by certain patients, as remarked by Séglas, is an index to the nature and seat of their hallucinations. Some keep their tongue firmly bitten between the teeth; others cram their mouth with pebbles, or compress their epigastrium tightly, under the impression that it is the source of their voice. Should such gestures persist while the hallucination does not, they may give rise to what we are in the habit of calling "tonic tics," or "tics of attitude," but we must repeat that the presence of a convulsive element is essential; however out of place or absurd the contractions are, if otherwise they are normal we are dealing with what Séglas designates stereotyped acts. To this question we shall return later.
TIC AND CONSCIOUSNESS
According to Guinon, proof that "convulsive" tic is conscious is furnished by the accurate description and rational explanation patients supply of their affliction. Similarly Letulle's "co-ordinated" tic is a conscious act, at least in its commencement; it is a "bad habit" which finally passes beyond the limit of consciousness.
Now, while no doubt most subjects show a keen appreciation of their tic when their attention is directed to it, they are none the less unconscious of it at the moment of its manifestation. This is the ground on which Letulle bases his statement that all tics, of whatsoever variety, are habitually outside the domain of consciousness. To this fact so much importance has been attached that the attempt has been made, more especially by Blocq and Onanoff,15 to differentiate the conscious from the unconscious tic.
In our opinion, the distinction is ambiguous and tends needlessly to complicate our ideas on the subject. The patient with "convulsive" tic is conscious of it in the sense that he is well aware of its existence, yet how can the gesture be a conscious one if it is synchronous with mental preoccupation? On the other hand, the patient with "co-ordinated" tic may bite his lips unconsciously, but he is by no means ignorant of his little failing.
This divergence of opinion depends entirely on the possibility of regarding the phenomena at different moments during their production. The subject is in a position to appreciate his state both before and after the tic, not during it. In a sense it may be said that tic is alternately conscious and unconscious, in which respect it is comparable to the obsession; the close analogy between the two conditions we shall indicate more fully later. As a matter of fact, the same holds true for every variety of spasm.
We are not disposed to introduce here a term sacred to the psychologist and to speak of the tic as subconscious. Pierre Janet does not admit the absolute unconsciousness of habit; even when the latter has degenerated into a tic, it is not outwith the realm of consciousness. We prefer not to venture, however, into the perilous region of the subconscious, in spite of our appreciation of the happy results attributable to its careful and discerning exploration by observers such as Janet himself.
According to Cruchet, certain so-called psychical tics are always subliminal – for instance, the imitation tics common in children and in idiots.
But if the consciousness of the normal adult be, as it admittedly is, a most elusive conception to define, how infinitely more precarious is the task in the case of idiots or infants! Cruchet says it is impossible to be sure whether at any given moment a tic has been above the threshold of consciousness or not; and we do not think the question will be elucidated by the introduction of data so difficult to comprehend as the consciousness, unconsciousness, or subconsciousness of the tic patient. In any case, these conceptions are quite inadequate for the establishment of useful distinctions. All that we can say is that the participation of consciousness in the phenomena of tic varies in time and degree. To hazard farther would be to invite disaster.
TIC AND POLYGON
The proposal has been made by Grasset to apply his attractive hypothesis of the cortical polygon to the interpretation of the pathogenesis of tic. It is desirable, first of all, to recall briefly the significance of the word polygon in the sense adopted by that neurologist.16
At the central end of the physiological ladder is the superior or cortical system of perception neurons whose cells form the grey matter of the convolutions. Physiological and clinical research necessitates the subdivision of this system into two groups – the neurons of psychical automatism, and the neurons of superior (i. e. voluntary or free) cerebration. The former function is not of the same level as the ordinary reflex arc, since it is in relation to co-ordinated, intelligent, and in a sense conscious acts; at the same time it is to be distinguished assiduously from the latter, in which we include our personality, moral consciousness, free will, and responsibility.
Activity on the part of the inferior psychical neurons is seen:
1. In normal individuals – during sleep, dreams, and acts of distraction.
2. In the nervous – in nightmares, oniric states, table turning, thought reading, the use of the divining rod, automatic writing, cumberlandism, spiritualism.
3. In the diseased – in somnambulism, catalepsy, hysteria, certain phenomena of epilepsy, hypnotism, double personality; also in some cases of aphasia, and in such conditions as astasia-abasia. Every manifestation of this inferior psychism is characterised by spontaneity, herein differing from mere reflex acts, but not by freedom, which is the propre of superior psychism.
The various neurons subserving the former or inferior function are cortical, and form the cortical polygon. Situated at a higher physiological level are those for the latter function, united in what I designate the centre O.
Grasset's general conception of tic is accordingly as follows:
In contradistinction to a pure reflex, a tic is a complex or associated act. There is, however, more than one centre for the elaboration of these complex or associated acts, notably the bulbo-medullary axis, and the cerebral polygon, as we call it. The former serves as centre not merely for simple reflexes, but for true associated acts also, such as conjugate deviation of the head and eyes, walking movements in the decerebrate animal, etc.
We can conceive, then, a first group of non-mental tics corresponding to and reproducing these movements of bulbo-medullary origin.17
Let us turn now to our polygon formed by the various centres of psychic automatism. Polygonal reactions, such as writing or speaking, exceed both simple reflexes and bulbo-medullary associated acts in complexity; they are to all appearance spontaneous and in a certain measure intellectual, but they are neither free nor conscious – attributes that distinguish the functions of the centre O, the seat of the personal, conscious, voluntary, responsible ego. The polygon consists of receptive sensory centres for hearing, vision, and general sensibility, and of transmitting motor centres for speaking, writing, and various body movements. They all communicate with each other, with O, and with the periphery, so rendering possible voluntary modification of automatic action. In some cases, on the contrary, there may be a sort of dissociation between O. and the polygon, when the activity of the latter becomes supreme, as during sleep – we dream with our polygon – or in distraction.
In states intermediate between the physiological and the pathological, pure independent polygonal action may reveal itself in the remarkable phenomena of nightmare, the divining rod, table turning, automatic writing, etc., while certain aphasias and agraphias, somnambulism, catalepsy, and various hysterical conditions constitute the pathology of the polygon.
The fact that all mental attributes and functions are situate in O definitely negatives, in my opinion, any classification in the category of mental diseases of such conditions as hysteria, so many of whose manifestations are polygonal alone.
Our second group of tics – polygonal tics, we may style them – are correspondingly associated, co-ordinated, and psychical, but not mental; they have nought to do with the superior psychism of O.
Finally, in direct and strict dependence on an actual idea is a third group of tics, the psychical tics properly so called.
We have reproduced Grasset's theory in some detail since it is one of the two most recent contributions to the study of the tic's pathogenesis. The other is that of Brissaud.
An apparent lack of harmony between the rival hypotheses