Computational protocol: Long-Term Effects of Attentional Performance on Functional Brain Network Topology

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Protocol publication

[…] The time series of each voxel was corrected for head motion and slice timing offsets using SPM8 (http://www.fil.ion.ucl.ac.uk/spm/). The functional images were spatially normalized to standard stereotaxic MNI space (Montreal Neurological Institute; http://www.mni.mcgill.ca/) and regionally parcellated using a template image comprising 442 cortical and subcortical brain regions to estimate the mean fMRI time series for each region for each participant during each RS and task period , . In order to avoid possible biasing effects of parcel sizes on functional connectivity , , we ensured that the range in size of the 442 nodes generated by sub-parcellating the AAL template was substantially smaller (1.55–3.08 cm3;) than the range in size of the 90 nodes of the template (1.76–40.83 cm3, regions of cerebellum were excluded; see ). Note that we performed the main statistical analyses of the resting state periods also with alternative templates in order to assure that our main findings were not driven by the choice of a single parcellation template (see ).To reduce motion effects motion parameters of the spatial realignment were regressed out from the mean time series. Previous studies documented the behavioural relevance of graph metrics based on fMRI signal oscillations in the frequency range just below 0.1 Hz –. Therefore, each regional time series was band-pass filtered (wavelet scale 3: 0.042–0.083 Hz) using the maximum overlap discrete wavelet transform (MODWT) . For each pair of nodes the wavelet correlation was estimated and the absolute correlation values resulted in a 442 by 442 association matrix for each subject, RS and task period. The global strength of connectivity was computed as the mean of each association matrix. To compute the nodal connectivity strength of a particular node we averaged the functional connectivity between this node and all other nodes within the network. […]

Pipeline specifications

Software tools SPM, AAL
Applications Magnetic resonance imaging, Functional magnetic resonance imaging
Organisms Homo sapiens