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optic thalami as the primary seat of hallucinations, admitting the constant spread of lesions from the thalami to the cortex ;* and Dr. W. J. Micklet considers—as the result of a number of very careful necropsies—that in cases of hallucination “thalamic disease plays a less important part than cortical.” But on the other hand, he did not find that the lesions were definitely associated with the spots in the cortex which Ferrier and the advocates of restricted cortical localisation mark out as the visual and the auditory centres; while lesions at these spots—the angular gyrus and the first temporo-sphenoidal convolutionseem to be found in cases where no hallucination has been observed. I This want of correspondence will seem less surprising if we remember the vast number of casual hallucinations where nothing that could be called a lesion exists; and also that the more persistent hallucinations of the insane belong, as a rule, to the earlier period of irritation, rather than to the later one when marked lesion has supervened, and dementia is creeping on. Even if we take subsequent cortical lesion as a sign that the weak spot existed from the first in the highest part of the brain, this would be no proof that the specific sensory centre is cortical. If lesions are not bound to be locally restricted, much less are irritations; and there is nothing to refute the supposition above made, that, when the hallucination occurs, a current has passed downwards to the lower centre—the mischief in the cortex having been primarily an excitant of ideational activities only, and the hallucination being due (as Dr. Mickle well expresses it) to“ a tumultuous disorderly reaction of disturbed ideational centres upon sensorial.” The same may be said of the artificial irritation of the “cortical centres” during life. Ferrier regards the movements which result when an electrical stimulus is applied to these areas, as an indication that visual or auditory sensations (i.e., hallucinations) have been evoked. We may quite accept this interpretation, but still suppose that the primary seat of the sensation was not the spot where the stimulus was applied, but a lower centre on the path along which the irritation passed.||

* Gazette des Hôpitaur, Dec., 1880, p. 46.
t Journal of Mental Science, Oct., 1881, p. 382.
| Journal of Mental Science, Oct., 1881, p. 381, and Jan., 1882, p. 29.

§ Luys, Gazette des Hôpitaux, 1881, p. 276 ; Despine, Ann. Médico-psych., 6th series, Vol. VI., p. 375; Tamburini in the Revue Scientifique, Vol. XXVII.,

p. 141.

|| It may be remarked, by the way, that what has been here said as to the relation of hallucinations to cerebral localisation will apply, mutatis mutandis, to blindness. We may suppose the action of lower centres to be inhibited, as well as abnormally excited, by stimulation from above. Thus the fact that blindness follows certain cortical lesions does not by any means establish the location of the principal sensory centres in the cortex. And as it happens, some of the facts of blindness seem absolutely adverse to that location-I mean the

We are thus thrown back on less direct arguments, derived from the nature of the hallucinations themselves. And I think the mistake has again been in imagining that one or other of two alternatives must be exclusively adopted----that either the lower or the higher origin of hallucinations is the universal one. All, I think, that can be fairly said, is that, while the first mode of origin is a probable one for some cases, the second mode is a certain one for others. Hallucinations produced at the will of the percipient must first take shape above the sensory centres. For it is indisputable that the idea of the object to be projected—the picture, face, sentence, or whatever it may be—must precede its sensory embodiment as a thing actually seen or heard ; and the idea, as well as the volition, is an affair of the higher tracts; MM. Luys and Ritti will certainly not locate either of them in the optic thalami. But if the advocates of the first mode have thus ignored an important class of cases, the advocates of the second have errediby adopting a quasi-metaphysical standpoint. Thus Dr. Despine, who has given an extremely clear account of the centrifugal process (Annales Médicopsychologiques, 6th series, Vol. VI., p. 371), argues that for a hallucination to arise, we first need an idea—“ an object which does not exist; and if in a way it is endowed with existence, this, as a purely constructive act, can only emanate from the seat of the highest psychical activities. There is some originality in extracting a physiological conclusion from the relation of the mind to the non-existent. But at this rate the image of the sun's disc on the wall would originate in a constructive act of the mind : it is as much “ an object that does not exist” as the most elaborate phantasm. The non-existence of an object outside the organism is quite irrelevant to the course of nervous events inside ; and whether we regard a psychic act, for any given case, as constructive or receptive, depends simply on whether the nervous excitation is spon

