Human Vestibulo-Ocular Reflex Adaptation Reduces when Training Demand Variability Increases

Carlo N. Rinaudo, Michael C. Schubert, William V.C. Figtree, Phillip D. Cremer, Americo A. Migliaccio

Research output: Contribution to journalArticlepeer-review

Abstract

One component of vestibular rehabilitation in patients with vestibulo-ocular reflex (VOR) hypofunction is gaze-stabilizing exercises that seek to increase (adapt) the VOR response. These prescribed home-based exercises are performed by the patient and thus their use/training is inherently variable. We sought to determine whether this variability affected VOR adaptation in ten healthy controls (× 2 training only) and ten patients with unilateral vestibular hypofunction (× 1 and × 2 training). During × 1 training, patients actively (self-generated, predictable) move their head sinusoidally while viewing a stationary fixation target; for × 2 training, they moved their outstretched hand anti-phase with their head rotation while attempting to view a handheld target. We defined the latter as manual × 2 training because the subject manually controls the target. In this study, head rotation frequency during training incrementally increased 0.5–2 Hz over 20 min. Active and passive (imposed, unpredictable) sinusoidal (1.3-Hz rotations) and head impulse VOR gains were measured before and after training. We show that for controls, manual × 2 training resulted in significant sinusoidal and impulse VOR adaptation of ~ 6 % and ~ 3 %, respectively, though this was ~two-thirds lower than increases after computer-controlled × 2 training (non-variable) reported in a prior study. In contrast, for patients, there was an increase in impulse but not sinusoidal VOR response after a single session of manual × 2 training. Patients had more than double the variability in VOR demand during manual × 2 training compared to controls, which could explain why adaptation was not significant in patients. Our data suggest that the clinical × 1 gaze-stabilizing exercise is a weak stimulus for VOR adaptation.

Original languageEnglish (US)
Pages (from-to)193-206
Number of pages14
JournalJARO - Journal of the Association for Research in Otolaryngology
Volume22
Issue number2
DOIs
StatePublished - Apr 2021

Keywords

  • VOR adaptation
  • incremental frequency adaptation
  • variability of training demand
  • vestibular rehabilitation gaze-stabilizing exercises
  • vestibulo-ocular reflex (VOR)
  • × 1 and × 2 training

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Sensory Systems

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