8

  • 241

    Mohedano-MorianoA.Martinez-MarcosA.Pro-SistiagaP.BlaizotX.Arroyo-JimenezM. M.MarcosP.et al. (2008). Convergence of unimodal and polymodal sensory input to the entorhinal cortex in the fascicularis monkey. Neuroscience151, 255271. doi: 10.1016/j.neuroscience.2007.09.074

  • 242

    MontgomeryE. B.Jr. (2011). One view of the current state of understanding in basal ganglia pathophysiology and what is needed for the future. J. Mov Disord.4, 1320. doi: 10.14802/jmd.11003

  • 243

    MoreauC.OzsancakC.BlattJ. L.DerambureP.DesteeA.DefebvreL. (2007). Oral festination in Parkinson's disease: biomechanical analysis and correlation with festination and freezing of gait. Mov. Disord.22, 15031506. doi: 10.1002/mds.21549

  • 244

    MoserE. I.KropffE.MoserM. B. (2008). Place cells, grid cells, and the brain's spatial representation system. Annu. Rev. Neurosci.31, 6989. doi: 10.1146/annurev.neuro.31.061307.090723

  • 245

    MoserE. I.MoserM. B.RoudiY. (2014). Network mechanisms of grid cells. Philos. Trans. R. Soc. Lond. Ser. B Biol. Sci.369:20120511. doi: 10.1098/rstb.2012.0511

  • 246

    MosheiffN.BurakY. (2019). Velocity coupling of grid cell modules enables stable embedding of a low dimensional variable in a high dimensional n-eural attractor. elife8, 132. doi: 10.7554/eLife.48494

  • 247

    MullickA. A.MusampaN. K.FeldmanA. G.LevinM. F. (2013). Stretch reflex spatial threshold measure discriminates between spasticity and rigidity. Clin. Neurophysiol.124, 740751. doi: 10.1016/j.clinph.2012.10.008

  • 248

    MutchW. J.StrudwickA.RoyS. K.DownieA. W. (1986). Parkinson's disease: disability, review, and management. Br. Med. J. (Clin. Res. Ed.)293, 675677. doi: 10.1136/bmj.293.6548.675

  • 249

    NadasdyZ.NguyenT. P.TorokA.ShenJ. Y.BriggsD. E.ModurP. N.et al. (2017). Context-dependent spatially periodic activity in the human entorhinal cortex. Proc. Natl. Acad. Sci. USA114, E3516E3525. doi: 10.1073/pnas.1701352114

  • 250

    NadjarA.GerfenC. R.BezardE. (2009). Priming for l-dopa-induced dyskinesia in Parkinson's disease: a feature inherent to the treatment or the disease?Prog. Neurobiol.87, 19. doi: 10.1016/j.pneurobio.2008.09.013

  • 251

    NahimiA.KinnerupM. B.SommerauerM.GjeddeA.BorghammerP. (2018). Molecular imaging of the noradrenergic system in idiopathic Parkinson's disease. Int. Rev. Neurobiol.141, 251274. doi: 10.1016/bs.irn.2018.07.028

  • 252

    NakamuraR.NagasakiH.NarabayashiH. (1978). Disturbances of rhythm formation in patients with Parkinson's disease: part I. Characteristics of tapping response to the periodic signals. Percept. Mot. Skills46, 6375. doi: 10.2466/pms.1978.46.1.63

  • 253

    NambuA. (2008). Seven problems on the basal ganglia. Curr. Opin. Neurobiol.18, 595604. doi: 10.1016/j.conb.2008.11.001

  • 254

    NambuA.TachibanaY.ChikenS. (2015). Cause of parkinsonian symptoms: firing rate, firing pattern or dynamic activity changes?Basal Ganglia5, 16. doi: 10.1016/j.baga.2014.11.001

  • 255

    NambuA.TokunoH.TakadaM. (2002). Functional significance of the cortico-subthalamo-pallidal 'hyperdirect' pathway. Neurosci. Res.43, 111117. doi: 10.1016/S0168-0102(02)00027-5

  • 256

    NaumannR. K.Preston-FerrerP.BrechtM.BurgalossiA. (2018). Structural modularity and grid activity in the medial entorhinal cortex. J. Neurophysiol.119, 21292144. doi: 10.1152/jn.00574.2017

  • 257

    NeelyK. A.TessmerA.BinstedG.HeathM. (2008). Goal-directed reaching: movement strategies influence the weighting of allocentric and egocentric visual cues. Exp. Brain Res.186, 375384. doi: 10.1007/s00221-007-1238-z

  • 258

    NieuwboerA. (2008). Cueing for freezing of gait in patients with Parkinson's disease: a rehabilitation perspective. Mov. Disord.23, S475S481. doi: 10.1002/mds.21978

  • 259

    NieuwenhuysRVoogdJHuijzenC (eds.) (2008). The Human Central Nervous System. Berlin, Heidelberg, New York: Springer

