Surface tools

Welcome to Surface tools! a collection of tools for surface-based operations

Equivolumetric surfaces: creates equivolumetric surfaces based on the ratio of areas of the mesh surfaces, without the trouble of dealing with volumetric operations.

Equivolumetric surfaces (red) at 0.25, 0.5 and 0.75 cortical depth on the BigBrain. Euclidean surface (yellow) at mid depth. The euclidean surface samples different layers in gyri and sulci.

Euclidean vs equivolumetric intensity sampling. The laminar peaks are better aligned using equivolumetric sampling than euclidean sampling.

Written by Konrad Wagstyl and Alexander Huth at a Brain Hack, a version is also available in Pycortex. Casey Paquola and Richard Bethlehem were involved in piloting these scripts on CIVET and FreeSurfer respectively.

To get started you can clone the github repository into your folder of choice:

git clone https://github.com/kwagstyl/surface_tools

Install nibabel:

pip install nibabel

The code requires either CIVET and FreeSurfer to be installed.

CIVET usage:

python surface_tools/equivolumetric_surfaces/generate_equivolumetric_surfaces.py --smoothing 0 gray_left.obj white_left.obj 5 equi_left

Then you can use volume_object_evaluate to sample the intensities at the particular depth:
volume_object_evaluate volume.mnc equi_left0.5.obj equi_left_intensities0.5.txt

FreeSurfer usage

(we assume CIVET as default, so if using freesurfer, specify with the freesurfer flag):

python surface_tools/equivolumetric_surfaces/generate_equivolumetric_surfaces.py --smoothing 0 <subj>/surf/lh.pial <subj>/surf/lh.white 5 lh.equi --software freesurfer --subject_id SUBJECT_ID

Then you can use mri_vol2surf to sample the intensities at the particular depth:

mri_vol2surf --src volume.nii --out lh.equi_intensity_0.5.mgh --hemi lh --surf <subj>/surf/lh.equi0.5.pial --out_type mgh

If you notice any typos/bugs, or have any suggestions or improvements, we would really value your input. Either send us a pull request, email us at kw350@cam.ac.uk

Release notes

This code has so far been tested on:

• python 2.7 and 3.6, freesurfer v.6 and on linux (Ubuntu 16.04) and macOS (10.12.6)
• python 2.7, CIVET 2.1, Ubuntu 12.04

Acknowledgements:

The io_mesh code was copied and adapted from https://github.com/juhuntenburg/laminar_python, another great tool for doing volume-based equivolumetric laminar processing.

The equations for generating equivolumetric surfaces come from Waehnert et al 2014: "Anatomically motivated modeling of cortical laminae" https://doi.org/10.1016/j.neuroimage.2013.03.078

Code is demo-ed here on the BigBrain (Amunts et al., 2013), freely available histological atlas of the human brain https://bigbrain.loris.ca/

This work was partially supported by the Healthy Brains for Healthy Lives (HBHL) initiative and the Avrith MNI-Cambridge Neuroscience Collaboration.