This documentation is for development version 0.18.dev0.


mne.create_default_subject(fs_home=None, update=False, subjects_dir=None, verbose=None)[source]

Create an average brain subject for subjects without structural MRI.

Create a copy of fsaverage from the Freesurfer directory in subjects_dir and add auxiliary files from the mne package.

fs_home : None | str

The freesurfer home directory (only needed if FREESURFER_HOME is not specified as environment variable).

update : bool

In cases where a copy of the fsaverage brain already exists in the subjects_dir, this option allows to only copy files that don’t already exist in the fsaverage directory.

subjects_dir : None | str

Override the SUBJECTS_DIR environment variable (os.environ[‘SUBJECTS_DIR’]) as destination for the new subject.

verbose : bool, str, int, or None

If not None, override default verbose level (see mne.verbose() and Logging documentation for more).


When no structural MRI is available for a subject, an average brain can be substituted. Freesurfer comes with such an average brain model, and MNE comes with some auxiliary files which make coregistration easier (see Working with the average brain). create_default_subject() copies the relevant files from Freesurfer into the current subjects_dir, and also adds the auxiliary files provided by MNE.