Male and female brains operate differently at a molecular level, a Northwestern University research team reports in a new study of a brain region involved in learning and memory, responses to stress and epilepsy.Many brain disorders vary between the sexes, but how biology and culture contribute to these differences has been unclear. Now Northwestern neuroscientists have found an intrinsic biological difference between males and females in the molecular regulation of synapses in the hippocampus. This provides a scientific reason to believe that female and male brains may respond differently to drugs targeting certain synaptic pathways.