If we leave out the “MNI coordinates” part of this question and think in terms of the volume space coordinates of the individual being studied, it is perfectly valid to bring results from the group surface back to an individual’s physical volume space. Is a single coordinate what you need or would an ROI be better?
Matt. From: <hcp-users-boun...@humanconnectome.org<mailto:hcp-users-boun...@humanconnectome.org>> on behalf of "Stevens, Michael" <michael.stev...@hhchealth.org<mailto:michael.stev...@hhchealth.org>> Date: Tuesday, February 12, 2019 at 9:47 PM To: "hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>" <hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>> Subject: [HCP-Users] Individualized HCP parcel to MNI coord Hi everyone, I know by now this is a tired subject that’s come up in several ways on the HCP listserv over the past few years. But can y’all remind me the most straightforward way to go backwards from a given HCP parcel (e.g., IFSa) and find a reasonably close approximation in MNI space? The problems in working from “group level” surface data and the differences from subject to subject have been discussed here before. But I’m pretty sure I’m not risking those pitfalls with what I’m planning here. I’m finalizing a study design and I need a “starting point” to select precise brain stimulation coordinates for individuals. This study formulation is based on several years’ worth of my fMRI data in HCP space that I’ve done some things with ICA and DCM to put together some interesting systems-level circuit maps. Now, based on findings within HCP localized space, I want to use specific parcels to plan how best to modulate those circuits experimentally with tDCS. The catch… of course… is that the neurotargeting software works in voxelwise space. In practice, I suspect this won’t be too significant a hurdle. I envision taking each subject’s individual surface, backtracking a given HCP parcel to their own volume space, then use neurotargeting software to figure out how to optimize focality/field intensity to that region in volume space… purely on a subject-by-subject basis. Even the individual parcel-to-volume mapping would be nothing more than a starting point for individualized optimization. You can only do so much to maximize tDCS focality… even with impressive recent advances in multifocal current flow modeling. So there’s always going to be some slop. The trick simply is to minimize that slop as much as possible, including making sure I don’t inadvertently divert current through OTHER key regions of the neural circuit. So what I lack is a set of wb_command’s that can do that individualized back-tracking. If possible, I want to actually do this on my own data prior to finalizing the grant proposal I’m working up right now, just to be sure I’ve got all this right. I’ve already got some code (thank to y’all a few months back) that uses the –volume-to-surface-mapping command to go the OTHER way. Sure, I could make a string of guesses of which MNI coordinates might map best to my target parcels, and test iteratively over a 100 or so subject datasets until I find a convincing match. But it just seems “cleaner” if I could simply do the reverse of this… That is, truly go from a given parcel (e.g., IFSa) to MNI coordinate in each subject. I might’ve missed it, but I just don’t see an obvious command candidate for going in the other direction. If there’s not, is there a way to string together a bunch of other wb_command’s to achieve this result? Any guidance would be welcome. Thanks in advance! Mike Michael C. Stevens, Ph.D. Director, CNDLAB, Olin Neuropsychiatry Research Center Director, Child & Adolescent Research, The Institute of Living Adjunct Professor of Psychiatry, Yale University School of Medicine This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, or an employee or agent responsible for delivering the message to the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message, including any attachments. _______________________________________________ HCP-Users mailing list HCP-Users@humanconnectome.org<mailto: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
