SACCADIC AND ATTENTIONAL ABNORMALITIES IN PATIENTS WITH SCHIZOPHRENIA

Background. Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of re flexive attentional shifts. The aim of the study was to investigate wh ether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur w hen attentional shifts were made without eye movements (e.g. covert at tentional shifts). Methods. Fifteen medicated patients with chronic sc hizophrenia and 15 matched controls performed the antisaccade task and the covert orientating task (COVAT) where the probability of targets appearing at the same location of a peripheral cue was varied so that voluntary and reflexive orientating systems had the same goal (80 % pr obability of target and cued condition) or opposite goals (20 % probab ility of target at cued location). A condition where only reflexive or ientating was initiated was also included (50% probability of target a t cued location). For each of these conditions the stimulus onset asyn chrony (SOA) varied between 150 and 350 ms. Results, Patients with sch izophrenia showed normal latency and accuracy for visually guided sacc ades but increased error rates and latency on the antisaccade task. Fo r the COVAT, patients with schizophrenia were unable to use voluntary orientating strategies to inhibit reflexive shifts of covert attention . On conditions where only reflexive orientating was required or when the goals of the reflexive and voluntary orientating systems were the same, patients with schizophrenia showed normal performance. Conclusio ns. These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a re duced ability to utilize the voluntary orientating mode to control or inhibit reflexive orientating. This impairment of voluntary control is evident for both overt and covert attentional shifts.