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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melissaneuro
September 07, 2022 08:48AM
Hey,
I have looked into both codes (3dRSFC and DPABI's y_alff_falff.m, version 6.1).

I think the relevant line in DPABI y_alff_falff.m is 139: 
AllVolume(:,Segment) = 2*abs(fft(AllVolume(:,Segment)))/sampleLength;
with AllVolume being the reshaped to 2D, masked, detrended, and zero-padded 4D input time series (Segment is an option to separate data into junks to be more RAM memory friendly; can be ignored here)
and sampleLength being the number of time points.
Next, ALFF_2D is calculated as: 
ALFF_2D = mean(AllVolume(idx_LowCutoff:idx_HighCutoff,:));


As I am not really familiar with C, I did not fully understand whether this method is different compared to 3dRSFC (and the relevant lines of code starting from line 725). Could you maybe explain that a bit more?

Best, Melissa
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Subject Author Posted

f/ALFF calculation with 3dRSFC is different compared to DPABI output

melissaneuro August 29, 2022 08:53AM

Re: f/ALFF calculation with 3dRSFC is different compared to DPABI output

ptaylor August 29, 2022 02:45PM

Re: f/ALFF calculation with 3dRSFC is different compared to DPABI output

melissaneuro September 01, 2022 01:51PM

Re: f/ALFF calculation with 3dRSFC is different compared to DPABI output

melissaneuro September 07, 2022 08:48AM

Re: f/ALFF calculation with 3dRSFC is different compared to DPABI output

ptaylor September 07, 2022 05:02PM