Histogenesis and Morphogenesis of Cortical Structures

Abstract

Three important theories of nervous organization, valid for our time , emerged from the cell theory. Firstly, the demonstration that the nerve cell and fiber are parts of the same structure (first claimed by Remak, 1838) was the first step in the formulation of the neuron theory, which is discussed in Sections 5.1 and 6.1. Secondly, recognition that there are different types of nerve cells, even in the same region, was the beginning of the theory of neuronal typology. Thirdly, realization that there are regionally specific patterns of nerve cells and fibers , especially in the cerebral cortex, was the beginning of a theory of cytoarchitectonics (reviewed by Brodmann, 1909; Lorente de No, 1943; Kemper and Galaburde, 1984).

In my opinion there are only quantitative differences, not qualitative differences, between the brain of a man and that of a mouse. Accordingly, all cortical regions which are vested with a specific structure and a specific function and are differentiated in humans are also represented—with the corresponding simplification and reduction—in the mammals and probably even in the lower vertebrates.

Ramón y Cajal (1852—1934), Estudios sobre la corteza cerebral humana. III . Cortez motriz. Revista trimestral micrognifica 5:1—11 (1890)

That the cortex of the cerebrum, the undoubted material substratum of our intellectual activity, is not a single organ which enters into action as a whole with every psychical function, but consists rather of a multitude of organs, each of which subserves definite intellectual processes, is a view which presents itself to us almost with the force of an axiom....If... definite portions of the cerebral cortex subserve definite intellectual processes, there is a possibility that we may some day attain a complete organology of the brain-surface, a science of the localization of the cerebral functions.

Alexander Ecker (1816–1887), Die Hirnwindung des Menschen, 1869