Hi Greg, Thanks a lot for your reply. To express my question clearly, I compared the time points when cues appear in WM task. In the following table, the actual time points extracted from the EVs of sub 100307 are shown in the first column, and the corresponding time points in the second column are calculated by task design (based on the block duration and fixation duration decribed in paper). There are slight delay in every block, and the delay will accumulate to several seconds at the end of task, which is the same in my experiment with HCP tfMRI Eprime program. I guess the time error comes from tiny delay in each trial because the time mode of some stim slides are "event" mode, which will not compensate the “SyncSlide.OnsetDelay”. I'm wondering whether it is matter if the task programs are used in different labs and the "OnsetDelay" in different labs are a little different. For example, there is around 5 sec difference in total time of WM. I want to seek your advice on this matter. Any relevant information would be very helpful. Thanks a lot!
-- Meizhen Han PhD Candidate Center for MRI Research Peking University Beijing, China At 2018-02-24 01:57:49, "Burgess, Gregory" <gburg...@wustl.edu> wrote: There is no difference between the duration of the E-Prime tasks and the duration of the BOLD time series from the scan. There is likely a misunderstanding of what the duration should be, but I can’t help without knowing specifically what doesn’t line up in your opinion. There have been two things that have confused other users: 1) The “Run Duration” reported in HCP publications is the total duration reported by the scanner. But, that includes ~9.36s for scanner preparation and collection of the SBRef volume. That time period occurs before the BOLD time series and before the fMRI task begins, and should not be factored into task timing. 2) At the beginning of most tasks (all but LANGUAGE), there is an 8s “countdown” period before the first event in the task. Those 8s are included at the beginning of the BOLD time series image, and are included in the timing information in the EV files. So, if you haven’t included them in your estimation of the task timing, you might think that the task was too short or the scan too long. Please review Barch et al. (2013) which includes more detailed description of the tasks, and that should help you understand the timing information that we’ve released in the EV directories in the packages. --Greg ____________________________________________________________________ Greg Burgess, Ph.D. Staff Scientist, Human Connectome Project Washington University School of Medicine Department of Psychiatry Phone: 314-362-7864 Email: gburg...@wustl.edu On Feb 23, 2018, at 4:56 AM, HMZ <hmz...@163.com> wrote: Dear HCP experts, This is Meizhen Han from Peking University. Thanks for releasing the 7 fMRI tasks written in Eprime software used in Main HCP. I downloaded and run them on the Sinorad fMRI Stimili System in our lab. I find there is a slight difference between the actual time duration and the theoretical time duration calculated by task design. In addition, according to the related articles published by HCP groups, the scanning time for each task is a little longer (several seconds) than the theoretical time. I’m wondering whether did you encounter this slight delay in your experiment and data analysis, and how did you deal with it. Any relevant information would be very helpful. Thanks in advance! Meizhen Han PhD student Center for MRI Research Peking University | | 韩美贞 | | | | _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users The materials in this message are private and may contain Protected Healthcare Information or other information of a sensitive nature. If you are not the intended recipient, be advised that any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this email in error, please immediately notify the sender via telephone or return mail. _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org http://lists.humanconnectome.org/mailman/listinfo/hcp-users
