Dear Chris
You said you have 2 sessions, and that the percept was rated block-wise. Does 1 session = 1 block? Did the stimulation last for the whole session, or did it switch on and off during the session? I'm trying to establish if you're interested in brief changes in brain activity caused by the stimulation, or if the stimulation is tonic and you're interested in differences in the average brain activity between sessions.
Best
Peter
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Milde, Christopher
Sent: 06 April 2016 10:35
To: [log in to unmask]
Subject: [SPM] Applicability of DCM
Dear SPM-DCM experts,
Background:
We have an fMRI-design consisting of 2 session (experimental & control body site) within a patient group. In all sessions a standardized somatosensory stimulation was applied to the subjects. Stimulation at the experimental body site elicited an additional percept which was rated block-wise.
I was wondering whether our paradigm is suitable for the application of DCM? We have pure stimulation conditions, where the contextual modulation is the presence or absence of the additional percept in patients. We thought about concatenating the timecourses of the experimental and control session and investigating the change in the connectivity between the 3 ROIs in the presence (experimental) or absence (control) of the additional percept. Due to the fact that the stimulation and the additional percept are not independent (stimulation elicits additional percept), we are unsure if the paradigm is sufficient for DCM?
Thanks for your advice
Best, Chris
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