Hello
On Mon, 4 Feb 2002, David Glahn wrote:
> Can covariates be added to FEAT models? For example, if I measured heart
> rate during an FMRI experiment, how could I use that information as
> covariate in my more general activation-paradigm analysis (i.e. Partision
> variance associated with the heart rate)?
you can simply add it in as a custom waveform (FEAT->GLM->shape->custom)
as either 1-column or 3-column - see the manual for details. for this case
you probably want simple 1-column where each line in the text file
contains a value for each TR, to be used as a covariate. note that you may
want to turn off convolution, temporal derivative and/or temporal
filtering for such covariates. you _might_ also want to orthogonalise this
new EV wrt the other activation EVs.
Hope this is clear - get back to us if not.
Thanks, Steve.
Stephen M. Smith
Head of Image Analysis, FMRIB
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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