Attentional facilitation of response is impaired for antisaccades but not for saccades in patients with schizophrenia: implications for cortical dysfunction.

The facilitation of response known as the "gap effect" (a decrease of response latency), observed for saccades and antisaccades when attention is modulated prior to such eye movements, was studied in patients with schizophrenia and in controls. The hypothesis tested was whether patients would show a deficient attentional facilitation in response latency. Fifteen patients with schizophrenia and 17 healthy controls performed blocks of saccades and antisaccades in a "gap" condition and an "overlap" condition. Saccade and antisaccade response latencies as well as the error rate for antisaccades were measured for each subject. A similar gap effect (decrease in latency for the gap compared to the overlap condition) was present in the saccade task for patients and controls. In contrast the gap effect in the antisaccade task was absent in 50% of patients compared to none of the controls. This finding was interpreted as indicative of deficient preprocessing in antisaccade-specific cortical areas in schizophrenia (such as the prefrontal cortex), while visually guided saccade processing remained intact. Our results, in addition to many other recent findings, could lead to specific hypotheses on cortical dysfunction in schizophrenia.