mne.preprocessing.annotate_muscle_zscore¶

mne.preprocessing.annotate_muscle_zscore(raw, threshold=4, ch_type=None, min_length_good=0.1, filter_freq=(110, 140), n_jobs=1, verbose=None)[source]¶

Create annotations for segments that likely contain muscle artifacts.

Detects data segments containing activity in the frequency range given by filter_freq whose envelope magnitude exceeds the specified z-score threshold, when summed across channels and divided by sqrt(n_channels). False-positive transient peaks are prevented by low-pass filtering the resulting z-score time series at 4 Hz. Only operates on a single channel type, if ch_type is None it will select the first type in the list mag, grad, eeg. See 1 for background on choosing filter_freq and threshold.

Parameters

rawinstance of Raw: Data to estimate segments with muscle artifacts.
thresholdfloat: The threshold in z-scores for marking segments as containing muscle activity artifacts.
ch_type‘mag’ | ‘grad’ | ‘eeg’ | None: The type of sensors to use. If None it will take the first type in mag, grad, eeg.
min_length_goodfloat | None: The shortest allowed duration of “good data” (in seconds) between adjacent annotations; shorter segments will be incorporated into the surrounding annotations.``None`` is equivalent to 0. Default is 0.1.
filter_freqarray_like, shape (2,): The lower and upper frequencies of the band-pass filter. Default is (110, 140).
n_jobsint: The number of jobs to run in parallel (default 1). Requires the joblib package.
verbosebool, str, int, or None: If not None, override default verbose level (see mne.verbose() and Logging documentation for more). If used, it should be passed as a keyword-argument only.

Returns

annotmne.Annotations: Periods with muscle artifacts annotated as BAD_muscle.
scores_musclearray: Z-score values averaged across channels for each sample.

References

1: Suresh Muthukumaraswamy. High-frequency brain activity and muscle artifacts in MEG/EEG: a review and recommendations. Frontiers in Human Neuroscience, 7:138, 2013. doi:10.3389/fnhum.2013.00138.