Rapid Experience-Dependent Plasticity following Somatosensory Damage

Studies in nonhuman primates have provided evidence of rapid neural reorganization in somatosensory cortex after brain damage [1] and amputation [2]. Furthermore, there is also evidence of experience-dependent plasticity in both human [3-5] and nonhuman primates [6] that is induced by repetitive tactile stimulation. Given the evidence of plasticity subsequent to both neural damage and tactile experience, we hypothesized that somatosensory damage could lead to increased levels of experience-dependent tactile plasticity. To examine this hypothesis, the tactile localization judgments of two individuals with left hemisphere somatosensory damage subsequent to stroke were examined. Suprathreshold tactile stimuli were presented to the hand or forearm, and the effect of the location of previous stimulation on localization judgments for subsequent stimuli was examined. Results showed that, only on the contralesional limb, even a single tactile stimulation could induce a significant perceptual shift in localization judgments for subsequent stimuli, with shifts occurring in the direction of the preceding stimulation. These results provide novel evidence of a very rapid time course for substantive perceptual changes in tactile location perception in response to simple stimulation, revealing a highly plastic and dynamic tactile system even many years after neural damage.