[pymvpa] Using searchlight for quick spherical ROIs?

[Johan Carlin]

Hi all,

I have just started using PyMVPA for some fMRI analysis. It has worked like
a charm so far. :) Thanks very much for developing such a useful tool.

I would like to run a clasifier on a number of ROIs that were defined in a
univariate SPM analysis. The most obvious solution is to re-load the dataset
with a new mask for each ROI. However, I wonder if there is a quicker
option, using the Searchlight and the "center id" parameter?

The idea would be to start with a list of peak voxel coordinates for each
ROI from the nifti image, map these to feature IDs somehow, and pass the
list of ROI IDs to the Searchlight. The result would then be a (fast!)
searchlight analysis, that runs a spherical classifier centered on each ROI
in turn. The resulting classification map should only contain one voxel per
ROI.

Has anyone attempted something similar? I can't quite figure out how to map
the ROI coordinates in the original nifti to the feature ID that the
classifier runs on.

Any help would be greatly appreciated.

Johan
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