Mne Python Guide

MNE-Python Analysis Guide

Purpose

This skill encodes expert methodological knowledge for analyzing neurophysiological data (EEG, MEG, sEEG, ECoG, NIRS, eye-tracking) using MNE-Python (Gramfort et al., 2013; Gramfort et al., 2014). It covers the complete analysis pipeline with recommended parameters, code examples, and common pitfall warnings.

When to Use This Skill

Activate when the user:

• Asks about EEG/MEG/sEEG/ECoG/NIRS data analysis in Python
• Mentions MNE, MNE-Python, epochs, evoked, Raw, source estimate, ICA, ERP, ERF
• Wants to load neurophysiological data files (.fif, .edf, .bdf, .set, .vhdr, .mff, .cnt, .snirf)
• Needs preprocessing, time-frequency, source localization, decoding, or statistical testing guidance
• Wants to create MNE objects from numpy arrays or simulate data

Research Planning Protocol

1. State the research question — What is the user investigating?
2. Justify the method choice — Confirm MNE-Python fits their data type and goal.
3. Declare expected outcomes — What output format? (ERP plots, TFR maps, source maps, decoding accuracy)
4. Note assumptions and limitations — Data quality, sample size, MRI availability, montage info.
5. Present the plan and WAIT for confirmation before writing code.

Verification Notice

This skill was generated by AI from MNE-Python source code and academic literature. All parameters, thresholds, and citations require independent verification. If you find errors, please open an issue at https://github.com/NeuroAIHub/awesome_cognitive_and_neuroscience_skills/issues.

Reference Files (Progressive Disclosure)

This skill uses layered references. Read the relevant file when the user's question goes deeper than the overview below:

Pipeline Overview

Raw → Mark bad channels → Filter → ICA → Re-reference → Resample
  → Epochs → Evoked (ERP/ERF)
  → Time-Frequency (TFR/PSD)
  → Source Localization (MNE/dSPM/LCMV)
  → Decoding (MVPA)
  → Statistics (cluster permutation)

Core Data Structures

All objects carry an info attribute (mne.Info) with channel metadata that propagates through the pipeline.

Quick Start Pipeline

import mne
import numpy as np

# 1. Load
raw = mne.io.read_raw_fif('data_raw.fif', preload=True)
# or: raw = mne.io.read_raw_edf('data.edf', preload=True)

# 2. Preprocess
raw.filter(l_freq=0.1, h_freq=40.)           # bandpass
raw.notch_filter(freqs=[50, 100])              # line noise
ica = mne.preprocessing.ICA(n_components=20, random_state=97, max_iter=800)
ica.fit(raw.copy().filter(l_freq=1., h_freq=None))  # fit on 1 Hz highpass copy
eog_idx, _ = ica.find_bads_eog(raw)
ica.exclude = eog_idx
ica.apply(raw)
raw.set_eeg_reference('average')

# 3. Epoch
events, event_id = mne.events_from_annotations(raw)
epochs = mne.Epochs(raw, events, event_id, tmin=-0.2, tmax=0.5,
                    baseline=(None, 0), preload=True,
                    reject=dict(eeg=150e-6))

# 4. ERP
evoked = epochs['target'].average()
evoked.plot_joint()

# 5. Time-frequency
freqs = np.arange(4, 30, 2)
power = epochs.compute_tfr(method="morlet", freqs=freqs, n_cycles=freqs / 2.)
power.plot()

# 6. Source localization (requires anatomy)
noise_cov = mne.compute_covariance(epochs, tmax=0., method='auto')
fwd = mne.read_forward_solution('sample-fwd.fif')
inv = mne.minimum_norm.make_inverse_operator(epochs.info, fwd, noise_cov)
stc = mne.minimum_norm.apply_inverse(evoked, inv, lambda2=1./9., method='dSPM')

# 7. Decoding
from mne.decoding import SlidingEstimator, cross_val_multiscore
from sklearn.linear_model import LogisticRegression
from sklearn.pipeline import make_pipeline
from sklearn.preprocessing import StandardScaler
X = epochs.get_data(copy=True)
y = epochs.events[:, -1]
clf = make_pipeline(StandardScaler(), LogisticRegression(solver='liblinear'))
slider = SlidingEstimator(clf, scoring='roc_auc')
scores = cross_val_multiscore(slider, X, y, cv=5)

# 8. Statistics
from mne.stats import spatio_temporal_cluster_test
adjacency, _ = mne.channels.find_ch_adjacency(epochs.info, 'eeg')
T_obs, clusters, p_values, H0 = spatio_temporal_cluster_test(
    [X_cond1, X_cond2], adjacency=adjacency, n_permutations=1000)

Common Pitfalls

1. ICA on unfiltered data — Highpass ≥1 Hz before ICA fitting; slow drifts degrade decomposition (Jas et al., 2018)
2. Baseline correction before ICA — Apply baseline after ICA, not before
3. Filtering after epoching — Filter Raw, not Epochs, to avoid edge artifacts (Luck, 2014)
4. Wrong rejection thresholds — Start with EEG 100–150 µV, adjust via epochs.plot_drop_log()
5. Forgetting preload=True — Many operations require data in memory
6. Re-referencing timing — Set reference after ICA but before epoching
7. Events after resampling — Recompute events after downsampling, or resample Epochs directly
8. Legacy API — Use epochs.compute_tfr() / raw.compute_psd() instead of deprecated tfr_morlet() / psd_welch()
9. Decoding data leakage — Always cross-validate; never fit scaler on test data
10. Cluster test interpretation — Clusters show where effects exist, not their spatial/temporal extent (Maris & Oostenveld, 2007)

References

• Blankertz, B., et al. (2008). Optimizing spatial filters for robust EEG single-trial analysis. IEEE Signal Processing Magazine, 25(1), 41–56.
• Dale, A. M., et al. (2000). Dynamic statistical parametric mapping. Neuron, 26(1), 55–67.
• Gramfort, A., et al. (2013). MEG and EEG data analysis with MNE-Python. Frontiers in Neuroscience, 7, 267.
• Gramfort, A., et al. (2014). MNE software for processing MEG and EEG data. NeuroImage, 86, 446–460.
• Jas, M., et al. (2018). Autoreject: Automated artifact rejection for MEG and EEG data. NeuroImage, 159, 417–429.
• King, J.-R., & Dehaene, S. (2014). Characterizing the dynamics of mental representations. Trends in Cognitive Sciences, 18(4), 203–210.
• Luck, S. J. (2014). An Introduction to the Event-Related Potential Technique. MIT Press.
• Maris, E., & Oostenveld, R. (2007). Nonparametric statistical testing of EEG- and MEG-data. Journal of Neuroscience Methods, 164(1), 177–190.
• Pascual-Marqui, R. D. (2002). Standardized low-resolution brain electromagnetic tomography. Methods and Findings in Experimental and Clinical Pharmacology, 24(Suppl D), 5–12.
• Tallon-Baudry, C., et al. (1997). Oscillatory gamma-band activity induced by a visual search task. Journal of Neuroscience, 17(2), 722–734.