SSP-SIR

SSP-SIR combines an artifact signal-space projection with source-informed reconstruction through a lead field. It targets high-variance muscle artifact in TMS-evoked EEG [1].

Usage

from mne_denoise.sspsir import SSPSIR

model = SSPSIR(n_components=3, art_window=(0.005, 0.050))
clean = model.fit_transform(epochs)

Key points

• n_components is an artifact-component count or a high-frequency variance fraction. M sets the source-informed reconstruction rank.

• art_window=(tmin, tmax) estimates the artifact subspace in that interval. blend=”constant” applies the projected operator throughout; the default can use a time-local blend.

• An individual forward solution is preferred. Compatible EEG MNE input with a montage can use the spherical fallback when forward is omitted. MEG or mixed-channel MNE input and NumPy input require an explicit forward.

• NumPy input uses (n_channels, n_times) or (n_epochs, n_channels, n_times). Supported MNE containers are copied.

• The fitted lead field, artifact topographies, operators, kernel, and effective rank are available as diagnostics.

The projection can remove signal that shares the selected artifact subspace. Check the lead-field reference and reconstruction rank when interpreting evoked responses [2][3].

References

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[1]

Tuomas P. Mutanen, Matleena Kukkonen, Jaakko O. Nieminen, Matti Stenroos, Jukka Sarvas, and Risto J. Ilmoniemi. Recovering tms-evoked eeg responses masked by muscle artifacts. NeuroImage, 139:157–166, 2016. doi:10.1016/j.neuroimage.2016.05.028.

[2]

Tuomas P. Mutanen, Johanna Metsomaa, Matilda Makkonen, Giuseppe Varone, Laura Marzetti, and Risto J. Ilmoniemi. Source-based artifact-rejection techniques for tms–eeg. Journal of Neuroscience Methods, 382:109693, 2022. doi:10.1016/j.jneumeth.2022.109693.

[3]

Tuomas P. Mutanen, Ida Ilmoniemi, Iiris Atti, Johanna Metsomaa, and Risto J. Ilmoniemi. A simulation study: comparing independent component analysis and signal-space projection–source-informed reconstruction for rejecting muscle artifacts evoked by transcranial magnetic stimulation. Frontiers in Human Neuroscience, 18:1324958, 2024. doi:10.3389/fnhum.2024.1324958.