Wednesday, August 31, 2016

The Triune Model

 The Reptile Brain, Illustration by Joe Scordo for the book Hidden Scents.

In my book Hidden Scents, I use the triune model to organize the explanation of a neurological model. The brain is complex, and I am not a scientist.

 Christel Quek via Paul MacLean: The "nose-brain" is everything besides the neocortex - it is both the limbic and the reptile brain. (And for disambiguation purposes - sometimes the term "reptile brain" includes the limbic system.)

However, there are ways of organizing the many inter-related parts of the brain that are technically inaccurate, yet hold explanatory power. The most well-known of these is the 'left-brain' 'right-brain' model. The 'left brain' is logical and the 'right brain' is emotional, one is lines and forms, the other shape and color. One is acute attention and the other a passive radar.

Although this model is useful in describing some of the most basic features of the brain as they relate to neuroanatomy, it only goes so far, and must be altered, edited and rearranged many times to reveal the intricate details of brain function.

Regarding olfaction, the triune brain model is useful in that it juxtaposes the critical characteristics of olfactory neuroanatomy against all other senses - that being its intimacy with the limbic system, the seat of our emotions and unconscious behavior.

Triune Brain

The triune model of the mammalian brain is seen as an oversimplified organizing theme by some in the field of comparative neuroscience*

It continues to hold public interest because of its simplicity. While technically inaccurate as an explanation for brain activity, it remains one of very few approximations of the truth we have to work with:

---the "neocortex" represents that cluster of brain structures involved in advanced cognition, including planning, modeling and simulation;

---the "limbic brain" refers to those brain structures, wherever located, associated with social and nurturing behaviors, mutual reciprocity, and other behaviors and affects that arose during the age of the mammals;

---and the "reptilian brain" refers to those brain structures related to territoriality, ritual behavior and other "reptile" behaviors.

The broad explanatory value makes this approximation very engaging and is a useful level of complexity for high school students to begin engaging with brain research.

*Smith CU., 2010, The triune brain in antiquity: Plato, Aristotle, Erasistratus. Journal of the History of the Neurosciences, 19:1-14. doi:10.1080/09647040802601605

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