title: Quantitative Assessment of Head Motion toward Functional Magnetic Resonance Imaging during Stepping.
abstract: OBJECTIVE
  Stepping motions have been often used as gait-like patterns in functional magnetic resonance imaging (fMRI) to understand gait control. However, it is still very difficult to stabilize the task-related head motion. Our main purpose is to provide characteristics of the task-related head motion during stepping to develop robust restraints toward fMRI.
  
  
  METHODS
  Multidirectional head and knee position during stepping were acquired using a motion capture system outside MRI room in 13 healthy participants. Six phases in a stepping motion were defined by reference to the left knee angles and the mean of superior-inferior head velocity (Vmean) in each phase was investigated. Furthermore, the correlation between the standard deviation of the knee angle (θsd) and the maximum of the head velocity (Vmax) was evaluated.
  
  
  RESULTS
  The standard deviation of each superior-inferior head position and pitch were significantly larger than the other measurements. Vmean showed a characteristic repeating pattern associated with the knee angle. Additionally, there were significant correlations between θsd and Vmax.
  
  
  CONCLUSIONS
  This is the first report to reveal the characteristics of the task-related head motion during stepping. Our findings are an essential step in the development of robust restraint toward fMRI during stepping task.
authors.affiliation: Center for Cybernics Research, University of Tsukuba.
authors.forename: Kousaku
authors.initials: K
authors.lastname: Saotome
authors.forename: Akira
authors.initials: A
authors.lastname: Matsushita
authors.forename: Kei
authors.initials: K
authors.lastname: Nakai
authors.forename: Hideki
authors.initials: H
authors.lastname: Kadone
authors.forename: Hideo
authors.initials: H
authors.lastname: Tsurushima
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Sankai
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumura
mesh_terms: D000328:Adult; D005684:Gait; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008962:Models, Theoretical; D009043:Motor Activity / Q000502:physiology*; D055815:Young Adult