Origin and Nature of Emotions Part 8

Graves' Disease.--In Graves' disease the brain-cells show marked changes which are apparently the same as those produced by overwork, by the emotions, and by strychnin. In the postmortem examination of one advanced case it was found that a large number of brain-cells were disintegrated beyond the power of recuperation, even had the patient lived. This is undoubtedly the reason why a severe case of exophthalmic goiter sustains a permanent loss of brain power.

Insomnia.--The brains of rabbits which had been kept awake for one hundred hours showed precisely the same changes as those shown in physical fatigue, strychnin poisoning, and exhaustion from emotional stimulation. Eight hours of continuous sleep restored all the cells except those that had been completely exhausted.

This will explain the permanent ill effect of long-continued insomnia; that is, long-continued insomnia permanently destroys a part of the brain-cells just as do too great physical exertion, certain drugs, emotional strain, exophthalmic goiter, and hemorrhage.

We found, however, that if, instead of natural sleep, the rabbits were placed for the same number of hours under nitrous oxid anesthesia, not only did the brain-cells recover from the physical deterioration, but that 90 per cent. of them became hyperchromatic.

This gives us a possible clue to the actual chemical effect of sleep.

For since nitrous oxid owes its anesthetic effect to its influence upon oxidation, we may infer that sleep also r.e.t.a.r.ds the oxidation of the cell contents. If this be true, then it is probable that inhalation anesthetics exert their peculiar influence upon that portion of the brain through which sleep itself is produced.

If nitrous oxid anesthesia and sleep are chemically identical, then we have a further clue to one of the primary mechanisms of life itself; and as a practical corollary one might be able to produce artificial sleep which would closely resemble normal sleep, but which would have this advantage, that by using an anesthetic which interferes with oxidation the brain-cells might be reconstructed after physical fatigue, after emotional strain, or after the depression of disease.

In the case of the rabbit in which nitrous oxid was subst.i.tuted for sleep, the appearance of the brain-cells resembled that in but one other group experimentally examined--the brain-cells of hibernating woodchucks.

Insanity.--Our researches have shown that in the course of a fatal disease and in fatal exhaustion, however produced, death does not ensue until there is marked disorganization of the brain tissue.

In the progress of disease or exhaustion one may see in different patients every outward manifestation of mental deterioration, manifestations which, in a person who does not show any other sign of physical disease, mark him as insane. Take, for example, the progressive mental state of a brilliant scholar suffering from typhoid fever.

On the first day of the gradual onset of the disease he would notice that his mental power was below its maximum efficiency; on the second he would notice a further deterioration, and so the mental effect of his disease would progress until he would find it impossible to express a thought or to make a deduction.

No one can be philanthropic with jaundice; no one suffering from Graves' disease can be generous; no mental process is possible in the course of the acute infectious diseases. Just prior to death from any cause every one is in a mental state which, if it could be continued, would cause that individual to be judged insane.

If the delirium that occurs in the course of certain diseases should be continued, the patient would be judged insane.

In severe cases of Graves' disease the patient is insane.

Individuals under overwhelming emotion may be temporarily insane.

Every clinician has seen great numbers of cases in which insanity is a phase of a disease, of an injury, or of an emotion.

The stage of excitation in anesthesia is insanity.

The only difference between what is conventionally called insanity and the fleeting insanity of the sick and the injured is that of time.

We may conclude, therefore, what must be the brain-picture of the person who is permanently insane. This _a priori_ reasoning is all that is possible, since the study of the brain in the insane has thus far been confined to the brains of those who have died of some disease.

And it is impossible to say which changes have been produced by the fatal disease, and which by the condition which produced the insanity.

The only logical way by which to investigate the physical basis of insanity would be to make use of the very rare opportunities of studying the brains of insane persons who have died in accidents.

Our experiments have proved conclusively that whether we call a person fatigued or diseased, the brain-cells undergo physical deterioration, accompanied by loss of mental power (Figs. 40 to 43). Even to the minutest detail we can show a direct relationship between the physical state of the brain-cells and the mental power of the individual, that is, the physical power of a person goes _pari pa.s.su_ with his mental power.

Indeed, it is impossible to conceive how any mental action, however subtle, can occur without a corresponding change in the brain-cells. It is possible now to measure only the evidences of the effects on the brain-cells of gross and violent mental activity.

At some future time it will doubtless be possible so to refine the technic of brain-cell examinations that more subtle changes may be measured. Nevertheless, with the means at our disposal we have shown already that in all the conditions which we have studied the cells of the cortex show the greatest changes, and that loss of the higher mental functions invariably accompanies the cell deterioration.

A MECHANISTIC VIEW OF PSYCHOLOGY[*]

[*] Address delivered before Sigma Xi, Case School of Science, Cleveland, Ohio, May 27, 1913, and published in _Science_, August 29, 1913.

Traditional religion, traditional medicine, and traditional psychology have insisted upon the existence in man of a triune nature.

