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 Jun 11So this alternative theory turns the standard explanation on its head. Depressed people don't end up lying in bed because they are undercommitted to goals. They end up lying in bed because they are overcommitted to goals that are failing badly. The idea that depressed people cannot disengage efforts from failure is a relatively new theory. It has not been much tested in research studies. However, the idea is well worth exploring. It fits well clinically with the kinds of situations that often precipitate serious depression -- the battered wife who cannot bring herself to leave her troubled marriage, the seriously injured athlete who cannot bring himself to retire, the laid off employee who cannot bring herself to abandon her chosen career despite a lack of positions in her line of work. Seeing these depressions in terms of unreachable goals may be useful clinically, and may help us better understand how ordinary low moods can escalate into incapacitating bouts of depression.
