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Contribution Details

Type Journal Article
Scope Discipline-based scholarship
Title Free-energy and the brain
Organization Unit
Authors
  • K J Friston
  • Klaas Enno Stephan
Item Subtype Original Work
Refereed Yes
Status Published in final form
Language
  • English
Journal Title Synthese
Publisher Springer
Geographical Reach international
ISSN 0039-7857
Volume 159
Number 3
Page Range 417 - 458
Date 2007
Abstract Text If one formulates 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 it can be shown that the problems of inferring what cause our sensory input and learning causal regularities in the sensorium 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 information is generated. 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 the brain's organisation and responses.In this paper, we suggest that these perceptual processes are just one emergent property of systems that conform to a free-energy principle. The free-energy considered here represents a bound on the surprise inherent in any exchange with the environment, under expectations encoded by its state or configuration. A system can minimise free-energy by changing its configuration to change the way it samples the environment, or to change its expectations. 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 implies that the system's state and structure encode an implicit and probabilistic model of the environment. We will look at models entailed by the brain and how minimisation of free-energy can explain its dynamics and structure.
Free access at PubMed ID
Digital Object Identifier 10.1007/s11229-007-9237-y
PubMed ID 19325932
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Additional Information The original publication is available at www.springerlink.com