AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Iri9005
September 06, 2019 04:17PM
Hello AFNI experts,


I'm hoping to do a PPI analysis, given a multiband EPI time series data with a TR of 766ms and stimulus duration of 500ms (jittered fixation crosses are also multiples of 500: e.g, 3000, 5000, 10 000, etc.). For precisely synchronizing the stimulus onset times with a subTR grid, I would need to downsample my time series to a subTR grid of 2ms, which is not possible using 1dUpsample (upsample factors possible seem to range between 2-32). Given that, the best option I can think of is to downsample to a subTR grid of 383ms (using 1dUpsample with an upsample factor of 2). My questions are: is there a way to synchronize precisely my subTR grid and my stimulus times? If not, would an approximation (e.g., downsampling to a TR of 383ms) produce usable results? One of my candidate PPI regressors is blocked (negative emotion picture block; neutral emotion picture block), and the other is event-related (attention shift required vs not).



Thank you!!
Irena



Edited 1 time(s). Last edit at 09/09/2019 11:04AM by Iri9005.
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syncing stim times and subTR grid for gPPI

Iri9005 September 06, 2019 04:17PM