There is an evolving understanding that neuronal cortical connections can be altered and remodeled following injury to the central nervous system. Humans with stroke frequently show recovery of function that seems to be correlated with activation of regions both in the peri-infarct zone as well as in the hemisphere opposite to the stroke. Cerebral ischemic injury in animals is accompanied by hyperexcitability in tissue surrounding the ischemic core and frequently in homologous regions of the contralateral cortex. There is clinical and behavioral data showing that the degree of recovery can be altered using sensory augmentation including enriched environments and task-specific training. Recovery following chronic stroke can also be improved with pharmacological treatment, with the recovery dependent on activity during treatment. We will use hemodynamic image mapping to examine the reorganization of the brain following a focal cerebral ischemic insult and correlate this reorganization with behavioral recovery. Focal ischemia/reperfusion will be achieved using a compression model that results in ischemic damage confined to the posteriomedial barrel subfield of the first somatosensory cortex of the rat, and reorganization will be evaluated by examining the changes in the blood flow response maps to vibrissae stimulation. The mystacial vibrissae of the rat, with their corresponding representation in the somatosensory cortex, provides an ideal vehicle for studies dealing with damage and subsequent recovery in the central nervous system. Examination of how the brain reorganizes following ischemia/reperfusion to the rat barrel somatosensory cortex, as opposed to ablative injury, will provide valuable information about strategies for improving recovery following stroke. Strategies for altering reorganization of blood flow and metabolism that will be examined include administration of pharmacological agents and stromal cell, as well as targeted sensory augmentation.
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