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 19 Oct 11Brain, bodily awareness, and the emergence of a conscious self: these entities and their relations are explored by Germanphilosopher and cognitive scientist Metzinger. Extensively working with neuroscientists he has come to the conclusion that, in fact, there is no such thing as a "self" -- that a "self" is simply the content of a model created by our brain - part of a virtual reality we create for ourselves. But if the self is not "real," he asks, why and how did it evolve? How does the brain construct the self? In a series of fascinating virtual reality experiments, Metzinger and his colleagues have attempted to create so-called "out-of-body experiences" in the lab, in order to explore these questions. As a philosopher, he offers a discussion of many of the latest results in robotics, neuroscience, dream and meditation research, and argues that the brain is much more powerful than we have ever imagined. He shows us, for example, that we now have the first machines that have developed an inner image of their own body -- and actually use this model to create intelligent behavior. In addition, studies exploring the connections between phantom limbs and the brain have shown us that even people born without arms or legs sometimes experience a sensation that they do in fact have limbs that are not there. Experiments like the "rubber-hand illusion" demonstrate how we can experience a fake hand as part of our self and even feel a sensation of touch on the phantom hand form the basis and testing ground for the idea that what we have called the "self" in the past is just the content of a transparent self-model in our brains. Now, as new ways of manipulating the conscious mind-brain appear on the scene, it will soon become possible to alter our subjective reality in an unprecedented manner. The cultural consequences of this, Metzinger claims, may be immense: we will need a new approach to ethics, and we will be forced to think about ourselves in a fundamentally new way. At
