Origin and Nature of Emotions Part 6

Let us pa.s.s on to the discussion of another and perhaps even more interesting type of pain, that a.s.sociated with infection.

Not all kinds of infection are painful; and in those infections that may be a.s.sociated with pain there is pain only when certain regions of the body are involved. Among the infections that are not a.s.sociated with pain are scarlet fever, typhoid fever, measles, malaria, whooping-cough, typhus fever, and syphilis in its early stages.

The infections that are usually, though not always, a.s.sociated with pain are the pyogenic infections. The pyogenic infections and the exanthemata const.i.tute the great majority of infections and are the basis of the discussion which follows.

I will state one of my princ.i.p.al conclusions first, _i.

e_., that the only types of infection that are a.s.sociated with pain are those in which the infection may be spread by muscular action or those in which the fixation of parts by continued muscular rigidity is an advantage; and, further, as a striking corollary, that the type of infection that may cause muscular action when it attacks one region of the body may cause no such action when it attacks another region.

The primary, and perhaps the most striking, difference between the painless exanthemata and the painful pyogenic infections is that in the case of the exanthemata the protective response of the body is a chemical one,--the formation of antibodies in the blood, which usually produce permanent immunity,--while the response to the pyogenic infections is largely phagocytic. In the pyogenic infections, in order to protect the remainder of the body, which, of course, enjoys no immunity, every possible barrier against the spread of the infection is thrown about the local point of infection.

How are these barriers formed? First, lymph is poured out, then the part is fixed by the continuous contraction of the neighboring muscles and by the inhibition of those muscles that, in the course of their ordinary function, would by their contractions spread the infection.

Wherever there is protective muscular rigidity there is also pain.

On the other hand, in pyogenic infections in the substance of the liver, in the substance of the kidney, within the brain, in the retroperitoneal s.p.a.ce, in the lobes of the lung, in the chambers of the heart and in the blood-vessels of the chest and the abdomen, in all locations in which muscular contractions can in no way a.s.sist in localizing the disease, pyogenic infections produce no muscular rigidity and no pain. Apparently, therefore, only those infections are painful which are a.s.sociated with a protective muscular contraction.

This explains why tuberculosis of the hip is painful, while tuberculosis of the lung is painless.

There is a third type of pain which modifies muscular action in a curious way. We have already stated that local pain serves an adaptive purpose. In this light let us now consider headache.

Headache is one of the commonest initiatory symptoms of the various infections, especially of those infections which are accompanied by no local pain and by no local muscular action.

In peritonitis, cholecyst.i.tis, pleurisy, arthritis, appendicitis, salpingitis, child-birth, in obstructions of the intestinal and the genito-urinary tract, in short, in those acute processes in which the local symptoms are powerful enough to govern the individual as a whole,--to make him lie down and keep quiet, refuse food and possibly reject what is already in the stomach,-- in all these conditions there is rarely a headache, but in the diseases in which local pain is absent, such as the exanthemata, typhoid fever, and auto-intoxication, which have no dominating local disturbances to act as policemen to put the individual to bed and to make him refuse food that he may be in the most favorable position to combat the oncoming disease, in such cases in which these masterful and beneficent local influences are absent we postulate that headache has been evolved to perform this important service.

On the hypothesis that it is good for the individual who is acutely stricken by a disease or who is poisoned by autointoxication to rest and fast, and that the muscular system obeys the imperial command of pain, and in view of the fact that the brain is not only in constant touch with the conditions of every part of the body but that it is also the controlling organ of the body, one would expect that in these diseases the major pain whose purpose it is to govern general muscular action would be located in the head and there we find it.

How curious and yet how intelligible is the fact that, though a headache may be induced by even a slight auto-intoxication, an abscess may exist within the brain without causing pain.

