Menstrual cycle modulation of medial temporal activity evoked by negative emotion

Previous studies have indicated phase-related differences in HPA activity and amygdala responsiveness in women, such that the response to negative emotional images is reduced during high-estrogen phases of the menstrual cycle. Other research has indicated an opposite effect of exogenous progesterone, increasing amygdala activity at some doses. However, no study to date has assessed the response of the brain's arousal circuitry to negative images during the luteal phase, when both progesterone and estrogen levels are elevated. To address this question, 17 naturally cycling women were each scanned during the early follicular and mid-luteal phases of the cycle, and response to IAPS images was assessed by fMRI. The results indicated significantly increased activity in hippocampus and amygdala during mid-luteal scans when compared to scans in the early follicular phase. These findings suggest that progesterone-mediated effects dominate during the luteal phase, and further suggest that estrogen and progesterone may play opposing roles in modulating the brain's arousal circuitry.

Research highlights►In this study, the neural response to negatively arousing images was compared between women in the early follicular phase and mid-luteal phase of the menstrual cycle using fMRI. ►Negatively arousing pictures produced significantly increased activity in the amygdala and hippocampus. ►This effect was modulated by menstrual phase, such that the difference in signal in both amygdala and hippocampus between negative and neutral images was larger in the mid-luteal phase, when progesterone is elevated, than it was during the early follicular phase, when both estrogen and progesterone are at low levels. ►These findings suggest that the responsiveness of the brain's arousal circuitry varies significantly over the course of the menstrual cycle, and further suggest that the coupling of activity in these regions to arousal is increased with higher circulating progesterone levels.