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Campbell D, Murphy BA, Burkitt J, La Delfa N, Sanmugananthan P, Ambalavanar U, Yielder P. Cervico-Ocular and Vestibulo-Ocular Reflexes in Subclinical Neck Pain and Healthy Individuals: A Cross-Sectional Study. Brain Sci 2023; 13:1603. [PMID: 38002562 PMCID: PMC10670025 DOI: 10.3390/brainsci13111603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023] Open
Abstract
Alterations in neck sensory input from recurrent neck pain (known as subclinical neck pain (SCNP)) result in disordered sensorimotor integration (SMI). The cervico-ocular (COR) and vestibulo-ocular (VOR) reflexes involve various neural substrates but are coordinated by the cerebellum and reliant upon proprioceptive feedback. Given that proprioception and cerebellar processing are impaired in SCNP, we sought to determine if COR or VOR gain is also altered. COR and VOR were assessed using an eye-tracking device in 20 SCNP (9 M and 11 F; 21.8 (SD = 2.35) years) and 17 control (7 M and 10 F; 22.40 (SD = 3.66) years) participants. COR gain (10 trials): A motorized chair rotated the trunk at a frequency of 0.04 Hz and an amplitude of 5° while participants gazed at a circular target that disappeared after three seconds. VOR gain (30 trials): Rapid bilateral head movements away from a disappearing circular target while eyes fixated on the last observed target. Independent t-tests on COR and VOR gain were performed. SCNP had a significantly larger COR gain (p = 0.006) and smaller VOR gain (p = 0.487) compared to healthy controls. The COR group differences suggest an association between proprioceptive feedback and SMI, indicating COR may be a sensitive marker of altered cerebellar processing.
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Affiliation(s)
| | - Bernadette Ann Murphy
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON L1G 0C5, Canada; (D.C.); (J.B.); (N.L.D.); (P.S.); (U.A.); (P.Y.)
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Büki B, Tamás LT, Todd CJ, Schubert MC, Migliaccio AA. Absence of a vergence-mediated vestibulo-ocular reflex gain increase does not preclude adaptation. J Vestib Res 2021; 31:109-117. [PMID: 33427708 DOI: 10.3233/ves-201560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The gain (eye-velocity/head-velocity) of the angular vestibuloocular reflex (aVOR) during head impulses can be increased while viewing near-targets and when exposed to unilateral, incremental retinal image velocity error signals. It is not clear however, whether the tonic or phasic vestibular pathways mediate these gain increases. OBJECTIVE Determine whether a shared pathway is responsible for gain enhancement between vergence and adaptation of aVOR gain in patients with unilateral vestibular hypofunction (UVH). MATERIAL AND METHODS 20 patients with UVH were examined for change in aVOR gain during a vergence task and after 15-minutes of ipsilesional incremental VOR adaptation (uIVA) using StableEyes (a device that controls a laser target as a function of head velocity) during horizontal passive head impulses. A 5 % aVOR gain increase was defined as the threshold for significant change. RESULTS 11/20 patients had >5% vergence-mediated gain increase during ipsi-lesional impulses. For uIVA, 10/20 patients had >5% ipsi-lesional gain increase. There was no correlation between the vergence-mediated gain increase and gain increase after uIVA training. CONCLUSION Vergence-enhanced and uIVA training gain increases are mediated by separate mechanisms and/or vestibular pathways (tonic/phasic). The ability to increase the aVOR gain during vergence is not prognostic for successful adaptation training.
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Affiliation(s)
- Béla Büki
- Department of Otolaryngology, Karl Landsteiner University Hospital Krems, Krems an der Donau, Austria
| | - László T Tamás
- Department of Otolaryngology, Petz Aladár Teaching Hospital, Györ, Hungary
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
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Rinaudo CN, Schubert MC, Figtree WVC, Cremer PD, Migliaccio AA. Human Vestibulo-Ocular Reflex Adaptation Reduces when Training Demand Variability Increases. J Assoc Res Otolaryngol 2020; 22:193-206. [PMID: 33090309 DOI: 10.1007/s10162-020-00775-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 10/14/2020] [Indexed: 12/18/2022] Open
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.
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Affiliation(s)
- Carlo N Rinaudo
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Phillip D Cremer
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia.,Royal North Shore Hospital, Sydney, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia. .,University of New South Wales, Sydney, NSW, 2033, Australia. .,Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA. .,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia.
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Figtree WVC, Schubert MC, Rinaudo CN, Migliaccio AA. The instantaneous training demand drives vestibulo-ocular reflex adaptation. Exp Brain Res 2020; 238:2965-2972. [PMID: 33070228 DOI: 10.1007/s00221-020-05953-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/09/2020] [Indexed: 11/28/2022]
Abstract
The vestibulo-ocular reflex (VOR) maintains stable vision during rapid head rotations by rotating the eyes in the opposite direction to the head. The latency between onset of the head rotation and onset of the eye rotation is 5-8 ms in healthy humans. However, VOR latency can be 3-4 times larger in patients treated with intra-tympanic gentamicin. A prior study showed that latency can be trained with head rotations at 0.2 Hz. We sought to determine how the VOR is affected when a delay between vestibular and visual stimuli is added during adaptation training with high-frequency head rotations (impulses), where the VOR is the main vision-stabilizing system. Using a variant of the incremental VOR adaptation technique, the delay between head rotation onset and movement onset of a visual target was gradually increased. With this training, the instantaneous VOR gain demand (= target/head velocity) varied from less than unity to greater than unity during each head impulse, albeit in a consistent and repeatable way. We measured the active and passive VOR gain and latency before and after VOR adaptation training in healthy normal subjects. There was no significant change in VOR latency across subjects; however, there was a significant decrease in VOR gain of - 6.0 ± 4.5%. These data suggest that during high-frequency head rotations delay/latency is interpreted as a changing instantaneous VOR gain demand. Although the gain demand in this study had a complex trajectory, adaptation was evident with the VOR seeming to use an average of the instantaneous gain demand.
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Affiliation(s)
- William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Carlo N Rinaudo
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia. .,University of New South Wales, Sydney, NSW, 2033, Australia. .,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA. .,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia.
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Retinal Image Slip Must Pass the Threshold for Human Vestibulo-Ocular Reflex Adaptation. J Assoc Res Otolaryngol 2020; 21:277-285. [PMID: 32232608 DOI: 10.1007/s10162-020-00751-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/12/2020] [Indexed: 10/24/2022] Open
Abstract
We sought to determine whether repeated vestibulo-ocular reflex (VOR) adaptation training to increase the VOR gain (eye/head velocity) had a lasting effect in normal subjects and whether there was a retinal image slip tolerance threshold for VOR adaptation. We used the unilateral incremental VOR adaptation technique and horizontal active (self-generated, predictable) head impulses as the vestibular stimulus. Both active and passive (imposed, unpredictable) head impulse VOR gains were measured before and after unilateral incremental VOR adaptation training. The adapting side was pseudo-randomized for left or right. We tested ten normal subjects over one block (10 sessions over 12 days) of VOR adaptation training and testing, immediately followed by a second block (5 sessions over 19 days) of testing only without training. Our findings show robust short-term VOR adaptation of ~ 10 % immediately after each 15-min training session, but that the daily pre-adaptation gain was most different on days 1 and 2, and for subsequent training days before saturating to ~ 5 % greater than the pre-adaptation gain on day 1. This increase was partially retained for 19 days after regular training stopped. The data suggest that stable vision in normal subjects is maintained when there is < 5 % deviation in VOR gain from the original baseline, which corresponds to < 9°/s retinal image slip. Below this threshold, there is poor adaptive drive to return the gain to its original baseline value.
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Rinaudo CN, Schubert MC, Figtree WVC, Todd CJ, Migliaccio AA. Human vestibulo-ocular reflex adaptation is frequency selective. J Neurophysiol 2019; 122:984-993. [PMID: 31339801 DOI: 10.1152/jn.00162.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The vestibulo-ocular reflex (VOR) is the only system that maintains stable vision during rapid head rotations. The VOR gain (eye/head velocity) can be trained to increase using a vestibular-visual mismatch stimulus. We sought to determine whether low-frequency (sinusoidal) head rotation during training leads to changes in the VOR during high-frequency head rotation testing, where the VOR is more physiologically relevant. We tested eight normal subjects over three sessions. For training protocol 1, subjects performed active sinusoidal head rotations at 1.3 Hz while tracking a laser target, whose velocity incrementally increased relative to head velocity so that the VOR gain required to stabilize the target went from 1.1 to 2 over 15 min. Protocol 2 was the same as protocol 1, except that head rotations were at 0.5 Hz. For protocol 3, head rotation frequency incrementally increased from 0.5 to 2 Hz over 15 min, while the VOR gain required to stabilize the target was kept at 2. We measured the active and passive, sinusoidal (1.3Hz) and head impulse VOR gains before and after each protocol. Sinusoidal and head impulse VOR gains increased in protocols 1 and 3; however, although the sinusoidal VOR gain increase was ~20%, the related head impulse gain increase was only ~10%. Protocol 2 resulted in no-gain adaptation. These data show human VOR adaptation is frequency selective, suggesting that if one seeks to increase the higher-frequency VOR response, i.e., where it is physiologically most relevant, then higher-frequency head movements are required during training, e.g., head impulses.NEW & NOTEWORTHY This study shows that human vestibulo-ocular reflex adaptation is frequency selective at frequencies >0.3 Hz. The VOR in response to mid- (1.3 Hz) and high-frequency (impulse) head rotations were measured before and after mid-frequency sinusoidal VOR adaptation training, revealing that the mid-frequency gain change was higher than high-frequency gain change. Thus, if one seeks to increase the higher-frequency VOR response, where it is physiologically most relevant, then higher-frequency head movements are required during training.
