BrainVoyager version: 22.4.6
Dataset used: Getting Started Guide data
This document shows in a step by step example how to create a region of interest (ROI) in FMR space.
To start, we open an FMR document, in this case the preprocessed dataset of our sample dataset sub-01.
We would like to define a small region of interest in the occipital cortex of the left hemisphere. For a better selection of the ROI we zoom into a single slice (CTRL + right mouse click). Now we can select a ROI by holding down the left mouse button and dragging the mouse:
When releasing the mouse button an outline of the selected ROI will be displayed in the FMR and a time course window showing the mean signal time course of all voxels within the ROI will be invoked. To see all options of the ROI Time Course window, we need to click once in the time course.
Now we can inspect the number of voxels included in our selected ROI by clicking on 'Options.'
To save the ROI, we close the ROI Time Course Options and use the menu item 'Analysis -> Region-Of-Interest Analysis..' or 'CTRL+R'. In the appearing 'Region-Of-Interest' dialog we need to click 'Save' and choose a filename for the selected ROI. Afterwards we can close the 'Region-Of-Interest' dialog and also the ROI Time Course window.
If we would like to reload the newly saved ROI we can use the same menu item as before for saving: 'Analysis -> Region-Of-Interest Analysis..' or 'CTRL+R'.
The same workflow can be used when saving an ROI while a statistical map is overlaid on the FMR. In the screenshot below the following contrast was computed [Houses_RVF +1] + [Faces_RVF +1] ≠ [Faces_LVF -1] + [Houses_LVF -1]. We can select again a region in the left hemisphere:
Please check again the the number of voxels in the selected ROI. This time you will see that although significant and non-significant voxels can be found in the green rectangle, only the 9 significant voxels are included in the ROI details:
We can save the ROI again by selecting 'Analysis -> Region-Of-Interest Analysis..'.
In sum, it is important to keep in mind that the ROI definition depends on the presence of a statistical map.
If no statistical map is overlaid on the FMR, all voxels within the green rectangle of a selected region will be included when saving the ROI. However, when a statistical map is present, only supra-threshold voxels will be included when saving the ROI.