The Story of the Mind · Part 8

Further, we find this organ in some degree duplicating the function of the second-level centres, for fibres go out from these intermediate masses to certain areas of the hemispheres, which reproduce locally the senses of hearing, sight, etc. By these fibres the functions of the senses are "projected" out to the surface of the brain, and the term "projection fibres" is applied to the nerves which make these connections. The hemispheres are not content even with the most important of all functions--the strictly intelligent--but they are jealous, so to speak, of the simple sensations which the central brain masses are capable of awaking. And in the very highest animals, probably only monkeys and man, we find that the hemispheres have gone so far with their jealousy as to usurp the function of sensation. This is seen in the singular fact that with a monkey or man the removal of the cortical centres makes the animal permanently blind or deaf, as the case may be, while in the lower animals such removal does not have this result, so long as the "second-level" organs are unimpaired. The brain paths of the functions of the second and first levels taken together constitute the so-called "voluntary circuit" (see Fig. 2).

In addition to this general demarcation of functions as higher and lower--first, second, and third level--in their anatomical seat, many interesting discoveries have been made in the localization of the simpler functions in the cortex itself. The accompanying figures (Figs. 3 and 4) will show the principle centres which have been determined; and it is not necessary to dwell upon additional details which are still under discussion. The areas marked out are in general the same on both hemispheres, and that is to say that most of the centres are duplicated. The speech centres, however, are on one side only. And in certain cases the nervous fibres which connect the cortex with the body-organs cross below the brain to the opposite side of the body. This is always true in cases of muscular movement; the movements of the right side of the body are controlled by the left hemisphere, and vice versa. The stimulations coming in from the body to the brain generally travel on the same side, although in certain cases parallel impulses are also sent over to the other hemisphere as well. For example, the very important optic nerve, which is necessary to vision, comes from each eye separately in a large bunch of fibres, and divides at the base of the brain, so that each eye sends impulses directly to the visual centres of both hemispheres.

Of all the special questions which have arisen about the localization of functions in the nervous system, that of the function of certain areas known as "motor centres" has been eagerly discussed. The region on both sides of the fissure of Rolando in Fig. 3 contains a number of areas which give, when stimulated with electricity, very definite and regular movements of certain muscles on the opposite side of the body. By careful exploration of these areas the principal muscular combinations--those for facial movements, neck movements, movements of the arm, trunk, legs, tail, etc.--have been very precisely ascertained. It was concluded from these facts that these areas were respectively the centres for the discharge of the nervous impulses running in each case to the muscles which were moved. The evidence recently forthcoming, however, is leading investigators to think that there is no cortical centre for the "motor" or outgoing processes properly so called, and that these Rolandic areas, although called "motor," are really centres for the incoming reports of the movements of the respective muscles after the movements take place, and also for the preservation of the memories of movement which the mind must have before a particular movement can be brought about (the mental images of movement which we called on an earlier page Kinæsthetic Equivalents). These centres being aroused in the thought of the movement desired, which is the necessary mental preparation for the movement, they in turn stimulate the real motor centres which lie below the cortex at the second level. This is in the present writer's judgment the preferable interpretation of the evidence which we now have.

