Our Three Brains

One of the topics which appears again and again in the Buddhist teachings is that of the five aggregates. I briefly wrote about these in a blog last year here. Since then I have been looking for other ways to analyse them. The five aggregates are very important in the understanding of Buddhism judging by their frequency and also the meticulous way that the Buddha describes the way which they operate. To recap, the five aggregates are as follows:

1. bodies (our physical manifestation)
2. feelings (our pleasant, unpleasant or neutral sensations)
3. perceptions (our memory and our ability to identify objects)
4. mental formations (our ability to form complex ideas and mental objects)
5. consciousness (our ability to note things as they occur)

I think that one of the best ways of relating to the five aggregates is by comparing them against the different areas of the human brain. It is generally accepted in the scientific community that the human brain has evolved in stages and thus there are very clearly defined areas in the brain which come from different ages in evolution.

At the centre of the human brain there is what scientists call the reptilian brain, brain stem or R complex. This core of the brain has the job of keeping vital internal organs functioning but it is also responsible for generating feelings and urges like pleasure, pain and fear. This corresponds to what the Buddha calls the feeling aggregate which consists of the basic notions of pleasant, unpleasant and neutral feelings.

Surrounding this R complex is a brain which is very similar to an ordinary mammal's brain. This part of the brain is the seat of higher order functions such as long term memory and perception. A dog or a cat would recognise objects such as toys for example and play with them much in the same way that an infant human would. This part of the brain is called the old mammalian brain or the limbic system and corresponds to what the Buddha calls the perception aggregate.

Surrounding this mammalian brain is the cerebral cortex or neocortex which is the most developed in humans. It is where our singular intelligence, imagination and creativity spring from. This is where complex mental objects are formed. The Buddha describes this process as mental formations. The most complex mental object is the self object or the illusion of self. One of the goals in Buddhism is to dispel this illusion of a self. It is the self-centred world which is the world of suffering.

I suggest that 2500 years ago, the Buddha discovered something that neuroscientists have only recently discovered in the last century, that there are different centres of our brains which act and behave somewhat independently of each other and give rise to different classes of mental phenomena. No matter how much I study Buddhism, it never ceases to amaze me.

How does the last aggregate of consciousness relate to the other ones? When an external object and one of our senses makes contact (e.g. we see a dog), consciousness arises due to this contact and the first area of the brain to be activated by this consciousness is the R complex (feeling: we have a pleasant feeling maybe). Then the consciousness flows outwards and the limbic system ponders over the object (perception: we recognise it is as our dog who is happy to see us). Finally, the neocortex gets involved and investigates the consciousness arisen (mental formations: we think about what food we are going to feed our dog today).

Thus we could list the three aggregates of feeling, perception and mental formations in both the Buddha's language and also as the part of the brain which corresponds to that aggregate. The other two aggregates are also listed for completeness.

1. bodies (pali: rupa), physical body
2. feelings (pali: vedana), R complex, reptilian brain
3. perceptions (pali: sañña), limbic system, mammalian brain
4. mental formations (pali: sankhara), neocortex, higher brain
5. consciousness (pali: viññana), unknown location, phenomenon of quantum physics

Metta,
John


The brain of a Buddhist monk at rest (left image) and during mediation (right image). One can observe increased prefrontal activity in the left cortex compared to the right one during meditation. Newberg A, Alavi A, Baime M, Pourdehnad M, Santanna J, d’Aquili E. (2001). The measurement of regional cerebral blood flow during the complex cognitive task of meditation: a preliminary SPECT study. In Psychiatry Res, vol. 106(2), p. 113-22.