Where is the Cortex?

Abstract

It is fairly easy to provide a description of the cortical histology which could serve as an adequate criterion for the identification of almost any piece of cortex from any mammal, and for the exclusion of almost any other piece of the brain. Thus the structural traits of the cortex in general seem to be well defined. Yet it is quite a different matter to define the limits of the cortical tissue in any particular brain, in both the topographic sense, and in the sense of a distinction of the extreme varieties of cortical build which are still to be considered as cortex from similar structures which are definitely no longer part of it. This problem is, of course, common to many biological contexts, where the definition of a certain type (of tree, of sense organ, of society, of linguistic syntax) becomes quite elusive when put to the test of a decision procedure capable of recognizing every instance of it.