Neuroimaging studies show that some women's brains can compensate for the surging hormones of PMS, allowing them to better regulate their moods. Researchers led by Weill Medical College of Cornell University's Emily Stern gave females subjects a battery of tasks while using functional MRI to scan their brains both before their periods and directly afterwards. The women's brains showed greater activity in the frontal cortex – the region that regulates emotions – during the premenstrual part of the cycle, but not other times. Stern and her colleagues speculate that women who show these brain changes may be practicing a sort of mind over mood control of their PMS behavioral symptoms. More from pnas.org.