We are interested in extracting the time-course of activity in a group of
> voxels around a local maxima. Ideally we wish to extract the time course
> from all voxels active in a particular cluster. We have set the fMRI_UFp
> variable to 1 in order to have information about all the voxels and are
> using the spm_regions.m script version 2.8 (Karl Friston 00/11/22) for
> extracting the average timecourse in a volume of Interest(VOI) covering
> the entire cluster.
> Is there any other procedure available for extracting average(along with
> standard error) time course of a group of all active clusters surviving a
> particular threshold.
Hi,
We have written a toolbox that does this - MarsBar - http://
www.mrc-cbu.cam.ac.uk/Imaging/marsbar.html. It is still in alpha, but is
fairly stable at the moment. One advantage of the toolbox is that you do not
need to set the UFp to 1 to save all the data, and you don't suffer from the
small rounding errors incurred by the compression that SPM uses, because it
gets the data from the raw images. You have a lot of data there, so I can't
guarantee it will be any quicker than SPM... Your technique would be to make
an ROI from the SPM analysis (ROI->Build->Activation cluster), and then
ROI->Extract data. Don't forget to download the bugfix routines in the
MarsBar directory...
Best,
Matthew
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