MacLean's Triune Brain Nonsense? Options

[Unknown]

Is MacLean's Triune Brain concept utter nonsense with no basis in neuroscience? I'm inclined to think it is, and have been told as much from many neuroscientists. Yet, the triune brain concept remains popular with laymen and the general public. Why is this? Here's an excerpt from a pro-MacLean site over his Triune Brain theory, to give you an idea of what his theory is all about.

[rhymer]

I hadn't realised Mclean was the source of this theory, which seems sensible to me from my own experiences.
I don't really bother whether there are three brains as separate entities, considering them myself as three 'layers' of development. Each has specialised functions for survival which may or may not be superceded by higher levels.
It seems to fit in with evolutionary ideas, and the way different groups of functions disappear as a brain nears death [ie., an ascendency of functions which decays in order of complexity].

What alternative theories exist?

[Unknown]

[Paul King]

[Rick]

Perhaps if we think we understand the brain we have over-simplified it. We should also note that the older brain portions have kept evolving right along with the growth of the neocortex. Today's reptilian brain may be much more capable than the brains of reptiles that lived 300 million years ago.

[Hey Hey]

[Rick]

The crocodilians have had similar body form for 300 million years. It would be interesting to see brain size per body weight graphed as a function of time.

[Hey Hey]

[rhymer]

There is a lot of possibly relevant (at least related) info here

http://www.bbsonline.org/Preprints/OldArch...bbs.finlay.html

[Unknown]

[Hey Hey]

[Paul King]

[Enki]

Oho!

[Unknown]

Hi Enki,

are these the three layers?

Obsolete.
Hopeful.
Over-the-top.

Hence Oho?

[Enki]

Hi Unknown,

Oho means oho my dear.

Bests,
Enki

[rhymer]

Thanks Enki, but I must admit, I thought that was what Father Christmas said?

[Enki]

[Unknown]

[avisolo]

Read what Maclean himself said about it here:
http://www.d.umn.edu/~rlloyd/EducatorsInstitute/Mac2.htm

[Unknown]

[Paul King]

Read what Maclean himself said about it here:
http://www.d.umn.edu/~rlloyd/EducatorsInstitute/Mac2.htm

It's a good link and makes for an interesting read but I still think Maclean's triune brain concept is childishly naive and explains nothing. Anyone sufficiently appreciative of the brain 's organization and complexity will tell you the same thing.

The value of the triune brain concept is as a point of view, not as an explanation of mechanism. It is a systemic way of thinking about the cause of behavior that is an improvement over Freud but still a long way from what is "really" going on.

The strength of the idea (the intuition, really), is that most instinctual behaviors (what he calls ancestral memories selected by evolution) are encoded in the circuits and pathways of the limbic system and below. Conversely, most cognitive functioning, acquired memories and skills are encoded in the cerebral cortex.

Current theories still support this basic separation, however the models have come a long way since MacLean's time. The neocortex, for example, is not at all separate and independent from the older parts of the brain. MacLean did not say that it was, but he did seem to talk about it that way. What MacLean really said was that the limbic system is a fairly self-contained, tightly interconnected system, and current theories would not contradict that.

Today's explanations of brain mechanism focus much more on statistical learning models and pattern classification. The current models around emotion tend to map the phenomena people associate with emotions onto reinforcement learning and behavior strategy selection paradigms. The trend these days seems to be not so much in understanding instinctual wiring, but in understanding learned behaviors. Learned behaviors are often the interaction of certain neural pathways and circuits (which could be called instinctual) with structured adaptive processes that lead to the formation of optimal behavior.

Emotions are being understood these days in terms of neurotransmitter systems and their relationship to behavior strategy optimization processes, for example, the study of "neuroeconomics" and neural mechanisms of decision making, risk assessment, and exploratory learning.

[lucid_dream]

Paul MacLean should have recanted his utterly ridiculous Triune Brain Theory decades ago.

It's amazing that you still find blatantly false theories of the brain floating around! MacLean's theory is right alongside Aristotle's notion of the brain as a cooling system.

[TaylorS]

IMO the Triune Brain hypothesis is at most, a profound oversimplification. Our brain stem, cerebellum, and mid-brain are not unchanged relics, they have evolved right along with the cerebrum, it's just not as obvious because evolution tends to be conservative and economical, you don't need to create new structures if you can just "reprogram" structures already there for new purposes. The cerebellum, especially, does not get the respect it deserves; it's not only important in coordinating movement, but is also plays a role in coordinating our thought patterns. Certain parts of the thalamus are vital in maintaining a state of conscious awareness, damage to those regions will turn you into a vegetable.

[Cassox]

I don't really see what the problem with the triune theory would be. Obviously, its an oversimplification, but does that mean there is nothing to it? It makes sense that the brain would develop in stages. So what if the initial stages had nothing to do with reptile brains? So what if the brain acts together , rather than in three distinct manners? There are some strong correlations between the functions assigned and simpler organsims, both anatomically and physiologically.

Some of the arguements that have presented against the triune theory are blatant non sequitors. The thalamus is neccessary for consciousness, so it can't be part of a lower brain system? Ummm, ok. Isn't brain function dependant on your heart beating? The heart regulates itself without input from the brain other than to change heart rate and perhaps one could say a bit of vasodilation/constriction. Does this mean that the heart and the brain are one? Dependency on lower brain function for cognition in no way works against the triune model; in fact, it's part of the theory. Memory formation is primarily accomplished by the paleomamalian brain.

MacLean is essentially saying that certain functions arose through evolution over time. Its not saying that these functions came about from a completely new brain that appeared on top. It's saying that in order to better accomplish functions the brain changed and new components arose. A few major changes caused major anatomical changes. If you don't like the idea that there are three brains, then say that there are 20. It doesn't really matter because its arbitrary. He simply identified what he ( and many others) regard as the changes with the largest impact.

The only reason I can see for people to be against this idea is that they are
"good christians" who refuse to understand evolution. Is it better to say that McLean is wrong. God made the brain? C'mon. Maybe he was wrong about his specifics.... but the general idea is pretty solid.

[Cassox]

Out of curiosity, if research were to find that nootropics such as piracetam did not cross the blood brain barrier, would you assume then that it can't possibly do anything?