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"""
===============================================================================
Compute a sparse inverse solution using the Gamma-Map empirical Bayesian method
===============================================================================
See [1]_ for details.
References
----------
.. [1] D. Wipf, S. Nagarajan
"A unified Bayesian framework for MEG/EEG source imaging",
Neuroimage, Volume 44, Number 3, pp. 947-966, Feb. 2009.
DOI: 10.1016/j.neuroimage.2008.02.059
"""
# Author: Martin Luessi <mluessi@nmr.mgh.harvard.edu>
# Daniel Strohmeier <daniel.strohmeier@tu-ilmenau.de>
#
# License: BSD (3-clause)
import numpy as np
import mne
from mne.datasets import sample
from mne.inverse_sparse import gamma_map, make_stc_from_dipoles
from mne.viz import (plot_sparse_source_estimates,
plot_dipole_locations, plot_dipole_amplitudes)
print(__doc__)
data_path = sample.data_path()
subjects_dir = data_path + '/subjects'
fwd_fname = data_path + '/MEG/sample/sample_audvis-meg-eeg-oct-6-fwd.fif'
evoked_fname = data_path + '/MEG/sample/sample_audvis-ave.fif'
cov_fname = data_path + '/MEG/sample/sample_audvis-cov.fif'
# Read the evoked response and crop it
condition = 'Left visual'
evoked = mne.read_evokeds(evoked_fname, condition=condition,
baseline=(None, 0))
evoked.crop(tmin=-50e-3, tmax=300e-3)
# Read the forward solution
forward = mne.read_forward_solution(fwd_fname)
# Read noise noise covariance matrix and regularize it
cov = mne.read_cov(cov_fname)
cov = mne.cov.regularize(cov, evoked.info, rank=None)
# Run the Gamma-MAP method with dipole output
alpha = 0.5
dipoles, residual = gamma_map(
evoked, forward, cov, alpha, xyz_same_gamma=True, return_residual=True,
return_as_dipoles=True)
###############################################################################
# Plot dipole activations
plot_dipole_amplitudes(dipoles)
# Plot dipole location of the strongest dipole with MRI slices
idx = np.argmax([np.max(np.abs(dip.amplitude)) for dip in dipoles])
plot_dipole_locations(dipoles[idx], forward['mri_head_t'], 'sample',
subjects_dir=subjects_dir, mode='orthoview',
idx='amplitude')
# # Plot dipole locations of all dipoles with MRI slices
# for dip in dipoles:
# plot_dipole_locations(dip, forward['mri_head_t'], 'sample',
# subjects_dir=subjects_dir, mode='orthoview',
# idx='amplitude')
###############################################################################
# Show the evoked response and the residual for gradiometers
ylim = dict(grad=[-120, 120])
evoked.pick_types(meg='grad', exclude='bads')
evoked.plot(titles=dict(grad='Evoked Response Gradiometers'), ylim=ylim,
proj=True, time_unit='s')
residual.pick_types(meg='grad', exclude='bads')
residual.plot(titles=dict(grad='Residuals Gradiometers'), ylim=ylim,
proj=True, time_unit='s')
###############################################################################
# Generate stc from dipoles
stc = make_stc_from_dipoles(dipoles, forward['src'])
###############################################################################
# View in 2D and 3D ("glass" brain like 3D plot)
# Show the sources as spheres scaled by their strength
scale_factors = np.max(np.abs(stc.data), axis=1)
scale_factors = 0.5 * (1 + scale_factors / np.max(scale_factors))
plot_sparse_source_estimates(
forward['src'], stc, bgcolor=(1, 1, 1),
modes=['sphere'], opacity=0.1, scale_factors=(scale_factors, None),
fig_name="Gamma-MAP")
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