title: Independent component analysis-based method for electroencephalogram analysis during photic stimulation.
abstract: BACKGROUND
  Intermittent photic stimulation (IPS) leads to phase- and time-locked activities in the electroencephalogram (EEG). While the first are easily obtained by means of averaging techniques (the evoked response), this latter reflects changes in the ongoing EEG that are important in event-related synchronization/desynchronization (ERS/ERD) studies. Techniques have been proposed for assessing such changes but they only provide the spectral estimate of the time-locked activities.
  
  
  METHODS
  An independent component analysis-based method is proposed for the EEG analysis during IPS. Artificially generated sinusoidal functions at the stimulation frequency and harmonics are used together with the acquired EEG signal to build the observed vector that is presented to the ICA algorithm.
  
  
  RESULTS
  The proposed method was evaluated with simulated data and applied to EEG signals acquired on two electrodes placed over the occipital region showing that this method is capable of providing a suitable estimation of the ongoing EEG activities in both time and frequency domains.
  
  
  CONCLUSIONS
  The results were compared with a coherence-based method, showing that the proposed method can estimate the power spectrum of the ongoing EEG activity as precisely as the coherence-based method with the advantage of allowing the ongoing EEG activity in time domain to be also obtained.
  
  
  CONCLUSIONS
  The application of the proposed method could be used for ERS/ERD studies, since it separates evoked responses, which are phase-locked to the stimuli, from those that change the ongoing EEG in a time-locked manner to the external stimulation.
authors.affiliation: Engineering Department, Federal University of Lavras, P.O. Box 3037, 37200-000 Lavras, MG, Brazil. Electronic address: danton@deg.ufla.br.
authors.forename: Danton Diego
authors.initials: DD
authors.lastname: Ferreira
authors.affiliation: Engineering Department, Federal University of Lavras, P.O. Box 3037, 37200-000 Lavras, MG, Brazil. Electronic address: tmartins@engautomacao.ufla.br.
authors.forename: Thais Martins
authors.initials: TM
authors.lastname: Mendes
authors.affiliation: Signal Processing Lab, COPPE/POLI, Federal University of Rio de Janeiro, P. O. Box 68504, 21941-972 RJ, Brazil. Electronic address: seixas@lps.ufrj.br.
authors.forename: José Manoel
authors.initials: JM
authors.lastname: de Seixas
authors.affiliation: Electrical Engineering Department, Federal University of Juiz de Fora, 36036-030 MG, Brazil. Electronic address: augusto.santiago@ufjf.edu.br.
authors.forename: Augusto Santiago
authors.initials: AS
authors.lastname: Cerqueira
authors.affiliation: Biomedical Engineering Program, Federal University of Rio de Janeiro, P.O. Box 68510, 21941-972 RJ, Brazil. Electronic address: amflms@peb.ufrj.br.
authors.forename: Antonio Mauricio Ferreira Leite
authors.initials: AM
authors.lastname: Miranda de Sá
mesh_terms: D000465:Algorithms; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D009778:Occipital Lobe / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D014796:Visual Perception / Q000502:physiology
keywords: EEG; ICA; Photic stimulation