Hybrid wavelet and EMD/ICA approach for artifact suppression in pervasive EEG

- Exploration of two hybrid motion artifact removals, WPTEMD and WPTICA, without a priori knowledge in low density EEG.
- Performance comparison with state-of-the-art artifact removal algorithms.
- Two datasets used: (a) semi-simulated and (b) motion artifact EEG data (eight types) recorded with 19-channel wireless EEG.
- Performance measures: RMSE, Artifact to Signal Ratio, Time morphology, Frequency spectrum and Scalp topography.
- WPTEMD outperforms other techniques for highly contaminated data.

BackgroundElectroencephalogram (EEG) signals are often corrupted with unintended artifacts which need to be removed for extracting meaningful clinical information from them. Typically a priori knowledge of the nature of the artifacts is needed for such purpose. Artifact contamination of EEG is even more prominent for pervasive EEG systems where the subjects are free to move and thereby introducing a wide variety of motion-related artifacts. This makes hard to get a priori knowledge about their characteristics rendering conventional artifact removal techniques often ineffective.New methodIn this paper, we explore the performance of two hybrid artifact removal algorithms: Wavelet Packet Transform followed by Independent Component Analysis (WPTICA) and Wavelet Packet Transform followed by Empirical Mode Decomposition (WPTEMD) in pervasive EEG recording scenario, assuming existence of no a priori knowledge about the artifacts and compare their performance with two existing artifact removal algorithms.ResultsArtifact cleaning performance has been measured using Root Mean Square Error (RMSE) and Artifact to Signal Ratio (ASR)-an index similar to traditional Signal to Noise Ratio (SNR), and also by observing normalized power distribution topography over the scalp.Comparison with existing method(s)Comparison has been made first using semi-simulated signals and then with real experimentally acquired EEG data with commercially available 19-channel pervasive EEG system Enobio corrupted by eight types of artifact.ConclusionsOur explorations show that WPTEMD consistently gives best artifact cleaning performance not only in semi-simulated scenario but also in the case of real EEG data containing artifacts.