Abnormalities of smooth pursuit eye movements have been consistently shown to be related to schizophrenia. Purely saccadic abnormalities have been reported as well. Rapidly developing technologies in oculomotor assessment no make it possible to pursue these pioneering efforts which amount to one of the strongest relationships between the clinical diagnosis of schizophrenia and brain function. The proposal will advance knowledge of eye movements in schizophrenia. At present, the specific disturbances of oculomotor physiology are not clear, and it is also not clear whether disturbances in attentional systems are responsible for observed oculomotor deficits. Furthermore, relationships in schizophrenia between smooth pursuit abnormalities and saccadic abnormalities are not well understood. The availability of well developed eye movement tasks from animal and neurologic research provides an opportunity to assess both saccadic and smooth pursuit function in detail (although saccadic control pathways are probably better anatomically defined than are smooth pursuit control circuits). Because of evidence for anterior cortical dysfunction in schizophrenia, the saccadic tasks are designed to assess the relative contributions of anterior and posterior cortex to the control of more voluntary versus more reflexive types of eye movements. Paradigms that allow testing the ability to disengage and redirect visual attention irrespective of an ocular motor response will also be used. It is hypothesized that schizophrenic patients will show particular abnormalities on saccade tests that depend on internally goal-guided, volitional control; and, furthermore, that such abnormalities are not simply manifestations of other alterations in the maintaining, disengaging, or redirecting of attention. Both initiation and steady state phases of smooth pursuit will be assessed. The predictive component of steady state pursuit will be examined, and is hypothesized to be related to higher order saccadic abnormalities. Oscillations will also be examined in pursuit tasks. Sixty schizophrenic patients, 40 bipolar, and 40 normal controls will be tested. Eye movement abnormalities appear to be genetically related to schizophrenia. Improved specification of these abnormalities and related brain systems will advance development of epidemiologic and family pedigree research on the neurobiology of schizophrenia. Better understanding of brain function and malfunction in schizophrenia and bipolar disorder might ultimately lead to effective screening and preventive interventions.
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