Motor activity

“ It is, in the cases noted, at once sensory and motor, or at any rate involves motor elements. And the effect of the activity of such motor elements is both to increase the distinctness of the image and to prolong the duration of the process by which it is apprehended. The sensory process thus stands in intimate dependence on the motor. Nor would failure to move the eyes or any other organ with the movement of attention, if established, be conclusive as against the presence of motor elements. A motor impulse or idea does not always result in apparent peripheral movement. ”

“ This psychomotor side of the process, and not the mere muscle activity as such, is indeed the essential factor which should interest us. The results of exercise are a training of the central apparatus of the brain and not of the muscular periphery. The further development of those experiments soon led to complex questions, which referred not only to the mere change in the motor efficiency, but to the learning of particular groups of movements and to the influences on the exactitude and reliability of the movements. ”

“ Experiment and pathology, despite all the contradictions, seem to point to the existence of a motor zone on the surface of the hemispheres. This means that certain parts of the brain are directly concerned with the movements of particular muscles and groups of muscles; also, that these parts can not be shown to be connected with sensations. The natural, primary occasions of their activity may be the states of consciousness which we call volitions; they are not, so far as evidence goes, the states of consciousness we call sensations. ”

“ The sensori-motor relation is observed not only in the lowest forms of psychic life, but also in the highest. In the highest form of mental life we still meet with the same factor of motor reactions. Mental activity tends to pass into action. Psychic processes, motor and glandular reactions are interrelated. All along the course of mental activity reaction is present as its invariable concomitant. Some muscles are in a state of tension, others in a condition of relaxation. ”

“ In the last few years, however, the psychologists have learned a great deal about the motor aspects of mental activity. They have demonstrated that almost any simple act of attention involves muscular innervation and, contrariwise, that motor exercise quickens intelligence. Psychology teaches that body and mind have grown up together and that the latter has no raison d'être apart from motor adjustment. ”

“ A lower motor center is a group of motor and central neurones, lying anywhere in the cord or brain stem, and capable of directly arousing a certain coördinated muscular movement. One such unit gives flexion of the leg, another gives extension of the leg, a third gives the rapid alternation of flexion and extension that we see in the scratching movement of the dog. Such a motor center can be aroused to activity by a sensory stimulus, and the resulting movement is then called a reflex. ”

“ If the motor cells are distinct structures, they are as insentient as the motor nerve-trunks are after the posterior roots are cut. If they are not distinct structures, but are only the last sensory cells, those at the 'mouth of the funnel,' [460] then their consciousness is that of kinæsthetic ideas and sensations merely, and this consciousness accompanies the rise of activity in them rather than its discharge. ”

“ The complex coordination of orientation and space adjustment, such as the maintenance of equilibrium, walking, running, jumping, flying, swimming, etc., represent more complex activity. A still higher aggregate is to be found in the association of groups and systems of sensori-motor reactions within the sphere of a sense-organ with the complex coordination of motor adjustment of the whole body. The highest aggregates are to be found in the association of all the motor reactions organized within the different spheres of sense-organs with the complex motor coordination of body-adjustments. ”

“ In close connection with these stimuli of pressure are those of muscular movement, whether unimpeded or impeded. We need not enter into the difficult question how far the "muscular sense" is connected with the activity of the motor nerves, and how far with sensory fibres attached to the muscular or the adjacent tissues. ”

“ To start a mechanism that will produce well-ordered movement, as when I lift this book from the table, impulses or messages, whatever you like to call them, must first be transmitted from the body itself to the brain. Such messages may come to the brain by nerve-fibres from some organ of sense, it may be from the skin, or from the eyes, or from the muscles themselves, but they must be sent to the brain before the brain will send out messages along motor nerves to groups of muscles which are called into action, so as to perform a definite movement. ”

“ Is the time in which the greatest exactitude is produced, the same for every group of muscles; that is, has every motor apparatus the same natural rhythm? and: Is this natural rhythm a constant rapidity for all motor nerve-centres or does it depend upon the complexity and character of the movement? ”

“ Such objects are of value as educational materials to the degree to which they call for necessary muscular adjustments similar to those which the race from the earliest times has experienced. Every sensation or thought, the psychologists affirm, naturally stimulates a motor adjustment which reinforces the original sensory or central impulse which originated the motion. ”

“ By the Spontaneity of Movement is meant the tendency of human beings, and of animals generally, to begin acting without the express stimulus of sensation from without, and by virtue of the fund of power residing in the active organs themselves. By means of nourishment, the animal is disposed to pass into movement, from the mere abundance of the motor energy in the nerve centres and in the muscles. ”

“ REGRESSION As I have stated in a previous paper, [15] the pathogenesis of tics and allied conditions can best be appreciated by viewing the subject from an evolutionary standpoint. In our reactions and adaptations to the varying experiences with which we meet we respond by one or more of several methods of motor reaction. These motor expressions are of increasing complexity as we ascend the scale of evolution and development. One of the simplest kinds of adaptation is by simple, reflex muscular action, the response being anatomical and not physiological in its extent. ”

“ Modern physiology, from its objective point of view, is engaged over finer and finer issues of microscopic and experimental work; and, from its subjective point of view, is becoming more and more psychological, seeking a higher level of interpretation, and a statement of the departmental life of the brain in terms of ever-increasing complexity. The motor centres, governing the voluntary purposeful movements of the body, are considered to be not simply motor, but “psycho-motor” ”

