The Integrative Action of the Nervous System

The views of James, Lange, and Sergi have common to them this, that the psychical process of emotion is secondary to a discharge of nervous impulses into the vascular and visceral organs of the body suddenly excited by certain peculiar stimuli, and that it depends upon the reaction of those organs. Pro- fessor James's position in the matter is, however, not wholly like that of Professor Lange. In the first place, he does not consider vasomotor reaction to be primary to all the other organic and visceral disturbances that carry in their train the psychological appanage of emotion ; and Professor Sergi, though more nearly in harmony with Lange, agrees with James so far. In the sec- ond place, Professor James seems to distinctly include other " motor " sensations and centripetal impulses from musculature other than visceral and vascular, among those which casually contribute to emotion. Thirdly, he urges his theory as one completely competent only for the ** coarser " emotions, among which he instances ** fear, anger, love, and grief." For Lange and Sergi the basis of apparition of all feeling and emotion is physiological, visceral, and organic, and has its seat for the former authority exclusively, and for the latter eminently, in the vasomotor system.

To obtain some test of this view is not difficult by experi- ment.^^^ Appropriate spinal and vagal transection removes completely and immediately the sensation of the viscera and of all the skin and muscles behind the shoulder (Fig. 70). The procedure at the same time cuts from connection with the organs of consciousness the whole of the circulatory apparatus of the body. I have had under observation dogs in which this has been carried out. I will cite an animal selected because of

Figure 70. — Diagram to indicate the extent of the parts still retaining sensitivity after combined spinal and vagosympathetic nerve sections described in the text. The extent j of skin surface left sentient is delimited by the continuous (not dotted) lines in the i figure. The limit of "deep," i.e. muscular, articular, etc., sensitivity also corresponds j with this line. But the limit to which the respiratory and alimentary tracts still re- i tained sensation is shown by dotted outlines of the larynx and upper part of oesophagus. ] From anatomical data it is presumed that the trachea and oesophagus had been de- prived of all sensitivity somewhere about those levels. The curved line behind the chest indicates the diaphragm as the only muscle behind the shoulder still retaining afferent

laboratory attendants, one of whom had her in charge, toward ;: some persons and toward several inmates of the animal house ; she frequently showed violent anger. Her ebullitions of rage '\ were sudden. Their expression accorded with a description | furnished by Darwin.^ Besides the utterance of the growl, " the ears are pressed closely backwards, and the upper lip is ^ retracted out of the way of the teeth, especially of the canines." | The mouth was slightly opened and lifted, the eyelids widely ^

parted, the pupils dilated. The hair along the mid-dorsum, fi-om !j close behind the head to a point more than half-way down the trunk, became rough and bristling. The reduction of the field of sensation in this animal by the procedure above mentioned produced no obvious diminution of her emotional character. Her anger, her joy, her disgust, and when provocation arose, her fear, remained as evident as ever. Her joy at the approach or notice of the attendant, her rage at the intrusion of a cat with which she was unfriendly, remained as active and thorough. But among the signs expressive of rage the bristling of the coat along the back no longer occurred. On the other hand, the eyes were well opened and the pupils dis- tinctly dilated in the paroxysm of anger. Since by the transec- tion the brain had been shut out from discharging impulses via the cervical sympathetic the dilatation of pupil may have occurred by inhibition of the action of the oculomotor centre.

The coming of a visitor whose advent months before had elicited violent anger, again provoked an exhibition of wrath significant as ever. The expression was that of aggressive rage. The animal followed each movement of the stranger as though of an opponent, growling viciously. A cat with which she was never friendly, and a monkey new to the laboratory, approach- ing too near the kennel, excited similar outbursts. No doubt was left in our minds that sudden attacks of violent anger were still easily excited. But she also gave evidence daily that she had the accession of joyous pleasure and delight she had always shown at the approach of the attendant the first thing of a morn- ing, or at feeding time, or when caressed by him, or encouraged by his voice.

