Wednesday, October 1, 2014

Triune brain


Triune brain

 Paul D. MacLean
 The triune brain consists of the reptilian complex, the paleomammalian complex (limbic system), and the neomammalian complex (neocortex), viewed as structures sequentially added to the forebrain in the course of evolution.

The reptilian complex, also known as the R-complex or "reptilian brain" was the name MacLean gave to the basal ganglia, structures derived from the floor of the forebrain during development. The term derives from the fact that comparative neuroanatomists once believed that the forebrains of reptiles and birds were dominated by these structures. MacLean proposed that the reptilian complex was responsible for species-typical instinctual behaviors involved in aggression, dominance, territoriality, and ritual displays.

The paleomammalian brain consists of the septum, amygdalae, hypothalamus, hippocampal complex, and cingulate cortex. MacLean first introduced the term "limbic system" to refer to this set of interconnected brain structures in a paper in 1952. MacLean's recognition of the limbic system as a major functional system in the brain was not widely accepted among neuroscientists, and is generally regarded as his most important contribution to the field. MacLean maintained that the structures of the limbic system arose early in mammalian evolution (hence "paleomammalian") and were responsible for the motivation and emotion involved in feeding, reproductive behavior, and parental behavior.

The neomammalian complex consists of the cerebral neocortex, a structure found uniquely in higher mammals, specifically humans. MacLean regarded its addition as the most recent step in the evolution of the mammalian brain, conferring the ability for language, abstraction, planning, and perception.

An old theory based on behavior, but there is little doubt about three sources of motivation to eat, a physical, an emotion - automatic, and a rational. We have only power over the ration, which has never driven me to eat anything, but it is the only brake on the eating system.

Over at my other blog we have experts blowing smoke and telling us that the intellectual part is in control. Perhaps for them, but not for most of us. We (I) need to sell it to the emotional/physical part of me before recovery can happen. 

It is a lot to absorb. It may take a day or two. Ah well, life goes on.

No comments: