Functional Brain Reorganization in stroke Recovery

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The process of recovery of basic sensory, motor, and higher cognitive and linguistic functions, following stroke, is not well understood. Also poorly understood are the neurophysiological mechanisms that mediate the effectiveness of therapies, like the Constraint-Induced Therapy (CIT), which are reputed to enhance the recovery process. It has been suggested, however, that, fundamentally, recovery is a result of functional reorganization of the brain. Before the advent of functional neuroimaging, evidence supporting this notion consisted entirely of indirect inferences from clinical or behavioral data. Recently, however, we and others, using Magnetoencephalography (MEG) and other functional neuroimaging methods, have begun accumulating direct evidence of brain plasticity and functional reorganization. In this Program Project we plan to investigate systematically the extent and type of reorganization, using MEG-derived brain activation profiles, during spontaneous recovery from stroke, of the following behavioral and cognitive functions: First, expressive and receptive language; second, motor; and third, somatosensory and spatial attention functions. We also plan to study the effects of CIT used to enhance the recovery process of language and sensorimotor functions, on these activation profiles. We expect that the extent and type of reorganization observed will vary as a function of lesion parameters, assessed through structural MRI, and neuropsychological testing. Finally, we will attempt to specify the repercussions of reorganization of the mechanisms of the compromised functions for the mechanisms of functions unaffected by the stroke using, once again, MEG mapping.