PowerPoint Presentation - Surface-Based Cross-Subject Analysis

7/2/2004 SSCC/NIMH 23

Things to lose some sleep over

•When mapping data from volume to surface domains

–If mapping assigns multiple voxels to one node

•How do you deal with functional data sets?

–Do you average statistics?

–Do you apply a threshold before or after averaging?

»What if some of the voxels are active and some are not?

•These problems are best avoided by:

–Mapping the time series data onto the surface

–Performing statistical analysis directly in the surface domain using 3dSomething AFNI programs

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•When combining surface data across subjects

–Same concerns as with volumetric group analysis

•You can also create volumetric data from surface-based data

–use 3dSurf2Vol, the reciprocal of 3dVol2Surf