Brain activity

“ 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. ”

“ Authorities differ as to how far it is possible to localise the functions of the brain; but this at least seems pretty clear--that none of the functions of mind are performed without real activity in the mass of grey and white nervous matter named 'the brain.' Now, this is not a matter for the physiologist alone, but for every mother and father of a family ”

“ 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 use of the brain along chosen lines will, on well-known physiological principles, increase its organization and therefore its power for manifesting psychic phenomena. These two factors will continue to act and react in the future as they have in the past, increased psychical activity enlarging the brain, and the more highly organized brain augmenting the psychic phenomena. What is true of the mind in general is also true of its varied manifestations. ”

“ It is when the Brain is growing, that the direction of its structure can be most strongly and persistently given to it. Thus the Habits of Thought come to be formed, and those Nerve-tracks laid down which (as the Physiologist believes) constitute the Mechanism of Association, by the time that the Brain has reached its maturity; and the Nutrition of the organ continues to keep up the same mechanism, in accordance with the demands upon its activity, so long as it is being called into use. ”

“ Its Importance for Psychology.—There remains a condition of general neural activity so important as to deserve a chapter by itself—I refer to the aptitude of the nerve-centres, especially of the hemispheres, for acquiring habits. An acquired habit, from the physiological point of view, is nothing but a new pathway of discharge formed in the brain, by which certain incoming currents ever after tend to escape. ”

“ If the brain is capable of what is commonly named mental activity, all that science has demonstrated is susceptibility and motor activity, that is nerve impulse involving molecular and muscular action, and this carries no explanation of mental action. ”

“ Long ago we discovered that, unaided, the mind will function with only a small portion of its specialized cells. This stimulant forces conscious activity upon all parts of the cortex; in the process of stimulation, your brain will receive the full knowledge of basic principles which we ourselves have developed. ”

“ When nervous movements are transmitted to the cortex of the brain, they not only awaken consciousness, or make the individual aware of something, but the present impression also leaves certain permanent effects in the nervous tissue of the cortex itself. Since, however, cortical activity implies consciousness, the retention of such a tendency within the cortical centres will imply, not an habitual act in the ordinary sense, but a tendency on the part of a conscious experience to repeat itself. ”

“ Here, then, we have an extraordinary exaltation of the Automatic action of the Brain, manifesting itself in the rapidity and intensity of the current of Thought; while the controlling power of the Will is not only relatively, but absolutely reduced. And this modification of the normal form of mental activity is clearly referable to the perversion of the normal action of the Blood upon the Brain, which is due to the introduction of a new Physical agent into the former. ”

“ The brain has, as it were, a fountain of supply for the nervous fluid, which flows to all the nerves, and stimulates them to action. Some brains have a larger, and some a smaller fountain; so that a degree of mental activity that would entirely exhaust one, would make only a small and healthful drain upon another. ”

“ Hence the data thus far accumulated in evidence of the actual structure, size, and weight, of the human brain fall far short of what is requisite for a solution of many questions in reference to the relations between cerebration and mental activity. From time to time men of science have sought by example, as well as by precept, to lessen such impediments to scientific research. ”

“ This is the rationale of the pathological treatment of the brain. Tell an overworked president of a railway company, who falls asleep at the directors' meeting, that he must rest, or die of softening of the brain, and he will smile a sad reply that he can not rest. He is right, thus far: he can not rest his whole brain, but he can rest the cerebellum—the seat of the will-power—by bringing into higher activity and more frequent exercise the upper and frontal lobes. ”

“ Nervous action also involves physico-chemical changes of matter and the expenditure of energy. This is true even of the activity of the brain associated with sensation, perception, emotion, volition and other psychical phenomena, and therefore the higher nervous centres require rest, during which they are protected from the stream of impressions flowing in from the sense-organs, and in which waste matters are removed and the cerebral material is recuperated for another time of wakeful activity. ”

“ The two physical conditions necessary for habit formation, easily impressed brain cells, and activity making these impressions, are at their best during this period. Every time an act is performed, a nervous force passes through the brain, stimulating nerves and muscles to action, and leaving the trace of its passage. ”

“ Hence the nervous system becomes oppressed, the brain frequently congested, and the intellectual faculties no longer enjoy their wonted activity. In the mean time, the system endeavours to relieve itself by throwing a counter-stimulus upon certain other organs, the functions of which are morbidly increased. ”

“ Also, we shall observe the same individual under the various conditions of hunger and repletion, of sleep or want of sleep, of cold or heat, of health or disease. And we shall see how all the phenomena, which our inductive observation can collect, agree or disagree with the laws laid down by those who have by experiment investigated the physiology of the nervous system. From one method—dissection of the actual brain—we shall not learn much. When the action is over and the force departed, the actual structure teaches us little about the working. ”

“ Every known mental manifestation is associated with organic movement, and in man both mind and its expressive movements are centred in the cerebro-spinal portion of the nervous system, and especially in its encephalic ganglia, the brain. ”

“ When we emerge from this necessary field of labor, we come to those functions peculiar to the proper brain. Here all is continual action. Thought, imagination, will, the conflicting passions, language, and even articulation, claim their first impulse from the nervous centre. The idlest reverie, as well as the most profound study, taxes the brain. ”

“ All the materials of our thought are due to the way in which one elementary process of the cerebral hemispheres tends to excite whatever other elementary process it may have excited at some former time. The number of elementary processes at work, however, and the nature of those which at any time are fully effective in rousing the others, determine the character of the total brain-action, and, as a consequence of this, they determine the object thought of at the time. ”

“ 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? ”

“ 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. ”

“ We have seen that the nervous system not only regulates most of the existing functions of the body, but that it has indirectly influenced the development of various bodily structures and certain mental qualities, and that these powers of mind depend on the development of the brain. ”

“ 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 function of the brain—which must be regarded as the bulbous root of a nervous plant whose branches grow downwards—is twofold; to affect, and to be affected. In its active or positive condition it affects the whole of the vital and muscular processes in the man, finding expression in vital action. ”

“ 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. ”

“ It is only within the present century that the functions of the nervous system began to be understood, and only within the last few years that its relations to mental activity have been intelligently studied. ”

“ The physiology, however, of the brain and nervous system is in a state of such rapid advance, and is continually bringing forth such new and interesting results, that if there be really a connection between mental peculiarities and any varieties cognizable by our senses in the structure of the cerebral and nervous apparatus, the nature of that connection is now in a fair way of being found out. ”

“ 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. ”

“ 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. ”

“ It is this vital principle that coordinates the movements of brain cells which represent {133} the physical processes underlying memory and the nervous elements of the sensitive and motor phenomena of the organism. Reflection on the physical mechanism underlying mental operations of various kinds, demands the vitalistic explanation much more than the physiological phenomena which have converted physiologists to the old way of thinking in our time. ”

“ Although we cannot follow the movements of individuals in a battle, yet we may predict the result of the combat; and thus, we judge of the functions of the brain without the ability to reveal the actions of one of the organic molecules of which it is composed. We aim to give a general, reasonable, and popular description of cerebral functions and their bearing upon health and disease. ”

“ The function of nerves is to carry impulses—like telegraph wires. The functions of brains is something else.” But, confronted with such awesome experimental difficulties, with no comprehensive mathematical theory in sight, we are largely limited otherwise to verbal discourses, rationales and theorizing, a hopelessly clumsy tool for the development of an adequate understanding of brain function. ”

“ The localization of many of the cerebral functions, the discovery of a psychomotor tract, and the constant accessions to our knowledge of the physiology of the brain are throwing much light on the subject. ”