The Speech Zone.--Many interesting facts of the relation of body and mind have come to light in connection with the speech functions. Speech is complex, both on the psychological and also on the physiological side, and easily deranged in ways that take on such remarkable variety that they are a source of very fruitful indications to the inquirer. It is now proved that speech is not a faculty, a single definite capacity which a man either has or has not. It is rather a complex thing resulting from the combined action of many brain centres, and, on the mental side, of many so-called faculties, or functions. In order to speak a man normally requires what is called a "zone" in his brain, occupying a large portion of the outside lateral region (see Fig. 5). It extends, as in the figure, from the Rolandic region (K), where the kinæsthetic lip-and-tongue memories of words are aroused, backward into the temporal region (A), where the auditory memories of words spring up; then upward to the angular gyrus in the rear or occipital region (V), where in turn the visual pictures of the written or printed words rise to perform their part in the performance; and with all this combination there is associated the centre for the movements of the hand and arm employed in writing, an area higher up in the Rolandic region (above K). In the same general zone we also find the music function located, the musical sounds being received in the auditory centre very near the area for words heard (A) while the centre for musical expression is also in the Rolandic region. Furthermore, as may be surmised, the reading of musical notation requires the visual centre, just as does the reading of words. In addition to this, we find the curious fact that the location of the whole speech zone is in one hemisphere only. Its location on the left or the right, in particular cases, is also an indication as to whether the person is right-or left-handed; this means that the process which makes the individual either right or left-handed is probably located in the speech zone, or near it. A large majority of persons have the speech zone in the left hemisphere, and are right-handed; it will be seen that the figure (5) shows the left hemisphere of the brain, and with it the right hand holding the pen.

Defects of Speech--Aphasia.--The sorts of injury which may befall a large zone of the brain are so many that well-nigh endless forms of speech defect occur. All impairment of speech is called Aphasia, and it is called Motor Aphasia when the apparatus is damaged on the side of movement.

If the fibres coming out from the speech zone be impaired, so that the impulses can not go to the muscles of articulation and breathing, we have Subcortical Motor Aphasia. Its peculiarity is that the person knows perfectly what he wants to say, but yet can not speak the words. He is able to read silently, can understand the speech of others, and can remember music; but, with his inability to speak, he is generally also unable to write or to perform on a musical instrument (yet this last is not always the case). Then we find new variations if his "lesion"--as all kinds of local nervous defects are called--is in the brain centre in the Rolandic region, where arise the memories of the movements required. In this latter case the aphasic patient can readily imitate speech so long as he hears it, can imitate writing so long as it lies before him, but can not do any independent speaking or writing for himself. With this there goes another fact which characterizes this form of aphasia, and which is called Cortical, as opposed to the Subcortical Motor Aphasia described above, that the person may not be able even to think of the words which are appropriate to express his meaning. This is the case when those persons who depend upon the memories of the movements of lip and tongue in their normal speech are injured as described.

Besides the two forms of Motor Aphasia now spoken of, there are certain other speech defects which are called Sensory Aphasia. When a lesion occurs in one of the areas of the brain in the speech zone in which the requisite memories of words seen or heard have their seat--as when a ball player is struck over the sight centre in the back of the head--special forms of sensory aphasia show themselves. The ball player will, in this case, have Visual Aphasia, being unable to speak in proportion as he is accustomed in his speaking to depend upon the images of written or printed words. He is quite unable to read or write from a copy which he sees; but he may be able, nevertheless, to write from dictation, and also to repeat words which are spoken to him. This is because in these latter performances he uses his auditory centre, and not the visual. There are, indeed, some persons who are so independent of vision that the loss of the visual centre does not much impair their normal speech.

When, again, an injury comes to the auditory centre in the temporal region, we find the converse of the case just described; the defect is then called Auditory Aphasia. The patient can not now speak or write words which he hears, and can not speak spontaneously in proportion as he is accustomed to depend upon his memories of the word sounds. But in most cases he can still both speak and write printed or written words which he sees before him.

These cases may serve to give the reader an idea of the remarkable delicacy and complexity of the function of speech. It becomes more evident when, instead of cases of gross lesion, which destroy a whole centre, or cut the connections between centres, we have disease of the brain which merely destroys a few cells in the gray matter here or there. We then find partial loss of speech, such as is seen in patients who lack only certain classes of words; perhaps the verbs, or the conjunctions, or proper names, etc.; or in the patients who speak, but yet do not say what they mean; or, again, in persons who have two verbal series going on at once, one of which they can not control, and which they often attribute to an enemy inside them, in control of the vocal organs, or to a persecutor outside whose abuse they can not avoid hearing. In cases of violent sick headache we often miscall objects without detecting it ourselves, and in delirium the speech mechanism works from violent organic discharges altogether without control. The senile old man talks nonsense--so-called gibberish--thinking he is discoursing properly.

