Dear all,
I have a specific question on the Conn Toolbox
I'm currently working on an fMRI study where each subject participated in two types of sessions, one rest and one task. However, I'm encountering an issue related to the difference in repetition time (TR) between the two sessions. Specifically, the rest session has a TR of 1 second, while the task session has a TR of 2 seconds.
I've been exploring the Conn Toolbox foranalysis, and while I've found in the setup section a way to specify different TRs across subjects, I haven't found a straightforward method to specify different TRs for each session within the same subject.
Could someone please confirm if it is possible to specify distinct TRs for each session in the Conn Toolbox? Alternatively, if this feature is not available, I would appreciate any suggestions for effectively comparing the rest and task sessions directly.
Thank you!
Best regards,
Nicolas Farron
Dear Nicolas,
Yes, the simplest way to do that is to enter NaN in the "Repetition Time" field, which will have CONN read the TR value from your functional .json files (e.g. if your functional files are named func.nii then edit or create a file named func.json in the same folder with the information for that subject/run). In each .json file a field named "RepetitionTime" can indicate the TR value -in seconds- of that functional data (so it can have a different value for each run and/or for each subject).
That said, if you are going to be comparing connectivity estimates from data with different TR's I would probably suggest to make sure to use a low-pass filter that is set to a value below the Nyquist frequency of the longest-TR case (in your case .25Hz) so that possible differences in connectivity across different frequency bands do not potentially confound those between-run comparisons.
Hope this helps
Alfonso
Originally posted by Nicolas Farron:
Dear all,
I have a specific question on the Conn Toolbox
I'm currently working on an fMRI study where each subject participated in two types of sessions, one rest and one task. However, I'm encountering an issue related to the difference in repetition time (TR) between the two sessions. Specifically, the rest session has a TR of 1 second, while the task session has a TR of 2 seconds.
I've been exploring the Conn Toolbox foranalysis, and while I've found in the setup section a way to specify different TRs across subjects, I haven't found a straightforward method to specify different TRs for each session within the same subject.
Could someone please confirm if it is possible to specify distinct TRs for each session in the Conn Toolbox? Alternatively, if this feature is not available, I would appreciate any suggestions for effectively comparing the rest and task sessions directly.
Thank you!
Best regards,
Nicolas Farron