Mind, Brain and Buddhism
Posted on July 15th, 2013
On July 20, 2007, neurologists at the University of Marseille revealed the remarkable case of the 44-year-old French tax official who had been doing just fine with a fluid-filled cavity taking up most of the space where his brain should have been. He had gone to the hospital in 2003 complaining of a slight weakness in his left leg. When the doctors scanned his brain they found mostly a black hole.
The patient told the attending physicians that as a six-month-old baby he had suffered from hydrocephalus (commonly known as Ãƒ¢Ã¢”š¬Ã…“water on the brainÃƒ¢Ã¢”š¬Ã‚) and that a shunt had been inserted to drain away the fluid. His physician ordered a tomography scan (CT) and an MRI (magnetic resonance imaging scan) and discovered that the lateral ventricles, chambers that hold and cushion the brain, were extremely enlarged. In the normal brain, these ventricles are very small.
Upon close examination, the doctors found that a massive cavity had built up in the manÃƒ¢Ã¢”š¬Ã¢”ž¢s skull and that it had filled with fluid and a thin sheet of functioning brain tissue, which was pushed back against the inner walls of his cranium.
Tests performed by the medical team revealed that the patient was neither physically nor mentally disabled by his strange condition and that it had not hindered his socialization. The man was married with two children and carried out his duties at the tax office without difficulty.
With a weight of about three pounds, the human brain is regarded as an astonishing instrument. According to neuroscientists the neocortex, the outer layer of the brain, by which we perform higher thinking, consists of a thin sheet of cells about 2.5 millimeters in thickness. The neocortex is also made up of cortical blood vessels and supportive cells for the neuronal (nerve) matrix. If the neocortex is damaged in humans and higher mammals, the result is a condition known as decorticate rigidity in which the thinking processes are shut down.
From the perspective of (western) human evolution, the neocortex is built upon the older brain in the cerebellum and brainstem which perform the autonomic functions, such as heart rate, blood pressure, and the onset of sleep. The brainstem is a primitive area of the brain that merges the lower brain into the spinal cord. Scientists believe that without the neocortex, consciousness as we understand it would not exist. However, studies have shown that the neocortex canÃƒ¢Ã¢”š¬Ã¢”ž¢t even stay awake to perform the simplest of tasks without constant stimulation from the brainstem.
Although the neocortex is considered the crowning achievement of human evolution, it does contain large cavities without any brain cells, as well as considerable amounts of cerebrospinal fluid, white matter, blood vessels, blood, and Ãƒ¢Ã¢”š¬Ã…“non-thinking cells.Ãƒ¢Ã¢”š¬Ã‚ Also, as we saw earlier some individuals have been able to function with only a tiny fraction of the brainÃƒ¢Ã¢”š¬Ã¢â‚¬or no brain at all.
The reductionist view popular with many scientists and philosophers is that knowledge of the neuronal structures and functions (or their molecular underpinnings) is sufficient for defining and explaining consciousness and mental activities. But then how could we explain the case of the French tax official and others who do not have a defined brain?
Today we are virtually forced by the scientific establishment to regard conscious subjective experience as a phenomenon that somehow emerges from an appropriate system of activities of the physical nerve cells in the brain.
According to western neuroscience our subjective experiences are based on widespread networks of thousands of nerve cells, located in separate places in the brain. Also, appropriate nerve cell activities can influence the content, or even the existence, of subjective experiences.
How can conscious subjective experience arise from activities of nerve cells in the brain? That is, how can the mental arise from the physical?
Is the reverse true? That is, can our conscious intentions really influence or direct the nerve cell activities in the performance of a freely voluntary act? Can we consider conscious experiences as real phenomenon that are not reducible to the physical activities of the neurons in the brain?
According to Buddhist teachings it is specifically mentioned that consciousness and physical body are interdependent. When the Buddha explains the constituents of the physical body, he had referred to the brain as matthalunga but had not given any special attention to it and it is not maintained that brain is the seat of mental activity.Ãƒ”šÃ‚ According to Dr. Y. Karunadasa, in one of the books of the Abhidhamma Pitaka the physical basis of mind is referred to, but apparently it does not identify what it is. It says: “whatever materiality on which mind and mind-consciousness depend, that materiality is a condition by way of support to mind and mind-consciousness”.
