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Journal club 25 Apr. ’08

Journal club 25 Apr. ’08. A method for functional network connectivity among spatially independent resting-state components in schizophrenia Jafri et al., NeuroImage 39 (2008) 1666-81. Introduction. Functional connectivity methods Seed-voxel functional connectivity mapping

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Journal club 25 Apr. ’08

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  1. Journal club 25 Apr. ’08 A method for functional network connectivity among spatially independent resting-state components in schizophrenia Jafri et al., NeuroImage 39 (2008) 1666-81

  2. Introduction • Functional connectivity methods • Seed-voxel functional connectivity mapping • Independent component analysis • Functional network connectivity: time dependence among ICA components • Applicable to cognitive or motor tasks, or resting state • Group comparisons • Schizophrenia

  3. Materials & Methods • Subjects • 29 schizophrenics • 25 matched healthy controls • Scanning • 3.0-T GE-EPI fMRI • TR = 1.86 s • 162 acquisitions [!] • Preprocessing • Motion correction • Spatial smoothing, FWHM = 10 mm [?] • Normalization to MNI, conversion to T&T

  4. Materials & Methods • Group-sICA • All subjects pooled, verified per group • InfoMax algorithm • 30 components extracted • Temporal concatenation and back-reconstruction • 7 components systematically [?] selected on the basis of correlations with CSF and GM

  5. Results

  6. Materials & Methods • Correlation and lag analysis • Band-pass filtering at f = 0.037-0.37 Hz (i.e., T = 2.69-26.9 s) • Interpolation to higher time resolution [?] • For each of 21 pairs of components, determined maximal correlation coefficient ρ and corresponding time lag δ (−5 s < δ < 5 s) • Significant correlations extracted using t-test at p < 0.05 • Group comparisons using conservative t-test at q < 0.05 • Resampling by subsampling groups • Resampling by relabeling groups

  7. Results

  8. 50% 60% 50% 70% 55% 65% 65% Results

  9. Remarks • Network connectivity methods are feasible • Significant outcomes in individuals • Significant differences between groups • The method can be expanded • SEM • GCA • EEG • Statistics remain doubtful • Can t-tests be performed on correlation coefficients ρ? • How did corrections for multiple comparisons take place?

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