Abnormal functional motor lateralization in healthy siblings of patients with schizophrenia

Earlier neuroimaging studies of motor function in schizophrenia have demonstrated reduced functional lateralization in themotor network duringmotor tasks. Here, we used event-related functionalmagnetic resonance imaging during a visually guided motor task in 18 clinically unaffected siblings of patients with schizophrenia and 24 matched controls to investigate if abnormal functional lateralization is related to genetic risk for this brain disorder. Whereas activity associated withmotor task performance wasmainly contralateral with only a marginal ipsilateral component in healthy participants, unaffected siblings had strong bilateral activity with significantly greater response in ipsilateral and contralateral premotor areas aswell as in contralateral subcortical motor regions relative to controls. Reduced lateralization in siblingswas also identified with ameasure of laterality quotient. These findings suggest that abnormal functional lateralization of motor circuitry is related to genetic risk of schizophrenia.