In the brain, these thoughts can often be traced to overreactivity in the amygdala, a small site in the middle of the brain that, among its many other functions, responds to novelty and threat. When the amygdala works as it should, it orchestrates a physiological response to changes in the environment. That response includes heightened memory for emotional experiences and the familiar chest pounding of fight or flight. But in people born with a particular brain circuitry, the kind seen in Kagan’s high-reactive study subjects, the amygdala is hyperreactive, prickly as a haywire motion-detector light that turns on when nothing’s moving but the rain. Other physiological changes exist in children with this temperament, many of them also related to hyperreactivity in the amygdala. They have a tendency to more activity in the right hemisphere, the half of the brain associated with negative mood and anxiety; greater increases in heart rate and pupil dilation in response to stress; and on occasion higher levels of the stress hormones cortisol and norepinephrine.
thinkahol * on 03 Sep 10In an illustration more typical of Pinker's cultural taste, he quotes the opening scene of Woody Allen's movie Annie Hall, when the young Alvy Singer tells a psychiatrist that he won't do his homework because the universe is expanding. If the universe is going to fall apart, he says, what is the point of human existence? "What has the universe got to do with it?" his mother wails at him. "You' re here in Brooklyn! Brooklyn is not expanding!" That kind of reductionism is confusing two levels of analysis," Pinker says. "We have meaning and purpose here inside our heads, being the organisms that we are. We have brains that make it impossible for us to live our lives except in terms of meaning and purpose. The fact that you can look at meaning and purpose in one way, as a neuro-psychological phenomenon, doesn' t mean you can' t look at it in another way, in terms of how we live our lives." The collection of genes known as Steven Pinker made the point most forcibly in How The Mind Works, where he explained his own decision not to have children - which apparently runs counter to the demands of evolution - and says that if his genes don't like it, "they can take a running jump." http://www.guardian.co.uk/Archive/Article/0,4273,3926387,00.html Steven Pinker
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