In the main cases of Aphasia of distinct sensory and motor types psychological analysis is now so adequate and the anatomical localization so far advanced that the physicians have sufficient basis for their diagnosis, and make inferences looking toward treatment. Many cases of tumour, of clot on the brain, of local pressure from the skull, and of hæmorrhage or stopping up of the blood vessels in a limited area, have been cured through the indications given by the particular forms and degrees of aphasia shown by the patients. The skull is opened at the place indicated by the defect of speech, the lesion found where the diagnosis suggested, and the cause removed.

This account of Localization will suggest to the reader the truth that there is no science of Phrenology. No progress has been made in localizing the intelligence; and the view is now very general that the whole brain, with all its interchange of impulses from part to part, is involved in thinking. As for locating particular emotions and qualities of temperament, it is quite absurd. Furthermore, the irregularities of the skull do not indicate local brain differences. It is thought that the relative weight of the brain may be an indication of intellectual endowment, especially when the brain weight is compared with the weight of the rest of the body, and that culture in particular lines increases the surface of the cortex by deepening and multiplying the convolutions. But these statements can not be applied off-hand to individuals, as the practise of phrenology would require.

Defects of Memory--Amnesia.--The cases given just above, where the failure of speech was seen to be due to the loss of certain memories of words, illustrate also a series of mental defects, which are classed together as Amnesias. Any failure in memory, except the normal lapses which we call forgetfulness, is included under this term. Just as the loss of word memories occasions inability to speak, so that of other sorts of memories occasions other functional disturbances. A patient may forget objects, and so not know how to use his penknife or to put on his shoes. He may forget events, and so give false witness as to the past.

One may forget himself also, and so have, in some degree, a different character, as is seen, in an exaggerated way, in persons who have so-called Dual Personality. These patients suddenly fall into a secondary state, in which they forget all the events of their ordinary lives, but remember all the events of the earlier periods of the secondary personality. This state may be described as "general" amnesia, in contrast to the "partial" amnesia of the other cases given, in which only particular classes of memories are impaired.

The impairment of memory with advancing years also illustrates both "general" and "partial" Amnesia. The old man loses his memory of names, then of other words, then of events, and so gradually becomes incapable of much retention of any sort.

Defects of Will--Aboulia.--A few words may suffice to characterize the great class of mental defects which arise on the side of action. All inability to perform intentional acts is called Aboulia, or lack of Will. Certain defects of speech mentioned above illustrate this: cases in which the patient knows what he wishes to say and yet can not say it. This is the type of all the "partial" Aboulias. There may be no lack in determination and effort, yet the action may be impossible. But, in contrast with this, there is a more grave defect called "general" Aboulia. Here we find a weakening of resolution, of determination, associated with some lack of self-control showing itself frequently by a certain hesitation or indecision. The patient says: "I can not make up my mind," "I can not decide." In exaggerated cases it becomes a form of mania called "insanity of doubt." The patient stands before a door for an hour hesitating as to whether he can open it or not, or carries to its extreme the experience we all sometimes have of finding it necessary to return again and again to make sure that we have locked the door or shut the draught of the furnace.

With these illustrations our notice of mental defects may terminate. The more complex troubles, the various insanities, manias, phobias, etc., can not be briefly described. Moreover, they are still wrapped in the profoundest obscurity. To the psychologist, however, there are certain guiding principles through the maze of facts, and I may state them in conclusion.

