The Effects of Menstrual Cycle Phase on Processing of Emotional Images

The ovarian hormone levels can affect subjective ratings and modulate late positive potential (LPP) amplitudes evoked by images of varying appeal. The present study examines how different progesterone levels influence the valence, arousal ratings and mean LPP amplitudes evoked by pleasant, neutral, and unpleasant images. Twenty-three healthy females were grouped by menstrual cycle days (estradiol and progesterone levels): 10 were included in the follicular phase group and 13 were included in the luteal phase group. Each female rated the affective images in terms of valence and arousal while event-related potentials (ERPs) were measured. The valence ratings of pleasant images were higher in follicular phase group than in luteal, but the same effect was not seen in the arousal ratings. The arousal ratings to unpleasant images were higher than those to pleasant in luteal, but not in follicular phase group. However, the mean amplitude of the early LPP (450700 ms) was significantly greater to pleasant than to neutral and unpleasant stimuli, but did not differ between follicular and luteal phase groups. The mean amplitude of the late LPP (700-950 ms) was significantly larger to pleasant and unpleasant compared to neutral images, but did not differ between menstrual cycle phase groups. Correlation analysis showed a significant negative relationship between progesterone levels and arousal ratings of pleasant and unpleasant images in luteal phase group. Arousal scores for unpleasant images negatively correlated with mean LPP amplitudes to unpleasant images at Pz site in the luteal phase group. The present study provides evidence that subjective ratings of affective images of different attractiveness could be influenced by female menstrual cycle phase, but mean amplitudes of LPP (450-950 ms) are not affected. However, results of correlational analysis suggest that valence, arousal ratings and mean LPP amplitudes are susceptible to the influence of hormone progesterone in luteal phase.