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| Research article summary (published 30 Jul 2003): |
Dynamic causal modelling.
Full Abstract
In this paper we present an approach to the identification of nonlinear input-state-output systems. By using a bilinear approximation to the dynamics of interactions among states, the parameters of the implicit causal model reduce to three sets. These comprise (1) parameters that mediate the influence of extrinsic inputs on the states, (2) parameters that mediate intrinsic coupling among the states, and (3) [bilinear] parameters that allow the inputs to modulate that coupling. Identification proceeds in a Bayesian framework given known, deterministic inputs and the observed responses of the system. We developed this approach for the analysis of effective connectivity using experimentally designed inputs and fMRI responses. In this context, the coupling parameters correspond to effective connectivity and the bilinear parameters reflect the changes in connectivity induced by inputs. The ensuing framework allows one to characterise fMRI experiments, conceptually, as an experimental manipulation of integration among brain regions (by contextual or trial-free inputs, like time or attentional set) that is revealed using evoked responses (to perturbations or trial-bound inputs, like stimuli). As with previous analyses of effective connectivity, the focus is on experimentally induced changes in coupling (cf., psychophysiologic interactions). However, unlike previous approaches in neuroimaging, the causal model ascribes responses to designed deterministic inputs, as opposed to treating inputs as unknown and stochastic.
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Author information
Author/s: Friston, K J (KJ); Harrison, L (L); Penny, W (W);
Affiliation: The Wellcome Department of Imaging Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK. k.friston(-atsign-)fil.ion.ucl.ac.uk
Journal and publication information
Publication Type: Journal Article; Research Support, Non-U.S. Gov't
Journal: NeuroImage (Neuroimage), published in United States. (Language: eng)
Reference: 2003-Aug; vol 19 (issue 4) : pp 1273-302
Dates: Created 2003/09/01; Completed 2003/10/23; Revised 2007/11/15;
PMID: 12948688, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
Comments and Corrections
CommentIn: Neuroimage. 2006 May 1;30(4):1243-54. (PMID: 16387513)
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