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Dear Daniel,
The default in the GUI is TR / 2, and that’s what I’ve always used. Different values can be entered per ROI because you may have regions
which are far apart in the brain, and so their acquisition is delayed in time. If practice, I suspect the HRF delay is large enough that it won’t make much difference.
You could investigate changing this and see if it makes a difference to your results. E.g. imagine region 1 is near the bottom of the
brain, region 2 near the top of the brain and you have an ascending acquisition sequence with volume TR of 3 seconds. You could try setting the delays to [0 3]. Use Bayesian Model Selection to compare this model against a model with delays of TR / 2 for all
regions.
Best,
Peter
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
On Behalf Of Daniel Gutierrez Barragan
Sent: 05 October 2015 09:53
To: [log in to unmask]
Subject: [SPM] DCM.delays inquiry
Hello all,
I am working on performing DCM from script and was wondering if there are any specific recommendations regarding the DCM.delay information that DCM needs to be fed with. I know that these correspond to slice-timing temporal correction,
but my question is if there is a preferred reference (slice with delay zero)? or if it is better to do it according to acquisition sequence used?
Best regards,
Daniel Gutierrez Barragan, PhD Student
Center for Neuroscience and Cognitive Systems (CIMeC)
Italian Institute of Technology (IIT)
University of Trento
Rovereto (TN): Palazzo Fedrigotti - corso Bettini 31