title: Long-lasting effects of neck muscle vibration and contraction on self-motion perception of vestibular origin.
abstract: OBJECTIVE
  To show that neck proprioceptive input can induce long-term effects on vestibular-dependent self-motion perception.
  
  
  METHODS
  Motion perception was assessed by measuring the subject's error in tracking in the dark the remembered position of a fixed target during whole-body yaw asymmetric rotation of a supporting platform, consisting in a fast rightward half-cycle and a slow leftward half-cycle returning the subject to the initial position. Neck muscles were relaxed or voluntarily contracted, and/or vibrated. Whole-body rotation was administered during or at various intervals after the vibration train. The tracking position error (TPE) at the end of the platform rotation was measured during and after the muscle conditioning maneuvers.
  
  
  RESULTS
  Neck input produced immediate and sustained changes in the vestibular perceptual response to whole-body rotation. Vibration of the left sterno-cleido-mastoideus (SCM) or right splenius capitis (SC) or isometric neck muscle effort to rotate the head to the right enhanced the TPE by decreasing the perception of the slow rotation. The reverse effect was observed by activating the contralateral muscle. The effects persisted after the end of SCM conditioning, and slowly vanished within several hours, as tested by late asymmetric rotations. The aftereffect increased in amplitude and persistence by extending the duration of the vibration train (from 1 to 10min), augmenting the vibration frequency (from 5 to 100Hz) or contracting the vibrated muscle. Symmetric yaw rotation elicited a negligible TPE, upon which neck muscle vibrations were ineffective.
  
  
  CONCLUSIONS
  Neck proprioceptive input induces enduring changes in vestibular-dependent self-motion perception, conditional on the vestibular stimulus feature, and on the side and the characteristics of vibration and status of vibrated muscles. This shows that our perception of whole-body yaw-rotation is not only dependent on accurate vestibular information, but is modulated by proprioceptive information related to previously experienced position of head with respect to trunk.
  
  
  CONCLUSIONS
  Tonic proprioceptive inflow, as might occur as a consequence of enduring or permanent head postures, can induce adaptive plastic changes in vestibular-dependent motion sensitiveness. These changes might be counteracted by vibration of selected neck muscles.
authors: Department of Experimental Medicine, University of Perugia, Italy.
authors: Vito Enrico
authors: VE
authors: Pettorossi
authors: Department of Experimental Medicine, University of Perugia, Italy.
authors: Roberto
authors: R
authors: Panichi
authors: Department of Experimental Medicine, University of Perugia, Italy.
authors: Fabio Massimo
authors: FM
authors: Botti
authors: Department of Experimental Medicine, University of Perugia, Italy.
authors: Andrea
authors: A
authors: Biscarini
authors: Institute of Human Physiology, Catholic University, Roma, Italy.
authors: Guido Maria
authors: GM
authors: Filippi
authors: Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Italy; Centro Studi Attività Motorie, Fondazione Salvatore Maugeri (IRCCS), Pavia, Italy. Electronic address: marco.schieppati@unipv.it.
authors: Marco
authors: M
authors: Schieppati
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D013997:Time Factors; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D014732:Vibration; D055815:Young Adult
keywords: Contraction; Long-lasting effects; Neck proprioception; Self-motion perception; Vestibular; Vibration; Whole-body yaw rotation