Stimulation

“ The definition in short is: “Stimulus is every alteration in the external vital conditions.”
This definition gives to the conception of stimulation its most complete, that is to say, its generally applicable and simplest form. The great importance from a methodical standpoint of38 this definition of stimulation for the research of life is evident. Our whole experimental natural science always employs for investigation of any state or process the same method: the state or process to be observed is studied under systematically altered conditions. ”

“ Although countless results of individual effects of stimulation have been studied, the attempt has never been made to establish a general physiology of the laws of stimulation and consider it as an independent problem. ”

“ When it is physiologically understood that what is called stimulation or excitement is, in absolute fact, a relaxation, I had nearly said a paralysis, of one of the most important mechanisms in the animal body—the minute, resisting, compensating circulation—we grasp quickly the error, in respect to the action of stimulants, in which we have been educated, and obtain a clear solution of the well-known experience that all excitement, all passion, leaves, after its departure, lowness of heart, depression of mind, sadness of spirit. ”

“ The result of excitation, or if one will, of stimulation of a living part, can, therefore, according to circumstances, be either merely a functional process, or there can be a more or less intense nutritive activity produced without the function being necessarily at the same time activated, or finally, it is possible11 that a process of formative change may occur which produces new elements in greater or less numbers. ”

“ But further, the restriction of the term stimulation to those alterations which increase the course of the changes in the living substance involves the observer in still greater contradictions. It can easily be shown that one and the same factor in one and the same form of living substance has now an exciting, now a depressing effect on the vital processes. ”

“ It is more precise, however, to speak of conductivity of excitation, for it is not the primary influencing external stimulus which is conducted in the living substance, but the excitation which it has produced. I have intentionally considered only the excitating effects of stimulation, and not those of the depressing reactions, as only excitations, not depressions, are conducted by the living substance. ”

“ These principles of an exact conditional investigation must also guide us in the analysis of the processes of stimulation. The process of stimulation is especially apt to tempt one to employ the old conception of cause, for it belongs to that group of processes which originate from an already existing system by the addition of a new factor. An electric stimulus acts on the muscle. The muscle contracts. The stimulus is considered the cause of the contraction. ”

“ And the specific sensation, or movement, which results from stimulation of a nerve depends not on the nerve, but on the mechanism of which the nerve is one element. Sensations of touch, temperature, and pain are assuredly specific; they are as unlike each other as a sensation of taste is unlike a sensation of smell. ”

“ According to this interpretation the primary tissue of experience of the emotional order, felt as an unanalysed complex, is generated by the stimulation of the sensorium by afferent or incoming physiological impulses from the special senses, from the organs concerned in the responsive behaviour, from the viscere and vaso-motor system. ”

“ Under increasing intensity of stimulation, the amplitude of response undergoes an increase which reaches a limit.
6. Sub-minimal stimulus induces a response of opposite sign to that under moderate stimulation.
7. Under rapidly succeeding stimuli, the individual responses become fused; the curve rises to a maximum, when the force of restitution balances the force of distortion due to stimulation. ”

“ If it could be shown that an organ, when stimulated with such excess that it resulted in its deterioration, produced its specific sensation and yet no pain in connection with the stimulation, a valid argument would certainly be had against the theory I defend ”

“ The physiologist, the zoölogist, the botanist, the psychologist, the pathologist, have to deal, day in, day out, with the effects of stimulation on the living substance. No living substance exists without stimulation. In the vital manifestations of all organisms the interplay of the most varied stimuli produces an enormous and manifold variety of effects. Experimental biological science employs artificial stimulation as the most important aid in the methodic production of certain effects of stimulation. The number of researches in which special effects of stimulation are treated is endless. ”

“ We found that when a sense organ is stimulated by its appropriate type of stimulus, this stimulation travels through the sensory nerves and sets up an excitation in the brain. This excitation in the brain gives us sensation. We see if the eye is stimulated. ”

“ This is the secondary extension of the result of stimulation from the part of a living organism directly and primarily affected by the stimulus, to the surrounding structures. All living substance has the capability of conducting an excitation, which is produced locally through a catalytic stimulus, to a neighboring part, not directly affected by the stimulus. It finds its highest development in the nerve, but in no living structure is it completely absent. ”

“ If we disregard the distinction between mind and body, we may say that the stimulus for a response may be an idea as well as a perception, the perception arising from the immediate stimulation of a sense organ, and the idea arising from an excitation of the brain not caused by an immediate stimulation of a sense organ.
Instincts and Habits. In human action it is evident that there is always a stimulus to start the nerve-impulse which causes the action. If we make inquiry concerning the connection between the stimulus and response ”

“ 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. ”

“ Those that are stimulated are the entire muscular system, the vasomotor and locomotor systems, the senses of perception, the respiration, the mechanism for erecting the hair, the sweat-glands, the thyroid gland, the adrenal gland (Cannon) , and the special senses. On the other hand, all the digestive and procreative functions are inhibited. What is the significance of this stimulation of some and inhibition of other organs? As far as we know, the stimulated organs increase the efficiency of the animal for fight or for flight. ”

“ The heart itself under the influence of nervous stimulation may in a moment change its customary order and rate of action, and in extreme cases cease to beat. The whole mental processes, as well as the functions of organic life, may be seriously involved. ”

“ See on P the record of muscle curve. We may stimulate the living substance in various ways—by light, or by thermal, chemical, electrical, or mechanical stimuli. Of these, the electric means of stimulation is the most convenient, whereas the mechanical causes fewest complications. With regard to the response of living substances, the most important matters for study are the responses to single stimulus and the modification of response by fatigue and by drugs. ”