Few dogs, even when very hungry, can be prevailed upon to touch dog's flesh as food. Almost all turn from it with signs of repugnance and dislike. I had strictly refrained from testing this animal previously with regard to disgust at dog's flesh off"ered in her food. Flesh was given her daily in a bowl of milk, and this she took with relish. The meat was cut into pieces rather larger than the lumps of sugar usual for the break- fast table. It was generally horse-flesh, sometimes ox-flesh. We proceeded to the observation thus: the bowl was placed

by the attendant in the corner of the stall with milk and meat it^ every way as usual ; but the meat was flesh from a dog killed on the previous day. Our animal eagerly drew itself toward the food ; it had seen the other dogs fed, and evidently was itself hungry. Its muzzle had almost dipped into the milk before it suddenly seemed to find something there amiss. It hesitated, moved its muzzle about above the milk, made a venture to take a piece of the meat, but before actually seizing it stopped short and withdrew again from it. Finally, after some further examination of the contents of the bowl (it usually commenced by taking out and eating the pieces of meat), without touching them, the creature turned away from the bowl and withdrew itself to the opposite side of the cage. Some minutes later, under encouragement from us to try the food again, it returned to the bowl. The same hesitant display of conflicting desire and dis- gust was once more gone through. The bowl was then removed by the attendant, emptied, washed, and horse-flesh similarly prepared and placed in a fresh quantity of milk was offered in it to the animal. The animal once more drew itself toward the bowl, and this time began to eat the meat, soon emptying the dish. To press the flesh upon our animal was of no real avail on any occasion ; the coaxing only succeeded in getting her to, as it were, re-examine but not to touch the morsels. The impression made on all of us by the dog's behaviour was that something in the dog's flesh was repulsive to her, and excited dis- gust unconquerable by ordinary hunger. Some odour attaching to the flesh seemed the source of its recognition.

It would be instructive for judging the part played by the cerebral hemisphere in the reactions of coarser emotion did we know whether repugnance to dog's flesh as food would be ex- hibited by a dog after ablation of the cerebral hemispheres. Even the primitive emotions seem to involve perception — seem little other than sense-perceptions richly suffused with affec- tive tone. Goltz's^^ dogs after ablation of the hemispheres evinced signs of hunger, namely restlessness when their feed- ing hour was deferred. When a little quinine (bitter) was ' added to the sop of meat and milk the morsels taken into

the mouth were at once rejected. No inducement or scold- ing modified this unfailing and unhesitating rejection. Goltz adds that he threw to his own house dog a piece of the same doctored meat. The creature wagged its tail and took it eagerly, then pulled a wry face, and hesitated, astonished. But on a look of encouragement from its master the dog swallowed it. He overcame his instinctive rejection of it, and thus, as Goltz remarks, by his self-control gave proof of the intact cerebrum he possessed.

Fear appeared clearly elicitable (as also in dogs with spinal cervical transection only. Fig. 71). The attendant approaching from another room of which the door stood open, chid the dog in high scolding tones. The creature's head sank, her gaze turned away from her advancing master, and her face seemed to betray dejection and anxiety. The respiration became unquiet, but the pulse never changed its rate. In the dog, after transection of the spinal cord, the regions of the body which have been thus made purely " spinal " con- tinue their life in many respects normally. The hairy " coat " changes in spring. The oestral periods recur even when the transection is performed in puppyhood, and altogether headward of the spinal origin of the sympathetic system, e.g. at the cervi- cal segment. Goltz ^ observed successful impregnation and parturition, and suckling completed without obvious abnormal- ity. In my own observations 2^^* the natural instinct of the female toward the male at oestrum was seen indubitably dis- played after the spinal cord had been transected in the cervical region more than a year previously.

It may be objected to these experiments that although the animals expressed emotion they may yet have felt none. Had their expression been unaccompanied by, and had they not led on to, trains of acts logically consonant with their expressed emotion, that objection would have weight. Where ^q fades of anger is followed by actions of advance and attack with all appearance of set purpose, I find it difficult to think that the perception initiat- ing the wrathful expression should bring in sequel angry conduct and yet have been impotent to produce " angry feeling."

Figure 71. — Record of the arterial pressure in a dog forty-one days after spinal transection at the 7th cervical segment. The arterial pressure is high and good in spite of the tran- section, the period of vasomotor shock having passed by. For the short period marked by the signal the noise of the vibrator of an inductorium sounded and was heard by the animal. The point of the signal marked nearly 8 mm. further to the right than did the kymograph pen. The inhibition of the heart is shown by the oscillations on the kymo- graph trace. The line marked " Zero of B. /*." signifies the height of the zero of the manometer recording the arterial pressure.

