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you might also check out the ROI analysis software here: http://spm-toolbox.sourceforge.net/ cheers russ Matthew Brett wrote: > Hi, > > > If one wanted to extract fMR data from a particular small region of the brain > > - let's say the anterior inferior cingulate cortex - is this the best way to > > handle in spm99? > > > > 1. draw VOIs for each subject (how can you make sure it's exactly the same are > > in each subject?) > > 2. estimate a specified model just for the VOIs? > > A team of us have written an SPM toolbox that is designed to do just this sort > of thing. It is currently more or less in alpha state, but we have started to > use it in our lab. You would be welcome to a copy of the software if you want > to try it. One approach to ROI analysis is indeed to define the VOI for each > subject (without ever normalizing the data to a template). This has > advantages if you have some reliable method of knowing where the region is - > for example from anatomy, or another task from the same subject. Another > approach is to spatially normalize the data, and define the region on the > template. In neither case can you be sure your VOI is in exactly the same > place - in the first case due to imprecision in the metrics you have used to > define the region, in the second, because we cannot easily know how well the > normalization has succeeded in overlapping homologous areas, > > Best, > > Matthew -- --- Russell A. Poldrack, Ph.D. Assistant Professor of Radiology MGH-NMR Center Building 149, 13th St. Charlestown, MA 02129 Phone: 617-726-4060 FAX: 617-726-7422 Email: [log in to unmask] Web Page: http://www.nmr.mgh.harvard.edu/~poldrack