When an obliterative endarteritis is threatening a leg with anemic gangrene, or when one lies too long in the same position on a hard bed, there is threatening injury from local anemia, and as a result there is acute pain, but when the obliterative endarteritis threatens anemia of the brain, or when an embolism or thrombosis has produced anemia of the brain, there may be no accompanying pain.

The probable explanation of the pain which results in the first instance and the lack of pain in the second is that in the former muscular action const.i.tutes a self-protective response, but in the other it does not.

Diseases and injuries of the brain are notoriously difficult to diagnosticate. This may well be because it has always been so well protected by the skull that there have been evolved within it few tell-tale self-protective responses, so that in the presence of injury and disease within itself the brain remains remarkably silent.

It should occasion no surprise that there are in the brain no receptors, the mechanical stimulation of which can cause pain, because its bony covering has always prevented the adaptive implantation within it of contact pain receptors. Dr. Frazier tells me that in the course of his operations on the brains of unanesthetized patients he is able to explore the entire brain freely and without pain.

From my own experience I am able to confirm Dr. Frazier's observation.

In addition, the two-stage operation for the excision of the Ga.s.serian ganglion provides an observation of extraordinary interest.

If at the first seance the ganglion is exposed, but is not disturbed except by the iodoform gauze packing, then on the following day the gauze may be removed, the ganglion picked up, and its branches and root excised without anesthesia and without pain.

The same statement and explanation may be made regarding the distribution of pain receptors for physical contact within the parenchyma of the liver, the gall-bladder, the abdominal viscera, the spleen, the heart, the lungs, the retroperitoneal tissue, the deep tissue of the back, the vertebrae, and in certain portions of the spinal cord.

Just what is the distribution of the receptors for heat and for cold I am unable to state, but this much we do know, that without anesthesia the intestines may be cauterized freely without the least pain resulting, and in animals the cauterization of the brain causes no demonstrable change in the circulatory or respiratory reactions.

It is probable therefore that the distribution of the pain receptors for physical contact and for heat are limited to those parts of the body that have been exposed to injurious contacts with environment.

Of special significance is the pain which is due to cold, which increases muscular tone and produces s.h.i.+vering. The general increase in muscular tone produces an interesting postural phenomenon: the limbs are flexed and the body bent forward, a position which probably is due to the fact that the flexors are stronger than the extensors.

As muscular action is always accompanied by heat production, the purpose of the muscular contraction and the s.h.i.+vering is quite certainly caused by cold to a.s.sist in the maintenance of the normal body temperature.

We have now discussed many of the causes of pain and in each instance we have found an a.s.sociated muscular action which apparently serves some adaptive purpose (Figs. 24 and 25). If we a.s.sume that pain exists for the purpose of stimulating muscular reactions, we may well inquire what part of the nervous are is the site of the sensation of pain--the nerve-endings, the trunk, or the brain?

Does pain result from physical contact with the nerve-endings, with the physical act of transmitting an impression along the nerve trunk, or with the process within the brain-cells by which energy is released to cause a motor act?

It seems most probable that the site of the pain is in the brain-cells.

If this be so, then what is the physical process by which the phenomena of pain are produced? The one hypothesis that can be tested experimentally is that pain is a phenomenon resulting from the rapid discharge of energy in the brain-cells. If this be true, then if every pain receptor of the body were equally stimulated in such a manner that

{ill.u.s.t. caption = FIG. 25.--FEAR AND AGONY. "Amid this dread exuberance of woe ran naked spirits wing'd with horrid fear."-- Dante's "Inferno," Canto XXIV, lines 89, 90. all the stimuli reached the brain-cells simultaneously, the cells would find themselves in equilibrium and no motor act would be performed.

But if all the pain receptors of the body but one were equally stimulated, and this one stimu-lated harder than the rest, then the latter would gain possession of the final common path, the sensation of pain would be felt, and a muscular contraction would result.

It is well known that when a greater pain is thrown into compet.i.tion with a lesser one, the lesser is completely submerged.