W A weaker point in such experimentation is that although the visceral and vascular and much of the muscular mechanism of emotional expression was cut off, a small but notable fraction of the latter, namely the facial, still remained open to react on the centres with which consciousness is colligate. Nevertheless, in view of these observations the vasomotor theory of the production of emotion becomes, I think, untenable, also that visceral sensations or presentations are necessary to emotion. A mere remnant of all the non-projecting or affective senses was left, and yet emotion persisted. If I understand it aright, Professor James' and Lange's theory lays stress on organic and visceral presentations, but re-presentations of the same species might no doubt be put forward in their place. That would be a different matter. To exclude the latter hypothesis, the deprivation of vascular and organic sensation might have to date from a very early period of the individual life. Professor Lloyd Morgan writes 2^^* in respect to the above experiments, " The avenues of connection were closed after the motor and visceral effects had played their part in the genesis of the emo- tion on the hypothesis that the emotion is thus generated. Al- though new presentative data of this type were thus excluded, their re-presentative after-effects in the situation were not ex- cluded." But it is noteworthy that one of the dogs under observation had been deprived of its sensation when only nine weeks old. Disgust for dog's flesh could hardly arise from the experience of nine weeks of puppyhood in the kennel.

We are forced back toward the likelihood that the visceral expression of emotion is secondary to the cerebral action occur- ring with the psychical state. There is a strong bond between emotion and muscular action. Emotion " moves " us, hence the word itself. If developed in intensity, it impels toward vigor- ous movement. Every vigorous movement of the body, though its more obvious instrument be the skeletal musculature of the limbs and trunk, involves also the less noticeable co-operation of the viscera, especially of the circulatory and respiratory. The extra demand made upon the muscles that move the frame involves a heightened action of the nutrient organs which sup-

ply to the muscles the material for their energy. This increased action of the viscera is colligate with this activity of muscles. We should expect visceral action to occur along with the muscu- lar expression of emotion. The close tie between visceral action and states of emotion need not therefore surprise us. That emotion is primarily a cerebral reaction obtains sup- port from observations where the hemispheres of the brain have been removed. Goltz observed a dog kept many months in that condition. It on no occasion gave any evidence of joy or pleasure in commerce either with man or beast. Of sexual emotion it never gave a sign. Anger or displeasure, Goltz says, it repeatedly expressed, both by gesture and by voice. Save for these expressions of displeasure, it was indifferent and supremely neutral to its surroundings. We are, of course, in observations such as this, hopelessly cut off from introspective help. It can be urged that the expression of emotion might be provocable and nevertheless the psychical emotion remain absent. On such an hypothesis the same stimulus which excited the mind must excite concurrently and per se motor centres producing movement appropriate to an affective process in the mind. This is not improbable. All sensations referred to the body itself rather than ittterpreted as qualities of objects in the external worlds tend to be tinged with " feeling." Sense-organs which initiate sensations tinged with feeling tend to excite motor centres directly and imperatively. Hence in animals reduced to merely spinal condition stimuli calculated to produce pain (although, of course, unable to do so in a spinal animal) evoke movements appropriate for escape from or removal of the stimu- lus applied. Now " feeling" is implicit in the emotional state; the state is an " affective state." In the evolution of emotion the revival of " feelings " pleasureable and painful must have played a large part. Hence the close relation of emotion with sense-organs that can initiate bodily pain or pleasure, and hence its connection with impulsive or instinctive movement.

There is no wide interval between the reflex movement of the spinal dog whose foot attempts to scratch away an irritant applied to its back — both leg and back absolutely detached from con- sciousness — and the reaction of the decerebrate dog that turns and growls and bites at the fingers holding his hind foot too roughly. In the former case the motor reaction occurs, although the mind is not even aware of the stimulus, far less percipient of it as an irritant. The action occurs, and plays the panto- mime of feeling; but no feeling comes to pass. In the latter case the motor reaction occurs and is expressive of emotion ; but it is probably the reaction of an organic machine which can be started working, though the mutilation precludes the psychosis.

