help > RE: Motion measure AFTER scrubbing
Oct 28, 2019  02:10 PM | Jeffrey Johnson - Boston University
RE: Motion measure AFTER scrubbing
Dear Jordan and others,
Did you ever find away to obtain summary motion measures (e.g., average framewise displacement) for only valid scans for specific conditions (like pre and post)? The instructions outlined in this thread are very clear and easy to follow for computing summary values for a specific condition or for all valid scans across the full timeseries, but I can't figure out how to combine the two and get them for valid scans within a specific condition. 

Thanks for any advice!

Jeff

Originally posted by Jordon Tng:
Dear CONN Users,

Is it possible to look at the motion measures separately for pre-post for valid scans only? I understand that to do so a new condition should be created, but have no idea how to do so.

Thanks in advance
Originally posted by Alfonso Nieto-Castanon:
Dear Jeff and Hannes,

You are right that the original QA motion and global change second-level covariates computed automatically during preprocessing are computed by aggregating across all timepoints (across multiple sessions and multiple conditions). If you want to compute these separately for each condition you can simply use the 'covariate tools. compute summary measures' function to do this. The QA_timeseries first-level covariate contains the global change and framewise displacement timeseries so it is just a matter of computing the aggregated measure that you wish for each of these timeseries (e.g. average or maximum value across timepoints) and making sure to select the 'condition-specific measures' checkbox so that the measures are computed separately for each condition (e.g. go to 'covariates.first-level' tab, select the 'QA_timeseries' covariate, click on 'covariate tools.compute aggregate measures', then select 'raw values', 'average', and 'do not aggregate', check the 'condition-specific measures' and click 'Ok').

If you want to compute the measures separately for each session simply make sure that you define a new set of conditions first where each condition looks at the data of a single-session (e.g. see the 'pre-post' example in the manual for how to define conditions associated with individual sessions).  

Perhaps it is a good idea to try to change the default behavior and have CONN create condition-specific QA measures also during preprocessing? (let me know your thoughts; by default the QA measures created during denoising are computed separately for each condition, the reason that the ones generated during processing are not is that we cannot safely assume that conditions have been yet defined at the time when people run preprocessing)

Hope this helps
Alfonso
 
Originally posted by Jeff Browndyke:
I have a similar need for the mean Global and max Global QA variables.  Aggregating the QA across time points and conditions makes it difficult to assess for systematic differences x time point (or condition).

Jeff

Threaded View

TitleAuthorDate
hannes berg Jun 15, 2017
Alfonso Nieto-Castanon Jun 16, 2017
Larry Lai Jul 6, 2018
Jordon Tng Jul 6, 2018
hannes berg Jun 16, 2017
Jeff Browndyke Jun 16, 2017
Alfonso Nieto-Castanon Jun 16, 2017
Jordon Tng Aug 1, 2018
RE: Motion measure AFTER scrubbing
Jeffrey Johnson Oct 28, 2019
Jeff Browndyke Jun 18, 2017
hannes berg Jun 16, 2017