In this manner the school-boy initiates the novice into the mystery of the painless plucking of hair. The simultaneous, but severe application of the boot to the blindfolded victim takes complete and exclusive possession of the final common path and the hair is painlessly plucked through the triumph of the boot stimulus over the hair stimulus in the struggle for the possession of the final common path. Another argument in favor of this hypothesis that pain is an accompaniment of the release of energy in the brain- cells is found in the fact that painless stimuli received through the special senses may completely submerge the painful stimuli of physical injury; for although the stimuli to motor action, which are received through the senses of sight, hearing, and smell, cause even more powerful motor action than those caused by physical contact stimuli, yet they are not accompanied by pain.

Examples of this triumph of stimulation of the special senses over contact stimulation are frequently seen in persons obsessed by anger or fear, and to a less degree in those obsessed by s.e.xual emotion.

In the fury of battle the soldier may not perceive his wound until the emotional excitation is wearing away, when the sensation of warm blood on the skin may first attract his attention.

Religious fanatics are said to feel no pain when they subject themselves to self-injury. Now, since both psychic and mechanical stimuli cause motor action by the excitation ofprecisely the same mechanism in the brain, and since the more rapid release of energy from psychic stimuli submerges the physical stimuli and prevents pain, it would seem that pain must be a phenomenon which is a.s.sociated with the process of releasing energy by the brain-cells. Were physical injury inflicted in a quiescent state equal to that inflicted in the emotional state, great pain and intense muscular action would be experienced.

Now the emotions are as purely motor excitants as is pain.

The dynamic result is the same the princ.i.p.al difference being the greater suddenness and the absolute specificity of the pain stimuli as compared with the more complex and less peremptory stimuli of the emotions.

A further evidence that pain is a product of the release of brain-cell energy is the probability that if one could pierce the skin at many points on a limb in such a manner that antagonistic points only were equally and simultaneously stimulated, then an equilibrium in the governing brain- cells would be established and neither pain nor motion would follow. An absolute test of this a.s.sumption cannot be made but it is supported by the obtainable evidence.

We will now turn to a new viewpoint, a practical as well as a fascinating one, which can best be ill.u.s.trated by two case histories: A man, seventy-eight years old, whose chief complaint was obstinate constipation, was admitted to the medical ward of the Lakeside Hospital several years ago. The abdomen was but slightly distended; there was no fever, no increased leukocytosis, no muscular rigidity, and but slight general tenderness. He claimed to have lost in weight and strength during the several months previous to his admission.

A tentative diagnosis of malignant tumor of the large intestine was made, but free movements weresecured rather easily, and we abandoned the idea of an exploratory operation. The patient gradually failed and died without a definite diagnosis having been made by either the medical or the surgical service. At autopsy there was found a wide-spread peritonitis arising from a perforated appendix.

A child, several years old, was taken ill with some indefinite disease.

A number of the ablest medical and surgical consultants of a leading medical center thoroughly and repeatedly investigated the case.

Although they could make no definite diagnosis they all agreed that the trouble surely could not be appendicitis because there was neither muscular rigidity nor tenderness.

The autopsy showed a gangrenous appendix and general peritonitis.

How can these apparently anomalous cases be explained?

These two cases are ill.u.s.trations of the same principle that underlies the freedom from pain which results from the use of narcotics and anesthetics, the same principle that explains the fact that cholecyst.i.tis may occur in the aged without any other local symptoms than the presence of a ma.s.s and perhaps very slight tenderness; and that accounts in general for the lack of well-expressed disease phenomena in senility and in infancy. The reason why the aged, the very young, and the subjects of general paresis show but few symptoms of disease is that in senility the brain is deteriorated, while in infancy the brain is so undeveloped that the mechanism of a.s.sociation is inactive, hence pain and tenderness, which are among the oldest of the a.s.sociations, are wanting.

Senility and infancy are by nature normally narcotized.

