Interaction of hippocampo-neocortical neuronal assemblies during learning and sleep
-
1
UNIC, CNRS, France
-
2
Universiteit van Amsterdam , Netherlands
Sleep is determinant for memory consolidation. Neuronal assemblies formed during previous waking experiences reactivate spontaneously in the hippocampus and the neocortex during sleep episodes, and in particular Slow Wave Sleep (SWS), possibly important for memory stabilization during offline periods. Hippocampal replay events are associated with high frequency (~200 Hz) oscillations in the LFP called ripples. Hippocampal reactivation may lead reactivation of neocortical assemblies and thus contribute to the stabilization of long term memory trace in the neocortex. Learning of complex behavioral strategies is thought to recruit the prefrontal cortex (PFC) which receives a unilateral and monosynaptic projections from the hippocampus. Simultaneous recordings of hippocampal Local Field Potentials (LFP) and large ensemble of isolated units in the PFC while the animal was learning different behavioral contingencies, showed that neurons tend to self-organize in pools of correlated units. Those subgroups of cells were identified by mean of principal component analysis on awake binned spike trains. The projection of instantaneous population vectors from a sleep period onto a given principal component from waking quantifies the timecourse of reactivation of cells during sleep. Reactivation, averaged over whole SWS episodes, was higher in the sleep following the task (sleep POST) than during a control sleep epoch prior to task (sleep PRE). The reactivation took the form of short lasting events (~100 ms) and strong co-firing among the subgroups of cells corresponding to waking assemblies. Amplitude and inter-event intervals for these transients followed power-law distributions. Replay events in the PFC tend to occur at times of hippocampal ripples, hence pointing out an enhanced coordination between the two structures. Furthermore, this relationship was modulated by learning as prefrontal assemblies formed upon rule acquisition were the ones which were most likely replayed with hippocampal reactivations in subsequent sleep episodes. In another experiment, simultaneous recordings of up to ~120 isolated neurons over a large portion of the neocortex were carried out while the animal was performing repetitive and over-trained behavior. Neuronal assemblies, extracted with the same method as above, showed also prominent reinstatement during sleep but both in PRE and POST epochs. However, these reactivations occurred more often at times of hippocampal ripples in sleep POST than in sleep PRE, suggesting an enhanced hippocampo-neocortical dialogue in sleep following immediately task performance, even for pre-existing neuronal patterns. The time resolution of the measure can not determine if these reactivations are lead by one or the other structure, or if they are just coordinated. These assemblies were distributed over the neocortex, often recruiting neurons in both hemispheres. Hence, the reactivation process is largely distributed and could contribute to plasticity over long-range populations as suggested by previous findings on cell pair recordings in different neocortical structures. In new conditions, performance optimal neuronal patterns are reactivated with the hippocampus, most certainly to be consolidated. Conversely, re-experience in familiar situations would transiently make the already consolidated neocortical memory traces coordinated to hippocampal assemblies, thus allowing them to be transformed or updated in case of environmental changes.
This work was supported by European Community contracts FP6-IST 027819 (Integrating Cognition, Emotion and Autonomy), FP6-IST-027140 (Bayesian Approach to Cognitive Systems) and FP6-IST-027017 (NeuroProbes).
Conference:
Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010.
Presentation Type:
Poster Presentation
Topic:
Poster session I
Citation:
Peyrache
A and
Battaglia
FP
(2010). Interaction of hippocampo-neocortical neuronal assemblies during learning and sleep.
Front. Neurosci.
Conference Abstract:
Computational and Systems Neuroscience 2010.
doi: 10.3389/conf.fnins.2010.03.00075
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
19 Feb 2010;
Published Online:
19 Feb 2010.
*
Correspondence:
Adrien Peyrache, UNIC, CNRS, Sophia Antipolis Méditerranée, France, France.adrien.peyrache@gmail.com