Gordon Johnson: Now that we see the relationship between the hippocampus and the amygdala talk to us about the role that the amygdala plays and then the role it plays in memory.
Dr. Erin Bigler: Well, the amygdala is again another one of those structures that has multiple functions but it’s often thought of as a major area of the brain that’s involved in emotion and emotional reaction and especially like a fear reaction. Again, going back to evolutionary kinds of things, from the life preservation perspective if there’s a fearful stimulus that’s something that we should immediately react to, to withdraw from, like for example a snake on the ground. And we should immediately be able to lay down a memory, that’s a snake, that’s bad and remember the spot. So that is one of the functions that’s thought to be played by this particular, brain structure and why it’s so close to the hippocampus because not only does it have to have a quick pathway into motor areas, which it does, to react and reaction reflexively but it also has a connection to lay down that memory.
Gordon Johnson: Now if we were going to compare the role that the amygdala plays in a gazelle versus human being it would be a little bit different?
Dr. Erin Bigler: It would. On one level in terms of sort of the complexity of maybe the processing but at another level it would be very similar. In fact the, the mouse or the rat amygdala which is studied directly with a variety of techniques, basically follows that pattern that I was mentioning.
Gordon Johnson: And humans do have the same, flight for life reflex that a gazelle does.
Dr. Erin Bigler: That’s correct, we just have more ways to mediate it. Mediate it and suppress it. In fact one of the things that we believe is the case in a variety of neuropsychiatric disorders is that over activation of the amygdala or under activation of the amygdala may actually relate to the disorder.
Gordon Johnson: Now some memories we remember too well, some memories we put an emotional component on it. Is the amygdala part of the problem or part of what’s going on in that process?
Dr. Erin Bigler: Exactly. In fact, the amygdala, hippocampal and then we haven’t talked about it yet but we’re going to talk about the hypothalamus; so the amygdala, hippocampal, hypothalamic connection is thought to be a very, very big part of post-traumatic stress disorder. You’re absolutely correct, some highly emotionally charged, life threatening events, may over stimulate this particular, system and actually cause neural dysregulation and maybe even structural changes that occur from the over emotionality of that circumstance.