title: Muscle artifacts in multichannel EEG: characteristics and reduction.
abstract: OBJECTIVE
  To study the characteristics of unintentional muscle activities in clinical EEG, and to develop a high-throughput method to reduce them for better revealing drug or biological effects on EEG.
  
  
  METHODS
  Two clinical EEG datasets are involved. Pure muscle signals are extracted from EEG using Independent Component Analysis (ICA) for studying their characteristics. A high-throughput method called ICA-SR is introduced based on a new feature named Spectral Ratio (SR).
  
  
  RESULTS
  The spectral and temporal characteristics of the muscle artifacts are illustrated using representative muscle signals. The spatial characteristics are presented at both the group- and the subject-level, and are consistent under three different electrode reference methodologies. Objectively compared with an existing method, ICA-SR is shown to reduce more artifacts, while introduce less distortion to EEG. Its effectiveness is further demonstrated in real clinical EEG with the help of a CO(2)-inhalation EEG recording session.
  
  
  CONCLUSIONS
  The characteristics of unintentional muscle activities align with the reported characteristics of controlled muscle activities. Artifact spatial characteristics can be EEG equipment dependent. The ICA-SR method can effectively and efficiently process clinical EEG.
  
  
  CONCLUSIONS
  Armed with advanced signal processing algorithms, this study expands our knowledge of muscle activities in EEG from muscle-controlled experiments to general clinical trials. The ICA-SR method provides an urgently needed solution with validated performance for efficiently processing large volumes of clinical EEG.
authors.affiliation: Biometrics Research, Merck Research Laboratories, Merck & Co. Inc., Rahway, NJ 07065-0900, USA. junshui_ma@merck.com
authors.forename: Junshui
authors.initials: J
authors.lastname: Ma
authors.forename: Peining
authors.initials: P
authors.lastname: Tao
authors.forename: Sevinç
authors.initials: S
authors.lastname: Bayram
authors.forename: Vladimir
authors.initials: V
authors.lastname: Svetnik
mesh_terms: D016477:Artifacts; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D004569:Electroencephalography; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation