How does brain development in the womb differ in boys and girls?

In the womb, the developing brain is exposed to hormones that affect how it forms; boys get more testosterone, which favors development of the left side of the brain, and girls get more estrogen, which sparks more connections throughout the brain. This, in part, explains the difference in communication and perception between the two sexes. Imaging studies have shed light on these differences as researchers examine brain parts that "light up" during verbal exchanges.