Disturbances in the control of saccadic eye movement and eye-head coordination in schizophrenics

Some schizophrenic patients have been known to have frontal cortical dysfunction. In view of the evidence that voluntary purposive eye movements and rapid head movements involve areas of the frontal cortex, investigations of saccade performance have been carried out on schizophrenics in various laboratories. We have compared performance of schizophrenic patients in tasks involving inhibition of reflexive saccades (no-saccade) and initiation of saccades without target (memory-saccade) with performance in the antisaccade task. These measures were also compared with results of eye-head coordination tasks. Schizophrenics showed more errors and significantly longer latencies, with lower peak velocities at large amplitudes, in both the antisaccade task and the memory-saccade task. Performance with coordinated eye-head movement was basically similar, except for significantly longer latencies of head movement. These results suggest that schizophrenics may have a disturbance in initiating and executing purposive saccades without targets, and that dysfunction of the frontal cortex may contribute to this disturbance.