And with the gesture and the attitude will occur the visceral concomitant. It would be consonant with what we know of reflex action, if the spur that started the muscular expression should simultaneously and of itself initiate also the visceral adjunct reaction. It is almost impossible to believe that with the mere stump of brain that remained to Goltz's dog there could be any elaboration of a percept. All trace of memory seemed lacking to the creature. Yet though not evincing other emotion, anger it showed as far as expression can yield such revelation. Fear, joy, affection seem, therefore, in the ex- perience of this skilled observer of animal behaviour, to demand higher nervous organization than does anger. Be that as it may, the retention of its expression by Goltz's dog indicates that by " retrogradation " the complex movement of expression has in certain emotions passed into a simpler reflex-act. Under the canalizing force of habit the determining motives become, even in impulsive acts, weaker and more transient. The external stimulus originally aroused a strongly affective group of ideas, which operated as a motive, but now it causes a discharge of the act before it can be apprehended as an idea. The impulsive movement of a " lower," " coarser," so-called " animal " emotion, has in this case become an automatic reflex no longer neces- sarily combined with the psychical state whence it arose, of which it is normally at once the adjunct and the symbol.

In view of these general considerations and of the above experiments, we may with James accept visceral and organic sensations and the memories and associations of them as con- tributory to primitive emotions, but we must regard them as| reinforcing rather than initiating the psychosis. Organic and| vascular reaction, though not the actual excitant of emotion, strengthen it. This is the kernel of the old contention about actuality of emotion in the art of the artist. Hamlet's descrip- tion of the actor as really moved by his expression may be accepted as an answer.

Conversely, as Lloyd Morgan 2^^* writes, " Whatever be the exact psychological nature of the emotions, it may be regarded as certain that they introduce into the conscious situation ele- ments which contribute not a little to the energy of behaviour." A feeling of pain and a protective reflex movement — either of defence or escape — are concurrent in the reaction of an animal to a hurtful stimulus of the skin. Reflexes to which emotion is adjunct are not only prepotent (Lect. VI) but are imperative, that is, volition cannot easily suppress them. Now, the morphological disposition of the nervous channels is such that the physiologist can, by suitable severance of the spinal path to the brain, sunder the reflex movement from the sensa- tion, leaving the former effect but perforce annulling the latter. The former is, however, in absence of the latter, not left un- altered; it is abnormally reduced, especially in duration {v. supra, p. 252). The pseudaffective reactions indicative of re- sentment and defence are, after ablation of the cerebral cortex, short-lived, the simulacra of mere flashes of mimetic passion. No cerebral reverberation descends to prolong and develop further the protective movement set going as a spinal reflex. This con- trasts strongly with the fairly normal course that the headward part of the reflex, after loss of its vascular and visceral fields, runs. The difference argues that the reverberation from the trunk, limbs, and viscera counts for relatively little, even in the primitive emotions of the dog, as compared with the cerebral reverberation to which is adjunct the psychical component of emotional reaction.

Argument: Remarkable that electrical stimuli applied to the organ of mentality yield with regularity certain localized movements from certain restricted areas of its surface. Functional topography of "motor" cortex in the chimpanzee, orang-utan, and gorilla. The cerebral fissures, not functional boundaries. The anthropoid ape has a direct pyramidal tract like that of man. Recovery of function not due to symmetrical part of opposite hemisphere taking on supple- mental work. Inhibition as elicitable from the cortex. Reciprocal innervation of antagonistic eye-muscles. Reciprocal inhibition in other muscular groups. Seat of the inhibition subcortical in these cases. Reciprocal innervation in willed movements. Preponderant representation in the " motor " cortex of the same movements as are preponderantly elicitable as local reflexes from the cord and bulb. Scanty representation of certain movements as cortical and local spinal reactions alike. Appearance under strychnine and tetanus toxin of these movements reversing the normal direction of the preponderance. This due to these agents transmuting reciprocal inhibition into excitation. Decerebrate rigidity. A system of tonic innen^ation in action. Strychnine and tetanus toxin augment this innervation. Hughlings Jackson's "co-operative antagonism" of paired systems of innervation, one tonic, the other phasic. De- cerebrate rigidity and hemiplegic rigidity. The relation of the cortex to receptor organs ; the pre-emiment representation in it of the *' distance-receptors."

