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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November 19, 2021 10:09AM
Hi Mary,

To be sure, are you running 3dDeconvolve/3dREMLfit using -stim_times_AM2, where each event has an attached modulator in {0,1,2,3} (or {-1.5, -.5, .5, 1.5})?

If so, that assumes a linear relationship between the modulator and the amplitude of the BOLD response, where the output (at each voxel) is a beta for the mean response, and a beta for the incremental effect of the modulator.

Since the output is a mean and slope for the modulated conditions, there isn't really so much to plot.

What you might want to do is model all 4 levels separately, and then run a simple linear fit to that. That could be compared with the outputs from 3dDeconvolve (they should be similar), and it could be viewed as a 4-point time series, or even as scatter plots over ROIs/clusters, say.

Does this seem reasonable?

- rick
Subject Author Posted

Amplitude Modulation Analysis

mritchi6 November 18, 2021 10:40AM

Re: Amplitude Modulation Analysis

rick reynolds November 19, 2021 10:09AM

Re: Amplitude Modulation Analysis

mritchi6 November 22, 2021 10:05AM

Re: Amplitude Modulation Analysis

rick reynolds November 23, 2021 12:17AM

Re: Amplitude Modulation Analysis

mritchi6 November 23, 2021 09:50AM