Braincase

“ Mind has been enabled to read the impressions that are made in and on the substance of brain convolutions, but at the same time has been and is insensible to the existence of the convolutions themselves. It is as though we could read the letters of the manuscript that bears them without having conceived of a necessity for the existence of a printed surface, such as paper or anything outside the letters. Had anatomists never dissected a brain, the human family would to-day live in absolute ignorance of the nature of the substance that lies within the skull. ”

“ That all we call mind is indissolubly connected with matter through the grey cells of the brain and other nervous ganglia. This is positive. If the skull could be removed without injury to the living organism, a skilful physiologist could play with his finger on the human brain, as on that of a dog, pigeon, or other animal, and by pressure on different notes, as on the keys of a piano, annihilate successively voluntary motion, speech, hearing, sight, and finally will, consciousness, reasoning power, and memory. But beyond this physical science cannot go. ”

“ As the spinal cord developed greater ganglia at one of its extremities, the more important of the psychic manifestations were passed on to these superior ganglia. Out of these developed the hind-brain, the mid-brain, the fore-brain, the total cerebrum in man, so that, as Goethe guessed, the skull is only the greatest of the vertebræ, and to the cellular contents of this crowning structure were at last transferred those neuroses which accompany human consciousness.
Consciousness is never strictly simple. ”

“ Our histologist, who had passed part of his life examining, under the microscope, fragments of cerebral matter, in following the forms of the cells, the course of the fibres, and the grouping and distribution of the fascia, made the following remark: “It is the fact that the study, however patient, minute, and thorough it might be, of this nerve-skein can never enable us to know what a state of consciousness is, if we do not know it otherwise; for never across the field of the microscope is there seen to pass a memory, an emotion, or an act of volition.” ”

“ Edinger [2] has shown that to the primitive division of the brain of the vertebrate (or the paleencephalon) , which is the bearer of the reflexes and the instincts, there has been gradually added with peculiar adjustments a newer division (the neencephalon) , which corresponds to the cerebrum, in which alone is centered the power of association, and of forming memory images. In proportion as the cerebral cortex increases, the primitive brain recedes, while in a corresponding ratio intelligence rises, and purblind instinct wanes. ”

“ As we study the nervous systems of animals, we find that with the apparent growth of intelligence there is a development of that part of the brain called the cerebrum. In so far as certain other parts of the brain are concerned—medulla, pons, mid-brain, basal ganglia cerebellum—we who are human are not essentially superior to the dog, the cow, the elephant or the monkey. But when the neopallium, or the cerebrum, is considered, the enormous superiority of man (and the superiority of the higher over the lower animals) becomes striking. ”

“ In other words, there is every reason to believe that numerous "centres," in this restricted sense, exist in the brain that have as yet eluded the investigator. Indeed, the current conception regards the entire cerebral cortex as chiefly composed of centres of ultimate co-ordination of impressions, which in their cruder form are received by more primitive nervous tissues—the basal ganglia, the cerebellum and medulla, and the spinal cord.
This, of course, is equivalent to postulating the cerebral cortex as the exclusive seat of higher intellection. ”

“ The cerebrum, or fore brain, is divided into two hemispheres, each of which is further divided into numerous lobes consisting of grey and white nervous substance and millions of nerve cells and fine blood vessels. The hemispheric ganglia are the instruments through which the intellectual powers manifest themselves. If these instruments have become imperfect in structure through retarded development by wrong environment and education, or have been damaged in any manner by severe shock, violence or disease, the manifestations of intelligence are affected in a corresponding degree. ”

“ Above, and on either side of the eyes, I saw the shadow of something white, soft, and spongy, in which I fancied I could detect a distinct likeness to a human brain, only on a large scale. There were the cerebral lobes, or largest part of the forebrain, enormously developed and overhanging the cerebellum, or great lobe of the hindbrain, and completely covering the lobes of the midbrain. On the cerebrum I even thought I could detect—for I have a smattering of anatomy—the usual convolutions, and the grooves dividing the cerebrum into two hemispheres. ”

“ If brain and nerves are practically identical, is it not plain that, instead of being confined to the cavity of the skull, there is not any part of the surface of the body that can be touched by a pin's point without pricking the brain? ”

“ He can predict all the movements that will take place as certainly as a chemist knows in advance the reaction he will obtain from mixing certain bodies.
Pathology confirms our conclusion respecting these higher functions of the cerebrum. Loss of cerebral substance, in man, is followed by a weakening of the intellectual powers. They make a very childish mistake who attempt to deal with the physiological materialism of our day by citing the American crow-bar case, or any number of cases of brain-loss unaccompanied by marked intellectual enfeeblement. ”

“ 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! ”

“ 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. ”

“ A careless observer, forgetting that a soft structure like the brain loses its proper shape the moment it is taken out of the skull, may indeed mistake the uncovered condition of the cerebellum of an extracted and distorted brain for the natural relations of the parts ”

