mne.beamformer.tf_dics

mne.beamformer.tf_dics(epochs, forward, noise_csds, tmin, tmax, tstep, win_lengths, freq_bins, subtract_evoked=False, mode='fourier', n_ffts=None, mt_bandwidths=None, mt_adaptive=False, mt_low_bias=True, reg=0.05, label=None, pick_ori=None, real_filter=False, verbose=None)[source]

5D time-frequency beamforming based on DICS.

Calculate source power in time-frequency windows using a spatial filter based on the Dynamic Imaging of Coherent Sources (DICS) beamforming approach [R6868]. For each time window and frequency bin combination cross-spectral density (CSD) is computed and used to create a beamformer spatial filter with noise CSD used for normalization.

Warning

This implementation has not been heavily tested so please report any issues or suggestions.

Parameters:

epochs : Epochs

Single trial epochs.

forward : dict

Forward operator.

noise_csds : list of instances of CrossSpectralDensity

Noise cross-spectral density for each frequency bin.

tmin : float

Minimum time instant to consider.

tmax : float

Maximum time instant to consider.

tstep : float

Spacing between consecutive time windows, should be smaller than or equal to the shortest time window length.

win_lengths : list of float

Time window lengths in seconds. One time window length should be provided for each frequency bin.

freq_bins : list of tuples of float

Start and end point of frequency bins of interest.

subtract_evoked : bool

If True, subtract the averaged evoked response prior to computing the tf source grid.

mode : str

Spectrum estimation mode can be either: ‘multitaper’ or ‘fourier’.

n_ffts : list | None

FFT lengths to use for each frequency bin.

mt_bandwidths : list of float

The bandwidths of the multitaper windowing function in Hz. Only used in ‘multitaper’ mode. One value should be provided for each frequency bin.

mt_adaptive : bool

Use adaptive weights to combine the tapered spectra into CSD. Only used in ‘multitaper’ mode.

mt_low_bias : bool

Only use tapers with more than 90% spectral concentration within bandwidth. Only used in ‘multitaper’ mode.

reg : float

The regularization for the cross-spectral density.

label : Label | None

Restricts the solution to a given label.

pick_ori : None | ‘normal’

If ‘normal’, rather than pooling the orientations by taking the norm, only the radial component is kept.

real_filter : bool

If True, take only the real part of the part of the cross-spectral-density matrices to compute real filters.

verbose : bool, str, int, or None

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

Returns:

stcs : list of SourceEstimate | VolSourceEstimate

Source power at each time window. One SourceEstimate object is returned for each frequency bin.

Notes

Dalal et al. [R6868] used a synthetic aperture magnetometry beamformer (SAM) in each time-frequency window instead of DICS.

References

[R6868](1, 2, 3) Dalal et al. Five-dimensional neuroimaging: Localization of the time-frequency dynamics of cortical activity. NeuroImage (2008) vol. 40 (4) pp. 1686-1700

Examples using mne.beamformer.tf_dics