He follows this natural cycle by examining the brains of rats, which mimic the changes in humans on a much shorter time scale. Girls undergo markedly less overproduction and pruning than boys. The reason probably involves early exposure to testosterone and other male hormones that determine the course of brain development. As children reach adolescence they become more vulnerable to schizophrenia, a serious disturbance in thinking, emotions, and behavior. The malleability of young brains leads to other problems when their owners are victims of physical and sexual abuse and witnesses to violence at home and other traumas.
Brain scans show fewer nerve cell connections between the left and right halves of the brain.
Fewer connections may result in a reduced ability to use thought and logic to control emotions. That, in turn, can lead to abrupt switches from rational to emotional, angry, or paranoid behavior. In extreme cases, it could provide the basis for development of multiple personalities. All the problems of integrating logical and emotional responses may occur as they do in other types of abuse. The researchers also find unexpected differences between men and women.