We shall now venture a glance at certain reactions of the cerebral hemisphere itself; our survey must be circumscript for several reasons. By use of such methods as we are em- ploying, artificial excitation and so on, and under such ob- servations as these allow, namely the initiation under narcosis of muscular movements or the recording of their immediate defects from normal movement, little light is given in regard to much that goes on in an organ whose chief function is mentality itself. Our expectation must be modest, for

modest assuredly must be the achievement reached by such means in a problem of such a nature. The very poverty of the achievement is itself an indication that the methods pursued by the physiologist successfully in other spheres of his study are here confronted with problems to which they are far less suited. It is not that I esteem lightly the labours of the many distinguished workers in this field. As far as the methods referred to can avail, it is to the skill with which they have been used that we owe what knowledge we have of the topo- graphical representation of movement in the various fields of cerebral cortex. We have only to remember how much more numerous the physiological facts concerning the cerebral cortex are to-day than prior to the experiments of Hitzig and Fritsch*^ and of Ferrier,^^ following on the observations of Broca,^ Hughlings Jackson,^ and Bastian.*^ Experiment had failed to get evidence of localization of function in the cortex of the hemispheres, though in microscopic structure that great sheet of gray matter presents such similarity to nervous formations regarded as nerve-centres elsewhere. Progress of knowledge in regard to the nervous system has been indissolubly linked with determination of localization of function in it. This has been so from the time of the Bell ^^-Magendie ^^ discovery of the dif- ference of function in the two spinal roots, and Flourens' ^^ de- limitation of the respiratory centre in the bulb. The discovery of localization of function in parts of the cortex has given the knowledge which now supplies to the student charts of the functional topography of the brain much as maps of continents are supplied in a geographical atlas. The student looking over the political map of a continent may little realize the complexity of the populations and states so simply represented.

We looking at the brain chart of the text-book may never forget the unspeakable complexity of the reactions thus rudely sym- bolized and spatially indicated. If we may be allowed an a priori consideration it is this, — that although it is not surprising that such territorial subdivision of function should exist in the cerebral cortex, it is surprising that by our relatively imperfect artifices for stimulation we should be able to obtain clear evidence thereof. The neurone chains that together build up the nervous system are in the architecture of that system so arranged that the longest of them all tend to pass through the cerebral cortex. Every increase in the number of links composing a nerve-cell chain seems to increase greatly the uncertainty of its reactions under artificial excitation. With increase in number of links goes increase in numbers of side branches and connections. The difficulty of getting long chains of nerve-cells to react in a regular way under artificial stimulation seems greatly enhanced by the multiplica- tion of the side connections. The momentary condition of any cell-chain is in part a function of the condition at the moment of all the other cell-chains with which it is connected. The cortex cerebri might therefore well have been expected to yield under artificial stimulation only extraordinarily inconstant results. To Hitzig and Fritsch, and to Ferrier, we owe the pregnant demonstration that as regards the motor region this expectation is not well founded.

It is only of the reactions of the Rolandic area of the cortex that I shall venture to speak. Ferrier showed that the applica- tion of faradic currents to that cortex excites with great regu- larity movements which vary in distribution as the electrodes are moved from place to place, but remain within limits constant under repeated application of the stimulus to any one and the same spot. Ferrier's mode of indicating the topographical arrangement of the reactions he obtained is seen in his well- known diagrams of the cortex. His motor centres, as he termed them, were marked in his figures by circular areas. '• The areas have no exact line of demarcation from each other, and where they adjoin stimulation is apt to produce conjointly the effect peculiar to each." ^^ He showed these motor centres to extend forward over the frontal lobe, produc- ing there movements of the eyeballs. Regarding their exten- sion round and over the upper edge of the hemisphere and down upon the mesial surface he noted them in the marginal convolution. "This convolution in the parieto- frontal region gave rise to movements of the head and limbs apparently

similar to those already obtained by stimulation of the corre- ; sponding regions on the external surface." ^^ This original research by Ferrier ranks among the classics ^ of experimental neurology and physiology. It has been followed \ by a number of kindred contributions from workers whose names { are familiar to us all, — Albertoni, Schafer, Munk, Luciani, Tarn- i burini, Paneth, Beevor, Horsley, Mott, Ballance, Mann, and others, j The detailed knowledge of the localization has been largely ; based on the cerebral cortex of the common ape, the macaque, j It was an interesting step further when Beevor and Horsley ^^7 \ published observations on the localization of the motor functions , in the central cortex of an orang-utan. Their experiment ] long remained the single one for which an anthropoid species ; had been laid under contribution. It exercised a notable influ- ence on the scheme of motor localization adopted as probably ' obtaining in the brain of man.

