title: Time series analysis of spontaneous upper-extremity movements of premature infants with brain injuries.
abstract: OBJECTIVE
  Comparisons of spontaneous movements of premature infants with brain injuries and those without brain injuries can provide insights into normal and abnormal processes in the ontogeny of motor development. In this study, the characteristics of spontaneous upper-extremity movements of premature infants with brain injuries and those without brain injuries were examined with time series analysis.
  
  
  METHODS
  Participants were 7 premature infants with brain injuries and 7 matched, low-risk, premature infants at the age of 1 month after term.
  
  
  METHODS
  A triaxial accelerometer was used to measure upper-extremity limb acceleration in 3-dimensional space. Acceleration signals were recorded from the right wrist when the infant was in an active, alert state and lying in the supine position. The recording time was 200 seconds. The acceleration signal was sampled at a rate of 200 Hz. The acceleration time series data were analyzed by nonlinear analysis as well as linear analysis.
  
  
  RESULTS
  The nonlinear time series analysis indicated that spontaneous movements of premature infants have nonlinear, chaotic, dynamic characteristics. The movements of the infants with brain injuries were characterized by larger dimensionality, and they were more unstable and unpredictable than those of infants without brain injuries.
  
  
  CONCLUSIONS
  As determined by nonlinear analysis, the spontaneous movements of the premature infants with brain injuries had the characteristics of increased disorganization compared with those of the infants without brain injuries. Infants with brain injuries may manifest problems with self-organization as a function of the coordination of subsystems. Physical therapists should be able to support interactions among the subsystems and promote self-organization of motor learning through the individualized provision of various sensorimotor experiences for infants.
authors.affiliation: School of Rehabilitation Sciences, Seirei Christopher University, 3453 Mikatahara, Kita-ku, Hamamatsu, Shizuoka 433-8558, Japan. shohei-o@seirei.ac.jp
authors.forename: Shohei
authors.initials: S
authors.lastname: Ohgi
authors.forename: Satoru
authors.initials: S
authors.lastname: Morita
authors.forename: Kek Khee
authors.initials: KK
authors.lastname: Loo
authors.forename: Chihiro
authors.initials: C
authors.lastname: Mizuike
mesh_terms: D000054:Acceleration; D001930:Brain Injuries / Q000503:physiopathology*; D016022:Case-Control Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000503:physiopathology*; D008297:Male; D009068:Movement / Q000502:physiology*; D013057:Spectrum Analysis; D013997:Time Factors; D034941:Upper Extremity / Q000502:physiology*