  • 260

    NonnekesJ.GiladiN.GuhaA.FietzekU. M.BloemB. R.RuzickaE. (2019a). Gait festination in parkinsonism: introduction of two phenotypes. J. Neurol.266, 426430. doi: 10.1007/s00415-018-9146-7

  • 261

    NonnekesJ.RuzickaE.NieuwboerA.HallettM.FasanoA.BloemB. R. (2019b). Compensation strategies for gait impairments in Parkinson disease: a review. JAMA Neurol.76, 718725. doi: 10.1001/jamaneurol.2019.0033

  • 262

    NonnekesJ.SnijdersA. H.NuttJ. G.DeuschlG.GiladiN.BloemB. R. (2015). Freezing of gait: a practical approach to management. Lancet Neurol.14, 768778. doi: 10.1016/S1474-4422(15)00041-1

  • 263

    NuttJ. G.BloemB. R.GiladiN.HallettM.HorakF. B.NieuwboerA. (2011). Freezing of gait: moving forward on a mysterious clinical phenomenon. Lancet Neurol.10, 734744. doi: 10.1016/S1474-4422(11)70143-0

  • 264

    NuttJ. G.ChungK. A.HolfordN. H. (2010). Dyskinesia and the antiparkinsonian response always temporally coincide: a retrospective study. Neurology74, 11911197. doi: 10.1212/WNL.0b013e3181d90050

  • 265

    OadesR. D.HallidayG. M. (1987). Ventral tegmental (A10) system: neurobiology. 1. Anatomy and connectivity. Brain Res.12, 117165. doi: 10.1016/0165-0173(87)90011-7

  • 266

    ObesoJ. A.MarinC.Rodriguez-OrozC.BlesaJ.Itez-TeminoB.Mena-SegoviaJ.et al. (2008a). The basal ganglia in Parkinson's disease: current concepts and unexplained observations. Ann. Neurol.64, S30S46. doi: 10.1002/ana.21481

  • 267

    ObesoJ. A.Rodriguez-OrozM. C.Benitez-TeminoB.BlesaF. J.GuridiJ.MarinC.et al. (2008b). Functional organization of the basal ganglia: therapeutic implications for Parkinson's disease. Mov. Disord.23, S548S559. doi: 10.1002/mds.22062

  • 268

    ObesoJ. A.Rodriguez-OrozM. C.StamelouM.BhatiaK. P.BurnD. J. (2014). The expanding universe of disorders of the basal ganglia. Lancet384, 523531. doi: 10.1016/S0140-6736(13)62418-6

  • 269

    OertelW. H.HenrichM. T.JanzenA.GeiblF. F. (2019). The locus coeruleus: another vulnerability target in Parkinson's disease. Mov. Disord.34, 14231429. doi: 10.1002/mds.27785

  • 270

    O'KeefeJ.DostrovskyJ. (1971). The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat. Brain Res.34, 171175. doi: 10.1016/0006-8993(71)90358-1

  • 271

    O'KeefeJ.RecceM. L. (1993). Phase relationship between hippocampal place units and the EEG theta rhythm. Hippocampus3, 317330. doi: 10.1002/hipo.450030307

  • 272

    OkumaY. (2006). Freezing of gait in Parkinson's disease. J. Neurol.253:VII27-32. doi: 10.1007/s00415-006-7007-2

  • 273

    OlafsdottirH. F.BushD.BarryC. (2018). The role of hippocampal replay in memory and planning. Curr. Biol.28, R37R50. doi: 10.1016/j.cub.2017.10.073

  • 274

    OlafsdottirH. F.CarpenterF.BarryC. (2016). Coordinated grid and place cell replay during rest. Nat. Neurosci.19, 792794. doi: 10.1038/nn.4291

  • 275

    OlafsdottirH. F.CarpenterF.BarryC. (2017). Task demands predict a dynamic switch in the content of awake hippocampal replay. Neuron96, 925935.e6. doi: 10.1016/j.neuron.2017.09.035

  • 276

    OliveiraR. M.GurdJ. M.NixonP.MarshallJ. C.PassinghamR. E. (1997). Micrographia in Parkinson's disease: the effect of providing external cues. J. Neurol. Neurosurg. Psychiatry63, 429433. doi: 10.1136/jnnp.63.4.429

  • 277

    O'NeillJ.BoccaraC. N.StellaF.SchoenenbergerP.CsicsvariJ. (2017). Superficial layers of the medial entorhinal cortex replay independently of the hippocampus. Science355, 184188. doi: 10.1126/science.aag2787

  • 278

    O'SuilleabhainP. E.MatsumotoJ. Y. (1998). Time-frequency analysis of tremors. Brain121, 21272134. doi: 10.1093/brain/121.11.2127

  • 279

    PackardM. G.McGaughJ. L. (1996). Inactivation of hippocampus or caudate nucleus with lidocaine differentially affects expression of place and response learning. Neurobiol. Learn. Mem.65, 6572. doi: 10.1006/nlme.1996.0007

  • 280

    ParkS. W.JangH. J.KimM.KwagJ. (2019). Spatiotemporally random and diverse grid cell spike patterns contribute to the transformation of grid cell to place cell in a neural network model. PLoS One14:e0225100. doi: 10.1371/journal.pone.0225100

  • 281

    ParkH.YoumC.LeeM.NohB.CheonS. M. (2020). Turning characteristics of the more-affected side in Parkinson's disease patients with freezing of gait. Sensors20, 115. doi: 10.3390/s20113098

  • 282

    Parkinson’s_Foundation (n.d.). Freezing. FL: 200 SE 1st Street, Ste 800, Miami, FL 33131, United States. Available at: https://www.parkinson.org/living-with-parkinsons/management/activities-daily-living/freezing (Accessed July 17, 2023).

