Neuronal plasticity in poststroke aphasia: insights by quantitative electroencephalography

After stroke, the interhemispheric reorganization of the neural network implicated in language is hypothesized to be a function not only at the site of the lesion but also of dynamic right hemispheric and subcortical neural systems. These neural systems may have different functional shares in the utilization of particular language tasks. Important insights in language rehabilitation have been gained by quantitative topographical electroencephalography. It has been demonstrated that abnormalities within and outside speech relevant areas are related to restitution of poststroke aphasia. In the ischemic regions they indicate local disturbances, outside they reflect failures in neuronal networks involved in the generation and propagation of the alpha-rhythm. Treatment by a neuromodulatory agent has shown a significant shift of alpha-rhythm from frontal to occipital regions which may be due to a restitution of corticothalamic circuits in parallel to an improvement of neuropsychological scores in different language domains.