The parietal area / by Geoffrey Jefferson.

  • Jefferson, Geoffrey, 1886-1961.
Date:
1914
Catalogue details

Licence: In copyright

Credit: The parietal area / by Geoffrey Jefferson. 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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    Reprinted from Review oj Neurology and Psychiatry, February 1914 i >• ! THE PARIETAL AREA. By GEOFFREY JEFFERSON, M.S. (Lond.), F.R.C.S. In two recent papers,1- 2 the writer has advanced some new views on the anatomy and development of the parietal and post- central areas of man. These views are based on the modern conception of the origin and cause of the cerebral sulci put forward by Elliot Smith. A brief account of this work of the last named will be found in the new Cunningham’s “ Text-Book of Anatomy,” and especially in the paper by him referred to below. Difference of structure of the various parts of the cortex is the principal factor in the causation of sulci. And with this difference of structure we may assume a difference of function. From this we may argue that as we trace the mammalian scale upwards we shall find that with evolution new sulci will appear to limit or infold the cortical areas with which the newly acquired functions are associated. There can be few functions, however, that are totally unrepresented on even the lowest brains. So that what probably happens in the anthropoids is this: the very high development of those cortical areas which are represented but slightly in the lowest animals. In such cases some of the ap- parently new sulci of the former will be merely exaggerations of slight puckerings on the cortex of the latter, whilst the remaining sulci will be quite new, being due to a differentiation of which there is no trace in lower brains. Since the cerebral sulci are called into being by the specialisa- tion of the cortex into areas, it follows that the sulci will be identical in different brains only if the structure of the brains is identically the same. It is the slight difference of structure, with the corresponding slight differences in the shape and disposition of the sulci, that causes bi’ains to be so different in appearance, even though belonging to animals of the same species. The more highly evolved any two brains are, the more dissimilar will they be; for now cortical specialisation will be reaching its highest 1,1 The Morphology of the Sulcus Interparietalis, B.N.A.,” Journal of Anatomy, July 1913. A Note on the Sulcus Post-centralis Superior,” Anatomiecher Anzieger, 1913, xliv.