“ This doctrine of the specific energy of the sense substance possesses an importance which extends far beyond the domain of the physiology of stimulation, for it forms the basis on which the whole theory of human knowledge must be built up, no matter how it may be constructed in detail. ”

“ The central process which initiates a reflex action may be excited by the external stimulation of a peripheral nerve, by the internal stimulation of a peripheral nerve, or by the irradiation from some other part of the central tissue. ”

“ We endure the excitation better and feel less fatigued, whatever it be. If by any chance, however, through illness or other cause, our stock of force becomes lessened, we find that we cannot so well endure our habitual stimuli, and they become painful instead of pleasant. Our feelings, then, are regulated partly by the amount of stimulation, partly by the condition in which our centres are when stimulated; and that which applies to pain applies also to pleasure. ”

“ I have in previous chapters explained that the direct application of stimulus gives rise in different organs to contraction, diminution of turgor, fall of motile leaf, electro-motive change of galvanometric negativity, and retardation of the rate of growth. I have also shown that indirect stimulation (i.e. application of stimulus at some distance from the responding organ) gives rise to a positive or erectile response of the responding leaf or leaflet (indicative of an increase of turgor) , often followed by normal negative response. The positive impulse travels quickly. ”

“ The relation between these stimulations and adjusted contractions must be such that increase of the one causes increase of the other; since the directions of the discharges being once established, greater stimulation causes greater contraction, and the greater contraction causing closer contact with the stimulating agent, causes increase of stimulus and is thereby itself further increased. ”

“ The state of tension is increased by every stimulation which falls short of a discharge; that is to say, faint and frequent stimulation augments the excitability, whereas328 powerful stimulation exhausts it. When, therefore, one wave succeeds another in the same direction, it reaches a centre more disposed to discharge ”

“ Very feeble stimulus thus induces an ac­cel­er­ation and strong stimulus a retardation of growth. I have frequently obtained positive mechanical and electrical responses under sub-minimal stimulation. As chemical substances often act as stimulating agents, the opposite effects of the same drug in small and large doses may perhaps prove to be a parallel phenomenon. ”

“ One wakes up the heart and viscera and leaves the brain stupefied, one gets at the brain, champagne fashion, and does nothing good for the solar plexus, and what I want, and what, if it's an earthly possibility, I mean to have—is a stimulant that stimulates all round, that wakes you up for a time from the crown of your head to the tip of your great toe, and makes you go two—or even three to everybody else's one. ”

“ Occasional accumulation of sensorial power in muscles subject to constant stimulus. In animals sleeping in winter. In eggs, seeds, schirrous tumours, tendons, bones. 3. Great exertion introduces pleasure or pain. Inflammation. Libration of the system between torpor and activity. Fever-fits. 4. Desire and aversion introduced. Excess of volition cures fevers. III. Of repeated stimulus. 1. A stimulus repeated too frequently looses effect. As opium, wine, grief. Hence old age. Opium and aloes in small doses. 2. A stimulus not repeated too frequently does not lose effect. ”

“ Agreeably to our last proposition, I proceed to remark, that the action of the brain, the diastole and systole of the heart, the pulsation of the arteries, the contraction of the muscles, the peristaltic motion of the bowels, the absorbing power of the lymphatics, secretion, excretion, hearing, seeing, smelling, taste, and the sense of touch, nay more, thought itself, are all the effects of stimuli acting upon the organs of sense and motion. These stimuli have been divided into external and internal. The external are light, sound, odours, air, heat, exercise, and the pleasures of the senses. ”

“ And in insane people in some cases the force of their muscular actions will be in proportion to the quantity of sensorial power, which they possess, and the quantity of the stimulus of desire or aversion, which excites their volition into action. At the same time in other cases the stimulus of pain or pleasure, and the stimulus of external bodies, may excite into action the sensorial powers of sensation and irritation, and thus add greater force to their muscular actions. ”

“ A quantity of stimulus greater than natural, producing an increased exertion of sensorial power, whether that exertion be in the mode of irritation, sensation, volition, or association, diminishes the general quantity of it. ”

“ To call all mental processes reactions means that it is always in order to ask for the stimulus. Typically, the stimulus is an external force or motion, such as light or sound, striking on a sense organ. There are also the internal stimuli, consisting of changes occurring within the body and acting on the sensory nerves that are distributed to the muscles, bones, lungs, stomach and most of the organs. The sensations of muscular strain and fatigue, and of hunger and thirst, are aroused by internal stimuli, and many reflexes are aroused in the same way. ”

“ The physical organism is undoubtedly the means by which the mental susceptibility to pleasure or pain is reached from the external universe; but, unless there is a mental organism to feel the pleasure or the pain, the action of the physical organization is nothing but the excitation of the nervous system. I, therefore, [Pg 532] make a distinct class among the mental systems, and assign to it the faculty of experiencing mental pleasure or mental pain as a capacity distinct from the pleasurable or painful excitation of our nerves. ”

“ Thus, a sensation which embraces within its range the whole spiritual being agitates in the same measure the whole framework of the organic body,—heart, veins and blood, muscles and nerves, all, from those mighty nerves that give to the heart its living impulse of motion down to the tiny and unimportant nerves by which hairs are attached to the skin, share equally its influence. Everything tends to a more violent motion. If the sensation be an agreeable one, all these parts will acquire a higher degree of harmonious activity ”