Dear all,
I am doing PPIs on some event related data using SPM2.
My question is about plotting regression lines between the adjusted signal
of 2 regions, in each psychological contexts A and B, to visualize the
change in the regression slopes (as shown by Friston et al. 97)
As discussed in a recent post, it is necessary to partition the time series
according to each psychological context:
http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0701&L=SPM&P=R11549&D=0&I=-3&X=6520700FF66F7CFD59
Nevertheless in ER designs, the psychological variable PPI.P (PSY convolved
with HRF) is a bit messier than for block designs, one has to choose an
appropriate threshold to correctly assign scans to context A (PPI.P>thresh)
or B (PPI.P<thresh) and not to baseline for example.
Many thanks for suggestions,
Swann
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