The senile are pa.s.sing through the twilight into the night; while infants are traversing through the dawn into the day.

Hence it is that the diagnosis of injury and disease in the extremes oflife is beset by especial difficulties, since the entire body is as silent as are the brain, the pericardium, the mediastinum, and other symptomless areas. For the same reason, when a patient who is seriously ill with a painful disease turns upon the physician a glowing eye and an eager face, and remarks how comfortable he feels, then the end is near. This is a brilliant and fateful clinical mirage.

When one reflects on the vast amount of evidence as to the origin and the purpose of pain, he is forced to conclude that pain is a phenomenon of motor stimulation, and that its princ.i.p.al role is the protection of the individual against the gross and the microscopic enemies in his environment. The benefits of pain are especially manifested in the urgent muscular actions by means of which the body moves away from physical injury; obstructions of the hollow viscera are overcome; rest is compelled in the acute infections-- the infected points are held rigidly quiet, the muscles of the abdomen are fixed, and harmful peristalsis is arrested in peritonitis; while there is absolutely no pain in the diseases or injuries which affect those regions of the body in which in the course of evolution no pain receptors were placed, or in those diseases in which muscular inhibition or contraction is of no help.

In a biologic sense pain is closely a.s.sociated with the emotional stimuli, for both pain and the emotions incite motor activity for the good of the individual. The frequent occurrence of post-operative and post- traumatic pain is accounted for by the fact that the operation or the injury has lowered the threshold of the brain- cells to trauma; the brain and not the local sensitive field is the site of the pain.

I have found that, by blockingthe field of operation with local anesthesia, post-operative pain is diminished; that is, since the local anesthesia prevents the strong stimuli of the trauma from reaching the brain, its threshold is not lowered.

There is a close resemblance between the phenomena of pain habit, of education, of physical training, of love and of hate. In education, in pain habit, in all emotional relations, a low brain- cell threshold is established which facilitates the reception of specific stimuli; all these processes are motor acts, or are symbolic of motor acts, and we may be trained to perceive misfortune and pain as readily as we are trained to perceive mathematical formulae or moral precepts.

In each and every case, readiness of perception depends, as it seems to me, upon a modified state of the brain-cells, their threshold especially, the final degree of perception possible in any individual being perhaps based on the type of potential molecules of which the brain is built.

We must believe also that every impression is permanent, as only thus could an individual animal or a man be fitted by his own experience for life's battles. LAUGHTER AND CRYING What is laughter?

What is its probable origin, its distribution, and its purpose?

Laughter is an involuntary rhythmic contraction of certain respiratory muscles, usually accompanied by certain vocal sounds.

It is a motor act of the respiratory apparatus primarily, although if intense it may involve not only the extraordinary muscles of respiration, but most of the muscles of the body. There are many degrees of laughter, from the mere brightening of the eyes, a fleeting smile, t.i.ttering andgiggling, to hysteric and convulsive laughter.

Under certain circ.u.mstances, laughter may be so intense and so long continued that it leads to considerable exhaustion.

The formation of tears is sometimes a.s.sociated with laughter.

When integrated with laughter, the nervous system can perform no other function. Crying is closely a.s.sociated with laughter, and in children especially laughter and crying are readily interchanged.

We postulate that laughter and weeping serve a useful purpose.

According to Darwin, only man and monkeys laugh (Fig. 26); other animals exhibit certain types of facial expression accompanying various emotions, but laughter in the sense in which that word is commonly used is probably an attribute of the primates only, although it is probable that many animals find subst.i.tutes for laughter.

The p.r.o.neness of man to laughter is modified by age, s.e.x, training, mental state, health, and by many other factors. Healthy, happy children are especially p.r.o.ne to laughter, while disease, strong emotions, fatigue, and age diminish laughter. Women laugh more than do men.

