Elektrophysiologische Korrelate der selektiven Aufmerksamkeit bei Schizophrenen

Abstract

Attentional dysfunctions are considered to be core schizophrenic symptoms. Selective attention to specific attributes of auditory stimuli results in characteristic changes of event-related brain potentials. Depending on stimulation rate, either an Nl enlargement or a more enduring „processing negativity” (19) is found. Twelve schizophrenics, diagnosed according to DSM III-R, 12 patients with alcohol dependency, and 12 matched normal controls took part in an auditory selective attention task with fast (2 Hz) or slow (1 Hz) stimulation rate. Schizophrenics made more errors and had slower reaction times, as compared with both other groups. This behavioral impairment was paralleled by a significantly smaller early phase (200-400 ms) of the processing negativity (Nd, fig. 2). Groups did not differ for a later phase of Nd. The smaller N1 amplitude of schizophrenics was probably a concomitant of neuroleptic medication, because group differences for N1-amplitude disappeared when neuroleptic dosage was statistically controlled for. Alcoholics, but not schizophrenics did have a smaller P300 amplitude than normals (fig. 3). The results are consistent with the assumption that an impaired matching process between stored and momentary information underlies some of the attentional difficulties in schizophrenia.