In order to have a reference surface for group studies, we built a surface template of the cortical surface. The HipHop138 template has been built by averaging the surfaces of 138 subjects after running the HipHop surface parameterization on these subjects. Both hemispheres have been processed separately.

HipHop138 is available by downloading the hiphop138-Template.tgz file. It is a tgz archive that can be extracted with the following command:

tar xzvf hiphop138-Template.tgz

It will create a diectory called ‘hiphop138-Template/’ that contains:

• hiphop138_<L/R>white.gii → the surface of each hemisphere
• hiphop138_<L/R>white_<lat/lon>.gii → the corresponding longitude and latitude files that have been produced by the HipHop parameterization process.
• hiphop138_<L/R>white_parcels_marsAtlas.gii → the corresponding parcellations produced by the MarsAtlas parcellation process.
• hiphop138_<L/R>white_spherical.gii → spherical versions of each hemisphere. These are needed to compute the correspondence between any subject’s cortical surface and the template.
• hiphop138_<L/R>_pole_cingular.gii -> a mask of the cingular pole for each hemisphere.

HipHop138 has been built using subjects from the OASIS database, after the following processing steps:

• Segmentation performed using FreeSurfer 5.1
• Importation in BrainVisa 4.4
• Mesh and sulci extraction, and sulci automatic labelling performed using the Morphologist pipeline (BrainVisa 4.4).
• HipHop parameterization pipeline and MarsAtlas parcellation (BrainVisa 5.0)