Dear SPM users,
I'm analyzing fMRI data with SPM8b. Data were recorded during 4
functional sessions and 1 structural session:
- session 1, functional, 408 vol.
- session 2, functional, 408 vol.
- session 3, structural, 192 vol.
- session 4, functional, 408 vol.
- session 5, functional, 408 vol.
In each functional session, 4 volumes were recorded before the beginning
of the task (vol 1-4) and 4 after the end of the task (vol 405-408). So
only 400 volumes in each functional session are interesting for model
estimation (vol 5-404).
For model estimation, i want to treat all volumes as if they were coming
from a unique session (because it is basically the same task in the 4
functional sessions and i need to simplify the model). I will also use
the realignment corrections computed during the preprocessing as
regressors in the model.
I have 2 questions concerning the preprocessing:
- should i define 4 sessions for the realignment or make as if data were
coming from a unique session?
- which volumes should i delete during the preprocessing (e.g. vol 1-4
of the first session or of all 4 sessions, what about vol 405-408)?
Cheers,
--
Mathieu d'Acremont, Ph.D.
Chief Scientist [log in to unmask]
http://people.epfl.ch/mathieu.dacremont
Phone/Fax: +4121 693 00 91/20
Swiss Federal Institute of Technology (EPFL)
Laboratory for Decision-Making under Uncertainty
Odyssea 3 18
Station 5
CH-1015 Lausanne
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