Rats exposed to an antidepressant just before and after birth showed substantial brain abnormalities and behaviors, according to a new study. After receiving citalopram, a serotonin-selective reuptake inhibitor, during this critical period, long-distance connections between the two hemispheres of the brain showed stunted growth and degeneration. The animals also became excessively fearful when faced with new situations and failed to play normally with peers.