Hemispheric asymmetries in schizophrenia.

The growing literature on hemispheric asymmetries in schizophrenic populations is critically reviewed. Studies of lateral asymmetries in schizophrenics are discussed which have employed a wide range of methodologies, including assessment of motor, sensory, electrophysiological, neuropsychological, and structural abnormalities. This literature is discussed in relation to two theoretical viewpoints, one emphasizing impaired functioning of the corpus callosum, and the other positing left hemisphere overactivation and dysfunction in schizophrenic populations. It is concluded that the hypothesis of impaired callosal function has not been adequately tested because of methodological problems, the most serious of which is the failure to show differential deficit. The hypothesis of left hemisphere abnormality has gained consistent support, although methodological problems were noted. This research suggests a structural locus for schizophrenic pathology which is consistent with the symptomatology of the disorder, and provides avenues for further research.