The healthy, happy maturing young woman perhaps laughs most, especially when she is slightly embarra.s.sed. What causes laughter? Good news, high spirits, tickling, hearing and seeing others laugh; droll stories; flashes of wit; pa.s.sages of humor; averted injury; threatened breach of the conventions; and numerous other causes might be added.

It is obvious that laughter may be produced by diverse influences, many of which are so unlike each other that it would at first sight seem improbable that a single general principle underlies all.

Before presenting a hypothesis which harmonizes most of the facts, and which mayoffer an explanation of the origin and purpose of laughter, let us return for a moment to some previous considerations-- that man is essentially a motor being; that all his responses to the physical forces of his environment are motor; {ill.u.s.t. caption = FIG. 26.--LAUGHING CHIMPANZEE. "Mike," the clever chimpanzee in the London Zoo, evidently enjoys a joke as well as any one else.

(Photo by Underwood and Underwood, N. Y.)}

that thoughts and words even are symbolic of motor acts; that in the emotions of fear, of anger, and of s.e.xual love the whole body is integrated for acts which are not performed.

These integrations stimulate the brain-cells, the ductless glands, and other parts, and the energizing secretions, among which are epinephrin, thyroid and hypophyseal secretions, are thrown into the blood-stream, while that most available fuel, glycogen, is also mobilized in the blood.

This body-wide preparation for action may be designated kinetic reaction.

The fact that emotion is more injurious to the body than is muscular action is well known, the difference being probably caused by the fact that when there is action the above-mentioned products of stimulation are consumed, while in stimulation without action they are not consumed and must be eliminated as waste products.

Now these activating substances and the fuel glycogen may be consumed by any muscular action as well as by the particular muscular action for which the integration and consequent stimulation were made; that is, if one were provoked to such anger that he felt impelled to attack the object of his anger, one of three things might happen: First, he might perform no physical act but give expression to the emotion of anger; second, he might engage in a physical struggle and completely satisfy his anger; third, he might immediately engage in violent gymnastic exercises and thus consume all the motor-producing elements mobilized by the anger and thus clarify his body.

In these premises we find our explanation of the origin and purpose of laughter and crying, for since they consist almost wholly of muscular exertion, they serve precisely such clarifying purposes as would be served by the gymnastic exercises of an angry man.

As it seems to me, the muscular action of laughter clears the system of the energizing substances which have been mobilized in various parts of the body for the performance of other actions (Figs. 27 to 29). If this be true, the first question that presents itself is, Why is the respiratory system utilized for such a clarifying purpose?

Why do we not laugh with our feet and hands as well?

Were laughter expressed with the hands, the monkey might fall from the tree and, if by the feet, man might fall to the ground.

He would at least be ataxic. In fact, laughter has the great advantage of utilizing a group of powerful muscles which can be readily spared without seriously interfering with the maintenance of posture. Laughter, however, is only one form of muscular action which may consume the fuel thrown into the blood by excitation.

That these products of excitation are often consumed by other motor acts than laughter is frequently seen in public meetings when the stamping of feet and the clapping of hands in applause gives relief to the excitation (Fig. 30). Why the noise of laughter?

In order that the products of excitation may be quickly and completely consumed, the powerful group of expiratory muscles must have some resistance against which they can exert themselves strongly and at the same time provide for adequate respiratory exchange.

The intermittent closure of the epiglottis serves this purpose admirably, just as the horizontal bars afford the resistance against which muscles may be exercised. The facial muscles are not in use for other purposes, hence their contractions will consume a little of the fuel.

An audience excited by the words of an impa.s.sioned speaker undergoes a body-wide stimulation for action, all of which may be eliminated by laughter or by applause (Fig. 31).

Let us test this hypothesis by some practical examples.

The first is an incident that accidentally occurred in our laboratory during experiments on fear which were performed as follows: A keen, snappy fox terrier was completely muzzled by winding a broad strip of adhesive plaster around his jaw so as to include all but the nostrils.