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phenomena of so-called "psychical blindness, "where cortical lesion has produced loss of memory and of the higher functions of perception, while sensation (according to Munk's view) remains intact, and may gradually give rise to new perceptions and new memories. The observations of Munk and Goltz as to the survival of vision, though not of intelligent vision, after extensive cortical injury, seem distinctly favourable to the theory of the lower position of the specific sensory centres. Nor need that theory conflict with the most extreme view as to the absence of circumscribed areas in the cortex. Goltz himself would not deny that some place or places on the paths of the optic and the auditory nerve are specially connected with the fact that the stimulation of the one corresponds with sight, and of the other with sound. It cannot be maintained that this psychical distinction has no local representative ; for such a contention would logically lead to denying, e.g., that the corpora quadrigemina in the lower animals have any particular relation to vision. Thus, whatever be the final issue of the vexed question of cortical areas of perception, a local distinction of genuine centres of sensation somewhere in the brain seems as certain as the distinction of the external organs themselves.

even

taneous, or is received from below. Now this may be applied, as we have seen, to the lower centres of sensation as reasonably as to the higher tracts of perceptive ideation ; the former may construct as truly as the latter; that is to say, the configurations and activities of their cells may produce definite groupings of the sensory elements.

And for simple and recurrent forms of hallucination, much may be said in favour of this lower origin. It is in accordance with all that we know or conjecture as to nerve-tissue, that certain configurations and modifications of cells would be rendered easy by exercise; and thus the changes to which any morbid excitement gives rise might naturally be the same as have often before been brought about by normal stimulation from the retina or the ear. The elements would fall readily, so to speak, into the accustomed pattern. An object which has been frequently or recently before the eyes a word or phrase that has been perpetually in the ear-these may certainly be held capable of leaving organic traces of their presence, and so of establishing a sort of lower memory.

That this lower memory should act automatically, and independently of the will, seems natural enough when we remember how large a part

of the higher memory is also automatic : an unsought word, suddenly reverberating in the sensorium, is on a par with the images that emerge

into consciousness without our being able to connect them with our previous train of ideas. Now it is remarkable how large a number of hallucinations are of this primitive type. I mentioned above that, among the sane, the commonest of all cases is to hear the name called ; and even with the insane, the vocabulary of the imaginary voices often consists of only a few threatening or abusive words.* So of optical hallucinations. With the sane, a large number consist in the casual vision-an afierimage, as we might say—of a near relative or familiar associate. More persistent cases are still frequently of a single object. I have mentioned the doctor and the black cow; similarly a lady, when in bad health, always saw a cat on the staircase. And among the insane, a single imaginary attendant is equally common : our friend “Guiteau above was an instance. Wherever such simple cases are not connected with any special délire, or any fixed set of ideas, they may, I think, be fairly (though of course not certainly) attributed to an activity following the lines of certain established tracts in the sensorium.

We might compare this locality to a kaleidoscope, which when shaken is capable of turning out a certain limited number of combinations.

* On this subject, see Dr. V. Parant in the Ann. Médico-psych., 6th series, Vol. VII., p. 384. These embryonic hallucinations often develop into more complex form ; see Ball, Maladies Mentales, p. 67.

† Blandford, Insanity and its Treatment, p. 155. # Charcot (Le Progrès Médical, 1878, p. 38) has noted a curious form of

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saw

But, on the other hand, the astonishing variety and complexity of other cases-whether visual appearances or verbal sequences-seem absolutely to drive us to a higher seat of manufacture ; for they demand a countless store of elements, and limitless powers of ideal combination. The patient listens to long discourses, or holds conversations with his invisible friends; and what is heard is no echo of former phrases, but is in every way a piece of new experience. So, too, the number and variety of visual hallucinations which may occur to a single person, sometimes even within the space of a few minutes, is astonishing.