Of the three or four species of anthropoid apes that are ■ known, most authorities agree that it is the gorilla which pos- \ sesses the most highly developed cerebrum ; next to it probably ■ stands the chimpanzee, and a little below the chimpanzee comes Simia satyrus, the orang-utan. But there are great individual \ differences, and the simpler examples of chimpanzee brains seem \ inferior in development to well-developed examples of the brain i of the orang. I

A. S. Griinbaum^^^^ and myself have obtained observa- ' tions on cerebral localization in the several species of anthropoid ; apes. In the chimpanzee the scheme of topography we find ; existent is illustrated by the accompanying Figures 72 and 73. The so-called motor area occupies unbrokenly the whole ' length of the precentral convolution, and in most places the ^ greater part or the whole of its width. It extends into the depth : of the central sulcus, occupying the anterior wall, and in some \ places the floor, and in some extends even into the deeper ' part of the posterior wall of the fissure. We have examined ^ more than forty hemispheres, but have never found the motor area extend indubitably to the free face of the post-central \ convolution. This deUmitation agrees remarkably with the ;

original results obtained by Hitzig^* on the brain of the monkey, Itrnuus rhesus. At the upper mesial edge of the hemisphere the motor area extends round and down upon the mesial face of the hemisphere, but we have not found it reach the calloso-marginal fissure. The anterior limit of the motor region is in great part not coin- cident with any fissure. The front portion of the region usually dips into and across the upper part of the superior precentral fissure, and lower down it not infrequently dips into the inferior precentral fissure. Occasionally the front edge of the region dips into almost the whole length of the superior precentral sulcus. It is not the extent of the motor area which appears to be variable, the variant is the sulcus itself. The great variety of individual pattern exhibited by the convolutions and sulci in these richly convoluted brains gives opportunity for studying critically the claim of value of these fissures as landmarks in the topography of the cortex. From this point of view their use for strict localization is small. Not only are the extremes of pattern exhibited by the convolutions extraordinarily dif- ferent one from another, but the frequency of the individual variation is so great that hardly a pair can be found in which the existent convolutions are, when compared with the mi- nuteness applicable to functional centres, really closely alike. Schafer, in his important contribution to the physiology of the motor cortex in 1887,^^^* pointed out that the fissures of the cortex do not mark in any sense the boundaries of the functional areas of the organ. Our examination of the anthropoid brains we have worked through convinces us that not only do the fissures of the frontal region not mark physiological boundaries^ but that they are not closely reliable even as landmarks for the functional topography. Their relation is too inconstant, v.

Monakow^*^ has found the same uncertainty in the calcarine fissure in respect to visual cortex. The degree to which these fissures are subject to individual variation and the frequency of their asymmetry in the two hemispheres stands in contrast with the constancy from individual to individual and greater bilateral symmetry which holds good for the arrangement of the func- Figure 72 (from Grunbauni and Sherrington). — Brain of a chimpanzee {Troglodytes niger). Left hemisphere viewed from side and above so as to obtain as far as possible the configuration of the sulcus centralis area. The figure involves, nevertheless, considerable foreshortening about the top and bottom of sulcus centralis. The extent of the " motor " area on the free surface of the hemisphere is indicated by the black stippling, which extends back to ^t sulcus centralis. Much of the "motor" area is hidden in sulci; for instance, the area extends into the sulc. centralis and the sulc. precentrales^ also into occasional sulci which cross the precentral gyrus. The names printed large on the stippled area indicate the main regions of the "motor " area; the names printed small outside the brain, indicate broadly by their pointing lines the relative topography of some of the chief subdivisions of the main regions of the "motor" cortex. But there exists much overlapping of the areas and of their subdivisions which the diagram does not attempt to indicate.