Revised December 20, 2016; September 21, 2020
The triune brain model of the brain is no longer widely discussed. However, it provides a simple way to look at three major functions of the brain, as we will see below.
Triune Brain – Three Major Components of the Brain
1. Triune means “consisting of three.” The human brain, which is the most advanced for all animals, shows how different animals have “different levels” of consciousness.
- The brain has three distinctive regions (see the figure below): (1) brain stem (labeled “reptilian” in the figure), (2) limbic system, (3) cerebral cortex or just cortex (labeled “neo-cortex” in the figure).
- Details in Ref. 1. We will summarize very basic features of the “three parts” of the brain.
Reptilian Brain (Brain Stem and the Cerebellum)
2. The brain stem (reptilian brain maybe a misnomer, since reptiles have limbic systems) is the most primitive and all developed animals have it. It governs automatic physiological functions such as the heart rate, respiration, digestion, etc.
- And that is all lowest-ranked animals can do (automatically). They are almost like fully-automated robots.
The Limbic System
3. Animals with somewhat higher intelligence have a limbic system in addition to the brain stem. But still no triune brain.
- It coordinates sensory reception, memory, and unconscious emotional reactions. These animals with the limbic system — like snakes and lizards — just react spontaneously to external influences.
- Humans tend to do that too. In case of a threat, the limbic system instantaneously and automatically makes the “fight or flight” decision. We could say that automatic mano saṅkhāra arise via the limbic system. See, “Saṅkhāra – What It Really Means.”
- It is quite clear from the definition of an Arahant that even this instantaneous response can be completely tamed by cultivating wisdom (paññā,) i.e., by following the eightfold path.
The Cerebral Cortex (Neocortex)
4. The cerebral cortex (learning brain; neo-cortex in the figure) is the most advanced part of the brain. It can make “rational decisions” by contemplation but it is time delayed. Therefore, it is called the “thinking brain”.
- The cortex is responsible for language capability, logic, reasoning, learning, and critical thinking, the good stuff. All primates have it, but of course, the humans have the largest.
- In other words, we generate vaci and kaya saṅkhāra with the help of the neocortex.
- In contrast, even higher animals
- By controlling our vaci and kaya saṅkhāra, we have the ability to change our gati. This is the “modern scientific rationale” behind the basis of Buddha Dhamma. See, for example, “9. Key to Ānapānasati – How to Change Habits and Character (Gati).”
5. All our sensory inputs are processed in the neocortex before they are sent to the hadaya vatthu or the “seat of the mind” in the gandhabba close to our physical heart.
- Since it takes time for our brains to analyze the “incoming data”, normally there is about 100th of a second time delay between incoming sense inputs and our mind generating thoughts about that sensory input.
- The brain can handle only one sensory input at a time. This means it can handle only about 100 sense inputs in a second. So, even though our minds generate an initial response quickly, the follow-up “thoughts” are delayed due to this “processing delay” in the brain.
- This process discussed in detail at, “Citta and Cetasika – How Viññāṇa (Consciousness) Arises.”
- That pre-processing is minimal even in “higher animals” with small cortexes, like dogs and apes. This is why humans are unique. We have a large cortex that not only slows down the response time but also helps us “analyze the situation” rationally.
Ways to Improve Brain Functionality
6. Neural pathways in the brain strengthened by:
- Repeated application (meditation included). Repeated activity forms both good and bad habits as we discussed in several posts, and is the key in molding the character (gati); see, “The Law of Attraction, Habits, Character (Gati), and Cravings (Āsavas)“, and other related posts.
- Good foods and regular exercise increase the production of Dopamine and other good chemicals.
- Exercise and meditate! It will keep you healthy and alert; see, “‘Spark’ by John Ratey” for information on the value of a good exercise program.
7. Until about the late 1980s there was wide belief that one had just to live with the brain that one was born with. But since then the ability of the brain to change (neuroplasticity of the brain) has been demonstrated and studies on the effects of meditation on the brain have become an active research field.
- Of course, 2500 years ago the Buddha said that the mind is the precursor to everything. The mind does not arise from the brain. It controls all body parts, including the brain. See, “Brain and the Gandhabba.”
- The key is that insight meditation should DRASTICALLY change neural wirings. However, there have not been any brain scans of someone who has cultivated the “correct versions” of Satipaṭṭhāna and Ānapānasati meditation.
- There are other posts at the site which describe this “re-wiring” of the cortex that leads to change in our gati. See, for example, “9. Key to Ānapānasati – How to Change Habits and Character (Gati).”
Effects of Meditation on the Brain
8. As shown in the references below, there is compelling scientific evidence that even mundane versions of meditation improve both the cortex AND the limbic system.
- Those studies show that basic Samatha meditation helps, but Mettā Bhāvanā (compassion meditation) is particularly effective.
- It must be noted that Tibetan Samatha (breath meditation) or Mettā Bhāvanā (mundane version) are anariya versions. For the Ariya versions, see, “6. Anäpänasati Bhävanä (Introduction)” and “5. Ariya Mettā Bhāvanā (Loving Kindness Meditation)“. I am quite positive that a brain scan of an Ariya (Noble person) will yield more interesting results.
- For example, we also know that meditation affects breathing patterns (thus the brain stem). Therefore, meditation affects overall brain function. An Arahant can stop breathing for up to 7 days in Nirodha Samapatthi. It will be extremely interesting to see a brain scan of an Arahant.
The malleability of the Neocortex and the Limbic System
9. The following case illustrates the complex role played by the brain. A developed left brain (of the neo-cortex) indicates compassion for others and enhanced happiness for oneself, and a relatively larger right side indicates aggressive character.
- Here is the link to a video showing the results of brain scans of an advanced meditator who had done loving-kindness meditation for a long period of time compared to 150 non-meditators.
The discussion on the brain scan data is from about 17:00 to about 18:20 minutes if you don’t want to watch the full video.
- We must also keep in mind that Tibetan loving-kindness meditation is an anariya version of the Mettā Bhāvanā; see below.
Humans Have Control Over Their Lives
10. Furthermore, we are not programmed by our genes, environment, or even our past kamma. However, all of those can affect our destiny. The most powerful is our mind. In other words, citta niyama dominates kamma niyama.
- As the saying goes, “you can do anything that you put your mind to”. This is the true basis of free will.
11. Even though the scientists are making some progress regarding the mind, the brain is not the mind, just as the physical eye is not the cakkhu pasada rupa; see, “Manomaya Kaya (Gandhabba) and the Physical Body“, and other related posts. Yet it is essential to keep the physical eye (and other physical sense faculties) as well as the brain in good condition for the whole body and the mind to work properly.
- Finally, the triune brain model is no longer widely discussed. However, it provides a simple way to look at three major functions of the brain.
Next, “How Habits are Formed and Broken – A Scientific View“, …………………
1. Wikipedia article on Triune Brain. More details in “The Triune Brain”, by P. D. MacLean (1990).
2. “The emotional life of your brain” by Richard Davidson (2012).
3. “You are the Placebo – Making Your Mind Matter”, by Joe Dispenza (2014).
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