Predominant sensorimotor area left hemisphere dysfunction in schizophrenia measured by brain electrical activity mapping

Using a newly developed system of brain electrical activity mapping (Alvar Electronics, Paris), we studied 10 right-handed, schizophrenic subjects who had been treated with neuroleptics (5 of the disordered and 5 of the paranoid type) and compared them with 10 controls by applying a cortical activation schedule involving a multisensorimotor coordination task. All tasks were referenced to resting states after a specially designed relaxation program. In schizophrenics, we found high, predominantly bifrontal, delta and theta power values, which is in agreement with the literature, and low beta power values, which are possibly due to the neuroleptic treatment. The major result, however, was a widespread left hemisphere dysfunction during multisensorimotor activation, with a predominance over the primary sensory and motor cortical areas. The area of the supplementary motor regions was not affected. Combined with the evidence of genetic and psychometric studies, our results lend further support to the hypothesis that left hemisphere functioning in schizophrenia is impaired. They also suggest that there is a special and independent sensory and motor processing system impairment in schizophrenia.