Have we two brains or one?

  • Charles-Édouard Brown-Séquard
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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    movement and sensibility, serves only for the half of the body on the opposite side. II. In an article on “ Cerebral Localization ” * I have already given a number of arguments against the prevailing doctrines relating to the mechanism of brain functions. Among the con- clusions which I drew from the facts and reasonings contained in that paper, there are two which it is essential to renroduce: 1. Nerve cells endowed with any of the cerebral functions, instead of forming a kind of cluster, as is supposed, are disseminated through the whole encephalon, so that considerable alterations or destructive lesions can exist in one of the cerebral hemispheres, or in both, without the loss of voluntary movements, of sensibil- ity, or of any other brain function. 2. The complete disappear- ance of any cerebral function, in cases of organic brain lesion, is due to a suppressing influence exerted on all the nerve-cells that have a share in that function, in either the encephalon or the spinal cord. The mechanism of that disappearance is that of in- hibition, such as takes place in the heart when the activity of that organ is stopped by an irritation of more or less distant parts. III. The differences which are frequently found between vertebrate animals and man, are now justly considered as being generally mere differences in degree and not in kind. It is quite legitimate, therefore, to apply to man most of the results ob- tained from experiments on those animals. It is perfectly known and fully recognized by all physiologists that, in the scale of animals, from frog to man, new parts are gradually added to the nervous centres; that, consequently, certain functions of the nervous centres gain more and more power; and that new func- tions supervene which had no existence in animals compared to man, or in the higher groups of animals compared to the lower ones. Our purpose, therefore, is to make use discriminately of the results of experiments on animals, and to ask from a frog what it can give, and not what can be obtained only from ani- mals placed much higher in the scale. IV. The grounds for the views relating to the cerebral dual- ity which are generally admitted, are the following: 1. That an irritation of parts of one half of the brain causes movement in * Forum, April, 188S.
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