[Interhemispheric relations and brain plasticity]

The compensatory role of the contralateral hemisphere in patients with unilateral hemispheric lesions was investigated by a test consisting of learning a maze explored with the index finger commanded by the normal hemisphere. In patients with lesions of the left hemisphere training of the left hand was followed by a better performance of the right hand demonstrating an interhemispheric transfer. The inactivation of the nondominant hemisphere by intracarotid amobarbital injection in aphasic patients is followed by worsening of the verbal performance. This demonstrates the possible compensatory role of the nondominant hemisphere in patients with aphasia. The results are considered to be manifestations of the functional plasticity of the brain.