“ It is the universal motor adapted in the most exquisite manner to every form and state of the lungs, which communicate their general motion to every part of the body, and set every wheel in its infinitely complex organism revolving upon its axis, and give to every muscle and nerve the power to expand and contract and vibrate in the performance of its use, and in this way to fill every organ in the whole universe of the body with the power of sensation. ”

“ Thus not only the motor, but the sensor nervous system also, and the mental functions, are capable of being exercised and need it; and the muscles again appear to acquire a deeper importance in gymnastics. ”

“ To this intelligent distribution of the central nervous excitation in the co-operating groups are added a more perfect tact in appositeness, a surer realization of the direction of the intensity and the duration of the contractions, and a greater promptitude in grasping at once all the conditions of the effort. Thus is realized a perfectionment of the motor organs which is manifested externally by address, agility, and sureness of movements, and closely touches upon the higher qualities—confidence in one's strength and courage. ”

“ The discharge from the motor centre into the motor nerve is supposed to give a sensation sui generis, opposed to all our other sensations. These accompany incoming currents, whilst that, it is said, accompanies an outgoing current, and no movement is supposed to be totally defined in our mind, unless an anticipation of this feeling enter into our idea. The movement's degree of strength, and the effort required to perform it, are supposed to be specially revealed by the feeling of innervation. ”

“ Closely connected with these facts, perhaps only a somewhat different aspect of them, is the phenomenon of motor mechanization. Any movement repeated tends to become a circular reaction, as it is called; that is, the end of one repetition serves as a cue for the beginning of the next. ”

“ Moving objects exert, as is well known, a peculiar motor stimulation upon the eye, they draw our attention and our look after them. If the look really follows them ... we assume that they move. But if the eye, instead of following the moving objects, remains steadfastly at rest, it must be that the constant stimulus to motion which it receives is neutralized by an equally constant current of innervation flowing into its motor apparatus. ”

“ To accomplish a true reflex movement, a whole mechanism is necessary, set up in the spinal cord or the medulla. To choose voluntarily between several definite courses of action, cerebral centres are necessary, that is, crossways from which paths start, leading to motor mechanisms of diverse form but equal precision. ”

“ Functions of the Encephalic Animal.
A. ORGANS OF MOTION.
2770. Just as the nerves have a function in themselves, and one directed towards the subordinate organs, so also has the motor system.
2771. The motor system is in the first place doomed to serve the whole body, since it flexes it, moves it forwards and backwards and upon all sides. It is related principally to the movements of the vertebral column, and serves in numberless animals to effect the act of crawling or creeping. ”

“ Thus, an impulse which originally spread its effects over the whole body, or at least over many of its movable parts, is gradually determined to a single definite organ, in which it effects the contraction of a few limited muscles. In this change the thoughts and perceptions which start the impulse acquire more and more intimate causal relations with a particular group of motor nerves. ”

“ But the motor is in the two-fold sense of unmoved, and both motor, and moved—the unmoved is the practical good ; the motor and moved is the appetitive stimulus or appetition (for that which is moved moves only in so far as it desires, and appetite is a motion or an act of some kind) ; and the moved is the animal. As the organism by which appetite effects motion is obviously corporeal, its nature must be studied together with those functions which are common to the body and the Vital Principle. ”

“ It is nothing more than the measure of the motor impulses directed to the object of attention. And whether the motor impulse appears as the tendency to follow out the suggestions of motion in the object, all reduces to the same physiological basis. ”

“ The motor attitude of the animal towards the excitations of the external environment constitutes the predominant part of its objective world. The reactions with their sensori-motor effects are part and parcel of the total percept. Sensori-motor life gives reality to the world of objects. The spatial, the resistant, the material character of objects depends on our motor reactions which give content and reality to the world of things. ”

“ More than this, it is a fact that many activities originally voluntary become what is known as "acquired reflexes," or "motor habits," by means of certain nervous centers acquiring the habit of sending forth certain motor impulses in response to certain sensory reports. The familiar movements of our lives are largely performed in this way, as, for instance, walk [Pg 20] ing, using knife and fork, operating typewriters, machines of all kinds, writing, etc. ”

“ I see an example of it in the way in which many of them account for our thoughts and resolutions: they call them reflex action. The discovery of the nature of automatic motion was one of the most important discoveries of the last age. An action goes along a nerve to the centre of a ganglion, and comes out in motion by another nerve: thus, if a frog's foot is pricked, it is immediately drawn in. Of much the same kind is the reflex action of the sensori-motor system. ”

“ Everybody, too, must often have observed how the execution of any but mechanical movements arrests attention to thoughts or sensations, and how, vice versa, a striking impression or thought interrupts him in the performance of skilled movements. Let us suppose, then, that we have at any given moment a certain distribution of attention between sensory and motor presentations; a change in that distribution then will mean a change in the intensity of some of all of these. But, in the case of motor presentations, change of intensity means change of movement. ”

“ We note in the first place the motor manifestations: movements, gestures, and attitude of the body, a modification in the voice, blushing or pallor, tremors, changes in the secretions or excretions, and other bodily phenomena, varying in different cases. We may observe them in ourselves, in our fellows, and in animals. Although they may not always be motor in the strict sense, we may so call them, since they are all the result of a centrifugal action. ”