Head motion (quick question)

[Negar Memarian]

Hi, 

I'd like to compare rs-fMRI head motion between controls and patients and want to know if what I have done is correct:

For every subject, in order to calculate a single motion score that reflects the head motion across the entire scan session, I've averaged the values in: 

MNINonlinear\Results\rest_acq-ap_run-01\Movement_RelativeRMS.txt 
and
MNINonlinear\Results\rest_acq-pa_run-02\Movement_RelativeRMS.txt

and then ran a two-sample t-test to compare the mean motion of the patient group against the control group. Does this sound right?

Thank you,

Negar

[Harms, Michael]

Sure, that's fine if you just want to compare the two groups on that summary measure of mean relative motion.

 

Note that the mean for each fMRI run is already computed for you in the Movement_RelativeRMS_mean.txt file.

 

Also note that this FSL-based measure of relative movement is approximately half the magnitude of the Power's "FD" metric.  So, if comparing to other literature that quantified using FD, take that into account.

 

Cheers,

-MH

 

-- 

Michael Harms, Ph.D.

-----------------------------------------------------------

Professor of Psychiatry

Washington University School of Medicine

Department of Psychiatry, Box 8134

660 South Euclid Ave.

St. Louis, MO  63110

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[Negar Memarian]

Dear Michael,

Many thanks for your reply and helpful advice. Am I correct in assuming that what goes into HCP's ICA-FIX for denoising is also the Framewise Displacement (FD) as reflected in the movement parameters of "Movement_Regressors.txt"?

kind regards,

Negar

[Harms, Michael]

 

Hi,

Nothing in the HCPpipelines uses "FD", as formally defined in Power's work.

 

There IS an option in the HCP ICA-FIX pipeline to regress the motion parameters as part of the ICA-FIX cleaning, but we have not been using that for a while now.  (The default for that option is 'FALSE').

 

Cheers,

-MH

 

-- 

Michael Harms, Ph.D.

-----------------------------------------------------------

Professor of Psychiatry

Washington University School of Medicine

Department of Psychiatry, Box 8134

660 South Euclid Ave.

St. Louis, MO  63110

 

From: Negar Memarian <negar.m...@gmail.com>
Date: Friday, June 19, 2026 at 11:21 PM
To: "Harms, Michael" <mha...@wustl.edu>
Subject: Re: [hcp-users] Head motion (quick question)

 

Hi Michael,

 

I would greatly appreciate your insight about my last question, i.e., am I correct in assuming that what goes into HCP's ICA-FIX for denoising is also the Framewise Displacement (FD) as reflected in the movement parameters of "Movement_Regressors.txt"?

 

Kind regards,

Negar

 

[Negar Memarian]

Thank you.

Kind regards,

Negar