Somatosensory system

About: Somatosensory system is a research topic. Over the lifetime, 6371 publications have been published within this topic receiving 316900 citations.

Cortical Hypersynchrony Predicts Breakdown of Sensory Processing during Loss of Consciousness

Abstract: Intrinsic cortical dynamics modulates the processing of sensory information and therefore may be critical for conscious perception. We tested this hypothesis by electroencephalographic recording of ongoing and stimulus-related brain activity during stepwise drug-induced loss of consciousness in healthy human volunteers. We found that progressive loss of consciousness was tightly linked to the emergence of a hypersynchronous cortical state in the alpha frequency range (8-14 Hz). This drug-induced ongoing alpha activity was widely distributed across the frontal cortex. Stimulus-related responses to median nerve stimulation consisted of early and midlatency response components in primary somatosensory cortex (S1) and a late component also involving temporal and parietal regions. During progressive sedation, the early response was maintained, whereas the midlatency and late responses were reduced and eventually vanished. The antagonistic relation between the late sensory response and ongoing alpha activity held for constant drug levels on the single-trial level. Specifically, the late response component was negatively correlated with the power and long-range coherence of ongoing frontal alpha activity. Our results suggest blocking of intracortical communication by hypersynchronous ongoing activity as a key mechanism for the loss of consciousness.

Neural Basis of Touch and Proprioception in Primate Cortex.

Abstract: The sense of proprioception allows us to keep track of our limb posture and movements and the sense of touch provides us with information about objects with which we come into contact. In both senses, mechanoreceptors convert the deformation of tissues-skin, muscles, tendons, ligaments, or joints-into neural signals. Tactile and proprioceptive signals are then relayed by the peripheral nerves to the central nervous system, where they are processed to give rise to percepts of objects and of the state of our body. In this review, we first examine briefly the receptors that mediate touch and proprioception, their associated nerve fibers, and pathways they follow to the cerebral cortex. We then provide an overview of the different cortical areas that process tactile and proprioceptive information. Next, we discuss how various features of objects-their shape, motion, and texture, for example-are encoded in the various cortical fields, and the susceptibility of these neural codes to attention and other forms of higher-order modulation. Finally, we summarize recent efforts to restore the senses of touch and proprioception by electrically stimulating somatosensory cortex. © 2018 American Physiological Society. Compr Physiol 8:1575-1602, 2018.

Effects of somatosensory stimulation on motor function in chronic cortico-subcortical strokes.

Abstract: Somatosensory stimulation enhances aspects of motor function in patients with chronic, predominantly subcortical infarcts. We investigated the effects of somatosensory stimulation on motor function in stroke patients with predominantly cortical involvement in the middle cerebral artery territory in a double-blind, pseudorandomized crossover trial. Motor performance was evaluated with the Jebsen-Taylor test before, after 2-hour somatosensory stimulation, and after subsequent motor training (n=11). In one experimental session, patients were submitted to median nerve stimulation (MNS) and in the other session, to control stimulation (CS). The order of the sessions was counterbalanced across patients. Improvement in performance in the Jebsen-Taylor test after somatosensory stimulation and after motor training was significantly greater in the MNS session than in the CS session. Additionally, patients who received MNS in the second session maintained the beneficial effects of training 30 days later. A single MNS session improves hand motor function in patients with chronic cortico-subcortical strokes and appears to favor consolidation of training effects. Somatosensory stimulation may be an adjuvant tool for stroke rehabilitation in patients with cortical lesions.