The Limbic System Theory

-Why does the limbic system theory still persist?

While the concept of the “triune brain” is, as a whole, wrong, MacLean in 1970 did propose some interesting ideas about the evolution of the brain. He proposed that there are three main layers of evolutionary progress in the human brain. It starts in the middle with the most basic, the reptilian brain. The reptilian brain is the brainstem itself, and is responsible for the most basic of survival behaviors. The next layer out is what he called the paleomammilian brain, which is where MacLean says we find the limbic system. This part of the brain deals with social and emotions, and MacLean argues that most mammals have this. The third and most complex layer is the neomammilian or neocortex that deals with the highest of cognitive functions. LeDoux argues that while MacLean was fundamentally wrong about the physical layers of the brain, he was not far from the truth about the evolutionary brain. Emotions at the core are in part for survival, and so therefore the more complex the emotion, the more complex the functions needed.

-What remains relevant in limbic system theory?

Emotions are (in part) for survival, and the more complex the emotion, the more complex the system to process it must be (both in theory and in context). If an emotion or mood is as simple as fight or flight, then this is something that is instilled in reptiles, mammals, and humans alike. These emotions are more easily figured out in the human brain, and seem to be easier to experiment with as well as find out about. There has been a large amount of research on the amygdala and fight or flight response, which as was stated above, is a basic emotion that reptiles, mammals, and humans all seem to have alike. The mor...

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...here is still disagreement on what should go in the limbic system, as there is little hard evidence to support a definitive set of structures. Most researchers have agreed that it is a lot more complicated than they originally thought, and that if MacLean was very wrong about one thing, it was that he was much too simplistic in his approach to define what the emotional regulation process should be. Each time researchers learn more, they just discover that it is evermore increasingly complicated, and there seems to be more than one system for dealing

Works Cited

Dalgleish, T. (2004). The emotional brain. Nature Reviews Neuroscience, 5, 582-589.

Hensler, J. G. (2006). Serotonergic modulation of the limbic system.Neuroscience & Biobehavioral Reviews, 30(2), 203-214.

LeDoux, J. (1998). The emotional brain. London: Weidenfeld & Nicolson. (Chapter 4 will go on LN).