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

History of AFNI updates  

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September 13, 2020 09:51PM
HI Gang, Yes - that is exactly what I would like to do. Here is the specific outline.

For each subject:
1.I create artificial 'time-courses' for each condition of interest. Each beta series will contain the coef sub-bricks corresponding to individual stimuli within a specific condition. So if I have two conditions, I would have two separate time course files
2.For each condtion beta series, I run 3dNetCorr with an roi atlas and output the pearson and fisher z correlation matrices.
3.Then i will run additional analysis on subject-specific matrices (potentially network analysis), as well as group analysis on the matrices.
(BTW I just read your MBA paper, very cool!!)

Here are some of my questions
1. So my main needs are to figure out the best way to handle beta values that are outside the normal range (you said [-2, +2]). When I did a visual inspection on- one subject's beta series, there were two obvious spurious/giant betas, that corresponded to trials that had over half of their TRs removed. So those were easy to remove. However there are other voxel timeseries that sometimes have beta values outside of the +/-2 interval, but not so extreme. Like beta values of 3,4,5,6...etc. Since you had suggested masking out larger beta-values, I am trying to figure out what you mean exactly... For instance, some voxels might have a large beta value for one stimulus/ ("timepoint") but for all other timepoints the beta value might be fine. Would you still get rid of such a voxel?
If so, what is the correct command to create such a mask?

2. How exactly do you interpret scaled betas that are greater than +/-2 ? The goal of beta series analysis is to exploit the variability in one beta series to see if there are other series throughout the brain that it is correlated with, ie covaries with. So is there an argument for not masking out those beta values? (I apologize, i still don't have a strong enough understanding of collinearity and the size of betas, to know whether this is a ridiculous thought.)

3.An alternative analysis approach I would be interested in running is to use gPPI, (rather than or in addition to the beta series method) to assess condition-specific connectivity. However, I need to be able to run gPPI with a brain roi/parcellation scheme (ie. ROI to ROI connectivity), rather than seed ROI to all other voxels. Is there a way to do this in AFNI?

Thank you guys!
Subject Author Posted

3dNetCorr on Event-Related Task fmri

jyaros August 31, 2020 05:24PM

Re: 3dNetCorr on Event-Related Task fmri

ptaylor August 31, 2020 05:42PM

Re: 3dNetCorr on Event-Related Task fmri

Cesar Caballero Gaudes August 31, 2020 06:09PM

Re: 3dNetCorr on Event-Related Task fmri

jyaros August 31, 2020 07:56PM

Re: 3dNetCorr on Event-Related Task fmri

Cesar Caballero Gaudes September 01, 2020 05:43AM

Re: 3dNetCorr on Event-Related Task fmri

jyaros September 01, 2020 09:42AM

Re: 3dNetCorr on Event-Related Task fmri

gang September 01, 2020 02:33PM

Re: 3dNetCorr on Event-Related Task fmri

jyaros September 07, 2020 01:49AM

Re: 3dNetCorr on Event-Related Task fmri

gang September 08, 2020 09:00AM

Re: 3dNetCorr on Event-Related Task fmri

jyaros September 08, 2020 05:35PM

Re: 3dNetCorr on Event-Related Task fmri

gang September 09, 2020 11:29AM

Re: 3dNetCorr on Event-Related Task fmri

jyaros September 11, 2020 12:22AM

Re: 3dNetCorr on Event-Related Task fmri

gang September 12, 2020 12:42PM

Re: 3dNetCorr on Event-Related Task fmri

jyaros September 13, 2020 09:51PM

Re: 3dNetCorr on Event-Related Task fmri

gang September 14, 2020 02:04PM