The Male Brain by Louann Brizendine Read Free Book Online Page B

his brain to see the neutral faces of others as unfriendly. Researchers in Maine tested teens' perceptions of neutral faces by giving them a squirt of vasopressin nasal spray . They found that, under the influence of this hormone, the teen girls rated neutral faces as more friendly, but the boys rated the neutral faces as more unfriendly or even hostile. This may explain why the next time Jake saw Dylan, he thought his face looked angry when, in fact, Dylan was just bored. Jake's brain was being primed by hormones for getting into trouble.
    In animals that are in puberty, scientists have discovered that priming the males' brains with vasopressin and testosterone changes their behavior, too. The scientists found that the brain's two master sensors for emotions--the amygdala and hypothalamus--became supersensitive to potential threats when hormonally primed . And in animal studies in which male voles were given vasopressin, it resulted in more territorial aggression and mate protection .
    In humans, a potential threat is often signaled by a facial expression. Before puberty, when Jake had less testosterone and vasopressin, Dylan's bored face probably wouldn't have looked hostile or angry to him. But now everything was different. Evolutionary biologists believe seeing faces as angrier than they actually are serves an adaptive purpose for males. It allows them to quickly assess whether to fight or to run. At the same time, Jake and Dylan were also honing the ancient male survival skills of facial posturing and bluffing . They were learning to hide their emotions. Some scientists believe human males have retained beards and facial hair, even in warmer climates, in order to make them look fierce and hide their true emotions.
    In the male hierarchy of primates and humans, the angry face is used to maintain power . And the angriest faces typically belong to men with the highest testosterone, according to research . A study of teen boys in Sweden found that the ones with the most testosterone reacted more aggressively to threats . These boys with the highest testosterone also reported being more irritable and impatient . And in another study, testosterone levels rose in response to seeing an angry face, thus dialing up the brain circuits for aggression . So angry faces--real or imagined--ignite the male fighting spirit. As Jake and Dylan had experienced in their shoving match, this sudden anger can trigger a knee-jerk reaction--often surprising even to the fighters. If these two boys had lower testosterone and vasopressin, they would not have been so fired up to fight and wouldn't have felt compelled to even the score. But as it was, this hormone cocktail was keeping an irritable and sometimes irrational fire smoldering.

TUNING OUT
    The teen male not only sees faces differently than he did as a boy; he also begins to perceive voices and other sounds differently than he did before adolescence . And his changing hormones can make him hear things differently than girls his age. In Portugal, researchers found that during puberty, estrogen surges in females and testosterone surges in males increase the hearing differences between girls' and boys' brains , but the main difference is that some simple sounds, like white noise, are processed differently in the male brain. Liesbet Ruytjens and colleagues in the Netherlands compared the brain activity of seventeen-to twenty-five-year-old males and females as they processed the sound of white noise and as they processed the sound of music . The female brains intensely activated to both the white noise and to the music. The male brains, too, activated to the music, but they deactivated to the white noise. It was as if they didn't even hear it. The screening system in their male brains was automatically turning off white noise. Scientists have learned that during male fetal brain development, testosterone affects the formation of the auditory system and the connections within the brain, making it