Have we two brains or one?

  • Brown-Séquard, Charles-Edouard, 1817-1894.
Date:
[1890]
Catalogue details

Licence: Public Domain Mark

Credit: Have we two brains or one?. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the opposite side of the body. 2. That paralysis and anaesthesia appear always on the side opposite to that of a brain lesion. 3. That when a lesion has lasted some time in the so-called motor track of the encephalon, on one side, a secondary degener- ation is found which indicates that the channels of an order of the will to muscles pass to the opposite side of the body. I will now proceed to the examination of these various arguments, and at the same time will show that facts which are in harmony with the admitted doctrines can be, and ought to be, explained in quite a different way. I will, besides, try to establish that those facts, as well as a great many others, together with many arguments in opposition to those doctrines, all give support to the views I have proposed. V. It is well known that certain parts of one side of the sur- face of the brain can, when excited by galvanism, in mammals, give rise to movements in the limbs, face, eye, and trunk, on the opposite side. Those parts are called psycho-motor centers, and they are looked upon as acting on muscles by nerve currents descending to the crus cerebri, the pons Varolii, and the anterior pyramid on the same side, passing, where the pyramids decussate, into the posterior part of the lateral column of the spinal cord on the other side. That this view must be rejected, is clearly proved by the following facts. After having ascertained what degree of galvanic power can produce certain movements in the limbs, face, etc., on the side opposite to that of the psycho-motor centers which I irritate, I divide transversely either half of the pons Varolii, or of the medulla oblongata including the anterior pyramid, or the crus cerebri, on the side of the galvanization. I then apply again the same galvanic current to those pretended motor centers, and I find that, although the only supposed channels of communication between the brain on the excited side and the muscles on the opposite side, are divided, the action of galvanism is greater as the movements are more energetic. If the doctrines which are admitted were true, no movement at all could then be produced In other experiments, I have ascertained that after the section oi both anterior pyramids, the two so-called motor centers can act so as to cause movements almost as well as when the whole