Topography of CNV and PINV in schizophrenic patients and healthy subjects during a delayed matching-to-sample task

A multi-channel recording was used to comprehensively examine the topography of the PINV and topographical differences between CNV and PINV in schizophrenic patients and healthy controls: Scalp amplitude and scalp laplacian ICSD} maps of the terminal CNV ItCNVj and PINV, and the time course of the PINV aver four post-imperative intervals (1.0-3.0s after the imperative stimulus) were compared. CNV and PINV were induced in a modified visual delayed matching-te-sample task, in which the pattern of the imperative stimulus could either be clearly matched to one of two diamonds simultaneously presented as warning stimuli 1140 trials), or was ambiguous (65 trialsl with respect to the warning stimuli: presented 4 s earlier. Using a 32-channel electrode montage, the EEG was recorded from 12 schizophrenic patients and 11 controls. Statistical analyses on a subset of 18 electrodes confirmed topographical differences of CSD-maps between tCNV and PINV. Negativity increased from tCNV to PINV and was larger on ambiguous than clear trials. Controls exhibited a pronounced hemispheric asymmetry with larger PINV over the right, particularly over lateral fronto.temporal sites, whereas asymmetry was small with a. tendency for larger left·frontal PINV in patients. The topographical differences between tCNV and PINV suggest functional differences between the two components, In biological pSYChiatry, event-related brain potentials (ERPs) are investigated in order to study brain processes of psychiatric patients during the execution of selected cognitive or emotional tasks (cf. Cohen, 1990; Pritchard, 1986; Rockstroh, Elbert, Canavan, Lutzenberger,& Birbaumer, 1989). Smaller amplitudes of event-related potentials (ERP), in particular reduced amplitudes of P300 and contingent negative variation (CNV), have been repeatedly reported for schizophrenic patients relative to control groups (for reviews see Cohen, 1990; PIjichard, 1986; Rockstroh et aI., 1989). In contrast, a post-imperative negative variation (PINV) following an imperative stimulus is commonly observed in schizophrenic patients, but rarely found in healthy control subjects. The PINV in schizophrenic patients has Topography of CNV and PINV in schizophrenic patients and healthy subjects during a delayed matching-to-