Hello, > Including motion parameters should not remove any power from your signal > of interest if movement isn’t correlated with the task. I do not believe this is completely true as you do loose degrees of freedom by including further regressors, which may hurt you especially if you don't have too many scans to begin with. Also, your motion may be correlated with the task but still be insignificant (i.1., .1 in "rest" and .2 in "active" condition), which likely does not affect the signal but is still correlated with the task and thus is being attributed true signal. In other words, I do see drawbacks of routinely including motion parameters independent of the amount of motion. But that is just me ;) Best, Marko -- ===================================================================== Marko Wilke (Dr.med./M.D.) [log in to unmask] Universitäts-Kinderklinik University Children's Hospital Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology) Hoppe-Seyler-Str. 1, D - 72076 Tübingen Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473 =====================================================================