Mechanisms underlying functional recovery following stroke.

This article reviews recent evidence from animal experiments indicating that there is considerable potential for reorganization of representations and functions in in sensory and motor cortex following localized lesions or various manipulations of peripheral target structures. Three major mechanisms for this plastic reorganization are considered: unmasking of existing but functionally inactive pathways, sprouting of fibers from surviving neurons and formation of new synapses, and redundancy of CNS circuitry allowing alternative pathways to take over functions. Studies using positron emission tomography or transcranial magnetic stimulation suggest that similar forms of neuroplasticity may occur in the human brain and could contribute to functional recovery following stroke. The potential therapeutic implications are discussed.