On the influence of Suggestion in Modifying and directing Muscular Movement, independently of Volition by William Benjamin Carpenter 1852
See also Communicating with the Dead (Spirit World), 100 Books on DVDrom - For a list of all of my disks and digital books click here
[From a report of a Lecture at the Royal Institution, March 12, 1852.]
It now remains to inquire whether any such physiological account can be given of the "biological" state, as shall enable us to refer it to any of the admitted laws of action of the nervous system. This, the lecturer stated, was the point which he was the most desirous of elucidating; and in order to prepare his auditors for the reception of his views, he gave a brief explanation of those phenomena of "reflex" action (now universally recognized by physiologists), in which impressions made upon the nervous system are followed by respondent automatic movements. Such movements have hitherto been distinguished into the excitomotor, which are performed, without the exciting impression being necessarily felt, through the instrumentality of the spinal cord and the nerves connected with it; and the sensori-motor, in which sensation necessarily participates, the respondent motions not being executed unless the impressions are felt, and their instrument being the chain of sensory ganglia (collectively constituting the "sensorium ") which lies between the spinal cord and the cerebrum, and is intimately connected with both. The automatic movements of breathing and swallowing, which continue during a state of profound insensibility, are examples of the former group; whilst the start upon a loud sound, the closure of the lids to a flash of light, or the sneezing induced by the dazzling of the eyes, as well as by the irritation of the nasal passages, are instances of the latter. The whole class of purely emotional movements may be likened to these; for in so far as they are involuntary, and depend upon the excitation of certain states of mind by external impressions, they must be considered as "reflex" in the general sense of that term.
Now the usual modus operandi of sensations is to call forth ideas to the mind; and these ideas, associated or not with emotional states, become the subjects of intellectual processes, which result at last in a determination of the will. The movements we term voluntary or volitional differ from the emotional and automatic, in being guided by a distinct conception of the object to be attained, and by a rational choice of the means employed. And so long as the voluntary power asserts its due predominance, so long can it keep in check all tendency to any other kind of action, save such as ministers directly to the bodily wants, as the automatic movements of breathing and swallowing.
The cerebrum is universally admitted to be the portion of the nervous system which is instrumentally concerned in the formation of ideas, the excitement of the emotions, and the operations of the intellect; and there seems no reason why it should be exempted from the law of "reflex action," which applies to every other part of the nervous system. And as we have seen that the emotions may act directly upon the muscular system through the motor nerves, there is no a priori difficulty in believing that ideas may become the sources of muscular movement, independently either of volitions or of emotions.—-The relations of these different modes of action of the nervous system, and the place which this ideo-motor form of "reflex" operation will hold in regard to the rest, will be made more apparent by the following tabular arrangement:—
Now if that ordinary upward course of external impressions— whereby they successively produce sensations, ideas, emotions, and intellectual processes, the will giving the final decision upon the action to which they prompt—be anywhere interrupted, the impression will then exert its power in a transverse direction, and a "reflex" action will be the result. This is well seen in cases of injury to the spinal cord, which disconnects its lower portion from the sensorium without destroying its own power: for impressions made upon the lower extremities then excite violent reflex actions, to which there would have been no tendency if the current of nervous force could have passed upwards to the cerebrum. So, if sensations be prevented by the state of the cerebrum from calling forth ideas through its instrumentality, they may react upon the motor apparatus in a manner in which they would never do in its state of complete functional activity. This the Lecturer maintained to be the true account of the mode in which the locomotive movements are maintained and guided in states of profound abstraction, when the whole attention of the individual is so completely concentrated upon his own train of thought that he does not perceive the objects around him, although his movements are obviously guided by the impressions which they make upon his sensorium. And he adverted to a very remarkable case, in which the functional activity of the cerebrum seemed to have been almost entirely suspended for nearly a twelvemonth, and all the actions of the individual presented the automatic characters of consensual and reflex movements.
On the same grounds, it seems reasonable to suppose that when ideas do not go on to be developed into emotions, or to excite intellectual operations, they, too, may act (so to speak) in the transverse direction, and may produce respondent movements through the instrumentality of the cerebrum; and this will of course be most likely to happen when the power of the will is in abeyance, as has been shown to be the case in regard to the direction of the thoughts, in the states of electro-biology, somnambulism, and all forms of dreaming and reverie. Here the movements express the ideas that may possess the mind at the time; with these ideas, emotional states may be mixed up, and even intellectual operations may be (as it were) automatically performed under their suggestive influence. But so long as these processes are carried on without the control and direction of the will, and the course of thought is entirely determined by suggestions from without (the effects of which, however, are diversified by the mental constitution and habits of thought of the individual), such movements are as truly automatic as are those more directly prompted by sensations and impressions, although originating in a more truly psychical source. But the automatic nature of the purely emotional actions can scarcely be denied; and as it is in those individuals in whom the intellectual powers are the least exercised, and the controlling power of the will is the weakest, that the emotions exert the strongest influence on the bodily frame, so may we expect ideas to act most powerfully when the dominance of the will is for the time completely suspended.
Thus the ideo-motor principle of action finds its appropriate place in the physiological scale, which would, indeed, be incomplete without it. And, when it is once recognized, it may be applied to the explanation of numerous phenomena which have been a source of perplexity to many who have been convinced of their genuineness, and who could not see any mode of reconciling them with the known laws of nervous action. The phenomena in question are those which have been recently set down to the action of an "Od-force," such, for example, as the movements of the "divining-rod," and the vibration of bodies suspended from the finger; both which have been clearly proved to depend on the state of expectant attention on the part of the performer, his will being temporarily withdrawn from control over his muscles by the state of abstraction to which his mind is given up, and the anticipation of a given result being the stimulus which directly and involuntarily prompts the muscular movements that produce it.
For a list of all of my disks and digital books click here
No comments:
Post a Comment