Coordinate Space Transforms for Neuroimaging Templates — coordinate

Functions and constants for transforming coordinates between standard neuroimaging coordinate spaces, particularly MNI305 (fsaverage) and MNI152 (common fMRI template space).

Details

FreeSurfer's fsaverage surfaces are defined in MNI305 (Talairach-like) space, while most modern fMRI pipelines output data in MNI152 space. The difference is approximately 4mm, which matters for accurate volume-to-surface projections.

Coordinate Spaces

MNI305: FreeSurfer/Talairach space. Native space for fsaverage, fsaverage5, and fsaverage6 surfaces. Based on 305 subjects with linear registration to approximate Talairach space.
MNI152: ICBM 2009c space. The de facto standard for volumetric fMRI analysis. Used by FSL, SPM, fMRIPrep, and TemplateFlow's MNI152NLin2009cAsym template.

References

FreeSurfer CoordinateSystems documentation: https://surfer.nmr.mgh.harvard.edu/fswiki/CoordinateSystems

Wu et al. (2018). Accurate nonlinear mapping between MNI volumetric and FreeSurfer surface coordinate systems. Human Brain Mapping, 39(9), 3793-3808. doi:10.1002/hbm.24213