Opposing cortical forces: Alpha slowing and sensorimotor mu acceleration during motor-related BCI training
Fig 6
Comparison of absolute task correlations across spectral feature representations and datasets.
Boxplots summarize the distribution of subject-wise maximum absolute Pearson correlations between task reference signals and four EEG feature types: EKF-tracked alpha/mu frequency, EKF-tracked alpha/mu magnitude, the Frobenius norm of the EKF state covariance matrix (reflecting estimator uncertainty and dynamical stability), and conventional alpha/mu log-power, computed within the same dataset-specific frequency range used for EKF tracking by squaring and applying a base-10 logarithm to the bandpass-filtered signal. For each subject and feature, correlations were computed separately for all channels and the maximum absolute value across channels was retained to provide a single representative measure per participant. Results are shown for all four datasets, demonstrating that EKF-derived features exhibit consistently stronger task correlations than fixed-band log-power features (p < 0.05 after correction for multiple comparisons in all datasets).