First, all mental troubles involve diseases of the brain and can be cured only as the brain is cured. It does not follow, of course, that in certain cases treatment by mental agencies, such as suggestion, arousing of expectation, faith, etc., may not be more helpful here, when wisely employed, than in troubles which do not involve the mind; but yet the end to be attained is a physical as well as a mental cure, and the means in the present state of knowledge, at any rate, are mainly physical means. The psychologist knows practically nothing about the laws which govern the influence of mind on body. The principle of Suggestion is so obscure in its concrete working that the most practised and best-informed operators find it impossible to control its use or to predict its results. To give countenance, in this state of things, to any pretended system or practice of mind cure, Christian science, spiritual healing, etc., which leads to the neglect of ordinary medical treatment, is to discredit the legitimate practice of medicine and to let loose an enemy dangerous to the public health.

Moreover, such things produce a form of hysterical subjectivism which destroys sound judgment, and dissolves the sense of reality which it has taken modern science many generations to build up. Science has all along had to combat such wresting of its more obscure and unexplained facts into alliance with the ends of practical quackery, fraud, and superstition; and psychologists need just now to be especially alive to their duty of combating the forms of this alliance which arise when the newer results of psychology are so used, whether it be to supplement the inadequate evidence of "thought-transference," to support the claims of spiritualism, or to justify in the name of "personal liberty" the substitution of a "healer" for the trained physician. The parent who allows his child to die under the care of a "Christian Science healer" is as much a criminal from neglect as the one who, going but a step further in precisely the same direction, brings his child to starvation on a diet of faith. In France and Russia experimenting in hypnotism on well persons has been restricted by law to licensed experts; what, compared with that, shall we say to this wholly amateurish experimenting with the diseased? Let the "healer" heal all he can, but let him not experiment to the extremity of life and death with the credulity and superstition of the people who think one "doctor" is as good as another.

Second, many experts agree that diseases of the mind, whatever their brain seat may be, all involve impairment of the Attention. This, at any rate, is a general mark of a deranged or defective mind. The idiot lacks power of attention. The maniac lacks control of his attention. The deluded lacks grasp and flexibility of attention. The crank can only attend to one thing. The old man is feeble in the attention, having lost his hold. So it goes. The attention is the instrument of the one sort of normal mental activity called Apperception, and so impairment of the attention shows itself at once in some particular form of defect.

Third, it is interesting to know that in progressive mental failure the loss of the powers of the mind takes place in an order which is the reverse of that of their original acquisition. The most complex functions, which are acquired last, are the first to show impairment. In cases of general degeneration, softening of the brain, etc., the intelligence and moral nature are first affected, then memory, association, and acquired actions of all sorts, while there remain, latest of all, actions of the imitative kind, most of the deep-set habits, and the instinctive, reflex, and automatic functions, This last condition is seen in the wretched victim of dementia and in the congenital idiot. The latter has, in addition to his life processes and instincts, little more than the capacity for parrot-like imitation. By this he acquires the very few items of his education.

The recovery of the patient shows the same stages again, but in the reversed direction; he pursues the order of the original acquisition, a process which physicians call Re-evolution.

CHAPTER VI.

HOW WE EXPERIMENT ON THE MIND--EXPERIMENTAL PSYCHOLOGY.

In recent years the growth of the method of experimenting with bodies in laboratories in the different sciences has served to raise the question whether the mind may not be experimented with also. This question has been solved in so far that psychologists produce artificial changes in the stimulations to the senses and in the arrangements of the objects and conditions existing about a person, and so secure changes also in his mental states. What we have seen of Physiological Psychology illustrates this general way of proceeding, for in such studies, changes in the physiological processes, as in breathing, etc., are considered as causing changes in the mind. In Experimental Psychology, however, as distinguished from Physiological Psychology, we agree to take only those influences which are outside the body, such as light, sound, temperature, etc., keeping the subject as normal as possible in all respects.

A great many laboratories have now been established in connection with the universities in Germany, France, and the United States. They differ very much from one another, but their common purpose is so to experiment upon the mind, through changes in the stimulations to which the individual is subjected, that tests may be made of his sensations, his ability to remember, the exactness and kind of movements, etc.

