title: Cross-correlation analysis of the correspondence between magnetoencephalographic and near-infrared cortical signals.
abstract: OBJECTIVE
  The study of neurovascular coupling greatly benefits from combined measurements of neuronal and vascular signals. Two-step signal processing is developed to extract parameters describing the coupling.
  
  
  METHODS
  Using a magnetometer in an extremely well shielded room a broadband magnetoencephalogram was simultaneously measured with time-resolved near-infrared spectroscopy during a motor activity paradigm. The raw MEG and NIRS data were denoised separately using independent component analysis.
  
  
  RESULTS
  After averaging the resulting signals showed motor activity-related changes. The temporal correspondence between MEG and NIRS was assessed plotting a combined trajectory and calculating a cross-correlation. Compared to the MEG signal, at movement onset the NIRS signal showed an onset delay in the range of seconds.
  
  
  CONCLUSIONS
  Multi-variate signal pre-processing followed by temporal delay estimates demonstrated the extraction of neurovascular coupling parameters.
authors.affiliation: 1Physikalisch-Technische Bundesanstalt, Division of Medical Physics, Berlin, Germany. tilmann.sander-thoemmes@ptb.de
authors.forename: T H
authors.initials: TH
authors.lastname: Sander
authors.forename: A
authors.initials: A
authors.lastname: Liebert
authors.forename: M
authors.initials: M
authors.lastname: Burghoff
authors.forename: H
authors.initials: H
authors.lastname: Wabnitz
authors.forename: R
authors.initials: R
authors.lastname: Macdonald
authors.forename: L
authors.initials: L
authors.lastname: Trahms
mesh_terms: D002490:Central Nervous System / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography; D008962:Models, Theoretical; D009474:Neurons / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D015398:Signal Transduction / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D013223:Statistics as Topic; D013995:Time