How does stress affect the different sections of the brain?
We are looking at what happens to the amygdala – or what’s been called the “seat of emotion” – in response to repeated stress. I’ve noted that in the hippocampus the nerve cells shrink in response to repeated stress. But in the amygdala the nerve cells being to grow and produce more dendrites. This is linked to increased anxiety and fear. Subject a rat to a single traumatic stressor, say, restraining its movement, and within a matter of hours, there is a growth response in the amygdala. Over a course of days, without providing any additional stress, you will see a formation of new synaptic connections. This may be related to post-traumatic stress disorder in humans. This mechanism might explain why some people have a sustained fear response after a harrowing event. We’ve also found that the prefrontal cortex also shrinks in response to repeated stress. When all these things add up – shrinkage of the pre-frontal cortex and hippocampus, along with a growth response in the amygdala – you
