[The influence of sex and menstrual cycle on conditioned acquisition and extinction: Event-related potential research].

Previous studies have indicated phase-related differences in conditioned acquisition and extinction. In recent years, many researchers used event-related potential (ERP) technology to assess the extent of the acquisition and extinction. Therefore, this study was aimed to assess the sex- and menstrual cycle-dependent effects on the conditioned acquisition and extinction using ERP technology. Thirty-two females at two phases (menses phase, FM, and luteal phase, FL) of their menstrual cycle and 16 males participated in the experiment. The experiment consisted of two stages: acquisition stage and extinction stage. In the acquisition stage, in the predictable context, a condition stimulus (CS) was always followed by the presentation of a negative picture or a neutral picture; but in the unpredictable context, a CS was paired with a negative picture or a neutral picture 20% of the time. In the extinction stage, only CS was presented. The results showed that at acquisition stage, significant larger P2 amplitudes were recorded in female subjects in FL and FM in comparison with those of males. The female subjects in FL may acquire the strongest CS-US conditional connection. At extinction stage, the female subjects in FL showed larger P2 amplitudes than males, but there were no significant differences in P2 amplitudes between the males and females in FM. The results suggest that the females in FL allocate more attention resources to the acquisition of a conditioned response and delayed extinction. In conclusion, we suggest that female menstrual cycle may modulate conditioned acquisition and extinction processes, and our ERP data may provide an explanation for the premenstrual dysphoric disorder.