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Somatosensory system

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


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Journal Article
TL;DR: The results suggest that, physiologically, central somatosensory influence on the motor cortex is inhibitory, in contrast to the cerebellum normally exerts a facilitatory influence onThe motor cortex, which induces changes of intracortical excitability mainly in the affected hemisphere.
Abstract: Introduction A stroke may modulate motor cortex excitability. We examined if distinct ischemic brain lesions are associated with a specific pattern of excitability changes. We also investigated the effects of a rehabilitative therapy on motor excitability. Methods In stroke patients, the consequences of a) a lesion in the central somatosensory system, b) a cerebellar lesion and c) a two week period of Constraint-induced movement therapy (CIMT), on motor cortex excitability were studied. Transcranial magnetic stimulation techniques and functional magnetic resonance imaging (fMRI) were employed. Results Patients with a lesion in the primary somatosensory cortex or in the ventroposterolateral nucleus of the thalamus had a decreased intracortical inhibition on the affected side. Patients with lesions in the territory of the superior cerebellar artery had a loss of intracortical facilitation and an increase of intracortical inhibition. Patients with cortical lesions undergoing CIMT had a loss of intracortical inhibition prior to therapy. After CIMT, changes of ICI were stronger in the lesioned than in the non-lesioned hemisphere but could result either in an increase of ICI or a reduction of ICI. In three patients fMRI results showed that cortical activation was less post CIMT as compared to pre-treatment activation. In parallel, ICI was reduced after treatment. Conclusions Our results suggest that, physiologically, central somatosensory influence on the motor cortex is inhibitory. In contrast, the cerebellum normally exerts a facilitatory influence on the motor cortex. CIMT induces changes of intracortical excitability mainly in the affected hemisphere.

91 citations

Journal ArticleDOI
TL;DR: Normal corepresentation of nondominant dorsum hand (radial) inputs with the dominant (median or ulnar) inputs in the glabrous hand surface representation provides a clear vehicle for the biased patterns of reorganization occurring after peripheral nerve section.
Abstract: 1. The pattern of reorganization in area 3b of adult primates after median or ulnar nerve section suggests that somatic afferents from the dorsum of the hand, carried by the radial nerve, have preferential access to the cortical territories normally expressing glabrous inputs carried by the median and ulnar nerves. A likely mechanism underlying preferential access is preexisting, but silent, radial nerve inputs to the glabrous region of cortex. 2. We tested this by comparing the effects of electrical stimulation of median or ulnar versus radial nerves, on responses in the hand representation of area 3b. Laminar current source density and multiunit activity profiles were sampled with the use of linear array multicontact electrodes spanning the laminae of area 3b. Data were obtained from three squirrel monkeys anesthetized during recording. 3. Compared with colocated median or ulnar nerve responses, the radial nerve response had 1) an initial short-latency response in the middle laminae that was subtle; there was a small transmembrane current flow component without a discernable multiunit activity correlate; and 2) a laminar sequence and distribution of activity that was similar to those of the median or ulnar nerve responses (i.e., initial activation of the middle, followed by upper and lower laminae), but the significant current flow and multiunit response to radial nerve stimulation occurs 12-15 ms later. 4. Normal corepresentation of nondominant dorsum hand (radial) inputs with the dominant (median or ulnar) inputs in the glabrous hand surface representation provides a clear vehicle for the biased patterns of reorganization occurring after peripheral nerve section. The initial, "subtle" activity phase in the nondominant response is believed to reflect intracortical inhibition, and the later "significant" response phase, a rebound excitation, possibly compounded by an indirect or extralemniscal input. The spatiotemporal pattern of nondominant input is proposed to play a role in normal somatosensory perception.

90 citations

Journal ArticleDOI
TL;DR: Evidence in mice is provided that gamma oscillations causally contribute to pain perception, and a mechanistic framework for modulation of pain by specific activity patterns in the S1 cortex is described.
Abstract: In humans, gamma-band oscillations in the primary somatosensory cortex (S1) correlate with subjective pain perception. However, functional contributions to pain and the nature of underlying circuits are unclear. Here we report that gamma oscillations, but not other rhythms, are specifically strengthened independently of any motor component in the S1 cortex of mice during nociception. Moreover, mice with inflammatory pain show elevated resting gamma and alpha activity and increased gamma power in response to sub-threshold stimuli, in association with behavioral nociceptive hypersensitivity. Inducing gamma oscillations via optogenetic activation of parvalbumin-expressing inhibitory interneurons in the S1 cortex enhances nociceptive sensitivity and induces aversive avoidance behavior. Activity mapping identified a network of prefrontal cortical and subcortical centers whilst morphological tracing and pharmacological studies demonstrate the requirement of descending serotonergic facilitatory pathways in these pain-related behaviors. This study thus describes a mechanistic framework for modulation of pain by specific activity patterns in the S1 cortex. Gamma oscillations in somatosensory areas in humans correlate with pain perception and pain stimulus intensity, but could also reflect cognitive processes such as attention. Here the authors provide evidence in mice that these oscillations causally contribute to pain perception.

