Forebrain

“ There is no more interesting subject of inquiry open just now than that of the interaction between the thoughts of the mind and the configuration of the brain. The fair conclusion appears to be that each is greatly the cause of the other; that the character of the persistent thoughts actually shapes the cerebrum, while on the configuration of this organ depends in turn the manner of thoughts we think. Now, thought is, for the most part, automatic. We think, without intention or effort, as we have been accustomed to think, just as we walk or write without any conscious arrangement of muscles. ”

“ So the brain in man is “the one immediate bodily condition of the mental operations.” Take away all the brain and man’s body is a useless mass of protoplasm.
The brain’s varied and intricate nerve connections with all parts of the body, through nerves branching from the main trunks in the spinal cord, we shall not discuss, for you know them through your study of anatomy. For the purpose of our psychology we need consider only two of the main divisions of the brain—the cerebrum, which includes what we call the right and left hemispheres, and the cerebellum. ”

“ And the second may be summed up in saying that knowledge, if it is knowledge of what is outside the brain, cannot be manufactured inside the brain. It is admitted therefore practically by everyone that consciousness is not an effect of process in the cerebral cortex in the same way that the responsive movement of the muscles is such an effect. The brain directly connects the response of the body to the stimulus received but the consciousness that arises in the process is not part of the efficiency. ”

“ And to answer this question, we must know, first, the natural defects of the brain, and secondly, the peculiar powers of its mental correlate. Since consciousness is presumably at its minimum in creatures whose nervous system is simple, and at its maximum in the hypertrophied cerebrum of man, the natural inference is that, as an organe de perfectionnement, it is most needed where the nervous system is highly evolved ;' and the form our first question takes is: What are the defects characteristic of highly evolved nervous centres? ”

“ The experiences which we receive from the external world through our sense-organs and sense-centers in the brain are transformed into ideas by other brain-centers, and these are combined into inferences by association. These inferences are both inductive and deductive, processes which have equal value. Other complicated brain operations, the formation of chains of reasoning, abstraction and conception, imagination, consciousness, thought and philosophy, are all functions of the ganglionic cells of the cerebral cortex. ”

“ One thing is absolutely certain; that the mind resides in the brain; that in it inheres what constitutes us human; and that the conscious point resides in the centre of the encephalon, at that spot where all three brains meet, viz., cerebrum, cerebellum and medulla, or spinal marrow, which is an elongated brain, is a clear fact, the proof of which can be found by consulting any good anatomical and physiological atlas. ”

“ For, as I then observed, in this theory of nerve-fibres becoming more and more functionally developed by use, we probably have a physical explanation, which is as full and complete as such an explanation can ever be, of the genesis of mind. "For from the time that intelligence first dawned upon the scene of life, whenever a new relation had to be established in the region of mind, it could only be so established in virtue of some new line of discharge being excavated through the substance of the brain. ”

“ A functional distinction between the fore-brain and the remainder of the nervous system seems, in fact, that consciousness and physical reactions are adjunct to the fore-brain in a way in which they are not to the rest of the system. ”

“ It is not even correct to say that thought goes on in the brain. What goes on in the brain is an amazingly complex series of molecular movements, with which thought and feeling are in some unknown way correlated, not as effects or as causes, but as concomitants. So much is clear, but cerebral physiology says nothing about another life. Indeed, why should it? The last place in the world to which I should go for information about a state of things in which 110thought and feeling can exist in the absence of a cerebrum would be cerebral physiology! ”

“ Every one has long known that, without the brain, intelligence is not possible, but experiment has discovered exactly the part that is played by each portion of the organ. It teaches us that consciousness, or intelligence properly so called, resides in the cerebral lobes, while the lower portions of the brain contain nervous centres destined for organic functions of a lower kind. ”

“ The brain is regarded by physiologists and philosophers as the organ of the mind. Most writers consider it as an aggregate of parts, each charged with specific functions, and that these functions are the highest and most important in the animal economy. To the large brain, or cerebral lobes, they ascribe the seat of the faculties of thinking, memory, and the will. In man, this lobe extends so far backward as to cover the whole of the cerebellum. To the cerebellum, or little brain, is ascribed the seat of the animal, or lower propensities. ”

“ And the second is that the consciousness which arises in connection with cerebral process is not consciousness of cerebral process but of something which is altogether independent of cerebral process, something existing in a different space, it may be thousands or millions of miles away from the brain, and something existing at a different time, it may be ages before or even after the present moment at which the cerebral process takes place. ”

“ It is part of a complete nervous system and it is only a part of the brain that is concerned in mental process. A nervous system or something that closely corresponds to it seems to be a necessary acquirement of every living organism that moves freely, and its structure, however complex it may be in its higher development, is built up of a simple arrangement of cells and fibres that receive and transmit movement. Its function is to receive a stimulus and to transmit it to a centre where a responsive movement is prepared. ”

“ Like the reflex function of the nervous system, and like the still lower organic functions of secretion, excretion, circulation, respiration, etc., the wisdom and precision of its actions seem to be the result of structure, though unlike these the actions are not removed from the sphere of consciousness and will, if we call it intelligence; then it is not individual intelligence but cosmic intelligence, or the laws of Nature working through inherited brain-structure to produce wise results. ”

