I need to extract the beta weights from a cluster identified with FS-Fast in 
order to compute percentage signal change.  

1) I see a file called beta.nii.gz that appears to have the beta weight 
information.  It has a four dimensional structure and the fourth dimension 
appears to be the beta weights.  Is there an index somewhere as to which beta 
weight is which?  Or if not, how are they organized?

2) In order to extract the cluster, it looks like I would use mri_label2vol to 
convert cache.th20.neg.sig.ocn.annot into a volume where the voxels are tagged 
with the number of the corresponding cluster.

I could then use that to generate masks to extract the information I need for 
each cluster from beta.nii.gz.

Is that correct?

3) The final information that I would need is the canonical hrf shape generated 
by FSFAST for a single event.  I guess I could generate that by setting up a 
dummy analysis run with a single event of the desired duration and then look in 
the X variable in the resulting X.mat file?

Sorry for all the questions!

Joe




--------------------------------------------------------------------------------

Joseph Dien,
Senior Research Scientist
University of Maryland 

E-mail: jdie...@mac.com
Phone: 301-226-8848
Fax: 301-226-8811
http://joedien.com//











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