Neural modeling in cerebral dynamics.

For many years our current conception of neural modeling at cortical level has been marked by three convictions: (i) the representational, explanatory, and predictive capabilities of a model are always limited by the mathematical nature of the formal tools used in its formulation. The external observer in fact injects the additional knowledge, apparently resident in the model. (ii) The analogical and logical languages (and consequently, the neurophysiological data which serves as their basis) are not sufficient to describe, model and predict the most genuine aspects of the cortical determined behavior. (iii) We need new conceptual and formal tools capable of representing cooperative processes (not only physical interactions) in cerebral dynamics. In this paper, we use the neuropsychological findings on the residual function after traumatic and surgical lesions in animals and men, to think about the sort of requirements that are necessary to build these formal tools adequate to model neural information processing at cortical level. If we search for inspiration in the field of computation, we arrive to the conjecture that the cerebral dynamics is a dynamics of neurophysiological symbols and, consequently, we need a set of descriptions at an intermediate level (neural assemblies "programming"), in a similar way as we use programming languages at an intermediate level (the symbol level) between the physical machine and the knowledge level descriptions, in the sense of Newell and Marr.