[FieldTrip] Using an fMRI cluster as an ROI

Ross Wilson RXW494 at student.bham.ac.uk
Mon Jul 25 13:47:37 CEST 2016

Hello all!

I am attempting to use an fMRI cluster as an ROI to look at virtual electrode timecourses post-beamforming.

I have been using the aal atlas to find virtual electrodes of maximum change between baseline and stimulus period within, for example, the motor cortex afer beamforming. However, the virtual electrodes found are not necessarily in a position similar to that of the fMRI cluster and I'd like to be more specific than that if possible.

The template grid I have been using for beamforming is created from the T1 (code as below, in MNI space: ...fieldtrip\external/spm8/templates/T1.nii). Is it possible to transform an fMRI cluster (in MNI space) onto the template grid so that the data from specific grid points relating to that cluster can be extracted post-beamforming??

Any help with this would be great!

Thank you,

%%%tempale grid creation
T1 = ft_read_mri('F:\fieldtrip\external/spm8/templates/T1.nii');
T1.coordsys = 'spm';

cfg          = [];
template_seg = ft_volumesegment(cfg, T1);

cfg          = [];
cfg.method   = 'singleshell';
template_vol = ft_prepare_headmodel(cfg, template_seg);
template_vol = ft_convert_units(template_vol, 'cm');

cfg = [];
cfg.grid.xgrid  = -20:0.5:20;
cfg.grid.ygrid  = -20:0.5:20;
cfg.grid.zgrid  = -20:0.5:20;
cfg.grid.unit   = 'cm';
cfg.grid.tight  = 'yes';
cfg.inwardshift = 0.15;
cfg.vol        = template_vol;
template_grid  = ft_prepare_sourcemodel(cfg);
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