Hi,
This is a decription of my experiment setup. If I could get some pointers about my DCM work it will be great.
ROIs were selected based on group activation maps during the performance of a task. Using modification indices a SEM for this group was built. This SEM had good model fit (chi^2=0.003, p = 0.955). The connections derived for this model were used to test effective connectivity with DCM on each individual. The task was additionally included as an external influence affecting two ROIs. The DCM results showed very little intrinsic connectivity between these ROIs (<0.02) with low probabilities (<0.05). No bilinear interactions were included in the model. Close examination of the activation maps for each individual showed that high task activation was not present for each individual at the ROIs chosen.
Is it correct to infer that low connectivity was seen with DCM as strong task activation is necessary for connectivity? As I understand it intrinsic connectivity is a results from the responses at the ROIs and low activation will not result in high connectivity.
Regards,
Dhananjay
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