Construct validation of a DCM for resting state fMRI.
Bottom Line: Dynamic causal modelling (DCM) is a framework that allows for the identification of the causal (directed) connections among neuronal systems--known as effective connectivity.We also simulated group differences and compared the ability of spectral and stochastic DCMs to identify these differences.We show that spectral DCM was not only more accurate but also more sensitive to group differences.
Affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, 12 Queen Square, London WC1N 3BG, UK; Department of Electronic Engineering, NED University of Engineering and Technology, Karachi, Pakistan. Electronic address: email@example.com.Show MeSH
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Mentions: Post-hoc model optimization found the fully connected model to have the largest free energy, consistent with previous similar analyses (Li et al., 2012). Bayesian parameter averaging (BPA) was then used to calculate the expected posterior connectivity estimates, and posterior confidence intervals. The concordance between stochastic and spectral results was subsequently examined qualitatively. In Fig. 10, we show the results of both the stochastic and spectral DCM schemes. The left columns show the results of BPA. To focus on non-trivial connections, we only report connection strengths that exceed 0.05 Hz in strength. We also omit self-connections in these plots for simplicity. BPA results are fairly consistent when compared between the two schemes, especially the connections originating from the bilateral intraparietal cortex. There is some disagreement in some other connections originating from the PCC and mPFC. Furthermore, coupling strengths from stochastic DCM are relatively smaller in magnitude than those from the spectral DCM, which is in accordance with previous simulations demonstrating that stochastic DCM tends to underestimate the effective connectivity (see also above). In the middle column, we show the results of classical t-tests to see which of the connections are significantly different from zero. In the last column, only the significant connections surviving the corrected threshold (the broken red line) are shown.
Affiliation: The Wellcome Trust Centre for Neuroimaging, University College London, 12 Queen Square, London WC1N 3BG, UK; Department of Electronic Engineering, NED University of Engineering and Technology, Karachi, Pakistan. Electronic address: firstname.lastname@example.org.