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Saccadic and attentional abnormalities in patients with schizophrenia

Published online by Cambridge University Press:  01 September 1998

P. MARUFF
Affiliation:
Neurophysiology and Neurovisual Research Unit and Cognitive Neuropsychiatry Unit, Mental Health Research Institute of Victoria; and Department of Psychiatry, University of Melbourne, Parkville; School of Psychological Science, Faculty of Science and Technology, La Trobe University, Bundoora; and Swinburne University, Melbourne, Victoria; and Brain Research Unit, Drug and Alcohol Services, Westmead Hospital, Sydney, New South Wales, Australia
J. DANCKERT
Affiliation:
Neurophysiology and Neurovisual Research Unit and Cognitive Neuropsychiatry Unit, Mental Health Research Institute of Victoria; and Department of Psychiatry, University of Melbourne, Parkville; School of Psychological Science, Faculty of Science and Technology, La Trobe University, Bundoora; and Swinburne University, Melbourne, Victoria; and Brain Research Unit, Drug and Alcohol Services, Westmead Hospital, Sydney, New South Wales, Australia
C. PANTELIS
Affiliation:
Neurophysiology and Neurovisual Research Unit and Cognitive Neuropsychiatry Unit, Mental Health Research Institute of Victoria; and Department of Psychiatry, University of Melbourne, Parkville; School of Psychological Science, Faculty of Science and Technology, La Trobe University, Bundoora; and Swinburne University, Melbourne, Victoria; and Brain Research Unit, Drug and Alcohol Services, Westmead Hospital, Sydney, New South Wales, Australia
J. CURRIE
Affiliation:
Neurophysiology and Neurovisual Research Unit and Cognitive Neuropsychiatry Unit, Mental Health Research Institute of Victoria; and Department of Psychiatry, University of Melbourne, Parkville; School of Psychological Science, Faculty of Science and Technology, La Trobe University, Bundoora; and Swinburne University, Melbourne, Victoria; and Brain Research Unit, Drug and Alcohol Services, Westmead Hospital, Sydney, New South Wales, Australia

Abstract

Background. Abnormal performance on the antisaccade task suggests that patients with schizophrenia have difficulty with the inhibition of reflexive attentional shifts. The aim of the study was to investigate whether deficits in the inhibition of reflexive attentional shifts were specific to the oculomotor modality or whether they could also occur when attentional shifts were made without eye movements (e.g. covert attentional shifts).

Methods. Fifteen medicated patients with chronic schizophrenia 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% probability of target and cued condition) or opposite goals (20%probability of target at cued location). A condition where only reflexive orientating was initiated was also included (50% probability of target at cued location). For each of these conditions the stimulus onset asynchrony (SOA) varied between 150 and 350 ms.

Results. Patients with schizophrenia showed normal latency and accuracy for visually guided saccades but increased error rates and latency on the antisaccade task. For 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.

Conclusions. These results suggest the reflexive orientating mode is normal in patients with chronic schizophrenia. However, these patients have a reduced 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.

Type
Research Article
Copyright
© 1998 Cambridge University Press

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