Based on Abhidhamma teachings and Professor Nalin de SilvaÃƒ¢Ã¢”š¬Ã¢”ž¢s philosophy of Constructive Relativism (Ãƒ¢Ã¢”š¬Ã‹Å“PaticcasamuppadinÃƒ¢Ã¢”š¬Ã¢”ž¢ view) we say that interaction between the mind and the brain can go in both directions, in other words, subjective experiences are the result of the functional interdependency of mindÃƒ¢Ã¢”š¬Ã¢â‚¬Å“nervous system (central nervous system & peripheral nervous system) processes. Techniques such as functional MRI and regional cerebral blood flow (rCBF) have shown that cerebral events or processes can influence, control, and presumably Ãƒ¢Ã¢”š¬Ã…“produceÃƒ¢Ã¢”š¬Ã‚ mental events, including conscious ones. We believe that the reverse of this principle that mental processes can influence or control neuronal ones to be also true, although it has been generally unaccepted within the scientific community. We regard the mind as a stream of Ãƒ¢Ã¢”š¬Ã…“cittasÃƒ¢Ã¢”š¬Ã‚(the Pali word citta is derived from the verbal root citi, to cognize, to know) and to have a relative existence (relative to Ãƒ¢Ã¢”š¬Ã…“itÃƒ¢Ã¢”š¬Ã‚ self).
Before we go any further let me explain a bit about the neuronal communication theory in order to get a better understanding of our proposed theory.
Communication between neurons, or nerve cells, is regarded as the cellular basis for thinking, decision making, and control of muscular movements. Neurons are cells with a particular shape: they possess two types of long ramification, called the axon and the dendrites. The axon of one neuron is in contact with the dendrites of other neurons. These contacts are termed synapses or neuronalÃƒ”šÃ‚ junction. Each neuron forms thousands of synapses with other neurons. Neurons communicate by sending electric signals along their axons. When a signal reaches a synapse, it triggers the release of neurotransmitters, which are small molecules that diffuse in the intercellular space and activate receptor on the surface of the other cell forming the synapse. In turn, activated receptors generate electric signals of variable intensity. The signals coming from every synapses of a neuron passively converge to the base of its axon and are summed up. If the resulting signal is intense enough, the axon will actively propagate the signal further; otherwise, the signal will stop there.
We theorize that a single citta or a group of cittas with accompanying mental factors (cetasikas) can affect the probability of release of the chemical transmitter substance at synaptic junctions. This triggers the cascade of electrical signals necessary for neuronal communications. The probability of release could be dependent on the nature of the citta. LetÃƒ¢Ã¢”š¬Ã¢”ž¢s say according to diverse manifestations of citta(s) the probability of release of chemical transmitters fluctuate between 0 and 1. 0 being no chemical transmitter is released and 1 being appropriate trigger amount of chemical transmitter being released depending on manifested citta(s). We say that everything between 0 and 1 correspond to potentialities of subjective experiences. As to where and how exactly the interaction takes place and which sub-neuronal structure is directly involved is yet to be determined.
Furthermore, we say that interaction of cittas with sub-neuronal structures of five-sense-organs create neuronal communications necessary for perception and interaction of cittas with themselves creates the mind (or the illusion of a mind). Hence, as expected there is a built-in circular causality associated with this process which we believe exists until the emergence of cuti-citta (death consciousness) and the process starts all over again according to relinking-citta (patisandhi vinnana).
However, unlike physical emergent phenomena, the emergent subjective experience is not directly observable or measurable by any physical means, as subjective experience is only accessible to the individual having the experience. The emergent subjective experience of this system is unlike the properties of the responsible nerve cells, it could not have been a predicted outcome of these neural activities. For us Buddhists it should not be surprising that the emergent subjective experience exhibits unique unexpected characteristics. We hope to further develop this theory and add to its explanatory power. Clearly, the scope of further work is vast but our goal is to put the theory into experimentally testable formats (at least indirectly), which I believe is possible.
Please note that this is a brief description of a larger project in progress. The intention to develop such a theory is purely academic and in no way intended to give interpretations to Abhidhamma or assimilate Buddhist concepts to scientific theories. Our sole purpose is to create new knowledge based on Sinhala-Buddhism and in the process build our own neuropsychology and neurology. Any input is welcome.