ELECTROPHYSIOLOGICAL CORRELATES OF SELECT IVE ATTENTION IN SCHIZOPHRENICS

Attentional dysfunctions are considered to be core schizophrenic sympt oms. Selective attention to specific attributes of auditory stimuli re sults in characteristic changes of event-related brain potentials. Dep ending on stimulation rate, either an N1 enlargement or a more endurin g ''processing negativity'' (19) is found. Twelve schizophrenics, diag nosed according to DSM III-R, 12 patients with alcohol dependency, and 12 matched normal controls took part in an auditory selective attenti on task with fast (2 Hz) or slow (1 Hz) stimulation rate. Schizophreni cs made more errors and had slower reaction times, as compared with bo th other groups. This behavioral impairment was paralleled by a signif icantly smaller early phase (200-400 ms) of the processing negativity (Nd, fig. 2). Groups did not differ for a later phase of Nd. The small er N1 amplitude of schizophrenics was probably a concomitant of neurol eptic medication, because group differences for N1-amplitude disappear ed when neuroleptic dosage was statistically controlled for. Alcoholic s, but not schizophrenics did have a smaller P300 amplitude than norma ls (fig. 3). The results are consistent with the assumption that an im paired matching process between stored and momentary information under lies some of the attentional difficulties in schizophrenia.