Azin S Janani1, Tyler S Grummett2, Trent W Lewis3, Sean P Fitzgibbon4, Emma M Whitham5, Dylan DelosAngeles6, Hanieh Bakhshayesh3, John O Willoughby7, Kenneth J Pope3. 1. College of Science and Engineering, Flinders University, Adelaide, Australia; Medical Device Research Institute, Flinders University, Adelaide, Australia. Electronic address: azinsadat.janani@flinders.edu.au. 2. College of Science and Engineering, Flinders University, Adelaide, Australia; Medical Device Research Institute, Flinders University, Adelaide, Australia; Centre for Neuroscience, Flinders University, Adelaide, Australia. 3. College of Science and Engineering, Flinders University, Adelaide, Australia; Medical Device Research Institute, Flinders University, Adelaide, Australia. 4. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. 5. Department of Neurology, Flinders Medical Centre, Adelaide, Australia. 6. College of Science and Engineering, Flinders University, Adelaide, Australia; Centre for Neuroscience, Flinders University, Adelaide, Australia. 7. Centre for Neuroscience, Flinders University, Adelaide, Australia; College of Medicine and Public Health, Flinders University, Adelaide, Australia.
Abstract
BACKGROUND: Contamination of scalp measurement by tonic muscle artefacts, even in resting positions, is an unavoidable issue in EEG recording. These artefacts add significant energy to the recorded signals, particularly at high frequencies. To enable reliable interpretation of subcortical brain activity, it is necessary to detect and discard this contamination. NEW METHOD: We introduce a new automatic muscle-removal approach based on the traditional Blind Source Separation-Canonical Correlation Analysis (BSS-CCA) method and the spectral slope of its components. We show that CCA-based muscle-removal methods can discriminate between signals with high correlation coefficients (brain, mains artefact) and signals with low correlation coefficients (white noise, muscle). We also show that typical BSS-CCA components are not purely from one source, but are mixtures from multiple sources, limiting the performance of BSS-CCA in artefact removal. We demonstrate, using our paralysis dataset, improved performance using BSS-CCA followed by spectral-slope rejection. RESULT: This muscle removal approach can reduce high-frequency muscle contamination of EEG, especially at peripheral channels, while preserving steady-state brain responses in cognitive tasks. COMPARISON WITH EXISTING METHODS: This approach is automatic and can be applied on any sample of data easily. The results show its performance is comparable with the ICA method in removing muscle contamination and has significantly lower computational complexity. CONCLUSION: We identify limitations of the traditional BSS-CCA approach to artefact removal in EEG, propose and test an extension based on spectral slope that makes it automatic and improves its performance, and results in performance comparable to competitors such as ICA-based artefact removal.
BACKGROUND: Contamination of scalp measurement by tonic muscle artefacts, even in resting positions, is an unavoidable issue in EEG recording. These artefacts add significant energy to the recorded signals, particularly at high frequencies. To enable reliable interpretation of subcortical brain activity, it is necessary to detect and discard this contamination. NEW METHOD: We introduce a new automatic muscle-removal approach based on the traditional Blind Source Separation-Canonical Correlation Analysis (BSS-CCA) method and the spectral slope of its components. We show that CCA-based muscle-removal methods can discriminate between signals with high correlation coefficients (brain, mains artefact) and signals with low correlation coefficients (white noise, muscle). We also show that typical BSS-CCA components are not purely from one source, but are mixtures from multiple sources, limiting the performance of BSS-CCA in artefact removal. We demonstrate, using our paralysis dataset, improved performance using BSS-CCA followed by spectral-slope rejection. RESULT: This muscle removal approach can reduce high-frequency muscle contamination of EEG, especially at peripheral channels, while preserving steady-state brain responses in cognitive tasks. COMPARISON WITH EXISTING METHODS: This approach is automatic and can be applied on any sample of data easily. The results show its performance is comparable with the ICA method in removing muscle contamination and has significantly lower computational complexity. CONCLUSION: We identify limitations of the traditional BSS-CCA approach to artefact removal in EEG, propose and test an extension based on spectral slope that makes it automatic and improves its performance, and results in performance comparable to competitors such as ICA-based artefact removal.
Authors: Kenneth J Pope; Trent W Lewis; Sean P Fitzgibbon; Azin S Janani; Tyler S Grummett; Patricia A H Williams; Malcolm Battersby; Tarun Bastiampillai; Emma M Whitham; John O Willoughby Journal: Brain Behav Date: 2022-08-02 Impact factor: 3.405