Brain Focus And Adjustment For Recovery

The Brain And Behavior
Fear “amygdala”

When you are afraid, you are likely to have: • worried thoughts; and • physical sensations like a faster heart rate, sweating, increased breathing; and • behaviors, like trying to escape the situation that made you afraid in the first place!

There is a complicated series of events in the nervous system that leads to the physical sensations and behaviors of fear (the thought, we can't localize so well). Below you'll find details of the anatomy of this process -- but for a simple look at the "fear circuitry" of the brain,
The brain structure which appears to be at the very center of most of the brain events associated with fear is the "amygdala" (Greek for "almond", its shape). The amygdala seems to respond to severe traumas with an unerasable fear response ("post-traumatic stress disorder", or PTSD; It seems to be genetically different and "wired" for a higher level of fear in some individuals, such as those with panic disorder. And it recently has been shown to be larger in some people with bipolar disorder, though what that means is still a mystery.

You can see the amygdala clearly in this drawing: it's the small (almond-shaped, almost) bulge.

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Memory, Learning, and Emotion: the Hippocampus

Emotion and memory are very closely related. You know this from your experience. Go to a party; meet a bunch of new people. Which faces are you going to remember? The woman who made you laugh, the man who made you feel embarrassed, and your new boss -- the ones who had an emotional impact. So perhaps you would not be surprised to learn that the portion of the emotion system of the brain (the "limbic system") is in charge of transferring information into memory. From years of experiments and surgical experience, we now know that the main location for this transfer is a portion of the temporal lobe called the hippocampus.

You won't particularly impressed by its appearance. The hippocampus is included here because it is always cited as part of the "limbic system", and because there is striking new "news" about:

• how it works; • its vulnerability to stress; and • its rich supply of estrogen and progesterone receptors.

Notice the green portion of the brain: this is called the temporal lobe. It lies right under your temple. Memories of names live in this left temporal lobe: particularly people's names, names of animals, and names of tools. If you would like two paragraphs on "why these names?” The portion of the brain that helps those names get into memory in the first place, this hippocampus thing we are talking about, is also part of this temporal lobe. But you can't see it here, because it's on the inside folds, not the outside folds you see.

Function First, this part of the brain appears to be absolutely necessary for making new memories. If you didn't have it, you couldn't live in the present: you'd be stuck in the past of old memories. And this is common: Alzheimer's disease first and severely, before other parts of the cortex (later, the frontal lobes too). So memory is usually the first thing to start to falter in Alzheimer's -- the ability to make new ones, that is. Who visited yesterday? Where did I put the car keys? Why isn't there any mail today (when you brought it in 3 hours ago)? Secondly, the hippocampus seems to be involved in severe mental illnesses. In both schizophrenia and some severe depressions, the hippocampus appears to shrink. However, there is recent evidence that this shrinkage can be reversed and perhaps prevented in people with depression and bipolar disorder, with effective treatment.

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Brain Differences

Summary:
The bottom line: psychiatry is making progress. Although it is hard to spot differences in the brain by doing simple tests like a CT scan, or even an MRI, there are now consistent differences which are being shown that confirm the working hunch about bipolar disorder -- namely, that this is a condition in which emotions gain too much power over behavior. I know, is that not obvious? True, we already knew that just from
experience, as you surely know as well. But what we can now see is at least a glimpse of the brain mechanisms by which this occurs: too much activity in emotional centers, and too little in the frontal lobes that are supposed to be able to inhibit action. Moreover, these differences are present even when no symptoms are present.

Differences in size:
First the good news: many of the differences in brain size which have been shown in many studies of patients with mood problems can be reversed at least in part with effective treatment. Second, the take-home message for now: growing evidence suggests that each episode of severe mood symptoms is associated with increases in these brain size differences, and therefore aggressive pursuit of good symptom control may be associated with preventing some of the brain changes that unfortunately seem to progress in at least some forms of bipolar disorder. There are many more reasons for SPECT scan and multiple evaluations for effective treatment.

Although it has taken years to be certain, because not all studies have shown the same results, there is now fairly good agreement that the frontal cortex (which is associated with decision-making and controlling impulsive behavior) shrinks in size when bipolar disorder is allowed to progress. This is basically the same result which has been seen in severe forms of depression which remain untreated. Several studies have now shown that lithium appears to be capable of reversing this trend toward frontal atrophy.

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The Biologic Basis of Depression