From probabilities to percepts

Abstract

A brain charged with guiding its body through a complex and lively world from a position of solitary confinement inside its opaque skull faces a set of functional challenges beset with inverse and ill-posed problems at every turn. Uncertainty and ambiguity therefore encumber all cortical labors, making probability distributions the natural medium of its disambiguating inferential operations. This chapter proposes that those operations take place unconsciously, in keeping with Helmholtz’ original suggestion, and that the functional logic of an inherently probabilistic cortex implies a need for an extracortical “global best estimate buffer” as a means to complete cortical sensory disambiguation through a definitive but ephemeral estimate of current sensory circumstances. It further proposes that the contents of that extracortical buffer are conscious, not by virtue of anything being “added” to buffer operations in order to “make them conscious”, but by virtue of the format of buffer contents alone: its dynamics issue in a nested arrangement placing an ego-center in perspectival relation to a neural model of body-world interactions. Finally, the organization of the higher order nuclei of the dorsal thalamus are scrutinized for their suitability to implement the putative global best estimate buffer, with particular attention to the possibility that the caudal reaches of the dorsal pulvinar might host its specifically sensory aspects, i.e. sensory awareness. Keywords: ambiguity; architecture of consciousness; best estimate buffer; constraint satisfaction; format of sensory awareness; phenomenal content; probabilistic operations; pulvinar