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: firstname.lastname@example.org.Show MeSH
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Mentions: The Bayesian parameter averages of the group differences for each of the coupling estimates are presented in Fig. 6. The spectral scheme produces both highly accurate and precise estimates of the differences at the two connections manipulated. Any changes in coupling strengths that were not changed were < 0.05 Hz, and can thus be considered a small (and standardised) effect size in quantitative terms. Regarding stochastic DCM, group differences were less accurate but remain qualitatively similar (i.e., they are still in the correct direction). Estimates of differences in other parameters again remained < 0.05 Hz. When applying classical inference (as appears routine in such studies) to the Bayesian parameter averages, both schemes detected significant changes in the two manipulated parameters. The dotted red line corresponds to the thresholds for a nominal level of p = 0.05 uncorrected, whereas the broken red line corresponds to the corrected thresholds for the 16 tests. We used the self-connections for the correction but do not report the (non-significant) differences. For spectral DCM, both forward and backward connections are highly significant, even after correcting for multiple comparisons, and no other connection reached uncorrected threshold. Regarding stochastic DCM, although both backward and forward connections are still detected as the two most statistically significant connections, small changes estimated in a few other connections were found to be significant at corrected statistical thresholds, suggesting that sDCM is sensitive to group differences, but perhaps not as specific as spDCM.
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.