Saccadic distractibility in first-episode schizophrenia

Abstract

In the antisaccade paradigm, subjects are instructed to fixate a central point, and then move their eyes towards a position in space in the opposite direction but equidistant to a peripheral, sudden onset target. Antisaccade errors occur when subjects are “distracted” by the target and make a saccade towards it. These errors are more common in patients with schizophrenia but the underlying cause remains unclear. To determine whether antisaccade errors simply reflect a general inability to maintain fixation or are the consequence of a more specific deficit in the strategic control of internally generated actions, patients with first-episode schizophrenia and healthy controls performed three saccadic paradigms which shared the core feature of requiring a prepotent saccade to be suppressed, but varied in their concurrent cognitive demands. We found that both groups showed an increase in errors as the cognitive demands increased across task. However, this increase was significantly steeper in the schizophrenic patients than in the controls. We also found that schizophrenic patients were as able as controls to inhibit prepotent saccades towards a target in a paradigm with no other cognitive demands. Possible explanations of these results include reduced working memory resources and impaired motor preparation in schizophrenia.