Hi Michele
Physiological noise in fMRI can both mask activation, but it could
also look like activation (a trivial but common example is activation
in the ventricles). Cardiac noise is often modelled using a method
called RETROICOR described in a paper by Garry Glover from 2000. I
personally prefer to include these regressors in the designmatrix as
opposed to filtering in advance (as done in an ISMRM abstract from
1997 by Oliver Josephs). This has the advantage of easy adjustment of
the degrees of freedom, and easy visualisation of the effects.
Hope this helps
Torben
Torben Ellegaard Lund
Assistant Professor, PhD
The Danish National Research Foundation's Center for Functionally
Integrative Neuroscience (CFIN)
Aarhus University
Aarhus University Hospital
Building 30
Noerrebrogade
8000 Aarhus C
Denmark
Phone: +4589494380
Fax: +4589494400
http://www.cfin.au.dk
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@article{Glover2000,
Author = {G. H. Glover and T. Q. Li and D. Ress},
Journal = {Magn Reson Med},
Month = {7},
Pages = {162--7},
Title = {Image-based method for retrospective correction of
physiological motion effects in {fMRI}: {RETROICOR}},
Volume = {44},
Year = {2000}}
@article{Lund2006,
Author = {Lund, Torben E and Madsen, Kristoffer H and Sidaros, Karam
and Luo, Wen-Lin and Nichols, Thomas E},
Journal = {Neuroimage},
Number = {1},
Pages = {54--66},
Title = {Non-white noise in fMRI: does modelling have an impact?},
Volume = {29},
Year = {2006}}
On 07/06/2007, at 9.43, <Michele> <Butti> wrote:
> Dear all,
> I would like to insert as extra regressors in a fMRI analysis some
> physiological measurement acquired during the scanning procedure.
> Precisely, we recorded skin conductance and ECG. Making inference
> on these regressors should give information about liner correlation
> about physiological data and cerebral activation.
> I was wondering if this procedure can mask a brain activation
> tested with a regressor explaining the experiment.
> Thanks to all,
> Michele Butti
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