“ All Mental Process Accompanied by Neural Process.—Whatever the ultimate decision of psychologists may be regarding the relation of mind to the sensory and nervous mechanism of man it is certain that there is so close an association between them that the least alteration in the mechanism means a parallel effect in the mind, or in the words of Huxley, “every psychosis is definitely correlated with a neurosis.” The rind or cortex of gray matter which constitutes the surface of the large cerebral hemispheres of the [Pg 196] human brain is regarded as the seat of consciousness. ”

“ The cerebrum is the chief seat of the sensations, the intellect, the will, and the emotions. A study of cerebral injuries and diseases, and experiments upon the lower animals, prove that the hemispheres, and more especially the gray matter, are connected with mental states. The convolutions in the human brain are more prominent than in that of the higher animals, most nearly allied to man, although some species of animals, not especially intelligent, have marked cerebral convolutions. The higher races of men have more marked convolutions than those less civilized. ”

“ The local modification of the brain to which the recollection is attached being the same in each case, the psychological difference between the two recollections cannot have its ground in a particular difference of detail between the two cerebral mechanisms, but in the difference between the two brains taken each as a whole. The more complex of the two, in putting a greater number of mechanisms in opposition to one another, has enabled consciousness to disengage itself from the restraint of one and all and to reach independence. ”

“ One might cite the feeble-mindedness that results from meningitis, brain tumor, brain abscess, brain wounds, etc., as further evidence of the dependence of mind upon brain, of its status as a function of brain. No philosopher seriously doubts that equilibrium and movement are functions of the brain, and yet to prove this there is no evidence of any other kind than that cited to prove the relationship of mind to brain. [1] And what applies to the intelligence applies as forcibly to character, for purpose, emotion, mood, instinct and will are altered with these diseases. ”

“ But not only does the outward appearance of the brain change with the modification of its functions; it presents in its inner structure also a complexity that increases with the variety and intensity of the mental manifestations. As regards the texture of the brain, we are long past the days of Buffon, who considered the brains, as he contemptuously called them, a mucous substance of no importance. The advance of general anatomy and of histology has taught us that the cerebral organ possesses a texture more delicate as well as more complex than that of any other nerve-arrangement. ”

“ We may, however, notice here that, as in his nervous organization, no distinctly new parts are discoverable, but only general growth and development, and especially vast increase in the size and working capacity of the cerebrum, together with improved lines of communication between the different parts of the brain, so in the psychical manifestations which this enlarged and better-developed brain exhibits, no faculties are discovered beyond what these various developments in structure render possible. Does man possess intelligence? ”

“ A system of localization has been roughly mapped out, the result of careful laboratory work on animals and of studying the loss of various functions in human beings as related to the location of brain injuries.
From these experiments it seems proved that consciousness belongs only to the cortex or surface of the upper brain, and that the vast realm of the unconscious belongs to the lower brain centers. Hence the cortex is the organ of consciousness, and the lower centers are the repository of the unconscious until it again becomes conscious. ”

“ Destruction of certain definite portions of the cerebral hemispheres involves losses of memory and of acquired motor faculty of quite determinate sorts, to which we shall revert again under the title of aphasias. Taking all such facts together, the simple and radical conception dawns upon the mind that mental action may be uniformly and absolutely a function of brain-action, varying as the latter varies, and being to the brain-action as effect to cause. ”

“ Physiologists tell us that there are the almost inconceivable number of something like 7000 million nerve cells in the brain of the newly born child and these, which neither increase nor decrease throughout life, undergo a development of interconnection by means of the branching fibres they send out in every direction. When through disease or malformation or any other cause this development is arrested we have mental deficiency or idiocy.
The brain is an organ of immense complexity and has a great deal more to do than only to turn stimuli into sensations. ”

“ Diffuse lesions affect the mind more than those which are circumscribed—that is to say, limited to a certain part of the brain—as if the mental functions required the co-operation of the entire cerebral cortex. One will often find, for example, sound judgment in the subject of a marked paralysis, whilst it is very rare to find that good intelligence co-exists with any degree of microcephalus. ”

“ Another proof of progress might have been given, had time allowed of a reference to what has been done in the study of the brains of idiots, both morphologically and histologically, by Mierzejewski, Luys, and others, these results being sufficient to prove, had we no other evidence, the fundamental truth of cerebro-mental pathology—the dependence of healthy mind on healthy brain.
We are surely justified in expecting that by a prolonged examination of every part of the brain structure, and the notation of the mental symptoms, we shall arrive in future at more definite results ”

“ I would desire this evening to lay down and to enforce a principle that is, I think, not sufficiently, and often not at all, considered in practical medicine and surgery. It is founded on a physiological basis, and it is of the highest practical importance. The principle is that the brain cortex, and especially the mental cortex, has such a position in the economy that it has to be reckoned with more or less as a factor for good or evil in all diseases of every organ, in all operations and in all injuries. ”