  • 283

    PasquereauB.DeLongM. R.TurnerR. S. (2016). Primary motor cortex of the parkinsonian monkey: altered encoding of active movement. Brain139, 127143. doi: 10.1093/brain/awv312

  • 284

    PastollH.SolankaL.van RossumM. C.NolanM. F. (2013). Feedback inhibition enables theta-nested gamma oscillations and grid firing fields. Neuron77, 141154. doi: 10.1016/j.neuron.2012.11.032

  • 285

    PedrosaD. J.ReckC.FlorinE.PaulsK. A.MaaroufM.WojteckiL.et al. (2012). Essential tremor and tremor in Parkinson's disease are associated with distinct 'tremor clusters' in the ventral thalamus. Exp. Neurol.237, 435443. doi: 10.1016/j.expneurol.2012.07.002

  • 286

    PennerM. R.MizumoriS. J. (2012). Neural systems analysis of decision making during goal-directed navigation. Prog. Neurobiol.96, 96135. doi: 10.1016/j.pneurobio.2011.08.010

  • 287

    PenneyJ. B.Jr.YoungA. B. (1986). Striatal inhomogeneities and basal ganglia function. Mov. Disord.1, 315. doi: 10.1002/mds.870010102

  • 288

    Perez-EscobarJ. A.KornienkoO.LatuskeP.KohlerL.AllenK. (2016). Visual landmarks sharpen grid cell metric and confer context specificity to neurons of the medial entorhinal cortex. elife5, 121. doi: 10.7554/eLife.16937

  • 289

    Pernia-AndradeA. J.WengerN.EspositoM. S.TovoteP. (2021). Circuits for state-dependent modulation of locomotion. Front. Hum. Neurosci.15:745689. doi: 10.3389/fnhum.2021.745689

  • 290

    PieperhoffP.SudmeyerM.DinkelbachL.HartmannC. J.FerreaS.MoldovanA. S.et al. (2022). Regional changes of brain structure during progression of idiopathic Parkinson's disease—a longitudinal study using deformation based morphometry. Cortex151, 188210. doi: 10.1016/j.cortex.2022.03.009

  • 291

    PillyP. K.GrossbergS. (2013). How reduction of theta rhythm by medial septum inactivation may covary with disruption of entorhinal grid cell responses due to reduced cholinergic transmission. Front. Neural Circuits7:173. doi: 10.3389/fncir.2013.00173

  • 292

    PlotkinJ. L.GoldbergJ. A. (2018). Thinking outside the box (and arrow): current themes in striatal dysfunction in movement disorders. Neuroscientist25, 359379. doi: 10.1177/1073858418807887

  • 293

    PlotnikM.GiladiN.BalashY.PeretzC.HausdorffJ. M. (2005). Is freezing of gait in Parkinson's disease related to asymmetric motor function?Ann. Neurol.57, 656663. doi: 10.1002/ana.20452

  • 294

    PlotnikM.HausdorffJ. M. (2008). The role of gait rhythmicity and bilateral coordination of stepping in the pathophysiology of freezing of gait in Parkinson's disease. Mov. Disord.23, S444S450. doi: 10.1002/mds.21984

  • 295

    PostumaR. B.BergD.SternM.PoeweW.OlanowC. W.OertelW.et al. (2015). MDS clinical diagnostic criteria for Parkinson's disease. Mov. Disord.30, 15911601. doi: 10.1002/mds.26424

  • 296

    PowellD.MuthumaniA.XiaR. (2016). A comparison of the effects of continuous versus discontinuous movement patterns on parkinsonian rigidity and reflex responses to passive stretch and shortening. J. Nat. Sci.2, 119.

