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# -*- coding: utf-8 -*-
"""
.. _tut-eeg-fsaverage-source-modeling:
EEG forward operator with a template MRI
========================================
This tutorial explains how to compute the forward operator from EEG data
using the standard template MRI subject ``fsaverage``.
.. caution:: Source reconstruction without an individual T1 MRI from the
subject will be less accurate. Do not over interpret
activity locations which can be off by multiple centimeters.
.. contents:: This tutorial covers:
:local:
:depth: 2
"""
# Authors: Alexandre Gramfort <alexandre.gramfort@inria.fr>
# Joan Massich <mailsik@gmail.com>
#
# License: BSD Style.
import os.path as op
import mne
from mne.datasets import eegbci
from mne.datasets import fetch_fsaverage
# Download fsaverage files
fs_dir = fetch_fsaverage(verbose=True)
subjects_dir = op.dirname(fs_dir)
# The files live in:
subject = 'fsaverage'
trans = 'fsaverage' # MNE has a built-in fsaverage transformation
src = op.join(fs_dir, 'bem', 'fsaverage-ico-5-src.fif')
bem = op.join(fs_dir, 'bem', 'fsaverage-5120-5120-5120-bem-sol.fif')
##############################################################################
# Load the data
# -------------
#
# We use here EEG data from the BCI dataset.
#
# .. note:: See :ref:`plot_montage` to view all the standard EEG montages
# available in MNE-Python.
raw_fname, = eegbci.load_data(subject=1, runs=[6])
raw = mne.io.read_raw_edf(raw_fname, preload=True)
# Clean channel names to be able to use a standard 1005 montage
new_names = dict(
(ch_name,
ch_name.rstrip('.').upper().replace('Z', 'z').replace('FP', 'Fp'))
for ch_name in raw.ch_names)
raw.rename_channels(new_names)
# Read and set the EEG electrode locations
montage = mne.channels.make_standard_montage('standard_1005')
raw.set_montage(montage)
raw.set_eeg_reference(projection=True) # needed for inverse modeling
# Check that the locations of EEG electrodes is correct with respect to MRI
mne.viz.plot_alignment(
raw.info, src=src, eeg=['original', 'projected'], trans=trans,
show_axes=True, mri_fiducials=True, dig='fiducials')
##############################################################################
# Setup source space and compute forward
# --------------------------------------
fwd = mne.make_forward_solution(raw.info, trans=trans, src=src,
bem=bem, eeg=True, mindist=5.0, n_jobs=1)
print(fwd)
# for illustration purposes use fwd to compute the sensitivity map
eeg_map = mne.sensitivity_map(fwd, ch_type='eeg', mode='fixed')
eeg_map.plot(time_label='EEG sensitivity', subjects_dir=subjects_dir,
clim=dict(lims=[5, 50, 100]))
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