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BrainVoyager Surface Space Cortex Based Alignment Evaluation of CBA - Part II: Performing the cortex based alignment

Evaluation of CBA - Part II: Performing the cortex based alignment

Creating the alignment list

In the second part of the evaluation, we would like to check the improvement introduced by the Cortex-based alignment procedure. To do so, we first re-open the Cortex-based alignment dialog.

In the Options tab, we add all the different SMPs (as before in the Surface Maps dialog). Below the list, the Curvature radio button should be selected.

CBAEvaluation_CBAMenu
Figure 20: Cortex-Based Alignment menu entry

CBAEvaluation_AddSMPToCurvature
Figure 21: Add... SMP button in CBA options

After locating the SMP file, BrainVoyager will automatically ask for the corresponding SSM (sphere-to-sphere mapping) file, which results from the Cortex-based alignment procedure. In this case, we select the file <SUBJECT-NAME>_SPH_GROUPALIGNED.ssm. Then we redo these steps for all (i.e. in total 12) subjects.

CBAEvaluation_SSMSelector
Figure 22: File Selector for corresponding SSM file

CBAEvaluation_SMPCurvatureList
Figure 23: Completed list of curvature SMPs

It is advised to save this list as a CAL (curvature averaging list) file:

CBAEvaluation_SaveCAL
Figure 24: Save As dialog for CAL file

Averaging and Results

To start the overlay of the maps, please click the Average button. 
The result then clearly shows the improvement obtained by the Cortex-based alignment procedure. In the following two screenshots, the left hemisphere folding patterns are shown (from the same perspective) after and before the CBA. Of course there is still some variation, due to the idiosyncratic differences between the subjects.

CBAEvaluation_AverageButton
Figure 25: Average button in CBA options

CBAEvaluation_12AlignedMaps
Figure 26: The 12 aligned maps (after CBA)

CBAEvaluation_12UnalignedMaps
Figure 27: The 12 unaligned maps (before CBA)

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