The shapes and features of Dr. Bostock's apparitions were always completely new to him ; the seers of “ Faces in the Dark” who had in the course of their lives seen many thousand phantasmal faces, had never seen one that they recognised ; Nicolai, who never otherwise than perfectly sane and who eventually recovered, continually Troops of phantoms, most of them of an aspect quite new io him ; and in insanity such a phenomenon is common enough. Even in the casual hallucinations of the sane, what is seen is less commonly a mere revival of an object which the eyes have previously encountered than an unrecognised person. Here, then, we have an immense amount of high creative work—of what in psychical terms we should call par excellence the work of the imagination; and this is work which we have good grounds for supposing that the highest cortical tracts, and they alone, are capable of performing. From our experience of the number and mobility of the ideas and images that the mind in a normal state can summon up and combine, we know that the cells of the highest cerebral areas are practically unlimited in their powers of configuration and association; but we have no right to assume the same inexhaustible possibilities as existing independently in any specific sensory centre—we might almost as well expect a kaleidoscope to present us with an ever-fresh series of elaborate landscapes. And over and above all this, we can point to the constant connection between the delusions, the conceptions délirantes of the insane and their sensory hallucinations,* which makes it almost im

unilateral hallucination, which occurs sometimes to hysterical patients on the side on which they are hemianæsthetic-animals, passing rapidly in a row from behind forwards, which usually disappear when the eyes are turned directly to them. Examined by the ophthalmoscope, the eyes of these patients appear absolutely normal. Charcot attributes amblyopy and achromatopsy, occurring in the same persons (as well as in non-hysterical cases of hemianästhesia), to lesion at a point which he calls the carrefour sensitif in the hinder part of the internal capsule ; and I assume that he would refer the hallucination to the same point. If so, he may be quoted as an authority for the infra-cortical initiation of simple and recurrent forms of hallucination

Falret, Op. cit., p. 269 : Wundt, Op. cit., Vol. II., p. 356 ; Krafft-Ebing, Op. cit., p. 19; Griesinger, Op. cit., pp. 95-6.

possible not to regard the latter as a particular effect of the more widely diffused cerebral disturbance. The conclusion seems to be that for many hallucinations the mode of origin can be no other than what I have called the centrifugal.

I have throughout tried to express what I have called the centrifugal theory in such terms that it might be accepted even by those who locate the sensory centres themselves not below, but in, the cortex. According to these physiologists, the whole double transformation of physical impressions into visual or auditory sensations, and of these sensations into complete perceptions and mnemonic images, would be practically referred to one place. It must be admitted that this view seems at times connected with the want of a due psychological distinction between sensation and perception. But even supposing a specific centre of sensation to be thus equally the seat of psychic functions higher than sensation, it would still be none the less liable to be stimulated by parts of the cortex external to itself; and the nature of many hallucinations would still indicate that they depend on this stimulation, and not on a mere spontaneous quickening of morbid activity in the centre itself. For instance, a girl is violently distressed by seeing her home in flames, and for days afterwards sees fire wherever she looks.* One must surely trace the hallucination to the distress, and so to an

escape of current from the seat of ideas and images other than visual ones.

Again, in the cases described above where the hallucinations faithfully reflect the changes of the whole moral and intellectual bias, the local excitement in the sensory centre would still be traceable to an abnormally strong irradiation from the regions where the highest co-ordinations take place --these regions being themselves, ex hypothesi, already in state of pathological activity. The other hypothesis would be that the mere hyper-excitability at the centre itself made it impossible for images to arise without getting hurried on, so to speak, into sensations by the violence cf the nervous vibrations. This seems to be what Wundt has in view when he speaks of hallucinations as originating, not in an actual irritation, but in a heightened irritability, of the sensory centres. But then, what should cause images belonging to one particular order of ideas-the diseased order—to be picked out for this fate in preference to any others ? The hyperexcitable centre in itself, as an arena of images, could have no ground for such a partial selection among the crowd of them which emerge during every hour of waking life. Among the endless and multiform vibrations involved, why should

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Griesinger, Op. cit., p. 97, For an auditory case, cf. the account, in the Lyon Médical, Vol. XXXV., p. 437, of a young Frenchman who was rendered insane by the German invasion, and who was then haunted by the sound of guns firing.

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