Neural Propagation of Beliefs

TL;DR

This paper proposes a neural framework where populations encode probability densities, enabling Bayesian inference through neural circuits derived from belief networks, demonstrated with examples including sensory processing influenced by top-down information.

Contribution

It introduces a novel neural representation of probability densities using orthogonal functions, linking Bayesian belief networks to neural circuit models.

Findings

Neural populations can encode joint probability densities.

Neural circuits can perform Bayesian inference.

Top-down information influences sensory processing.

Abstract

We continue to explore the hypothesis that neuronal populations represent and process analog variables in terms of probability density functions (PDFs). A neural assembly encoding the joint probability density over relevant analog variables can in principle answer any meaningful question about these variables by implementing the Bayesian rules of inference. Aided by an intermediate representation of the probability density based on orthogonal functions spanning an underlying low-dimensional function space, we show how neural circuits may be generated from Bayesian belief networks. The ideas and the formalism of this PDF approach are illustrated and tested with several elementary examples, and in particular through a problem in which model-driven top-down information flow influences the processing of bottom-up sensory input.