Bimanual coordination in chronic schizophrenia

Anomalies of movement are observed both clinically and experimentally in sc hizophrenia. While the basal ganglia have been implicated in its pathogenes is, the nature of such involvement is equivocal. The basal ganglia may be i nvolved in bimanual coordination through their input to the supplementary m otor area (SMA). While a neglected area of study in schizophrenia. a bimanu al movement task may provide a means of assessing the functional integrity of the motor circuit. Twelve patients with chronic schizophrenia and 12 mat ched control participants performed a bimanual movement task on a set of ve rtically mounted cranks at different speeds (1 and 2 Hz) and phase relation ships. Participants performed in-phase movements (hands separated by 0 degr ees) and out-of-phase movements (hands separated by 180 degrees) at both sp eeds with an external cue on or off. All participants performed the in-phas e movements well. irrespective of speed or cueing conditions. Patients with schizophrenia were unable to perform the out-of-phase movements, particula rly at the faster speed, reverting instead to the in-phase movement. There was no effect of external cueing on any of the movement conditions. These r esults suggest a specific problem of bimanual coordination indicative of SM A dysfunction per se and/or faulty callosal integration. A disturbance in t he ability to switch attention during the out-of-phase task may also be inv olved. (C) 2001 Academic Press.