32k_fs_LR to MNI space

[Victoria Root]

Good morning, 

Is the 32k_fs_LR space comparable to MNI space? For example, if centre-of-gravity coordinates were calculated in 32k_fs_LR space could they be used to pinpoint the same area/voxel (relatively) in MNI space? 

Thank you in advance for your help,

Vicky

[Glasser, Matthew]

Not with any real level of accuracy (due to issues inherent in volume-based cortical averages not issues with the accuracy in surface space).  Have a look at this paper: https://www.pnas.org/content/115/27/E6356.short.  Overall, it is best to map any results from individual subject’s volumes to their surfaces and then make any comparisons across subjects on the surface.  Comparisons across subjects in MNI space just don’t work very well across most of the cerebral cortex.

 

Matt.

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[Coalson, Timothy Scott (S&T-Student)]

To expand on this, MNI space doesn't really deserve the word "pinpoint" for most of cortex, it is more in the category of "notion of general vicinity".  Since 32k_fs_LR is purely for cortical data, and uses more accurate registration methods than can be used for MNI volume space, reporting in MNI volume space will inevitably have considerably less precision for most cortical locations.

However, if you want to know what voxel in a particular subject contains a particular surface vertex, that can be done accurately (even within the MNI-registered version of their data) - the issue is that because cortical volume registration to MNI (or any other population-average template) isn't all that good (mainly because human cortical folding is rather variable), it will be a different voxel for the same vertex in most subjects, even in the nonlinear MNI-registered volumes.

Additionally, "center of gravity" discards some rather important information about areas (where the boundaries really are, and thus what the area's shape is).  We strongly recommend sharing the files that define the entire area(s) (and unthresholded beta maps, if applicable), rather than using/reporting center of gravity.  We made balsa.wustl.edu so that these kinds of files could be shared easily, leveraging the figure-making capabilities built into wb_view.

Tim

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From: Glasser, Matthew <glas...@wustl.edu>
Sent: Thursday, July 8, 2021 6:37 AM
To: hcp-...@humanconnectome.org <hcp-...@humanconnectome.org>
Subject: Re: [hcp-users] 32k_fs_LR to MNI space

 

To view this discussion on the web visit https://groups.google.com/a/humanconnectome.org/d/msgid/hcp-users/EA9373D0-8DA7-41A5-852E-85EF0BC995EC%40wustl.edu.