Selective influence of the menstrual cycle on perception of stimuli with reproductive significance: An event-related potential study

In this study, we examined changes in the event-related potential (ERP) to stimuli with and without reproductive significance occurring during the men strual cycle. Eleven spontaneously cycling women were tested during three m enstrual phases (menses, ovulatory phase, luteal phase) differing in plasma concentrations of gonadal hormones. ERPs were recorded while subjects were presented with slides showing pictures from four different stimulus catego ries (sexual stimuli, babies, people occupied with body care, ordinary peop le). Slides were presented randomly in the context of two tasks, requiring either affective processing (i.e., to judge the emotional content of a slid e as positive, neutral, or negative) or structural processing (i.e., to est imate the number of parallel thin lines inserted in each picture). Menstrua l phase primarily affected a late positive component (LPC) peaking 550-600 ms poststimulus. The effects were as follows: (i) During the ovulatory phas e, amplitude of the LPC to sexual stimuli was larger than that evoked by th e other stimulus categories. (ii) This relationship was not apparent during the other menstrual phases or (iii) during the ovulatory phase when the ta sk required structural processing. The ovulatory increase in LPC positivity to sexual stimuli suggests a greater valence of these stimuli during a pha se of increased sexual desire. The data indicate a specific effect of the m enstrual cycle on the processing of sexual stimuli that increases with deep er emotional processing.