“ Through these observations it has been possible to assign certain functions to parts of the physiological mechanism.
In the case of man, both by observation and experiment, “the nervous structure below the hemispheres of the cerebrum has been excluded from the possibility of acting as the immediate physical basis of mental states.” [9] The higher mental processes, which involve the possibility of speaking, calculating, and responding by learned reactions to complex situations, have their correlate in the cortex (the agglomeration of neurones in the cerebral hemispheres) . ”

“ If you say the Brain immits and directs these Spirits, how can that so freely and spontaneously move it self or another that has no Muscles? besides, Anatomists tell us, that though the Brain be the instrument of sense, yet it has no sense at all of it self; how then can that that has no sense direct thus spontaneously and arbitrariously the Animal Spirits into any part of the Body? an act that plainly requires determinate sense and perception. ”

“ Above all, the brain, especially the cerebrum, the crown and goal of vertebrate structure. The improvement is now practically altogether in the animal organs of locomotion and thought. Still, among these animal organs, the lower systems will lead in point of time. The brain must to a certain extent wait for the skeleton. ”

“ In the absence of a distinct nervous system, we have no right to look for its product, consciousness; and, even in those forms of animal life in which the nervous apparatus has reached no higher degree of development, than that exhibited by the system of the spinal cord [Pg 107] and the foundation of the brain in ourselves, the argument from analogy leaves the assumption of the existence of any form of consciousness unsupported. ”

“ The cellular matter in the spinal cord and lower parts of the brain has a very important work to perform in receiving messages from the senses and responding to them in directing the simpler reflex acts and movements which we learn to execute without our consciousness being called upon, thus leaving the mind free from these petty things to busy itself in higher ways. The cellular matter of the cortex performs the highest functions of all, for through its activity we have consciousness. ”

“ But the passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought and a definite molecular action in the brain occur simultaneously; we do not possess the intellectual organ, nor apparently any rudiment of the organ, which would enable us to pass by a process of reasoning from the one to the other. ”

“ Every impression of sense upon the brain, every current of molecular activity from one to another part of the brain, every cerebral action which passes into muscular movement, leaves behind it some modification of the nerve elements concerned in its function, some after-effect, or, so to speak, memory of itself in them which renders its reproduction an easier matter, the more easy the more often it has been repeated, and makes it impossible to say that, however trivial, it shall not under some circumstances recur. ”

“ And it seems impossible to doubt that it is the brain that produces the mind and not the mind that produces the brain, because the brain is an organ that develops continually throughout life and performs a multitude of other functions besides that of turning the excitation of its cells and fibres into sensations and perceptions, a function that seems to be intermittent and only called into activity at definite times and in special circumstances. ”

“ The more recent development of the mind has been in its intellectual powers, while its physical aptitudes have somewhat declined. This has not yielded any marked increase in the dimensions of the brain, but it may have had a decided effect upon the proportion of its parts, the regions of the cerebrum devoted to intellectual activity probably increasing at the expense of the motor and sensory regions, while the convolutions may have grown considerably more complicated. ”

“ The scalpel of the anatomist can nowhere discover in the full-grown brain an organ of veneration, or of hope, or of language, or of destructiveness, or of any other mental feature: nor can his microscope detect in nature's wondrous process of fashioning the brain any reason for the belief that the organ of mind is a collection of parts each devoted to the exercise of a special quality of mind. The arrangement which appears so clear on the phrenologist's bust is nowhere represented in the brain itself. ”

“ The characters of the brain vary immensely, nothing being less constant than the form and size of the cerebral hemispheres, and the richness of the convolutions upon their surface, while the most changeable structures of all in the human brain, are exactly those on which the unwise attempt has been made to base the distinctive characters of humanity, viz. the posterior cornu of the lateral ventricle, the hippocampus minor, and the degree of projection of the posterior lobe beyond the cerebellum. ”

“ The 'entire brain-process' is not a physical fact at all. It is the appearance to an onlooking mind of a multitude of physical facts. 'Entire brain' is nothing but our name for the way in which a million of molecules arranged in certain positions may affect our sense. On the principles of the corpuscular or mechanical philosophy, the only realities are the separate molecules, or at most the cells. Their aggregation into a 'brain' is a fiction of popular speech. ”

“ For, as we have seen, not only is the cerebro-spinal system, which is the organ of consciousness, the abode of all the special senses, such as sight, hearing, etc., and therefore our only source of information of the external world, but many organs of the body are under the joint control of both systems. ”

“ Surely no one who is cognisant of the facts of the case, nowadays, doubts that the roots of psychology lie in the physiology of the nervous system. What we call the operations of the mind are functions of the brain, and the materials of consciousness are products of cerebral activity. ”

“ Brain Complexity.—The most interesting feature of the discoveries in brain anatomy during the past generation, has been that the central nervous system is of even greater complexity than had been thought. Because of this, these new discoveries, instead of solving the biological mystery they subtend, or even helping very much to solve it, have made it still harder to understand just how we succeed in controlling and directing this immensely complex machine, of whose details we are utterly unconscious, yet which we learn to use with such discriminating nicety of adjustment and accomplishment. ”

“ It is not the process going on in our brain that we are aware of, but the process going on outside our brain, and although influences reach our brain from outside and although the physiological processes are directly connected with the outside world by the sense organs, yet these influences are stimuli which cannot be conceived as translating anything, even images of things, into the brain as a material out of which the brain might be conceived to produce the mind. ”