Among the anomalies associated with schizophrenic disorders are impaired antisaccadic test performance and amplitude reductions of the contingent negative variation (CNV). Before forewarned saccadic responses, a slow surface-negative potential similar to the CNV, the presaccadic negativity (PSN), arises. In the present study, we examined the topography of the PSN in schizophrenic and healthy participants during the execution of pro- and antisaccades.

Seventeen medicated patients with an ICD-10 schizophrenia diagnosis (F20; mean age 29.8 y, range 20 - 47; 12 male) and nineteen healthy controls (mean age 31.3 y, range 20 - 51; 13 male) matched with patients for age, sex, and eduction participated in our study. Horizontal pro- and anti-saccades were elicited in 4 blocks of 80 trials each (ABBA design; 40 stimuli to either side in each block; SOA = 3.5 s). The EEG was recorded from 32 channels with a Nihon Kohden AC amplifier (sample rate 256 Hz, time constant 10 s).

The results reveal the following statistically significant effects for the scalp potential data (ps < 0.05). Under all conditions and in all groups a PSN with a topographical maximum over the vertex arises. Schizophrenic patients exhibit generally reduced PSN amplitudes. The PSN is larger before anti- as compared to prosaccades in healthy controls but not in schizophrenic patients. Our results suggest impaired modulation of preparatory cortical activity in schizophrenic patients.

Research was supported by the Deutsche Forschungsgemeinschaft (DFG; Kl 985/6-1)