Three "ologies" have been developed for the study of each nature as a separate ent.i.ty--body, soul, and spirit--physiology, psychology, theology; physician, psychologist, priest. To the great minds of each cla.s.s, from the days of Aristotle and Hippocrates on, there have come glimmerings of the truth that the phenomena studied under these divisions were interrelated. Always, however, the conflict between votaries of these sciences has been sharp, and the boundary lines between them have been constantly changing.

Since the great discoveries of Darwin, the zoologist, biologist, and physiologist have joined hands, but still the soul-body-spirit chaos has remained. The physician has endeavored to fight the gross maladies which have been the result of disordered conduct; the psychologist has reasoned and experimented to find the laws governing conduct; and the priest has endeavored by appeals to an unknown G.o.d to reform conduct.

The great impulse to a deeper and keener study of man's relation, not only to man, but to the whole animal creation, which was given by Darwin, has opened the way to the study of man on a different basis.

Psychologists, physicians, and priests are now joining hands as never before in the great world-wide movement for the betterment of man.

The new science of sociology is combining the functions of all three, for priest, physician, and psychologist have come to see that man is in large measure the product of his environment.

My thesis to-night, however, will go beyond this common agreement, for I shall maintain, not that man is in _*large measure_ the product of his environment, but that environment has been the actual CREATOR of man; that the old division between body, soul, and spirit is non-existent; that man is a unified mechanism responding in every part to the adequate stimuli given it from without by the environment of the present and from within by the environment of the past, the record of which is stored in part in cells throughout the mechanism, but especially in its central battery--the brain.

I postulate further that the human body mechanism is equipped, first, for such conflict with environment as will tend to the preservation of the individual; and, second, for the propagation of the species, both of these functions when most efficiently carried out tending to the upbuilding and perfection of the race.

Through the long ages of evolution the human mechanism has been slowly developed by the constant changes and growth of its parts which have resulted from its continual adaptation to its environment.

In some animals the protection from too rough contact with surroundings was secured by the development of an outside armor; in others noxious secretions served the purposes of defense, but such devices as these were not suitable for the higher animals nor for the diverse and important functions of the human race.

The safety of the higher animals and of man had to be preserved by some mechanism by means of which they could become adapted to a much wider and more complex environment, the dominance over which alone gives them their right to be called "superior beings."

The mechanism by the progressive development of which living beings have been able to react more and more effectually to their environment is the central nervous system, which is seen in one of its simplest forms in motor plants, such as the sensitive plant and the Venus fly-trap, and in its highest development only in the sanest, healthiest, happiest, and most useful men.

The essential function of the nervous system was primarily to secure some form of motor activity, first as a means of securing food, and later as a means of escaping from enemies and to promote procreation.

Activities for the preservation of the individual and of the species were and are the only purposes for which the body energy is expended.

The central nervous system hag accordingly been developed for the purpose of securing such motor activities as will best adapt the individuals of a species for their self-preservative conflict with environment.

It is easy to appreciate that the simplest expressions of nerve response-- the reflexes--are motor in character, but it is difficult to understand how such intangible reactions as love, hate, poetic fancy, or moral inhibition can be also the result of the adaptation to environment of a distinctively motor mechanism. We expect, however, to prove that so-called "psychic" states as well as the reflexes are products of adaptation; that they occur automatically in response to adequate stimuli in the environment; that, like the reflexes, they are expressions of motor activity, which, although intangible and unseen, in turn incite to activity the units of the motor mechanism of the body; and finally, that any "psychic" condition results in a definite depletion of the potential energy in the brain-cells which is proportionate to the muscular exertion of which it is the representative.

That this nerve mechanism may effectively carry out its twofold function, first, of self-adaptation to meet adequately the increasingly complicated stimuli of environment; and second, of adapting the motor mechanism to respond adequately to its demands, there have been implanted in the body numerous nerve ceptors-- some for the transmission of stimuli harmful to the mechanism-- nociceptors some of a beneficial character--beneceptors; and still others more highly specialized, which partake of the nature of both bene- and nociceptors--the distance ceptors, or special senses.

A convincing proof that environment has been the creator of man is seen in the absolute adaptation of the nociceptors as manifested in their specific response to adequate stimuli, and in their presence in only those parts of the body which throughout the history of the race have been most exposed to harmful contacts.

We find they are most numerous in the face, the neck, the abdomen, the hands, and the feet; while in the back they are few in number, and within the bony cavities they are lacking.

Instances of the specific responses made by the nociceptors might be multiplied indefinitely. Sneezing, for example, is a specific response made by the motor mechanism to stimulation of nociceptors in the nose, while stimulation of the larynx does not produce a sneeze, but a cough; stimulation of the nociceptors of the stomach does not produce cough, but vomiting; stimulation of the nociceptors of the intestine does not produce vomiting, but increased peristaltic action.

There are no nociceptors misplaced; none wasted; none that do not make an adequate response to adequate stimulation.

