Focal stroke in the barrel cortex of rats enhances ipsilateral response to vibrissal input

Brain injury triggers spontaneous plasticity, often resulting in considerable restoration of function. To investigate mechanisms of this compensatory plasticity we followed changes in the brain's pattern of activation evoked by stimulation of vibrissae, after a focal cortical stroke which destroyed the cortical representation of vibrissae, the barrel cortex. The pattern of brain activation was visualized with [14C]-2-doexyglucose (2DG) autoradiography in rats 7 days after photothrombotic stroke. During isotope incorporation, vibrissae contralateral to stroke were stimulated. In control rats this stimulation activates the barrel cortex and the second somatosensory cortex in the contralateral hemisphere. Seven days after stroke in the barrel cortex, significant increases in activation were found in ipsilateral, uninjured hemisphere in the barrel cortex and anterior vibrissae representation, and also in regions not specifically connected to vibrissae stimulation, such as motor and auditory cortex. Shortly after cortical stroke, the intact hemisphere shows higher metabolic activation in several cortical regions, possibly due to abnormal interactions with the injured hemisphere.