The corpus callosum, interhemisphere interactions, and the function of the right hemisphere of the brain.

A complex clinical-neuropsychological study was performed by the Luriya method before and after surgery in 36 patients with arteriovenous malformations (AVM) of the corpus callosum. The symptoms of local lesions to the various parts of the corpus callosum are described. Symptoms of partial lesioning of the corpus callosum were found to be modality-specific, though only relatively. The symptoms of dyscopia or dysgraphia could appear in isolation fro each other. Combined lesions of the medial parts of the brain (cingulate cortex, frontal lobes) and the corpus callosum significantly increased the level of dysfunction of these medial parts. Patients with lesions to the anterior parts of the corpus callosum showed symptoms of frontal lobe dysfunction. Lesions to the corpus callosum led to dysfunction of the right hemisphere in the spheres of emotion, perception, and spatial activity. Previous studies have demonstrated that the right hemisphere integrates impulses from both sides of the space and is the first zone involved in activity, performing its initial stages. The author believes that this synthetic activity of the right hemisphere, with tight connections with the "conscious" left hemisphere, is required for the formation of the overall conceptualization of both individual objects and particular types of activity. From this point of view, it is the right hemisphere that can, in a sense, be regarded as dominant, rather than the left hemisphere.