90 citations

BookDOI
01 Jan 1996
TL;DR: Structural basis of information processing and neocortical neurotransmitters, and form processing and attention effects in the somatosensory system.
Abstract: Structural basis of information processing and neocortical neurotransmitters.- Divergence of thalamocortical projections and limits on somatosensory cortical plasticity.- Inhibitory circuitry in relation to the functional organization of somatosensory cortex.- Pain, temperature, and the sense of the body.- The functional role of a noninactivating sodium current in neocortical neurons.- Psychophysics of somatosensation.- Information processing channels in the sense of touch.- A novel approach for studying direction discrimination.- Tactile directional sensibility theoretical and functional aspects.- Experimental assessment of the temporal hypothesis of velocity scaling.- Vibrotactile adaptation of the RA system: A psychophysical analysis.- Tactile neural codes for the shapes and orientations of objects.- Tactual discrimination of softness: Abilities and mechanisms.- Representation of the shape and contact force of handled objects in populations of cutaneous afferents.- Haptic object processing I: Early perceptual features.- Haptic object identification II: Purposive exploration.- Cortical representation of somatosensation.- The somatosensory cortex.- The organization of lateral somatosensory cortex in primates and other mammals.- Serial processing in the somatosensory system of macaques.- Parallel processing in somatosensory areas I and II of the cerebral cortex.- Linearity as the basic law of psychophysics: Evidence from studies of the neural mechanisms of roughness magnitude estimation.- Form processing and attention effects in the somatosensory system.- Functional plasticity of cortical representations of the hand.- Sensory-motor interface.- Somatosensory signals and sensorimotor transformations in reactive control of grasp.- Strain-sensitive mechanoreceptors in the human skin provide kinaesthetic information.- A second tactile system in the human skin with unmyelinated primary afferents.- Factors influencing the perception of tactile stimuli during movement.- Changing the intended direction of movement.- Disturbances of motor behavior after parietal lobe lesions in the human.- Neuronal population behavior: Imaging techniques.- PET and fMRI scans of the cerebral cortex in humans and single neuron responses from SI in monkeys to rubbing embossed dot and grating patterns across a fingerpad.- Magnetic resonance functional mapping of cortical activation associated with differing sensorimotor hand paradigms.- Whole-head neuromagnetic recordings of human somatosensory cortical functions.- Optical imaging of intrinsic signals in somatosensory cortex.- Somatosensory and frontal cortical processing during pain experience.- Cortical Neurocomputation and modelling.- Local receptive field diversity within cortical neuronal populations.- Functional segregation and integration in the nervous system: Theory and models.

90 citations

Journal ArticleDOI
01 Dec 2002-Pain
TL;DR: This study strongly corroborates the posterior insular cortex as the primary somatosensory area for cortical processing of cold sensation and supports the role of SII and the cingulate cortex in mediating freeze‐pain.
Abstract: Clinical findings and recent non-invasive functional imaging studies pinpoint the insular cortex as the crucial brain area involved in cold sensation. By contrast, the role of primary (SI) and secondary (SII) somatosensory cortices in central processing of cold is controversial. So far, temporal activation patterns of cortical areas involved in cold processing have not been examined. Using magnetoencephalography, we studied, in seven healthy subjects, the temporo-spatial dynamics of brain processes evoked by innocuous and noxious cold stimulation as compared to tactile stimuli. For this purpose, a newly designed and magnetically silent cold-stimulator was employed. In separate runs, cold and painful cold stimuli were delivered to the dorsum of the right hand. Tactile afferents were stimulated by pneumatic tactile stimulation. Following innocuous cold stimulation (Δ T =5±0.3°C in 50±2 ms), magnetic source imaging revealed an exclusive activation of the contra- and ipsilateral posterior insular cortex. The mean peak latencies were 194.3±38.1 and 241.0±31.7 ms for the response in the ipsi- and contralateral insular cortex, respectively. Based on the measurement of onset latencies, the estimated conduction velocity of peripheral nerve fibres mediating cold fell in the range of Aδ-fibres (7.4±0.8 m/s). Noxious cold stimulation (Δ T =35±5°C in 70±12 ms) initially activated the contra- and ipsilateral insular cortices in the same latency ranges as innocuous cold stimuli. Additionally, we found an activation of the contra- and ipsilateral SII areas (peak latencies 304±22.7 and 310.1±19.4 ms, respectively) and a variable activation of the cingulate cortex. Notably, neither cold- nor painful cold stimulation produced an activation of SI. By contrast, the evoked cortical responses following tactile stimulation could be located to the contralateral SI cortex and bilateral SII. In conclusion, this study strongly corroborates the posterior insular cortex as the primary somatosensory area for cortical processing of cold sensation. Furthermore, it supports the role of SII and the cingulate cortex in mediating freeze-pain. Therefore, these results suggest different processing of cold, freeze-pain and touch in the human brain.

90 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023463
2022986
2021238
2020233
2019234