HI everyone,
I'm coming to you with a question about PPI, actually just to clarify I'm using the good contrast.
I have a numerical Stroop task and I'm investigating the effects of practice by comparing the first 2 blocks with the last 2 blocks of the task performed during MRI acquisition. I already finished the classic BOLD analysis and found interesting results, notably a change in the ACC and the IPS associated with practice. I then decided to use a PPI analysis to study the connectivity changes associated with practice using the ACC as a seed. I used the scripts developed by Rick:
- Extracted the times series from the ACC to use as my seed with cmd.ppi.1.get_timeseries
- Partitioned this time series based on when stimuli were being presented; and reconvolved into a regressor with cmd.ppi.2.make.regs
- Generated the PPI contrasts with cmd.ppi.3.proc.3dd.ppi
I then run a t-test to evaluate group difference between the last and first blocks and again found interesting clusters.
What I would like to do now is to extract each individual PPI parameter to correlate with each individual behavioral performance, to test whether changes in connectivity explains changes in performance. Initially, I thought about extracting t-scores for each participants but after looking at other papers, I noticed they are using the PPI beta magnitude so I think I should reproduce that.
I have with a PPI.full.stats for each subject , and I was wondering if it seems ok if I use this contrast called "PPI:LastIncongruent vs First Incongruent GLT#0 Coef" in the clusters of interest (as revealed by the t-test) ?
Thank you