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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 ArticleDOI
01 Sep 2000-Brain
TL;DR: These findings indicate that in writer's cramp the sensitivity of sensory input channels from the hand is wrongly set by the central command to move, and the sensory trick, by supplying additional input not usually present during unobstructed movement, is a manoeuvre to correct this imbalance.
Abstract: One characteristic of focal dystonia is the sensory trick, by which sensory input to a certain area of the body can reduce abnormal contractions in muscles nearby. This suggests that adjusting the link between sensory input and movement allows motor commands to be issued more effectively from the brain. To explore this sensorimotor link, we studied the attenuation (gating) of somatosensory evoked potentials (SEPs) before and during hand movements in patients with writer's cramp. For premovement gating, 10 patients and 11 age-matched normal subjects were given a warning sound followed 1s later by an electric stimulus to the right median nerve at the wrist. The latter served both as a reaction signal to start a finger extension task and as the input to evoke SEPs over the scalp. Because reaction times always exceeded 70 ms, short-latency SEPs thus obtained were unaffected by the afferents activated by the movement. The amplitudes of frontal N30 components were significantly decreased over the frontal leads compared with SEPs elicited at rest (P: < 0.002) in the normal group, whereas significant gating was found not for N30 but for frontal P22 (P: = 0. 002) in the patient group. For midmovement gating studies, SEPs to the right median nerve stimulation were recorded in 16 patients and 12 age-matched normal subjects at rest, and during active and passive finger extension-flexion movements. In contrast to the premovement SEPs, the frontal N30 was equally gated during active and passive movements both in the patient (P: < or = 0.002) and the normal group (P: < or = 0.003). These findings indicate that in writer's cramp the sensitivity of sensory input channels from the hand is wrongly set by the central command to move. Perhaps the sensory trick, by supplying additional input not usually present during unobstructed movement, is a manoeuvre to correct this imbalance. Dystonia may result not only from abnormalities in the central motor command but also from disturbed central processing of sensory input.

183 citations

Journal ArticleDOI
TL;DR: The results suggest that projections from the trigeminal system to the cochlear nucleus are increased and/or redistributed after hearing loss, and the finding that only neurons activated by trigaminal stimulation showed increased spontaneous rates after co chlear damage suggests that somatosensory neurons may play a role in the pathogenesis of tinnitus.
Abstract: Multisensory neurons in the dorsal cochlear nucleus (DCN) achieve their bimodal response properties [Shore (2005) Eur. J. Neurosci., 21, 3334-3348] by integrating auditory input via VIIIth nerve fibers with somatosensory input via the axons of cochlear nucleus granule cells [Shore et al. (2000) J. Comp. Neurol., 419, 271-285; Zhou & Shore (2004)J. Neurosci. Res., 78, 901-907]. A unique feature of multisensory neurons is their propensity for receiving cross-modal compensation following sensory deprivation. Thus, we investigated the possibility that reduction of VIIIth nerve input to the cochlear nucleus results in trigeminal system compensation for the loss of auditory inputs. Responses of DCN neurons to trigeminal and bimodal (trigeminal plus acoustic) stimulation were compared in normal and noise-damaged guinea pigs. The guinea pigs with noise-induced hearing loss had significantly lower thresholds, shorter latencies and durations, and increased amplitudes of response to trigeminal stimulation than normal animals. Noise-damaged animals also showed a greater proportion of inhibitory and a smaller proportion of excitatory responses compared with normal. The number of cells exhibiting bimodal integration, as well as the degree of integration, was enhanced after noise damage. In accordance with the greater proportion of inhibitory responses, bimodal integration was entirely suppressive in the noise-damaged animals with no indication of the bimodal enhancement observed in a sub-set of normal DCN neurons. These results suggest that projections from the trigeminal system to the cochlear nucleus are increased and/or redistributed after hearing loss. Furthermore, the finding that only neurons activated by trigeminal stimulation showed increased spontaneous rates after cochlear damage suggests that somatosensory neurons may play a role in the pathogenesis of tinnitus.

