Re: [Freesurfer] Different results in surface and volume analyses

Hi Doug,

Thanks for the response. Is this masking out of the cortical regions in the volume analysis a newer aspect of the processing stream? Previously I have seen this activation in the volume.

It would be great if you could let me know the flags to see the full volume analysis.

Thanks!

Emily

Message: 41 Date: Wed, 07 Aug 2013 19:29:33 -0400 From: Douglas N Greve greve@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Different results in surface and volume analyses To: freesurfer@nmr.mgh.harvard.edu Message-ID: 5202D85D.1090808@nmr.mgh.harvard.edu Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Emily, the processing stream is designed to mask out cortical regions from the volume analysis. The volume analysis is used for subcortical structures. To make sure that the same voxels are not analyzed twice, the cortical surface is masked out of the mni305 analysis. doug

ps. If you really want to see the full volume analysis, then there are some flags that will do this.

Message: 14 Date: Wed, 7 Aug 2013 13:15:37 -0400 From: Emily Boeke eboeke01@nmr.mgh.harvard.edu Subject: [Freesurfer] Different results in surface and volume analyses To: freesurfer@nmr.mgh.harvard.edu Message-ID: 948E8FDF-754A-4AE0-A0C9-86D848F1438A@nmr.mgh.harvard.edu Content-Type: text/plain; charset=us-ascii

Hello everyone,

I am looking at a visual stimulus vs fixation contrast in my individual subjects' data to make sure we are seeing normal activation there. If I look at the surface data in tksurfer, I see activation in the occipital cortex, but in the mni305 analysis, there is no activation in this region.

These are the preprocess , mkanalysis, and selxavg commands I used for the surface vs. mni305:

preproc-sess -s amur_dss -df sesspar -per-run -fwhm 5 -sliceorder down -surface fsaverage lhrh -mni305-2mm -fsd cond

mkanalysis-sess -fsd cond -surface fsaverage lh -fwhm 5 -paradigm Fear_Gen_Cond.par -event-related -TR 3 -nconditions 3 -polyfit 4 -spmhrf 0 -refeventdur 6 -analysis cond.sm05.lh -per-run -nskip 4 -stc down

mkanalysis-sess -fsd cond -surface fsaverage rh -fwhm 5 -paradigm Fear_Gen_Cond.par -event-related -TR 3 -nconditions 3 -polyfit 4 -spmhrf 0 -refeventdur 6 -analysis cond.sm05.rh -per-run -nskip 4 -stc down

mkanalysis-sess -fsd cond -mni305 2 -fwhm 5 -paradigm Fear_Gen_Cond.par -event-related -TR 3 -nconditions 3 -polyfit 4 -spmhrf 0 -refeventdur 6 -analysis cond.sm05.mni305 -per-run -nskip 4 -stc down

selxavg3-sess -s amur_dss -df sesspar -analysis cond.sm.lh selxavg3-sess -s amur_dss -df sesspar -analysis cond.sm.rh selxavg3-sess -s amur_dss -df sesspar -analysis cond.sm.mni305

Why might we be seeing this activation on the surface map but not the volume one?

Thanks! Emily