title: Event-related brain potential and postural muscle activity during standing on an oscillating table while the knee, hip, and trunk are fixed.
abstract: BACKGROUND
  In this study, a cast brace was used to immobilize the knee, hip, and trunk, and relations between the event-related brain potential (ERP) and postural muscle activity were investigated while standing on an oscillating table.
  
  
  METHODS
  Twelve healthy young adults maintained a standing posture for 1 min per trial while oscillating in the anteroposterior direction at 0.5 Hz with a 2.5-cm amplitude. Trials were performed without and with the cast brace (no-fixation and fixation condition, respectively) until the subject had adapted to the floor oscillation. The ERP from the Cz electrode, postural muscle activity, and joint movement range were analyzed for the first and last two trials (before and after adaptation, respectively).
  
  
  RESULTS
  Movement range of the hip and knee was lower in the fixation condition than in the no-fixation condition, and postural control was achieved by pivoting at the ankle. Peak muscle activity was largest in the gastrocnemius (GcM) in both conditions. GcM activity significantly increased after fixation and then decreased with adaptation. The time of peak erector spinae (ES) activity in the fixation condition was significantly earlier than in the no-fixation condition and was not significantly different from the time of the anterior reversal and peak of triceps surae activity. The negative ERP peaked approximately 80 ms after the anterior reversal. Significant correlations between the time of the peak negative ERP and the peak GcM, soleus, and ES activity were observed only after the adaptation, and were greater in the fixation condition (r = 0.83, 0.84, and 0.83, respectively) than in the no-fixation condition (r = 0.62, 0.73, and 0.51, respectively).
  
  
  CONCLUSIONS
  All joints of the leg and trunk except for the ankle were rigidly fixed by the cast brace, and the phase differences between body segments were very small in the fixation condition. High correlations between the time of the peak negative ERP and the peak GcM, soleus, and ES activity after adaptation in the fixation condition suggest that attention would be more focused on anticipatory processing of muscle sensory information from the triceps surae and/or ES, particularly GcM, which had the greatest activation.
authors.affiliation: Department of Sports and Health, Kanazawa Gakuin University, 10 Sue-machi, Kanazawa, 920-1392, Japan. fujikatu@kanazawa-gu.ac.jp.
authors.forename: Katsuo
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Department of Rehabilitation Science, Osaka Health Science University, 1-9-27 Tenma, Kita-ku, Osaka, 530-0043, Japan. mariko.irei@ohsu.ac.jp.
authors.forename: Mariko
authors.initials: M
authors.lastname: Irei
authors.affiliation: Department of Rehabilitation, Japan Health Care College, 6-17-3 Megumino-nishi, Eniwa, 061-1373, Japan. n_kiyota@nihoniryo-c.ac.jp.
authors.forename: Naoe
authors.initials: N
authors.lastname: Kiyota
authors.affiliation: Department of Physical Therapy, Faculty of Human Science, Hokkaido Bunkyo University, 5-196-1, Kogane-chuo, Eniwa, 061-1449, Japan. c-yaguchi@do-bunkyodai.ac.jp.
authors.forename: Chie
authors.initials: C
authors.lastname: Yaguchi
authors.affiliation: Department of Physical Therapy, Morinomiya University of Medical Sciences, 1-26-16 Nanko-kita, Suminoe-ku, Osaka, 559-8611, Japan. maeda@morinomiya-u.ac.jp.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Maeda
mesh_terms: D000328:Adult; D004576:Electromyography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D060726:Torso / Q000502:physiology; D055815:Young Adult