  • 297

    PowellD.ThrelkeldA. J.FangX.MuthumaniA.XiaR. (2012). Amplitude- and velocity-dependency of rigidity measured at the wrist in Parkinson's disease. Clin. Neurophysiol.123, 764773. doi: 10.1016/j.clinph.2011.08.004

  • 298

    RadovanovicD.PeikertK.LindstromM.DomellofF. P. (2015). Sympathetic innervation of human muscle spindles. J. Anat.226, 542548. doi: 10.1111/joa.12309

  • 299

    RaethjenJ.LindemannM.SchmaljohannH.WenzelburgerR.PfisterG.DeuschlG. (2000). Multiple oscillators are causing parkinsonian and essential tremor. Mov. Disord.15, 8494. doi: 10.1002/1531-8257(200001)15:1<84::AID-MDS1014>3.0.CO;2-K

  • 300

    RahmanS.GriffinH. J.QuinnN. P.JahanshahiM. (2008). The factors that induce or overcome freezing of gait in Parkinson's disease. Behav. Neurol.19, 127136. doi: 10.1155/2008/456298

  • 301

    RandM. K.LemayM.SquireL. M.ShimanskyY. P.StelmachG. E. (2010). Control of aperture closure initiation during reach-to-grasp movements under manipulations of visual feedback and trunk involvement in Parkinson's disease. Exp. Brain Res.201, 509525. doi: 10.1007/s00221-009-2064-2

  • 302

    RaudiesF.HasselmoM. E. (2015). Differences in visual-spatial input may underlie different compression properties of firing fields for grid cell modules in medial entorhinal cortex. PLoS.Comput. Biol.11, 127. doi: 10.1371/journal.pcbi.1004596

  • 303

    RedgraveP.RodriguezM.SmithY.Rodriguez-OrozM. C.LehericyS.BergmanH.et al. (2010). Goal-directed and habitual control in the basal ganglia: implications for Parkinson's disease. Nat. Rev. Neurosci.11, 760772. doi: 10.1038/nrn2915

  • 304

    RehmanR. Z. U.Del DinS.GuanY.YarnallA. J.ShiJ. Q.RochesterL. (2019). Selecting clinically relevant gait characteristics for classification of early Parkinson's disease: a comprehensive machine learning approach. Sci. Rep.9:17269. doi: 10.1038/s41598-019-53656-7

  • 305

    ReifensteinE. T.KempterR.SchreiberS.StemmlerM. B.HerzA. V. (2012). Grid cells in rat entorhinal cortex encode physical space with independent firing fields and phase precession at the single-trial level. Proc. Natl. Acad. Sci. USA109, 63016306. doi: 10.1073/pnas.1109599109

  • 306

    RidlerT.WittonJ.PhillipsK. G.RandallA. D.BrownJ. T. (2020). Impaired speed encoding and grid cell periodicity in a mouse model of tauopathy. elife9, 122. doi: 10.7554/eLife.59045

  • 307

    Rivera-OliverM.MorenoE.Alvarez-BagnarolY.Ayala-SantiagoC.Cruz-ReyesN.Molina-CastroG. C.et al. (2019). Adenosine A1-dopamine D1 receptor Heteromers control the excitability of the spinal Motoneuron. Mol. Neurobiol.56, 797811. doi: 10.1007/s12035-018-1120-y

  • 308

    RollandA. S.TandeD.HerreroM. T.LuquinM. R.Vazquez-ClaverieM.KarachiC.et al. (2009). Evidence for a dopaminergic innervation of the pedunculopontine nucleus in monkeys, and its drastic reduction after MPTP intoxication. J. Neurochem.110, 13211329. doi: 10.1111/j.1471-4159.2009.06220.x

  • 309

    RoseberryT. K.LeeA. M.LaliveA. L.WilbrechtL.BonciA.KreitzerA. C. (2016). Cell-type-specific control of brainstem locomotor circuits by basal ganglia. Cell164, 526537. doi: 10.1016/j.cell.2015.12.037

  • 310

    RosenZ. B.CheungS.SiegelbaumS. A. (2015). Midbrain dopamine neurons bidirectionally regulate CA3-CA1 synaptic drive. Nat. Neurosci.18, 17631771. doi: 10.1038/nn.4152

  • 311

    RowlandD. C.ObenhausH. A.SkytoenE. R.ZhangQ.KentrosC. G.MoserE. I.et al. (2018). Functional properties of stellate cells in medial entorhinal cortex layer II. elife7, 117. doi: 10.7554/eLife.36664

  • 312

    RueckemannJ. W.DiMauroA. J.RangelL. M.HanX.BoydenE. S.EichenbaumH. (2016). Transient optogenetic inactivation of the medial entorhinal cortex biases the active population of hippocampal neurons. Hippocampus26, 246260. doi: 10.1002/hipo.22519

  • 313

    RuggieroG.IavaroneA.IachiniT. (2018). Allocentric to egocentric spatial switching: impairment in aMCI and Alzheimer's disease patients?Curr. Alzheimer Res.15, 229236. doi: 10.2174/1567205014666171030114821

  • 314

    RyanM. B.Bair-MarshallC.NelsonA. B. (2018). Aberrant striatal activity in parkinsonism and levodopa-induced dyskinesia. Cell Rep.23, 34383446. doi: 10.1016/j.celrep.2018.05.059

  • 315

    RyckewaertG.LuyatM.RambourM.TardC.NoelM.DefebvreL.et al. (2015). Self-perceived and actual ability in the functional reach test in patients with Parkinson's disease. Neurosci. Lett.589, 181184. doi: 10.1016/j.neulet.2015.01.039

