Book T of C
Chap T of C
As researcher Richard Davidson said in 1999, there are two main circuits involved in emotional response. One is the anxiety and avoidance circuit, centered in the amygdalar region of the right hemisphere. The other is the optimistic, future-planning circuit, centered in the prefrontal cortex of the left hemisphere.
What changes in the brain might result from therapy?
If we take this literally, then Bloom's brief therapy strategy—or Lazarus's tactic of re-writing the scripts of negative emotions (previous page)—could be construed as an attempt to switch a troubled person's type of processing from one type to another: from worried, anxious processing to optimistic, planning processing. Such a change might even be visible on a brain scan. It would show up as a shift of activity from the right amygdalar region to the left frontal region or, judging from research in the 2000s (summarized below) it could show up in the synchronization of activity between the two areas, as the left frontal area regains control over the amygdala.
What is area 25 in the brain?
Within a few years of Davidson's hopeful speculations, neuroimaging research confirmed this basic idea. Patients with depressive disorders showed abnormalities in the anterior cingulate gyrus of the left frontal lobe, a brain area the experts call area 25. This happens to be the same area Posner pointed out as crucial to comprehensive forward planning and executive control in Chapter 2.
Area 25 is dependent upon serotonin, the same neurotransmitter boosted by anti-depressant drugs called serotonin-reuptake inhibitors (SRIs) such as Prozac, Luvox, Paxil, and their relatives. The obvious implication is that, if you boost activity in area 25, a depressed person may regain some executive control and ability to make rational plans. This may be the main mechanism of action for anti-depressants.
Adding to the big picture, people who inherit an allele (genetic locus) that reduces the volume of area 25 have increased risk of major depression, and their brains show reduced coupling of this area to the amygdala. So they have less executive control over the anxiety and avoidance-producing brain center, the amygdala. The plot thickens! The next logical step, taken in 2005 research, was to stimulate area 25 electrically. This relieved the symptoms of depression in people with a major depressive disorder. Apparently, boosting the activity in area 25 re-establishes some executive control over the worry center in the amygdala.
How does neuroimaging research support cognitive restructuring therapy?
This flurry of related, convergent research (reported in Insel, 2007) shows that the "tractability of emotion to neuroscience" anticipated by Davidson is coming true. The results of complex neuroimaging research are dovetailing with the results of therapy experience. A boost to rational thinking and executive planning (whether achieved by anti-depressants, brain stimulation, or cognitive restructuring therapy) can establish control over worries and anxieties that might otherwise govern behavior and emotions.
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Copyright © 2007 Russ Dewey