About this Research Topic
Humans interact and engage with the environment through movement. Recent studies have highlighted the great disproportion between sensory and motor spinal neurons while reiterating the idea that somatosensory information (i.e., the afferent information related to proprioceptive, thermal and painful stimuli) plays a crucial role in modulating efferent signals. Despite the abundance of sensory fibres, recording from afferent nerves is a challenging task yielding little information compared to the more accessible motor output. Investigating somatosensory integration through the observation of efferent output in intact and altered systems will improve the understanding, and enhance the modelling, of human motor control, with the latter providing the tools to systematically investigate the overall system. A new class of physiologically-inspired models could be the basis for revolutionizing the design of neurorehabilitation approaches, by promoting a bidirectional communication with bionic orthoses/prostheses and a natural interaction with human-centred hardware.
Contemporary neuromusculoskeletal models compute the mechanical output based on kinematic and/or electromyographic data, providing a quantitative description of the net efferent information while overlooking the actual efferent output. To improve this aspect, a better characterization of the sensory organs’ (e.g., muscle spindles, Golgi tendon organs) input is necessary. The advancements of these models have a direct impact on understanding neurophysiological processes as well as the design of neurorehabilitation interfaces.
Alterations in somatosensory information cause a reorganization of motor output both in the short spinal loops and long-distance (cortical) circuitries. Experimental procedures such as vibration, electrical stimulation, blood flow restriction, painful injections and temperature alteration, can cause an immediate redistribution of motor units' activity and create an excellent ground for an in-depth investigation of human motor control. Moreover, afferent information can slowly degenerate over time (e.g., chronic disease) or suddenly, yet permanently, be altered (e.g., traumatic nerve damage). These specific conditions offer an ethically acceptable alternative to experimentally-induced lesions in humans and allow a population-based comparison of intact and damaged individuals in terms of somatosensory integration (SMI). The newly acquired knowledge can be used to improve the recovery of neurological patients and foster new rehabilitation techniques.
Somatosensory feedback, if properly administered, promotes acceptance and embodiment of prostheses and orthoses. Furthermore, it allows the establishment of an immediate, natural communication with the users. Understanding the somatosensory channels allows us to precisely tune the amount and quality of transmitted information and to optimize human-machine interactions. Moreover, natural bidirectional interfaces promote user learning, allowing them to appreciate the full potential of the provided control.
This Research Topic aims to encompass the latest research in the field of SMI in humans, from experimental data to sensory-informed neuromusculoskeletal models and from neurorehabilitation to human-machine interaction. We welcome researchers to contribute original work of theoretical, computational, or experimental studies, and review articles focusing on understanding sensorimotor integration. The scope of this Topic includes, but is not limited to, new experimental approaches for a selective and controlled alteration of sensory information, development of sensation-aware neuromusculoskeletal models and the evaluation of sensory integration, substitution or function replacement in the context of human-machine communication.
Keywords: Somatosensory integration, Motor control, Neurorehabilitation, Human Machine Interface, Musculoskeletal Modelling
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