  • 316

    RyczkoD.DubucR. (2017). Dopamine and the brainstem locomotor networks: from lamprey to human. Front. Neurosci.11:295. doi: 10.3389/fnins.2017.00295

  • 317

    RyczkoD.GratschS.AuclairF.DubeC.BergeronS.AlpertM. H.et al. (2013). Forebrain dopamine neurons project down to a brainstem region controlling locomotion. Proc. Natl. Acad. Sci. USA110, E3235E3242. doi: 10.1073/pnas.1301125110

  • 318

    SargoliniF.FyhnM.HaftingT.McNaughtonB. L.WitterM. P.MoserM. B.et al. (2006). Conjunctive representation of position, direction, and velocity in entorhinal cortex. Science312, 758762. doi: 10.1126/science.1125572

  • 319

    SavelliF.LuckJ. D.KnierimJ. J. (2017). Framing of grid cells within and beyond navigation boundaries. elife6, 129. doi: 10.7554/eLife.21354

  • 320

    SavelliF.YoganarasimhaD.KnierimJ. J. (2008). Influence of boundary removal on the spatial representations of the medial entorhinal cortex. Hippocampus18, 12701282. doi: 10.1002/hipo.20511

  • 321

    ScattonB.SimonH.Le MoalM.BischoffS. (1980). Origin of dopaminergic innervation of the rat hippocampal formation. Neurosci. Lett.18, 125131. doi: 10.1016/0304-3940(80)90314-6

  • 322

    SchaafsmaJ. D.BalashY.GurevichT.BartelsA. L.HausdorffJ. M.GiladiN. (2003). Characterization of freezing of gait subtypes and the response of each to levodopa in Parkinson's disease. Eur. J. Neurol.10, 391398. doi: 10.1046/j.1468-1331.2003.00611.x

  • 323

    SchlesigerM. I.CannovaC. C.BoublilB. L.HalesJ. B.MankinE. A.BrandonM. P.et al. (2015). The medial entorhinal cortex is necessary for temporal organization of hippocampal neuronal activity. Nat. Neurosci.18, 11231132. doi: 10.1038/nn.4056

  • 324

    SchwarzP. B.PeeverJ. H. (2011). Dopamine triggers skeletal muscle tone by activating D1-like receptors on somatic motoneurons. J. Neurophysiol.106, 12991309. doi: 10.1152/jn.00230.2011

  • 325

    SharplesS. A. (2017). Dopamine pumping up spinal locomotor network function. J. Neurosci.37, 31033105. doi: 10.1523/JNEUROSCI.0019-17.2017

  • 326

    ShayC. F.FerranteM.ChapmanG. W.HasselmoM. E. (2016). Rebound spiking in layer II medial entorhinal cortex stellate cells: possible mechanism of grid cell function. Neurobiol. Learn. Mem.129, 8398. doi: 10.1016/j.nlm.2015.09.004

  • 327

    SidawayB.AaroeA.AlbertM.LePageK.DesrosiersG.KeithM.et al. (2018). Visual detection of affordances for aperture negotiation in people with Parkinson disease. Neuropsychologia120, 5964. doi: 10.1016/j.neuropsychologia.2018.10.010

  • 328

    SkaggsW. E.McNaughtonB. L.WilsonM. A.BarnesC. A. (1996). Theta phase precession in hippocampal neuronal populations and the compression of temporal sequences. Hippocampus6, 149172. doi: 10.1002/(SICI)1098-1063(1996)6:2<149::AID-HIPO6>3.0.CO;2-K

  • 329

    SkidmoreF. M.DragoV.PavB.FosterP. S.MackmanC.HeilmanK. M. (2009). Conceptual hypometria? An evaluation of conceptual mapping of space in Parkinson's disease. Neurocase15, 119125. doi: 10.1080/13554790802637743

  • 330

    SkoogB.NogaB. R. (1995). Dopaminergic control of transmission from group II muscle afferents to spinal neurones in the cat and guinea-pig. Exp. Brain Res.105, 3947. doi: 10.1007/BF00242180

  • 331

    SmithJ. G.HarrisJ. P.KhanS.AtkinsonE. A.FowlerM. S.EwinsD.et al. (2011). Motor asymmetry and estimation of body-scaled aperture width in Parkinson's disease. Neuropsychologia49, 30023010. doi: 10.1016/j.neuropsychologia.2011.06.025

  • 332

    SnijdersA. H.ToniI.RuzickaE.BloemB. R. (2011). Bicycling breaks the ice for freezers of gait. Mov. Disord.26, 367371. doi: 10.1002/mds.23530

  • 333

    SodumsD. J.BohbotV. D. (2020). Negative correlation between grey matter in the hippocampus and caudate nucleus in healthy aging. Hippocampus30, 892908. doi: 10.1002/hipo.23210

  • 334

    SolstadT.BoccaraC. N.KropffE.MoserM. B.MoserE. I. (2008). Representation of geometric borders in the entorhinal cortex. Science322, 18651868. doi: 10.1126/science.1166466

