PERSISTENCE OR PLASTICITY: EXAMINING HAND REPRESENTATIONS SUBSEQUENT TO CORTICOSPINAL TRACT LESIONS USING FMRI
Date
2019-05
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University of Delaware
Abstract
It has been widely accepted that plastic changes occur after damage to the brain to aid in functional and structural recovery. While there is ample evidence that plastic changes do indeed occur after damage, there is also evidence that certain representations within the brain may be preserved and unaffected by plasticity. Neural correlates of phantom limbs have been studied in depth, but no literature exists on the representations of paralyzed limbs in stroke patients after subcortical stroke resulting in hemiparesis. We utilized Representational Similarity Analysis to compare hand representations in primary motor (M1) and sensorimotor (S1) cortices of subcortical stroke patients to address the extent to which paralyzed hands representations are maintained after years of paralysis. Two patients (n = 2) with lesions to the corticospinal tract and intact motor cortices underwent functional MRI runs in which they were asked to perform individual digit movements on both hands. Functional activity for intact and paralyzed limb movements were then analyzed using RSA to map out hand representations in terms of inter-digit relationships. Paralyzed hand representations in both contralateral M1 and S1were found to be organized in a manner consistent with those of normally working hands. The ability to decode the digit relationships of a hand during “movements” of paralyzed limbs demonstrates that hand representations are preserved in M1 and S1 even after years of paralysis. This facilitates an investigation into the role of peripheral signals in maintaining the function and structure of bodily representations after brain damage.
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Keywords
Neuroscience, Hand representations, Corticalspina tract lesions,FMRI