Dear Tobias:
The standard recommendation has been to model all your sessions as one. I
guess another way would be to model each session separately, estimate the
PPIs and appropriate contrasts, and then forward multiple contrasts (i.e.,
from each PPI across sessions for a particular ROI) from each subject to
the second level using appropriate corrections for non-sphericity.
Darren
At 03:27 PM 10/22/2004, Tobias Egner wrote:
>Dear all,
>
>I would like to run PPIs on a couple of ROIs from an experiment that
>contained multiple sessions/runs. Analogous to including multiple runs in
>one fixed effects model at the single-subject level, I would like to build
>a PPI model containing PPI variables (PPI.ppi, PPI.P, PPI.Y) from multiple
>sessions/runs. It seems that the current (SPM2) PPI machinery is designed
>to only deal with a single-session model…does anyone know a solution to this?
>
>Many thanks,
>
>Tobias.
>
>Tobias Egner, PhD
>fMRI Research Center
>Columbia University
>Neurological Institute, Box 108
>710 West 168th Street
>New York, NY 10032
>Tel: (+1) 212 342 0121
>Fax: (+1) 212 342 0855
>Email: [log in to unmask]
>
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Darren R. Gitelman, M.D.
Cognitive Neurology and Alzheimer¹s Disease Center
Northwestern Univ., 320 E. Superior St., Searle 11-470, Chicago, IL 60611
Voice: (312) 908-9023 Fax: (312) 908-8789
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