  • 335

    SouzaB. C.TortA. B. L. (2017). Asymmetry of the temporal code for space by hippocampal place cells. Sci. Rep.7:8507. doi: 10.1038/s41598-017-08609-3

  • 336

    SpiegelJ.HellwigD.SamnickS.JostW.MollersM. O.FassbenderK.et al. (2007). Striatal FP-CIT uptake differs in the subtypes of early Parkinson's disease. J. Neural Transm. (Vienna)114, 331335. doi: 10.1007/s00702-006-0518-2

  • 337

    SpildoorenJ.VercruysseS.DesloovereK.VandenbergheW.KerckhofsE.NieuwboerA. (2010). Freezing of gait in Parkinson's disease: the impact of dual-tasking and turning. Mov. Disord.25, 25632570. doi: 10.1002/mds.23327

  • 338

    StanglM.AchtzehnJ.HuberK.DietrichC.TempelmannC.WolbersT. (2018). Compromised grid-cell-like representations in old age as a key mechanism to explain age-related navigational deficits. Curr. Biol.28, 11081115. doi: 10.1016/j.cub.2018.02.038

  • 339

    StensolaT.MoserE. I. (2016). “Grid cells and spatial maps in entorhinal cortex and hippocampus” in Micro-, Meso- and Macro-Dynamics of the Brain. eds. BuzsakiG.ChristenY. (Cham (CH): Springer Cham), 5980.

  • 340

    StensolaT.StensolaH.MoserM. B.MoserE. I. (2015). Shearing-induced asymmetry in entorhinal grid cells. Nature518, 207212. doi: 10.1038/nature14151

  • 341

    StensolaH.StensolaT.SolstadT.FrolandK.MoserM. B.MoserE. I. (2012). The entorhinal grid map is discretized. Nature492, 7278. doi: 10.1038/nature11649

  • 342

    StewartS.JeewajeeA.WillsT. J.BurgessN.LeverC. (2014). Boundary coding in the rat subiculum. Philos. Trans. R. Soc. Lond. Ser. B Biol. Sci.369:20120514. doi: 10.1098/rstb.2012.0514

  • 343

    StoianovI. P.PennartzC. M. A.LansinkC. S.PezzuloG. (2018). Model-based spatial navigation in the hippocampus-ventral striatum circuit: a computational analysis. PLoS Comput. Biol.14:e1006316. doi: 10.1371/journal.pcbi.1006316

  • 344

    SuryanarayanaS. M.Hellgren KotaleskiJ.GrillnerS.GurneyK. N. (2019). Roles for globus pallidus externa revealed in a computational model of action selection in the basal ganglia. Neural Netw.109, 113136. doi: 10.1016/j.neunet.2018.10.003

  • 345

    SwannN. C.de HemptinneC.MiocinovicS.QasimS.WangS. S.ZimanN.et al. (2016). Gamma oscillations in the hyperkinetic state detected with chronic human brain recordings in Parkinson's disease. J. Neurosci.36, 64456458. doi: 10.1523/JNEUROSCI.1128-16.2016

  • 346

    TakeuchiT.DuszkiewiczA. J.SonnebornA.SpoonerP. A.YamasakiM.WatanabeM.et al. (2016). Locus coeruleus and dopaminergic consolidation of everyday memory. Nature537, 357362. doi: 10.1038/nature19325

  • 347

    TangQ.BurgalossiA.EbbesenC. L.RayS.NaumannR.SchmidtH.et al. (2014). Pyramidal and stellate cell specificity of grid and border representations in layer 2 of medial entorhinal cortex. Neuron84, 11911197. doi: 10.1016/j.neuron.2014.11.009

  • 348

    ThautM. H.McIntoshG. C.RiceR. R.MillerR. A.RathbunJ.BraultJ. M. (1996). Rhythmic auditory stimulation in gait training for Parkinson's disease patients. Mov. Disord.11, 193200. doi: 10.1002/mds.870110213

  • 349

    TinazS.PillaiA. S.HallettM. (2016). Sequence effect in Parkinson's disease is related to motor energetic cost. Front. Neurol.7:83. doi: 10.3389/fneur.2016.00083

  • 350

    TotterdellS.MeredithG. E. (1997). Topographical organization of projections from the entorhinal cortex to the striatum of the rat. Neuroscience78, 715729. doi: 10.1016/s0306-4522(96)00592-1

  • 351

    TsanovM. (2017). Speed and oscillations: medial septum integration of attention and navigation. Front. Syst. Neurosci.11:67. doi: 10.3389/fnsys.2017.00067

  • 352

    TsaoA.SugarJ.LuL.WangC.KnierimJ. J.MoserM. B.et al. (2018). Integrating time from experience in the lateral entorhinal cortex. Nature561, 5762. doi: 10.1038/s41586-018-0459-6

  • 353

    TukkerJ. J.BeedP.BrechtM.KempterR.MoserE. I.SchmitzD. (2022). Microcircuits for spatial coding in the medial entorhinal cortex. Physiol. Rev.102, 653688. doi: 10.1152/physrev.00042.2020

