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help > RE: weighted glm script
Feb 26, 2021 05:02 PM | Alfonso Nieto-Castanon - Boston University
RE: weighted glm script
Hi Sam,
You are right, typically for pure resting state analyses using the default "hrf weighting" option or using "none" (no weighting) result in almost identical results. The hrf-weighting in this scenario will only slightly deweight the first few scans in your run (the weights are defined from the convolution of a rectangular block covering the entire length of your run, with SPM canonical hrf function), so if you do not notice any potential non-stationarity issues in the BOLD signal at the beginning of your scanning session then it is perfectly fine to skip hrf-weighting entirely for resting state analyses (see https://www.nitrc.org/forum/message.php?msg_id=18651 and related posts for additional details)
Best
Alfonso
Originally posted by Sam W:
You are right, typically for pure resting state analyses using the default "hrf weighting" option or using "none" (no weighting) result in almost identical results. The hrf-weighting in this scenario will only slightly deweight the first few scans in your run (the weights are defined from the convolution of a rectangular block covering the entire length of your run, with SPM canonical hrf function), so if you do not notice any potential non-stationarity issues in the BOLD signal at the beginning of your scanning session then it is perfectly fine to skip hrf-weighting entirely for resting state analyses (see https://www.nitrc.org/forum/message.php?msg_id=18651 and related posts for additional details)
Best
Alfonso
Originally posted by Sam W:
Thank you Alfonso, I'll do that!
However, I was also wondering if it makes sense to compute weighted connectivity matrices for resting-state data, given that there are no conditions to convolve the HRF with?
At first, I thought weighted connectivity matrices only apply to task-based fmri, but I think the documentation reads that it can also be applied to resting-state. But in that case what is the HRF convolved with, and how are the weights defined?
Best regards,
Sam
However, I was also wondering if it makes sense to compute weighted connectivity matrices for resting-state data, given that there are no conditions to convolve the HRF with?
At first, I thought weighted connectivity matrices only apply to task-based fmri, but I think the documentation reads that it can also be applied to resting-state. But in that case what is the HRF convolved with, and how are the weights defined?
Best regards,
Sam
Threaded View
| Title | Author | Date |
|---|---|---|
| Sam W | Feb 24, 2021 | |
| Alfonso Nieto-Castanon | Feb 24, 2021 | |
| Sam W | Feb 26, 2021 | |
| Alfonso Nieto-Castanon | Feb 26, 2021 | |