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Abstract:
After amputation of an arm the sensory input from the face
begins to activate the denervated hand territory in the Penfield
humunculus. Touching the face in some of these patients evokes
sensations referred to the missing (phantom) limb (Ramachandran et
al., 1992). We now report that a similar remapping effect may occur
in human patients after stroke. We examined a 56 year-old male who
sustained a left pontine hemorrhagic stroke and developed right
hemiparesis. The sensory examination revealed a glove-like
anesthesia affecting the right hand, forearm, and distal arm, and
parts of the right leg. Surprisingly, stimuli administered to some
skin regions of the right arm produced referred sensations, e.g.,
light touch stimuli delivered to the right thumb and index finger
were referred to the right knee, and light touch stimuli to the
right middle finger were referred to the right thigh. We conclude
(1) adult sensory areas retains a tremendous amount of latent
plasticity in humans following stroke. (2) Some hitherto
unexplained sensory phenomena in neurology can be explained in
terms of the same kinds of massive reorganization of sensory
pathways that is known to occur in amputees.
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