  • 354

    VagoL.UjfalussyB. B. (2018). Robust and efficient coding with grid cells. PLoS Comput. Biol.14:e1005922. doi: 10.1371/journal.pcbi.1005922

  • 355

    ValenciaM.ChavezM.ArtiedaJ.BolamJ. P.Mena-SegoviaJ. (2014). Abnormal functional connectivity between motor cortex and pedunculopontine nucleus following chronic dopamine depletion. J. Neurophysiol.111, 434440. doi: 10.1152/jn.00555.2013

  • 356

    van der MeerM. A.JohnsonA.Schmitzer-TorbertN. C.RedishA. D. (2010). Triple dissociation of information processing in dorsal striatum, ventral striatum, and hippocampus on a learned spatial decision task. Neuron67, 2532. doi: 10.1016/j.neuron.2010.06.023

  • 357

    van der MeerM. A.RedishA. D. (2011). Theta phase precession in rat ventral striatum links place and reward information. J. Neurosci.31, 28432854. doi: 10.1523/JNEUROSCI.4869-10.2011

  • 358

    van WijngaardenJ. B.BablS. S.ItoH. T. (2020). Entorhinal-retrosplenial circuits for allocentric-egocentric transformation of boundary coding. elife9, 125. doi: 10.7554/eLife.59816

  • 359

    VanderwolfC. H. (1969). Hippocampal electrical activity and voluntary movement in the rat. Electroencephalogr. Clin. Neurophysiol.26, 407418. doi: 10.1016/0013-4694(69)90092-3

  • 360

    VercruysseS.GilatM.ShineJ. M.HeremansE.LewisS.NieuwboerA. (2014). Freezing beyond gait in Parkinson's disease: a review of current neurobehavioral evidence. Neurosci. Biobehav. Rev.43, 213227. doi: 10.1016/j.neubiorev.2014.04.010

  • 361

    Verhagen MetmanL.EspayA. J. (2017). Teaching video neuro images: the underrecognized diphasic dyskinesia of Parkinson disease. Neurology89, e83e84. doi: 10.1212/WNL.0000000000004238

  • 362

    VermeirenY.De DeynP. P. (2017). Targeting the norepinephrinergic system in Parkinson's disease and related disorders: the locus coeruleus story. Neurochem. Int.102, 2232. doi: 10.1016/j.neuint.2016.11.009

  • 363

    VerschureP. F.PennartzC. M.PezzuloG. (2014). The why, what, where, when and how of goal-directed choice: neuronal and computational principles. Philos. Trans. R. Soc. Lond. Ser. B Biol. Sci.369:20130483. doi: 10.1098/rstb.2013.0483

  • 364

    VirmaniT.UrbanoF. J.BisagnoV.Garcia-RillE. (2019). The pedunculopontine nucleus: from posture and locomotion to neuroepigenetics. AIMS Neurosci.6, 219230. doi: 10.3934/Neuroscience.2019.4.219

  • 365

    Wagle ShuklaA.OunpraseuthS.OkunM. S.GrayV.SchwankhausJ.MetzerW. S. (2012). Micrographia and related deficits in Parkinson's disease: a cross-sectional study. BMJ Open2:e000628. doi: 10.1136/bmjopen-2011-000628

  • 366

    Weil-FugazzaJ.GodefroyF. (1993). Dorsal and ventral dopaminergic innervation of the spinal cord: functional implications. Brain Res. Bull.30, 319324. doi: 10.1016/0361-9230(93)90259-e

  • 367

    WichmannT.DeLongM. R.GuridiJ.ObesoJ. A. (2011). Milestones in research on the pathophysiology of Parkinson's disease. Mov. Disord.26, 10321041. doi: 10.1002/mds.23695

  • 368

    WillsT. J.CacucciF.BurgessN.O'KeefeJ. (2010). Development of the hippocampal cognitive map in preweanling rats. Science328, 15731576. doi: 10.1126/science.1188224

  • 369

    WitterM. P.DoanT. P.JacobsenB.NilssenE. S.OharaS. (2017). Architecture of the entorhinal cortex a review of entorhinal anatomy in rodents with some comparative notes. Front. Syst. Neurosci.11:46. doi: 10.3389/fnsys.2017.00046

  • 370

    WuT.ZhangJ.HallettM.FengT.HouY.ChanP. (2016). Neural correlates underlying micrographia in Parkinson's disease. Brain139, 144160. doi: 10.1093/brain/awv319

  • 371

    XiaR.PowellD.RymerW. Z.HansonN.FangX.ThrelkeldA. J. (2011). Differentiation between the contributions of shortening reaction and stretch-induced inhibition to rigidity in Parkinson's disease. Exp. Brain Res.209, 609618. doi: 10.1007/s00221-011-2594-2

