Large-Scale Reorganization in the Somatosensory Cortex and Thalamus after Sensory Loss in Macaque Monkeys
TLDR
A comparison of the extents of deafferentation across the monkeys shows that even if the dorsal column lesion is partial, preserving most of the hand representation, it is sufficient to induce an expansion of the face representation.Abstract:
Adult brains undergo large-scale plastic changes after peripheral and central injuries. Although it has been shown that both the cortical and thalamic representations can reorganize, uncertainties exist regarding the extent, nature, and time course of changes at each level. We have determined how cortical representations in the somatosensory area 3b and the ventroposterior (VP) nucleus of thalamus are affected by long standing unilateral dorsal column lesions at cervical levels in macaque monkeys. In monkeys with recovery periods of 22-23 months, the intact face inputs expanded into the deafferented hand region of area 3b after complete or partial lesions of the dorsal columns. The expansion of the face region could extend all the way medially into the leg and foot representations. In the same monkeys, similar expansions of the face representation take place in the VP nucleus of the thalamus, indicating that both these processing levels undergo similar reorganizations. The receptive fields of the expanded representations were similar in somatosensory cortex and thalamus. In two monkeys, we determined the extent of the brain reorganization immediately after dorsal column lesions. In these monkeys, the deafferented regions of area 3b and the VP nucleus became unresponsive to the peripheral touch immediately after the lesion. No reorganization was seen in the cortex or the VP nucleus. A comparison of the extents of deafferentation across the monkeys shows that even if the dorsal column lesion is partial, preserving most of the hand representation, it is sufficient to induce an expansion of the face representation.read more
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References
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Hand/Face Border as a Limiting Boundary in the Body Representation in Monkey Somatosensory Cortex
TL;DR: Electrophysiological mapping demonstrated the finer details of the representations of the hand, lower jaw, neck, and face in area 3b of normal macaque monkeys, and horizontal intracortical connections may form one substrate for representational plasticity in somatosensory cortex.
Journal ArticleDOI
Thalamic and Cortical Contributions to Neural Plasticity After Limb Amputation
TL;DR: Thalamic changes produced by limb amputation appear to be an important substrate of cortical reorganization, and a decrease in the frequency of abnormal stump/face fields in area 3b compared with VP and a reduction in the size of the fields suggests that cortical mechanisms of plasticity may refine the information relayed from thalamus.
Journal ArticleDOI
Pattern of peripheral deafferentation predicts reorganizational limits in adult primate somatosensory cortex.
TL;DR: The reorganization that can occur in somatosensory cortex following peripheral sensory loss is constrained by the precise content of the stimulus deprivation; that is, there is a limit to the set of new receptive fields cortical neurons can acquire.
Journal ArticleDOI
Remote activation of referred phantom sensation and cortical reorganization in human upper extremity amputees
Sabine M. Grüsser,W. Mühlnickel,Michael Schaefer,Kersten Villringer,Christoph Christmann,Caroline Koeppe,Herta Flor +6 more
TL;DR: The elicitation of phantom sensation in the arm by stimulation in the lower body part both ipsi- and contralateral to the amputation in two arm amputees is reported, suggesting that cortical structures other than SI might be contributing to the phenomenon of referred sensation.
Journal ArticleDOI
Limits on plasticity in somatosensory cortex of adult rats: hindlimb cortex is not reactivated after dorsal column section.
TL;DR: The results indicate that forelimb inputs do not substitute for missing hind Limb inputs in primary somatosensory cortex in rats and that the potential for somatotopic reorganization is more limited than previously thought.