Sensory maps in the human brain

Yang, Tony T.; Gallen, Christopher C.; Schwartz, Barry J.; Bloom, Floyd E.; Ramachandran, Vilayanur S.; Cobb, Steve

doi:10.1038/368592b0

Cited by 145 publications

(68 citation statements)

References 7 publications

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“…In patient FA, on the other hand, the maps showed a striking asymmetry caused, presumably, by the reorganized pathways in the left hemisphere. The "hand" area in the left hemisphere could no longer be discerned and this area could be activated by touching either the lower face or the "map" in his upper arm 10 cm above the line of amputation (49). If this effect is confirmed on additional patients, it would represent the first direct evidence for somatosensory remapping in human subjects spanning such large distances.…”

Section: Meg Correlates Of Remappingmentioning

confidence: 95%

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Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

Ramachandran

1993

Proc. Natl. Acad. Sci. U.S.A.

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Section: Meg Correlates Of Remappingmentioning

confidence: 95%

“…Obviously, MEG studies could also be useful in exploring remapping effects of the kind observed by Pons et al (33) and our group has recently undertaken such a study (49) in collaboration with Christopher Gallen and Tony Yang. Preliminary evidence from a single patient indicates that such remapping does indeed occur.…”

Section: Meg Correlates Of Remappingmentioning

confidence: 99%

Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

Ramachandran

1993

Proc. Natl. Acad. Sci. U.S.A.

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273

112

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“…Primary sensory and motor areas demonstrate functional plasticity in response to injury even in adults (32)(33)(34)(35)(36). SII directly connects not only with the ventral posterior nucleus of the thalamus (37,38), but also with SI in nonhuman primates (39).…”

Section: Discussionmentioning

confidence: 99%

An fMRI study of somatosensory‐implicated acupuncture points in stable somatosensory stroke patients

Jack

Yang

2006

Magnetic Resonance Imaging

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Purpose: To assess differences in brain responses between stroke patients and controls to tactile and electrical acupuncture stimulation using functional MRI (fMRI). Materials and Methods:A total of 12 male, clinically stable stroke patients with left side somatosensory deficits, and 12 age-matched male control subjects were studied. fMRI was performed with two different paradigms; namely, tactile stimuli and electrical stimulation at acupuncture points LI4 and LI11 on the affected side of the body. fMRI data were analyzed using SPM99.Results: Tactile stimulation in both patients and controls produced significant activation in primary and secondary sensory and motor cortical areas and cerebellum. Greater activation was present in patients than controls in the somatosensory cortex with both the tactile task and the acupuncture point (acupoint) stimulation. Activation was greater during the tactile task than the acupuncture stimulation in patients and normal controls. Conclusion:Differences observed between patients and controls on both tasks may indicate compensatory over recruitment of neocortical areas involved in somatosensory perception in the stroke patients. The observed differences between patients and controls on the acupoint stimulation task may also indicate that stimulation of acupoints used therapeutically to enhance recovery from stroke, selectively activates areas thought to be involved in mediating recovery from stroke via functional plasticity. fMRI of acupoint stimulation may illustrate the functional substrate of the therapeutically beneficial effect of acupuncture in stroke rehabilitation.

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“…This relationship was not significant for non-painful stimuli. To date, in most experiments concerning cortical reorganization after amputation or dorsal rhizotomy [1,2, 5,6,8], only unilateral effects in the primary somatosensory cortex contralateral to the lesion were studied. The bilaterality of the sites eliciting mislocalization in this study, however, cannot be explained solely on the basis of the generally known invasion of cortical projections from neighbouring areas into the 'amputation' zone.…”

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confidence: 99%

Cortical reorganization in human amputees and mislocalization of painful stimuli to the phantom limb

Knecht

Henningsen

Elbert

et al. 1995

Neuroscience Letters

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In human arm amputees, a significant relationship was found between the amount of reorganization in the primary somato-sensory cortex, and the amount of body surface from which painful stimuli evoked sensations that were perceived to be emanating from the now missing extremity, i.e. the phantom limb. This mislocalization could be evoked almost equally from stimulation of either side of the body. Based on these findings obtained by magnetic source imaging and psychophysical testing in eight amputees, it is concluded that the extent of the generally known cortical reorganization contralateral to the amputation is an indicator of more widespread plastic changes in the brain involving bilateral pathways.Keywords: Amputation; Cortex; Mislocalization; Phantom limb Cortical reorganization has received considerable attention because of its potential relevance to functional outcome following central nervous system injury [1][2][3][4]. Research with monkeys showed that, following removal of input from a portion of the primary somatosensory cortex by either amputation [1] or dorsal rhizotomy [2], there is a topographically systematic 'invasion' of the affected cortical zone by neighbouring cortical areas whose innervation has remained intact. In addition, it was observed that after arm amputation in humans, tactile stimulation of either the trunk or the face ipsilateral to the amputation stump can lead to a point-to-point somatotopic referral of stimuli applied to specific locations on the skin to specific locations on the phantom limb. This phenomenon, termed 'remapping', has been claimed to be the perceptual correlate of cortical reorganization reported in the primate studies [5]. However, in contrast we had previously demonstrated cortical reorganization with magnetic source imaging that was independent of somatotopic remapping after amputation [7].In the present study, we systematically investigated the relation of the amount of cortical reorganization and the amount, rather than the pattern, of mislocalization to the phantom limb. We had earlier found a nearly perfect correlation between cortical reorganization and phantom limb pain, indicating the importance of the nociceptive system for cortical reorganization [6]. In this study, we employed painful stimulation (pinprick) as well as stimulation in three other somesthetic modalities (touch by a cotton applicator, vibration by a tuning fork and heat by a 40°C thermode), in order to compare the capacity of the different modalities to produce mislocalization to the phantom limb. Since pinprick and thermode application also activate touch receptors, sites where the pin or thermode evoked the same referred sensation as the cotton applicator were not considered pain or heat points, respectively. Each of the four different types of stimuli was applied to 30 standard sites bilaterally on the body (ten on 0304-3940/95/$09.50

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Sensory maps in the human brain

Cited by 145 publications

References 7 publications

Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

Behavioral and magnetoencephalographic correlates of plasticity in the adult human brain

An fMRI study of somatosensory‐implicated acupuncture points in stable somatosensory stroke patients

Cortical reorganization in human amputees and mislocalization of painful stimuli to the phantom limb

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