  • 372

    XuZ.MoF.YangG.FanP.WangY.LuB.et al. (2022). Grid cell remapping under three-dimensional object and social landmarks detected by implantable microelectrode arrays for the medial entorhinal cortex. Microsyst. Nanoeng.8:104. doi: 10.1038/s41378-022-00436-5

  • 373

    YartsevM. M.UlanovskyN. (2013). Representation of three-dimensional space in the hippocampus of flying bats. Science340, 367372. doi: 10.1126/science.1235338

  • 374

    YeJ.WitterM. P.MoserM. B.MoserE. I. (2018). Entorhinal fast-spiking speed cells project to the hippocampus. Proc. Natl. Acad. Sci. U.S.A.115, E1627E1636. doi: 10.1073/pnas.1720855115

  • 375

    YeraganiV. K.TancerM.ChokkaP.BakerG. B. (2010). Arvid Carlsson, and the story of dopamine. Indian J. Psychiatry52, 8788. doi: 10.4103/0019-5545.58907

  • 376

    YoshidaM.TanakaM. (1988). Existence of new dopaminergic terminal plexus in the rat spinal cord: assessment by immunohistochemistry using anti-dopamine serum. Neurosci. Lett.94, 59. doi: 10.1016/0304-3940(88)90261-3

  • 377

    YoungD. E.WagenaarR. C.LinC. C.ChouY. H.DavidsdottirS.SaltzmanE.et al. (2010). Visuospatial perception and navigation in Parkinson's disease. Vis. Res.50, 24952504. doi: 10.1016/j.visres.2010.08.029

  • 378

    ZachH.DirkxM.BloemB. R.HelmichR. C. (2015). The clinical evaluation of Parkinson's tremor. J. Parkinsons Dis.5, 471474. doi: 10.3233/JPD-150650

  • 379

    ZarowC.LynessS. A.MortimerJ. A.ChuiH. C. (2003). Neuronal loss is greater in the locus coeruleus than nucleus basalis and substantia nigra in Alzheimer and Parkinson diseases. Arch. Neurol.60, 337341. doi: 10.1001/archneur.60.3.337

  • 380

    ZhamP.RaghavS.KempsterP.Poosapadi ArjunanS.WongK.NagaoK. J.et al. (2019). A kinematic study of progressive Micrographia in Parkinson's disease. Front. Neurol.10:403. doi: 10.3389/fneur.2019.00403

  • 381

    ZhangB.LiuJ. (2023). Hippocampal replay facilitates the formation of entorhinal grid cells. bioRxiv [Preprint]. doi: 10.1101/2023.02.19.529130

  • 382

    ZhongJ. Y.MoffatS. D. (2018). Extrahippocampal contributions to age-related changes in spatial navigation ability. Front. Hum. Neurosci.12:272. doi: 10.3389/fnhum.2018.00272

  • 383

    ZhouC.GuoT.WuJ.WangL.BaiX.GaoT.et al. (2021). Locus Coeruleus degeneration correlated with levodopa resistance in Parkinson's disease: a retrospective analysis. J. Parkinsons Dis.11, 16311640. doi: 10.3233/JPD-212720

  • 384

    ZhouT. L.TamuraR.KuriwakiJ.OnoT. (1999). Comparison of medial and lateral septal neuron activity during performance of spatial tasks in rats. Hippocampus9, 220234. doi: 10.1002/(SICI)1098-1063(1999)9:3<220::AID-HIPO3>3.0.CO;2-E

  • 385

    ZhuH.ClemensS.SawchukM.HochmanS. (2007). Expression and distribution of all dopamine receptor subtypes (D (1)-D (5)) in the mouse lumbar spinal cord: a real-time polymerase chain reaction and non-autoradiographic in situ hybridization study. Neuroscience149, 885897. doi: 10.1016/j.neuroscience.2007.07.052

  • 386

    ZilliE. A. (2012). Models of grid cell spatial firing published 2005-2011. Front. Neural Circuits6:16. doi: 10.3389/fncir.2012.00016

  • 387

    ZirhT. A.LenzF. A.ReichS. G.DoughertyP. M. (1998). Patterns of bursting occurring in thalamic cells during parkinsonian tremor. Neuroscience83, 107121. doi: 10.1016/s0306-4522(97)00295-9

Summary

Keywords

grid cell, Parkinson ‘s disease, allocentric, dopamine, medial entorhinal cortex, striatum, striato-HF/EC loop

Citation

Reinshagen A (2024) Grid cells: the missing link in understanding Parkinson’s disease?. Front. Neurosci. 18:1276714. doi: 10.3389/fnins.2024.1276714

Received

12 August 2023

Accepted

24 January 2024

Published

08 February 2024

Volume

18 - 2024

Edited by

Frank Hirth, King's College London, United Kingdom

Reviewed by

Patrick Santens, Ghent University, Belgium; Giorgio Vivacqua, Campus Bio-Medico University, Italy

Updates

Copyright

*Correspondence: Alexander Reinshagen,

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Outline

Figures

Cite article

Copy to clipboard


Export citation file


Share article

Article metrics