183 citations

Journal ArticleDOI
TL;DR: It is reconfirmed that a significant number--at least one-third--of motor responses are distributed outside the classic narrow cortical strip, and indicates that primary motor cortex may extend beyond the gyrus immediately anterior to the Rf.
Abstract: Classic neurosurgical teaching holds that once the Rolandic fissure (Rf) has been located, there are distinct differentiated primary motor and sensory functional units confined within a narrow cortical strip: Brodmann's Areas 4 and 6 for primary motor units in front of the Rf and 3, 1, and 2 for sensory units behind the Rf. To test this assumption, we examined in detail the records of cortical mapping done by electrical stimulation of the cerebral cortex via implanted subdural electrode grids in 35 patients with seizure disorders. Of 1381 stimulations of the electrode sites, 346 (25.1%) produced primary motor or motor-arrest and sensory responses in contralateral body parts: 56.8% were primary motor responses; 16.2% were motor-arrest; 22.5% were sensory; and the remaining 4.5% were mixed motor and sensory responses. Two-thirds (65.9%) of the primary motor responses were located within 10 mm of the Rf, and the remaining one-third (34.1%) were more than 10 mm anterior to the Rf or were posterior to the Rf. Furthermore, in the patient group with brain lesions, fewer than one-third (28.1%) of the responses were within the 10-mm narrow anterior strip. Our study reconfirmed that a significant number--at least one-third--of motor responses are distributed outside the classic narrow cortical strip. In patients with brain lesions, the motor representation is further displaced outside the narrow strip. This finding indicates that primary motor cortex may extend beyond the gyrus immediately anterior to the Rf.

183 citations

Journal ArticleDOI
TL;DR: The results support the hypothesis that the nervous system uses augmented sensory information differently depending both on the environment and on individual proclivities to rely on vestibular, somatosensory or visual information to control sway.
Abstract: The importance of sensory feedback for postural control in stance is evident from the balance improvements occurring when sensory information from the vestibular, somatosensory, and visual systems is available. However, the extent to which also audio-biofeedback (ABF) information can improve balance has not been determined. It is also unknown why additional artificial sensory feedback is more effective for some subjects than others and in some environmental contexts than others. The aim of this study was to determine the relative effectiveness of an ABF system to reduce postural sway in stance in healthy control subjects and in subjects with bilateral vestibular loss, under conditions of reduced vestibular, visual, and somatosensory inputs. This ABF system used a threshold region and non-linear scaling parameters customized for each individual, to provide subjects with pitch and volume coding of their body sway. ABF had the largest effect on reducing the body sway of the subjects with bilateral vestibular loss when the environment provided limited visual and somatosensory information; it had the smallest effect on reducing the sway of subjects with bilateral vestibular loss, when the environment provided full somatosensory information. The extent that all subjects substituted ABF information for their loss of sensory information was related to the extent that each subject was visually dependent or somatosensory-dependent for their postural control. Comparison of postural sway under a variety of sensory conditions suggests that patients with profound bilateral loss of vestibular function show larger than normal information redundancy among the remaining senses and ABF of trunk sway. The results support the hypothesis that the nervous system uses augmented sensory information differently depending both on the environment and on individual proclivities to rely on vestibular, somatosensory or visual information to control sway.

183 citations

Book ChapterDOI
TL;DR: Investigation of postural stabilization in altered visual, vestibular, and somatosensory conditions in humans subjected to either a fast unidirectional displacement or to a continuous sinusoidal movement of the standing support found no significant changes in the parameters of biomechanical parameters or in the responses of the anterior tibial and triceps surae muscles.
Abstract: Postural stabilization in altered visual, vestibular, and somatosensory conditions was investigated in humans subjected to either a fast unidirectional displacement or to a continuous sinusoidal movement of the standing support. Visual inputs were varied in four ways: (1)stroboscopic illumination, (2)stabilizing the visual surround with respect to head movements, (3)inducing apparent body movement in pitch using stripe patterns which moved continuously up or down in front of the subject, (4)eye closure. Static vestibular (and neck) input was modified by bending the head forwards or backwards, or to the right or left shoulder with the eyes closed. Somatosensory input from both feet was reduced by an ischaemic block at a level just above the ankle joints. With fast, transient, toe-up platform displacements (high-frequency test) neither the biomechanical parameters as measured by the displacement of the centre of foot pressure nor the early EMG responses of the anterior tibial and triceps surae muscles were modified by a manipulation of visual, vestibular or somatosensory feedback conditions. Sudden disturbances are obviously compensated by an early set of reflex-like muscle responses that, depending on the starting position, are stereotypically released without feedback control to save time at the expence of accuracy (emergency reaction). Continuous regulation of upright stance during sinusoidal displacement at 1 or 0.3 Hz (low-frequency test), however, clearly depends on visual, vestibular, and somatosensory feedback. Studies in patients should contain both tests, since each examines different functions of the very complex posture stabilizing network. Manipulations of sensory feedback, however, are only recommended in the low-frequency test. The experimental suppression or disturbance by disease of two of the three feedback loops invariably causes a conspicuous postural instability.

183 citations


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