Dear Bruce,

Thanks a lot for your help!

I now (roughly) ran the following pipeline but still did not manage to downsample my functional data in fsnative space:

1. run mri_vol2surf to map functional data onto fsnative surface:

My functional data contains one beta coefficient per voxel and represents a strong effect in auditory cortex regions. I see a similar pattern in volume and in surface space.

 

This the command I run:

mri_vol2surf --hemi $hemi \

--cortex \

               --mov $data_path/sub-${subj}_volume_func.nii.gz \

               --regheader sub-${subj} \

               --out $data_path/sub-${subj}_surface_func _hemi-$hemi.gii \

               --projfrac-avg 0.000 1.000 0.200 \

               --trgsubject sub-${subj} \

               --interp trilinear

 

2. run mri_surf2surf to downsample functional data in fsnative space:

The number of vertices in the downsampled sphere.reg file matches the number of vertices in the downsampled functional data but all I see when inspecting the data now is noise instead of auditory activation.

 

This is the command I run to downsample the sphere.reg file (downsampled file is stored in surf folder of dummy subject 99999):

mris_decimate -d 0.1 $data_path/surf/$hemi.sphere.reg $dummy_path/ surf/$hemi.sphere.reg

 

This is the command I run to downsample my functional data:

mri_surf2surf --hemi $hemi \

               --srcsubject sub-${subj} \

               --srcsurfval sub-${subj}_surface_func_hemi-$hemi.gii \

               --trgsubject sub-99999 \

               --trgsurfval sub-${subj}_surface_func_ds_hemi-$hemi.gii

 

Does anyone see what might go wrong here?

Any help would be greatly appreciated!

Cheers,

Ella