BrainVoyager version: 22.4.6
Dataset used: sub-02_ses-01_task-Localizer_run-01_bold of the Localizer data of newbi4fmri (Jody Culham and Kevin Stubbs and Ethan Jackson and Rebekka Lagace Cusiac (2020). newbi4fmri2020 Localizer. OpenNeuro. [Dataset] doi: 10.18112/openneuro.ds003433.v1.0.1, accessed 31 January 2023)

Preparation of the analysis

To run a Multi-Study GLM analysis in BrainVoyager three requirements need to be fullfilled:

• an anatomical VMR project has to be loaded to display the results of the statistic
• the functional data need to be available (properly aligned VTC files, one per run)
• one design matrix (SDM) for every functional run has to be available

If you want to run the same kind of analysis in the surface module, e.g. after performing the Cortex Based Alignment procedure, the corresponding file types (SRF, MTC) are needed.

Creating a combined VMR

The anatomical VMR dataset serves as basis for displaying the statistical results of the GLM analysis. One may decide to choose one single, normalized anatomical dataset of the sample, i.e. an individual VMR in Talairach or MNI space, depending on the normalized reference space used for the functional data.

Or one may choose to display the statistical maps on top of the default MNI template (a high-resolution T1-weighted non-linear ICBM-MNI 152 MRI atlas). This MNI template can be opened via File -> Open MNI VMR.

The third option allows to create an average of the (normalized) datasets of all participants included in the analysis.

An average VMR dataset (based on normalized VMR datasets of the sample) can be created via Volumes -> Average 3D Data Sets...:

On the level of surface analysis, there are, once again, more sophisticated approaches in BrainVoyager to create averages (Cortex Based Alignment).

Functional Data Preparation

Normally, one VTC (volume time course) file is created for every single functional run in BrainVoyager. When the data is compared across participants, one has to make sure to normalize the data either to Talairach or to MNI space. This is nicely described in the BrainVoyager Getting Started Guide, which can be found in the BrainVoyager folder of the Users directory (e.g. Users/<USER>/Documents/BrainVoyager/GettingStartedGuides).

From Stimulation Protocol to SDM

The design matrix (SDM: Single Study Design Matrix) is the crucial defining part of the GLM analysis, as it codes the exact timing of the GLM predictors within a functional run. An SDM file can be created via the Single Study General Linear Model dialog (see below). By using the Save.. button one can save the design matrix to disk. The SDM file is also automatically generated when running a Single Study GLM analysis for a functional run. However, please be aware that these files are named VTCfilename_autosave.sdm and will be overwritten every time a new GLM is computed for the same functional run.