A monograph on sleep and dream: their physiology and psychology

by Edward W. Cox

The experiments were conducted chiefly with monkeys and dogs. The former were the most valuable, because the brain structure of the monkey is almost identical with that of man. The experiments were certainly cruel and I should object to procure even such valuable knowledge at such a price. But, as it is obtained, we may use it.

The experiments were performed by making the animal insensible by chloroform and then extracting in mass certain portions of the brain, or destroying parts of the brain by the actual cautery. Electrodes were applied to the various parts of the brain to which access had been thus obtained and their effects upon the actions of the animal were carefully observed.

I will not attempt to detail these experiments—but merely state some of the results. For the many important facts that were discovered by them reference must be made to the valuable volume in which they are reported.

He found the entire brain to be connected with the nerve system by the process of interlacing. Excitation of the right brain was shown by the left side of the body; of the left brain by the right side. So it was with the nerves of the senses. Whether the like structure exists in the duplex organ of the intelligence he could not trace, because the mental results were incapable of being expressed by experiment upon animals, who cannot tell us what are their emotions. But he entertains no doubt that the same structural scheme is observed in the action of the two hemispheres also.

The great ganglia at the base of the brain, whether excited by electricity or destroyed by cautery, yielded the same result. They proved beyond doubt that their function is to direct the actions of the body under the peculiar conditions of its duplex structure—that is to say, a formation by two distinct and not wholly similar halves joined together and requiring community of action. This process of separate action for each part combined with motion in co-ordination—that is to say, the regulation of the motions of the limbs, so that the two halves of which the body is builded may act in definite relationship—was found to be the special business of those basal ganglia, any disturbance in those ganglia being attended with imperfect movements of the body, even to the extent of causing the animal to walk in a circle, having lost entirely the power to “walk straight.” The results of this ingenious experiment are extremely curious and throw great light on the physiology of locomotion.

The second division of the brain, lying in its centre, overlapped behind by the cerebrum, resting on the centres that direct bodily actions and dominated by the hemispheres that are the organs of the intelligence, is shown by these experiments to be the centre upon which the senses converge. To this common centre the impressions made upon the senses by the external world are conveyed. The experiments seem to indicate that a distinct ganglion is devoted to each sense, although all are united in one mass for the common purpose of reception of the information they bring. The destruction of different parts of this brain centre is found to be followed by the loss or impairment of different senses. It was found, also, that this part of the brain was duplex, like the other parts, for destruction of the right side of the ganglion caused paralysis of the senses on the left side of the body and vice versâ.

A question of much interest arises here. What is the precise function of this sense-receiving portion of the brain? Is itself perceptive of the sense-impressions brought to it, or is it merely the medium for transmitting those impressions to the hemispheres above? That in health it does communicate to the intelligence the same impressions that it receives there can be no doubt, for we take cognisance of them in almost every mental act. We know also that when the brain is diseased false impressions are conveyed to the Intelligence. But in exploring the psychology of Sleep and Dream, it would be of great advantage to ascertain if the same receiving portion of the brain is an active or merely a passive agent.

The experiments of Professor Ferrier are almost conclusive upon this most important point. He removed the two brain hemispheres of a monkey and of a dog. The animals lived and appeared to enjoy health, but they had lost intelligence. They had not, however, lost the use of the senses and they were manifestly conscious of the impressions brought by the nerves of sense. The external world continued to exist for them and was perceived by them as before the organs of the intelligence were removed. But when this central division of the brain was taken away and nothing left but the lower lobes that govern muscular motion, all the senses ceased to act, or consciousness of action had ceased. Nevertheless the power of locomotion and the co-ordinate action of the limbs was preserved with very little loss of power.

Above the central sense-organ tower two hemispheres—two brains, each distinct and complete in itself and each capable to act without the other. The function of these hemispheres is that we term mental. They are the organs of the intellect and of the sentiments. Through them we think, reason and feel. Injury to parts of these injures more or less, not the whole mind, but parts of the mind—certain mental faculties only. Destruction of the entire of these hemispheres is not death but idiotcy.

Let it then be clear in the mind of the reader, when surveying the phenomena of sleep and dream and inquiring into their causes, that for the purpose of such an outline of the Physiology of the Mind as this, the brain is to be viewed by him as having three marked divisions—the organ of the intelligence at the summit, of the senses in the centre, of bodily motion at the base.