THE STUDY of regional peculiarities of the structure of the cerebral cortex as revealed by certain features and the division of the cortex into structural units on the basis of these features constitute the main problem of the architectonics of the cerebral cortex. These features are of varying value. Some of them are of major importance and should form the basis for division of the cerebral cortex into main territories. Others are of more specific significance and serve to subdivide the main territories into regions, subregions, areas and subareas, according to a certain hierarchial order and depending on their relative importance. Finally, there is an enormous number of less important features, allowing subdivision of the cortex literally ad infinitum. As a matter of fact, no part of the cortex, however small it may be, exhibits absolute similarity to the neighboring part.
It would be possible to consider these structural modifications
FILIMONOFF IN. A RATIONAL SUBDIVISION OF THE CEREBRAL CORTEX. Arch NeurPsych. 1947;58(3):296-311. doi:10.1001/archneurpsyc.1947.02300320047002