Ivan Petrovitch Pavlov at 85, speaking at the XV International Physiological Congress, Leningrad, 1935

Excerpts from Lectures on Conditioned Reflexes, Volume II: Conditioned Reflexes and Psychiatry

Ivan Petrovitch Pavlov



(From Archives Internationales de Pharmacodynamie et de Therapie, 1930, in the volume dedicated to Cley and Heymans.)


AT THE present our material relates not only to normal activity but to pathology and to therapy. We have definite experimental neuroses in our animals (dogs) and in the same animals what is analogous to human psychoses, and we know their treatment. This was the raison d’être for my becoming thoroughly acquainted with psychiatry, of which practically no trace remained from my student medical days. Thanks to my medical colleagues I now have the opportunity to see different forms of mental disturbances. The first to come under my observation was schizophrenia. My attention rested particularly on the symptoms of apathy, dullness, immobility and stereotyped movements, and, on the other hand, playfulness, unconventionality and in general childish behaviour inappropriate to patients with such illnesses (hebephrenia and catatonia).

What is this from the physiological point of view? May not the physiologist group these phenomena, see in them a single general mechanism? Let us turn to the facts obtained from the conditioned reflex studies.

On the one hand the processes of excitation are constantly participating in the varied activity of the animal during the waking state, and on the other hand inhibition is ever appearing in the rôle of a guardian of the most reactive cells of the organism, the cortical cells of the cerebral hemispheres, protecting them against extraordinary tension of their activity when they meet with very strong excitations, securing for them necessary rest, after the usual daily work, in the form of sleep.

We have established beyond doubt the fact that sleep is inhibition spreading over all the hemispheres. We have also been able to study the intermediate phases between the waking state and complete sleep – the hypnotic phases. These phases appear to us, on the one hand, as different degrees of the extent of inhibition, i.e., a more or less spreading of inhibition in the areas of the hemispheres themselves and also in different parts of the brain; and, on the other hand, as different degrees of intensity of inhibition in the form of varying depths of inhibition at one and the same place. Naturally with the greater complexity of the human brain the hypnotic phenomena are considerably more varied in the human than in the animal. But it is possible that some of the hypnotic phenomena for one or another reason are more clearly marked in the animal, the more so because human hypnosis presents considerable variations depending upon the individual and the methods of hypnotization. Bearing in mind the whole symptom-complex of hypnosis, I shall in the future use the hypnotic phenomena observed in humans as well as in animals.

Studying the aforementioned schizophrenic symptoms I came to the conclusion that they are the expression of a chronic hypnotic state. Apathy, dullness, immobility, etc., are not necessarily manifestations of a hypnotic state unless I am able to find more justification for this view in the special symptoms.

First I shall mention the following facts. Apathy and dullness are generally expressed by the patient’s failures to react to questions, as if he were completely insensitive. However if these questions are put to him very softly in very quiet surroundings he answers. This is a characteristic hypnotic phenomenon..... It is to be regretted that for this very important symptom there is in the clinic no special name such as is given to other symptoms. In our animals this symptom is one of the most frequent signs of the beginning of hypnosis – met with in the so-called paradoxical phase in which the animal loses its reactions to strong stimuli, but reacts normally to the weak. In the well known case of a five-year sleep described by Janet, rapport with the patient was established only on this basis. Indeed the patient came out of the hypnotic state only at night when there was an interruption of the ordinary stimulations.

Negativism was manifested in the patients we analysed. Also in our experimental animals such negativism during the beginning of hypnosis was customary. With the conditioned food stimulus we feed the dog but he stubbornly turns away. Another interesting detail is especially marked in the inverse phase. When you remove the food from the dog he now attempts to get it. This can be repeated time after time. But when hypnosis disappears the dog greedily takes the food.

The analysis of the mechanism of this hypnotic symptom and of others I shall postpone until later, turning now to the evident facts of the hypnotic state.

One of the most extreme symptoms of schizophrenia with certain variations is stereotypy – a stubbornly continued repetition of the same movements. In several of our dogs too this is clearly observed. In the case of the conditioned food reflex, when the dog is fully awake, after feeding he habitually licks for a short time the front part of the body, the front part of the chest and the front paw. During beginning hypnosis this licking is exceedingly prolonged, often lasting until the next feeding Also other movements are repeated once they have been used by the animal in a certain way.

A common occurrence in schizophrenics is the so-called echolalia and echopraxia, i.e., the pronunciation by the patient of the words of the one with whom he is conversing and the performance of all the movements of the person to whom he is giving his attention. This is a familiar phenomenon in a hypnotised normal subject, which, as I recall, occurs especially easily and frequently during hypnosis produced by the so-called passes.

