Compute source power spectral density (PSD) in a label

Returns an STC file containing the PSD (in dB) of each of the sources within a label.

# Authors: Alexandre Gramfort <alexandre.gramfort@inria.fr>
#
# License: BSD-3-Clause
# Copyright the MNE-Python contributors.

import matplotlib.pyplot as plt

import mne
from mne import io
from mne.datasets import sample
from mne.minimum_norm import compute_source_psd, read_inverse_operator

print(__doc__)

Set parameters

data_path = sample.data_path()
meg_path = data_path / "MEG" / "sample"
raw_fname = meg_path / "sample_audvis_raw.fif"
fname_inv = meg_path / "sample_audvis-meg-oct-6-meg-inv.fif"
fname_label = meg_path / "labels" / "Aud-lh.label"

# Setup for reading the raw data
raw = io.read_raw_fif(raw_fname, verbose=False)
events = mne.find_events(raw, stim_channel="STI 014")
inverse_operator = read_inverse_operator(fname_inv)
raw.info["bads"] = ["MEG 2443", "EEG 053"]

# picks MEG gradiometers
picks = mne.pick_types(
    raw.info, meg=True, eeg=False, eog=True, stim=False, exclude="bads"
)

tmin, tmax = 0, 120  # use the first 120s of data
fmin, fmax = 4, 100  # look at frequencies between 4 and 100Hz
n_fft = 2048  # the FFT size (n_fft). Ideally a power of 2
label = mne.read_label(fname_label)

stc = compute_source_psd(
    raw,
    inverse_operator,
    lambda2=1.0 / 9.0,
    method="dSPM",
    tmin=tmin,
    tmax=tmax,
    fmin=fmin,
    fmax=fmax,
    pick_ori="normal",
    n_fft=n_fft,
    label=label,
    dB=True,
)

stc.save("psd_dSPM", overwrite=True)

320 events found on stim channel STI 014
Event IDs: [ 1  2  3  4  5 32]
Reading inverse operator decomposition from /home/circleci/mne_data/MNE-sample-data/MEG/sample/sample_audvis-meg-oct-6-meg-inv.fif...
    Reading inverse operator info...
    [done]
    Reading inverse operator decomposition...
    [done]
    305 x 305 full covariance (kind = 1) found.
    Read a total of 4 projection items:
        PCA-v1 (1 x 102) active
        PCA-v2 (1 x 102) active
        PCA-v3 (1 x 102) active
        Average EEG reference (1 x 60) active
    Noise covariance matrix read.
    22494 x 22494 diagonal covariance (kind = 2) found.
    Source covariance matrix read.
    22494 x 22494 diagonal covariance (kind = 6) found.
    Orientation priors read.
    22494 x 22494 diagonal covariance (kind = 5) found.
    Depth priors read.
    Did not find the desired covariance matrix (kind = 3)
    Reading a source space...
    Computing patch statistics...
    Patch information added...
    Distance information added...
    [done]
    Reading a source space...
    Computing patch statistics...
    Patch information added...
    Distance information added...
    [done]
    2 source spaces read
    Read a total of 4 projection items:
        PCA-v1 (1 x 102) active
        PCA-v2 (1 x 102) active
        PCA-v3 (1 x 102) active
        Average EEG reference (1 x 60) active
    Source spaces transformed to the inverse solution coordinate frame
Not setting metadata
70 matching events found
No baseline correction applied
Created an SSP operator (subspace dimension = 3)
3 projection items activated
Considering frequencies 4 ... 100 Hz
Preparing the inverse operator for use...
    Scaled noise and source covariance from nave = 1 to nave = 1
    Created the regularized inverter
    Created an SSP operator (subspace dimension = 3)
    Created the whitener using a noise covariance matrix with rank 302 (3 small eigenvalues omitted)
    Computing noise-normalization factors (dSPM)...
[done]
Picked 305 channels from the data
Computing inverse...
    Eigenleads need to be weighted ...
Reducing data rank 33 -> 33
Using hann windowing on at most 70 epochs

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Writing STC to disk...
[done]

View PSD of sources in label

plt.plot(stc.times, stc.data.T)
plt.xlabel("Frequency (Hz)")
plt.ylabel("PSD (dB)")
plt.title("Source Power Spectrum (PSD)")
plt.show()