Vasopressin and cognitive processes: two event-related potential studies.

Two experiments studied the influence of arginine-vasopressin (AVP) on cognitive processes by means of an electrophysiological measure, the late positive complex (LPC) of the event-related potential. The LPC varies systematically with cognitive processes. The classical oddball paradigm and an incidental memory task (structural encoding of emotional adjectives) were used. The two studies differed only in the dose of AVP (study 1: three time nasal application of 10 IU AVP; study 2: 20 IU). In study 1, AVP intake enhanced memory performance. The LPC elicited by oddball stimuli was not influenced by AVP, neither when compared before and after intake nor when compared to placebo treatment. However, specific influences of AVP on the LPC elicited during the structural encoding task were observed. In both studies, AVP intake resulted in a marked change of the scalp distribution of the P3 component, which is a prominent part of the LPC. Furthermore, subjects treated with the lower dose of AVP showed a more positive P3 component on emotional (negative and positive) adjectives, when compared to neutral ones. The results suggest that vasopressin influences the central nervous processing of the emotional content of stimuli.