A Bayesian and Emergent View of the Brain

Very simple psychophysiological visual tests suggest that the brain, instead of processing visual information in a passive way as was classically thought, in fact actively evaluates probabilities of the causes of visual data and continuously proposes to the mind the ones that are more likely to account for sensory inputs. In the past few years, Karl Friston, a researcher from University College of London, and his group have proposed a mechanism by which the brain successfully performs with great precision the inversion of probability densities necessary for this Bayesian computation. This mechanism would account for several anatomic structures of the cortex, explaining in particular the abundance of backwards interneuronal connections. The proposed picture of brain functioning is that of a dynamical process, far from the static image of a photographic plate. The result is an emergence, for the final picture of the world is a coherent vision where the more likely causes are proposed in a coherent manner. Although the theory accounts for the automatic, infraconscious side of the processing of information in the brain, it is in good accord with Roger Sperry’s theory of consciousness as a theory of strong emergence. It is too soon to evaluate the solidity of the law of “minimization of free energy” proposed by Friston not only as ruling the automatisms of the brain but as a general law of biology. This law is similar (although in contradistinction) to the second law of thermodynamics of increase of entropy (insofar as it explains the tendency of living beings for self-organization), and it is already looked at by some neuroscientists as a big step forward in deciphering the mysteries of the brain.

Affiliations: 1: CNRSParisremy.lestienne@bbox.fr