ABNORMALITIES OF SMOOTH PURSUIT AND SACCADIC CONTROL IN SCHIZOPHRENIA AND AFFECTIVE-DISORDERS

Smooth pursuit abnormalities have been reported in patients with schizophrenia and their first-degree relatives, suggesting that abnormal tracking may serve as a biological marker for schizophrenia. Recent studies in schizophrenic patients have found reduced pursuit gain, low initial acceleration and abnormal gain-corrective saccade interactions. Impaired saccadic initiation has been noted in anti-saccade tasks and in predictive saccade generation, as has saccadic hypometria. While abnormalities have been found in affective disorder patients, studies of their first-degree relatives suggest that abnormalities during pursuit are more closely associated with schizophrenia. Identification of specific defects allows informed speculation about their neural substrates and suggests possible relationships between the ocular motor defects and other cognitive and perceptual abnormalities associated with the major psychiatric disorders.