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A theory of cortical responses (2005)
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@MISC{Friston05atheory,
author = {Karl Friston},
title = {A theory of cortical responses },
year = {2005}
}
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Abstract
This article concerns the nature of evoked brain responses and the principles underlying their generation. We start with the premise that the sensory brain has evolved to represent or infer the causes of changes in its sensory inputs. The problem of inference is well formulated in statistical terms. The statistical fundaments of inference may therefore afford important constraints on neuronal implementation. By formulating the original ideas of Helmholtz on perception, in terms of modern-day statistical theories, one arrives at a model of perceptual inference and learning that can explain a remarkable range of neurobiological facts. It turns out that the problems of inferring the causes of sensory input (perceptual inference) and learning the relationship between input and cause (perceptual learning) can be resolved using exactly the same principle. Specifically, both inference and learning rest on minimizing the brain’s free energy, as defined in statistical physics. Furthermore, inference and learning can proceed in a biologically plausible fashion. Cortical responses can be seen as the brain’s attempt to minimize the free energy induced by a stimulus and thereby encode the most likely cause of that stimulus. Similarly, learning emerges from changes in synaptic efficacy that minimize the free energy, averaged over all stimuli encountered. The underlying scheme rests on empirical Bayes and hierarchical models
Keyphrases
cortical response free energy perceptual inference sensory input brain free energy brain attempt perceptual learning neuronal implementation evoked brain response empirical bayes sensory brain afford important constraint statistical physic modern-day statistical theory underlying scheme rest neurobiological fact likely cause plausible fashion original idea statistical term hierarchical model statistical fundament remarkable range synaptic efficacy
