EYE TRACKING ABNORMALITIES IN SCHIZOPHRENIA - EVIDENCE FOR DYSFUNCTION IN THE FRONTAL EYE FIELDS

Background: Eye tracking deficits are robust abnormalities in schizoph renia, bur the neurobiological disturbance underlying these deficits i s not known. Methods: To clarify the pathophysiology of eye tracking d isturbances in schizophrenia, we tested 12 first-episode treatment-nai ve schizophrenic patients and 10 matched healthy individuals on foveof ugal and foveopetal step-ramp pursuit tasks. Results: On foveopetal ta sks, the initiation of pursuit eye movements was delayed in schizophre nic patients, and their steady-state pursuit gain was reduced particul arly at slower target speeds (8 and 16 deg/sec), In foveofugal step-ra mp tasks, their primary catch-lip saccades were normal in latency and accuracy, but their postsaccadic pursuit in the first 100 msec after t he primary catch-up saccade was significantly reduced even relative to their slow steady-state pursuit, especially during and immediately af ter an acute episode of illness. Conclusions: These observations indic ate that motion-sensitive areas in posterior temporal cortex provide s ufficiently intact information about moving targets to guide accurate catch-rep saccades, but that the sensory processing of motion informat ion is not being used effectively for pursuit eye movements. Low-gain pursuit after the early stage of pursuit initiation suggests that the use of extraretinal signals about target motion (e,g,, anticipatory pr ediction) only partially compensates for this deficit. The pattern of low-gain pursuit, impaired pursuit initiation, and intact processing o f motion information for catch-lip saccades but not pursuit eye moveme nts, was consistent in the schizophrenic patients rested at five time points over a 2-year follow-up period, and implicates the frontal eye fields or their efferent or afferent pathways in the pathophysiology o f eye tracking abnormalities in schizophrenia. Biol Psychiatry 1998;34 :698-708 (C) 1998 Society of Biological Psychiatry.