The working of these laboratories and the sort of research carried out in them may be illustrated best, perhaps, by a description of some of the results, apparatus, methods, etc., employed in my own laboratory during the past year. The end in view will, I trust, be considered sufficient justification for the degree of personal reference which this occasions; since greater concreteness and reality attach to definite descriptions such as this. The other laboratories, as those at Harvard and Columbia Universities, take up similar problems by similar methods. I shall therefore go on to describe some recent work in the Princeton laboratory.

Of the problems taken up in the laboratory, certain ones may be selected for somewhat detailed explanation, since they are from widely different spheres and illustrate different methods of procedure.

I. Experiments on the Temperature Sense.--For a score of years it has been suspected that we have a distinct sense, with a nerve apparatus of its own, for the feeling of different temperatures on the skin. Certain investigators found that this was probably true; it is proved by the fact that certain drugs alter the sensibility of the skin to hot and cold stimulations.

Another advance was made when it was found that sensations of either hot or cold may be had from regions which are insensible at the same time to the other sort of stimulation, cold or hot. Certain minute points were discovered which report cold when touched with a cold point, but give no feeling from a hot object; while other points would respond only with a sensation from heat, never giving cold. It was concluded that we have two temperature senses, one for hot and the other for cold.

Taking the problem at this point, Mr. C.[3] wished to define more closely the relation of the two sorts of sensation to each other, and thought he could do so by a method by which he might repeat the stimulation of a series of exact spots, very minute points on the skin, over and over again, thus securing a number of records of the results for both hot and cold over a given area. He chose an area of skin on the forearm, shaved it carefully, and proceeded to explore it with the smallest points of metals which could be drawn along the skin without pricking or tearing. These points were attached to metallic cylinders, and around the cylinders rubber bands were placed; the cylinders were then thrust in hot or cold water kept at certain regular temperatures, and lifted by the rubber bands. They were placed point down, with equal pressure, upon the points of the skin in the area chosen. In this way, points which responded only to hot, and also those responding only to cold, were found, marked with delicate ink marks in each case, until the whole area was explored and marked in different colours. This had often been done before. It remained to devise a way of keeping these records, so that the markings might all be removed from the skin, and new explorations made over the same surface. This was necessary in order to see whether the results secured were always the same. The theory that there were certain nervous endings in the skin corresponding to the little points required that each spot should be in exactly the same place whenever the experiment was repeated.

[Footnote 3: Mr. J. F. Crawford, graduate student.]

Mr. C. made a number of so-called "transparent transfer frames." They are rectangular pieces of cardboard, with windows cut in them. The windows are covered with thin architect's paper, which is very transparent. This frame is put over the forearm in such a way that the paper in the window comes over the markings made on the arm. The markings show through very clearly, and the points are copied on the paper. Then certain boundary marks at the corners are made, both on the paper and on the arm, at exactly the same places, the frame is removed, and all the markings on the arm are erased except the boundary points. The result is that at any time the frames can be put over the arm again by matching the boundary points, and then the original temperature spots on the skin will be shown by the markings on the paper window.

Proceeding to repeat the exploration of the same area in this way, Mr. C makes records of many groupings of points for both hot and cold sensations on the same area; he then puts the frames one upon another, holds them up before a window so that they have a bright background, and is thus able to see at a glance how nearly the results of the different sittings correspond.

His results, put very briefly, fail to confirm the theory that the sense of temperature has an apparatus of fixed spots for heat and other fixed spots for cold. For when he puts the different markings for heat together he finds that the spots are not the same, but that those of one frame fall between those of another, and if several are put together the points fill up a greater or smaller area. The same for the cold spots; they fill a continuous area. He finds, however, as other investigators have found, that the heat areas are generally in large measure separate from the cold areas, only to a certain extent overlapping here and there, and also that there are regions of the skin where we have very little sense of either sort of temperature.