As soon as you change the design matrix, results will be different. In general term you can think of the data as a point in a N dimensional space and you project onto a subspace at P dimensions ie the nb of columns of the design matrix (see SPM book). As the
design matrix changes, so does the projection.
For the specific case a motion regressors many voxels will have some variance explained by these regressors so it is a good idea to include them, see a neuroimage paper from Lund.
Dr Cyril Pernet
BRIC / SINAPSE
University of Edinburgh
----- Reply message -----
From: "Yan Fang" <[log in to unmask]
Date: Fri, Aug 5, 2011 00:50
Subject: [SPM] motion regressors
To: <[log in to unmask]
Can I ask a question about motion regressors generated after realignment? I reorient all the images after realignment and coregistration. If I still add motion regressors to the design matrix, will this affect the result? Thank you!