Another most significant proof that the environment of the past has been the creator of the man of to-day is seen in the fact that man has added to his environment certain factors to which adaptation has not as yet been made. For example, heat is a stimulus which has existed since the days of prehistoric man, while the _x_-ray is a discovery of to-day; to heat, the nociceptors produce an adequate response; to the _x_-ray there is no response.

There was no weapon in the prehistoric ages which could move at the speed of a bullet from the modern rifle, therefore, while slow penetration of the tissues produces great pain and muscular response, there is no response to the swiftly moving bullet.

The response to contact stimuli then depends always on the presence of nociceptors in the affected part of the body and to the type of the contact. Powerful response is made to crushing injury by environmental forces; to such injuring contacts as resemble the impacts of fighting; to such tearing injuries as resemble those made by teeth and claws (Fig. 9). On the other hand, the sharp division of tissue by cutting produces no adaptive response; indeed, one might imagine that the body could be cut to pieces by a superlatively sharp knife applied at tremendous speed without material adaptive response.

These examples indicate how the history of the phylogenetic experiences of the human race may be learned by a study of the position and the action of the nociceptors, just as truly as the study of the arrangement and variations in the strata of the earth's crust discloses to us geologic history.

These adaptive responses to stimuli are the result of the action of the brain-cells, which are thus continually played upon by the stimuli of environment. The energy stored in the brain-cells in turn activates the various organs and parts of the body.

If the environmental impacts are repeated with such frequency that the brain-cells have no time for restoration between them, the energy of the cells becomes exhausted and a condition of shock results.

Every action of the body may thus be a.n.a.lyzed into a stimulation of ceptors, a consequent discharge of brain-cell energy, and a final adaptive activation of the appropriate part.

Walking, running, and their modifications const.i.tute an adaptation of wonderful perfection, for, as Sherrington has shown, the adaptation of locomotion consists of a series of reflexes-- ceptors in the joints, in the limb, and in the foot being stimulated by variations in pressure.

As we have shown, the bene- and nociceptors orientate man to all forms of physical contact--the former GUIDE HIM TO the acquisition of food and to s.e.xual contact; the latter DIRECT HIM FROM contacts of a harmful nature. The distance ceptors, on the other hand, adapt man to his distant environment by means of communication through unseen forces--ethereal vibrations produce sight; air waves produce sound; microscopic particles of matter produce smell.

The advantage of the distance ceptors is that they allow time for orientation, and because of this great advantage the majority of man's actions are responses to their adequate stimuli.

As Sherrington has stated, the greater part of the brain has been developed by means of stimuli received through the special senses, especially through the light ceptors, the optic nerves.

We have just stated that by means of the distance ceptors animals and man orientate themselves to their distant environment.

As a result of the stimulation of the special senses chase and escape are effected, fight is conducted, food is secured, and mates are found.

It is obvious, therefore, that the distance ceptors are the primary cause of continuous and exhausting expenditures of energy.

On the other hand, stimuli applied to contact ceptors lead to short, quick discharges of nervous energy. The child puts his hand in the fire and there is an immediate and complete response to the injuring contact; he sees a pot of jam on the pantry shelf and a long train of continued activities are set in motion, leading to the acquisition of the desired object.

The contact ceptors do not at all promote the expenditure of energy in the chase or in fight, in the search for food or for mates.

Since the distance ceptors control these activities, one would expect to find that they control also those organs whose function is the production of energizing internal secretions. Over these organs--the thyroid, the adrenals, the hypophysis--the contact ceptors have no control.

Prolonged laboratory experimentation seems to prove this postulate.

According to our observations, no amount of physical trauma inflicted upon animals will cause hyperthyroidism or increased adrenalin in the blood, while fear and rage do produce hyperthyroidism and increased adrenalin (Fig. 44) (Cannon). This is a statement of far-reaching importance and is the key to an explanation of many chronic diseases-- diseases which are a.s.sociated with the intense stimulation of the distance ceptors in human relations.

Stimuli of the contact ceptors differ from stimuli of the distance ceptors in still another important particular. The adequacy of stimuli of the contact ceptors depends upon their number and intensity, while the adequacy of the stimuli of the distance ceptors depends upon the EXPERIENCE of the species and of the individual.

That is, according to phylogeny and ontogeny this or that sound, this or that smell, this or that sight, through a.s.sociation recapitulates the experience of the species and of the individual-- awakens the phylogenetic and ontogenetic memory. In other words, sights, sounds, and odors are symbols which awaken phylogenetic a.s.sociation.

If a species has become adapted to make a specific response to a certain object, then that response will occur automatically in an individual of that species when he hears, sees, or smells that object.

Suppose, for example, that the shadow of a hawk were to fall simultaneously on the eyes of a bird, a rabbit, a cow, and a boy.

That shadow would at once activate the rabbit and the bird to an endeavor to escape, each in a specific manner according to its phylogenetic adaptation; the cow would be indifferent and neutral; while the boy, according to his personal experience or ontogeny, might remain neutral, might watch the flight of the hawk with interest or might try to shoot it.