Science in Christian Perspective
.The Mind-Brain Problem
There are two schools of thought regarding what our attitude toward areas of ignorance should be. The question of how our minds are related to the brain is one such area. One school of thinkers believes that when all the facts are known we will be able to explain how the mind works in terms of the anatomy and physiology of the brain. They do not have such an explanation yet, but are satisfied to wait for new knowledge, confident that when it comes it will confirm their belief just as past discoveries have. As one person expresses it, "In the past the more we have learned the more we have been able to explain, so we believe that we could explain it all if we knew enough." Dr. F. Bremer'1 says, "The physiologist who is faced with the problem of nervous integration hopes that eventually an illuminating synthesis will emerge from the experimental findings which he accumulates. Aware of the sterility of vitalistic evasions, he is a mechanist without illusions. By an act of deterministic faith, he accepts the theoretical possibility that all behavior may be explained in terms of the physicochemical activities of the neuronal network, the structure of which, infinitely complex though it be, appears to be decipherable."
The second school intuitively feels that our minds can manipulate nervous processes, just the way we are able to manipulate the objects of our environment, in creating things for a purpose. They are not willing to deny the existence of a mind which plays upon the brain the way a pianist plays a piano, just because science knows of no way of measuring this control. Our .common experience of being able to initiate, direct or inhibit specific acts, or thoughts convinces us of such a control.
Mind, then, is my subjective awareness of how I think and act. It is the pattern of activity of the constituent parts of my brain, my bone encased central nervous system. When this "pattern" of activity is interrupted in one way or another, mind ceases to exist. Mind is not the activity of the cerebral cortex per se, such as an alpha sleep rhythm, but an asynchronous "pattern" of activity.
From a physiological point of view the nervous system is organized on a reflex basis. The simple monosynaptic stretch reflex is an example of this. The sudden stretch of a muscle by striking its tendon, activates sensory receptors in the muscle. These receptors respond by sending a burst of nerve impulses along its axon to the cell body in the dorsal-root ganglion of the spinal
**Mr. Sinclair is a Research Assistant at the University of California Medical School, San Francisco.
cord, and into synaptic endings on die surface of the motor-horn cells of the same muscle. Through the release of a neurotransmitter, the motor cell membrane is depolarized to the level at which it, in turn, initiates a spike potential which propagates along its motor axon to the nerve-muscle junctions within the muscle. This electrical disturbance releases acetyl-choline which activates the muscle membrane to trigger the mynofibrils to shorten.
This reflex arc is anatomically built-in and it can be mapped out by suitable staining methods. Physiologically, however, it is complex. Both excitatory and inhibitory influences play upon the motor-horn cell. The fine muscular coordination of which we are capable is achieved by the frequency of firing and time of firing of individual motor cells. In this simple example, the contraction of the muscle is an appropriate response to the stretch of its sensory receptors.
In Pavlov's experiments, the secretion of saliva by his dogs, when a bell was sounded which previously was associated with the sight and smell of food, is an appropriate conditioned response. It readies the animal to chew and swallow the anticipated food. By such responses the brain enables the animal to maintain and reproduce itself within its environment.
On a trip north, I stopped to visit friends whom I had not seen or heard of for years. It was amazing how the familiar faces and places brought back memories that were otherwise forever lost to me. We can speak of this type of memory as "cue" dependent, for a sensory cue is needed to trigger it. Memory is an appropriate response to environmental "cues."
Sensory deprivation studies on normal students demonstrate how essential environmental stimuli are, in maintaining the integrity and activity of the mind.2 Sensory feed-back from proprioceptors activated by the responses we make enables us to monitor the appropriateness of our movements. Feed-back from our ears monitors our speech, and feed-back from our audience monitors our interpersonal behavior.
If mental functions can thus be described on a re ex basis, what does this imply relative to our subjective experience of freedom of choice and purpose? Let me suggest that the directing of thought rather than thought itself is peculiar to Mind. By directing our attention or changing our position we can limit the environmental stimuli to which we make a response, though we can not determine whether we will respond.or,not. -What this might mean physiologic4lly,is that I can only acti vate neurons through presently active ones, so that no irrunaterial force or entity can initiate mental activity. My mind is thus inextricably bound to the functional integration of the cells of my brain. This seeming paradox can be considered in a logical way also. My world view is a mental one. It is a projection of the sensory cues travelling in from my receptors. According to this point of view it is impossible to be both object and observer 3. We automatically exclude the observer, our minds, when we study nature objectively.
The idea has been expressed4 that the principle of indeterminacy allows for freedom of will, that we can not say, "behavior is causally determined," because it is not possible to experimentally establish the causal basis for it, I personally do not see how someone's knowledge of the laws of human behavior and a knowledge of my past behavior can prejudice the choice I make of an appropriate response to a given situation, unless perhaps I knew what he predicted and why. Even God's knowledge of what I am going to do does not deny me the freedom to do as I please, unless I voluntarily submit my will to His. Pharoah of ancient Egypt was not coerced by God to oppose the escape of Israel.
We have found in physics that there is a complementarity between our knowledge of matter as waves and as particles. Likewise, our knowledge of the behavior of the functional organism complements our knowledge of the chemical and physical processes associated with this behavior. So also, our subjective experience of nature as observers complements what we know of the physiology of nerve nets and of the behavior of other organisms. I conclude, therefore, that the ultimate reality of matter is not wholly explicable in terms of the behavior of individual quantal particles; that the phenomenon of life is not wholly explicable in terms of chemistry and physics; and that Mind is not wholly explicable in terms
He did it because he wanted to. God just made His plans for the plagues according to Pharoah's own freedom of choice in this matter.
The question of feed-back information which concerns the effectiveness of what we do in terms of why we do it, and the critical importance of the constant barrage of sensory stimuli, of which we are almost totally unaware, have scarcely been mentioned. The Moody Science Film, "Sense Perception," pointed out the inexplicable, though compelling mental reaction that one experiences when the sensory homestasis to which he is accustomed is altered too drastically. The questions of memory, consciousness, the unconscious, and the interplay of heredity and environment have Uewise been slighted. For these reasons I do not believe I can adequately convey my awareness of the extent of my personal freedom within my material, biological and spiritual frame of reference, nor indicate the critical areas where God and Faith in God can play a decisive role in determining how I think and feel. Perhaps all I can hope to do is to communicate an inquisitive, uncertain, tentative and critical attitude toward these matters.Conclusion
1 'Bremer, F., Handbook of Physiology, Sec. 1, Vol. 11, 1241 (1960)
2Hebb, D. 0., Am. Psychologist 13, 109 (1958)
3Schrbdinger, E., Mind and Matter, Cambridge Press, 1958.
4Eccles, J. C., The Neurophysiological Basis of Mind, Oxford Press, 1953.