title: Ocular and cardiac artifact rejection for real-time analysis in MEG.
abstract: BACKGROUND
  Recently, magnetoencephalography (MEG) based real-time brain computing interfaces (BCI) have been developed to enable novel and promising methods for neuroscience research. It is well known that artifact rejection prior to source localization largely enhances the localization accuracy. However, many BCI approaches neglect real-time artifact removal due to its time consuming process.
  
  
  METHODS
  The method (referred to as ocular and cardiac artifact rejection for real-time analysis, OCARTA) is based on constrained independent component analysis (cICA), where a priori information of the underlying source signals is used to optimize and accelerate signal decomposition. Thereby, prior information is incorporated by using the subject's individual cardiac and ocular activity. The algorithm automatically uses different separation strategies depending on the underlying source activity.
  
  
  RESULTS
  OCARTA was tested and applied to data from three different but most commonly used MEG systems (4D-Neuroimaging, VSM MedTech Inc. and Elekta Neuromag). Ocular and cardiac artifacts were effectively reduced within one iteration at a time delay of 1ms performed on a standard PC (Intel Core i5-2410M).
  
  
  METHODS
  The artifact rejection results achieved with OCARTA are in line with the results reported for offline ICA-based artifact rejection methods.
  
  
  CONCLUSIONS
  Due to the fast and subject-specific signal decomposition the new approach introduced here is capable of real-time ocular and cardiac artifact rejection.
authors: Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich GmbH, Jülich, Germany; Department of Neurology, RWTH Aachen University, Aachen, Germany; Jülich Aachen Research Alliance (JARA) - Translational Brain Medicine, Jülich, Germany. Electronic address: L.Breuer@fz-juelich.de.
authors: Lukas
authors: L
authors: Breuer
authors: Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich GmbH, Jülich, Germany.
authors: Jürgen
authors: J
authors: Dammers
authors: Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors: Timothy P L
authors: TP
authors: Roberts
authors: Institute of Neuroscience and Medicine (INM-4), Forschungszentrum Jülich GmbH, Jülich, Germany; Department of Neurology, RWTH Aachen University, Aachen, Germany; Jülich Aachen Research Alliance (JARA) - Translational Brain Medicine, Jülich, Germany.
authors: N Jon
authors: NJ
authors: Shah
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000502:physiology; D002648:Child; D004562:Electrocardiography / Q000379:methods; D004585:Electrooculography / Q000379:methods; D005133:Eye Movements / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation / Q000379:methods*; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D055815:Young Adult
keywords: Constrained independent component analysis (cICA); Cross trial phase statistics (CTPS); Magnetoencephalography (MEG); Ocular and cardiac artifact rejection for real-time analysis (OCARTA); Real-time artifact reduction