How much RAM do you have? The CIFTI files use far less RAM than the volume files, but contain all the grey matter information represented in a way that makes combining across subjects more accurate. If you don¹t use all the data your estimates of the subject¹s functional connectivity will be noisier and generally less stable (one 15 min run looks more different than another than if you compared two sets of 1 hour¹s worth of data). Also there are some left/right asymmetries in the data induced by the LR/RL phase encoding directions, which some people perceive as a problem (though if we had used AP/PA there would still be asymmetries posterior/anterior).
Peace, Matt. On 1/23/15, 6:44 AM, "Chao Liu" <[email protected]> wrote: >Dear HCP Experts, > >I am inspecting the HCP rfMRI data. For each subject, there are two >sessions with 2 runs (LR&RL) in each session, yielding 4 files in total. >Although we can concatenate all the four time series and do the >correlation, I found the memory needed is more than the memory I have on >lab computer, leading to a very slow calculation. So I am wondering the >difference between using only one run and using all the four runs. Will >it give wrong results if I use only one run? > >Many thanks! >Chao ________________________________ 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 [email protected] http://lists.humanconnectome.org/mailman/listinfo/hcp-users
