Two Views of the Cerebral Cortex

Abstract

The cerebral cortex, one half of the cerebral grey substance in mice and men, is what any detailed theory of the workings of the nervous system ought to explain, or at least, ought to make use of. In fact, theoretical papers ranging from 1943 to 1985 and from rather realistic views to frankly speculative constructs have made explicit reference to the cortex and perhaps even have influenced the ideas of some experimenters. Cortical anatomists and physiologists, in turn, learned to shape their findings so as to make them acceptable to the theoreticians. The resulting situation of reciprocal positive feedback had some stable solutions:

• 1. The random network with or without learning. Lashley’s philosophy is of this category, as is Hebb’s theory of cell assemblies. Rosenblatt’s perceptron is also a descendant.

• 2. The circuit diagram in the spirit of radio engineering. The amplifier entered neurophysiology from communication engineering and with it came various ideas, the most enticing being that of functional secrets embodied in loops of wires connecting tubes, condensers and the like. The neuroanatomists responded quickly with loops of fibres connecting various sorts of neurons in the cortex (Lorente de No and others).

• 3. The digital computer and a logical theory of nerve nets. This was soon recognized as a misleading analogy, but the digital computer has at any rate among all models of cortical function the unique distinction of being a very useful machine. And the theory formulated by McCulloch and Pitts (1956), made more palatable by Kleene (1956), lent the brain a flair of almightiness which was gratefully recognized by many.