A common manifestation in schizophrenics is catalepsy – the continued maintenance by the patient of any position of the body (which can be easily given to him without opposition of the muscles by another person) or of those positions which he himself takes under the influence of one or another temporarily acting stimulus. Again this is a symptom readily produced in normal hypnosis.

An obstinate symptom in some schizophrenics, appearing even in a definite form, is catatonia, i.e., a tense state of the skeletal musculature strongly opposed to every change in a given position of a part of the body. This catatonia is nothing more than the operation of tonic reflexes thanks to which a hypnotised normal subject may be made as stiff as a board.

Finally here, to this group of every variation of central inhibition. it is necessary to relate even the symptoms of playfulness and foolishness observed especially in hebephrenics, and also a capricious and aggressive excitement accompanying the above-mentioned symptoms in other schizophrenics. All these phenomena bring strongly to mind the usual picture of the beginning alcoholic intoxication, and also the characteristic state seen during awakening and especially during the falling to sleep of children and young animals such as puppies. In these cases there is reason to think they are the result of a beginning general inhibition of the cerebral hemispheres, as a consequence of which the neighbouring subcortex is not only freed from its usual control, the constant inhibition from the hemispheres during the waking state, but even, on the basic mechanism of positive induction, there ensues an excitatory chaotic condition in all the centres. Hence during alcoholic narcosis there appears without cause now an unusual frolicsomeness and gaiety, now sensitiveness and tears, now rage, and during the falling to sleep of children every possible caprice. An especially characteristic picture is the drowsy child during the middle months of its first year, when may be seen on its face the kaleidoscopic play of varied expressions – signs of a lack of organisation in childhood of the primitive sub-cortex. Thus the schizophrenic in certain phases and variations of its illness manifests this phenomenon now in long, now in short, periods.

After all the above cases one can hardly doubt that schizophrenia in certain variations and phases actually represents chronic hypnosis. That these variations and phases may continue for years is no refutation of this conclusion. If one may speak of a five-year sleep (case of Pierre Janet) and even of a twenty years’ sleep (Petersburg case) why can there not be such continued hypnosis, the more so because these examples are more correctly called hypnosis rather than sleep?

What produces the chronic hypnosis of schizophrenia? What is its physiology and pathology? What is its course and outcome?

The ultimate basis of this hypnosis is, of course, a weak nervous system, especially a weakness of the cortical cells. This weakness can issue from different causes – hereditary and acquired. We shall not concern ourselves with these causes. But naturally such a nervous system on meeting with difficulties – most frequently in the critical physiological and socialising period – after an overwhelming stimulation inevitably enters into a state of fatigue. But fatigue is one of the chief physiological impulses to the creation of the inhibitory process as a protective process. Hence chronic hypnosis, representing inhibition in various degrees of extension and tension. Thus this state is, on the one hand, pathological, as it deprives the patient of his normal activity; on the other hand it is in its mechanism physiological, a physiological measure because it conserves the cortical cells against a threatening destruction consequent to an overwhelming task. We now have in the laboratory an amazing example of continued inhibition restoring the weak cortical cells for a certain period to normal activity. There is good reason to think that while the inhibitory process is acting the cortical cells remain uninjured; for they may return to a completely normal condition, they may recover from an extreme exhaustion. This according to contemporary terminology is only a functional illness. That this is actually so is confirmed by the following facts: Certain forms of schizophrenia, particularly hebephrenia and catatonia, i.e., forms having a hypnotic character, according to Kraepelin, one of the greatest psychiatric authorities, result in a fair percentage of complete recoveries (catatonia to 15%), which is not true in certain other forms, particularly paranoia.

In conclusion allow me to make a therapeutic suggestion, hardly altogether sentimental and yet not professional. Although there has been no revolutionary progress in the treatment of the mentally ill from ancient times until our own, we have, I think, nothing to regret. The majority of the patients still retaining consciousness to a certain degree can sustain on the one hand violent stimulations in the form of crises and extraordinary scenes, and on the other hand as direct force, but it is necessary to consider as useless an added threat to the weak cortical cells. Consequently we should as soon as possible think of such mentally ill as we do of other suffering patients, whose feelings of human dignity are not so severely tried.

Ivan Petrovitch Pavlov, Lectures on Conditioned Reflexes, Volume II: Conditioned Reflexes and Psychiatry, translated and edited by W. Horsley Gantt, Lawrence & Wishart Ltd., London 1941.

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