A free energy principle for the brain.

Full Abstract

By formulating Helmholtz's ideas about perception, in terms of modern-day theories, one arrives at a model of perceptual inference and learning that can explain a remarkable range of neurobiological facts:
using constructs from statistical physics, the problems of inferring the causes of sensory input and learning the causal structure of their generation can be resolved using exactly the same principles. Furthermore, inference and learning can proceed in a biologically plausible fashion. The ensuing scheme rests on Empirical Bayes and hierarchical models of how sensory input is caused. The use of hierarchical models enables the brain to construct prior expectations in a dynamic and context-sensitive fashion. This scheme provides a principled way to understand many aspects of cortical organisation and responses. In this paper, we show these perceptual processes are just one aspect of emergent behaviours of systems that conform to a free energy principle. The free energy considered here measures the difference between the probability distribution of environmental quantities that act on the system and an arbitrary distribution encoded by its configuration. The system can minimise free energy by changing its configuration to affect the way it samples the environment or change the distribution it encodes. These changes correspond to action and perception respectively and lead to an adaptive exchange with the environment that is characteristic of biological systems. This treatment assumes that the system's state and structure encode an implicit and probabilistic model of the environment. We will look at the models entailed by the brain and how minimisation of its free energy can explain its dynamics and structure.

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Author information

Author/s: Friston, Karl (K); Kilner, James (J); Harrison, Lee (L);

Affiliation: The Wellcome Department of Imaging Neuroscience, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3B, United Kingdom. k.friston(-atsign-)fil.ion.ucl.ac.uk

Grants: (Agency:Wellcome Trust)

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Review

Journal: Journal of physiology, Paris (J Physiol Paris), published in France. (Language: eng)

Reference: -2006 Jul-Sep; vol 100 (issue 1-3) : pp 70-87

Dates: Created 2006/12/04; Completed 2007/02/20; Revised 2007/08/13;

PMID: 17097864, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Afferent Pathways - physiology
Animals
Attention - physiology
Bayes Theorem
Brain - physiology
Brain Mapping
Computer Simulation

Computer Simulation
Entropy
Humans
Learning - physiology
Models, Neurological
Probability
Visual Perception - physiology

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