From Scientific American:
For the first time, scientists have pinpointed an area of the brain involved in a woman’s menstrual cycle. The research, reported online this week by the Proceedings of the National Academy of Sciences, shows contrasts in activity over the course of a month and provides a baseline for understanding the emotional and behavioral changes that 75 percent of all women report experiencing before, during and after their period. For any woman who has found herself becoming inexplicably angry or sad during her menstrual cycle, the possibility that her “time of the month” may be responsible is not news. But although a great deal of research has looked at the influence of hormones on nerves, very little work has delved into the role a woman’s menstrual cycle can play in the emotions.