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Affiliation(s)
- Carlo N Rinaudo
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, Australia
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia.,Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
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Schubert MC, Migliaccio AA. New advances regarding adaptation of the vestibulo-ocular reflex. J Neurophysiol 2019; 122:644-658. [PMID: 31215309 DOI: 10.1152/jn.00729.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This is a review summarizing the development of vestibulo-ocular reflex (VOR) adaptation behavior with relevance to rehabilitation over the last 10 years and examines VOR adaptation using head-on-body rotations, specifically the influence of training target contrast, position and velocity error signal, active vs. passive head rotations, and sinusoidal vs. head impulse rotations. This review discusses optimization of the single VOR adaptation training session, consolidation between repeated training sessions, and dynamic incremental VOR adaptation. Also considered are the effects of aging and the roles of the efferent vestibular system, cerebellum, and otoliths on angular VOR adaptation. Finally, this review examines VOR adaptation findings in studies using whole body rotations.
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Affiliation(s)
- Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, Australia.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.,School of Biomedical Sciences, University of Newcastle, Newcastle, New South Wales, Australia
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Visual Performance and Perception as a Target of Saccadic Strategies in Patients With Unilateral Vestibular Loss. Ear Hear 2019; 39:1176-1186. [PMID: 29578887 DOI: 10.1097/aud.0000000000000576] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To evaluate the ability of saccadic strategies developed during vestibular compensation to reduce the effect of an impaired vestibulo-ocular reflex (VOR) on a retinal smear and image motion sensation. DESIGN Twenty patients with unilateral vestibular loss were examined with a video head impulse test before and after vestibular rehabilitation (VR) with the use of gaze stabilization and refixation saccades training. Head and eye velocity functions were processed to infer the retinal eccentricity, and through its correlation with visual acuity (VA), several measurements are proposed to evaluate the influence of VR on saccades behavior and visual performance. To isolate the effect of saccades on the findings and avoid bias because of gain differences, only patients whose VOR gain values remained unchanged after VR were included. RESULTS Improved contribution of covert saccades and reduction of overt saccades latency were measured after VR. We found significant differences when assessing both the interval less than 70% VA (50.25 ms), which is considered the limit of a moderate low vision, and less than 50% VA (39.515 ms), which is the limit for severe low vision. Time to recover a VA of 75% (near normal) was reduced in all the patients (median: 56.472 ms). CONCLUSION Despite the absence of VOR gain improvement, patients with unilateral vestibular loss are able to develop saccadic strategies that allow the shortening of the interval of retinal smear and image motion. The proposed measurements might be of use to evaluate VR outcomes and visually induced impairment.
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Incremental Vestibulo-ocular Reflex Adaptation Training Dynamically Tailored for Each Individual. J Neurol Phys Ther 2019; 43 Suppl 2:S2-S7. [DOI: 10.1097/npt.0000000000000269] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gimmon Y, Migliaccio AA, Todd CJ, Figtree WVC, Schubert MC. Simultaneous and opposing horizontal VOR adaptation in humans suggests functionally independent neural circuits. J Neurophysiol 2018; 120:1496-1504. [DOI: 10.1152/jn.00134.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The healthy vestibulo-ocular reflex (VOR) ensures that images remain on the fovea of the retina during head rotation to maintain stable vision. VOR behavior can be measured as a summation of linear and nonlinear properties although it is unknown whether asymmetric VOR adaptation can be performed synchronously in humans. The purpose of the present study is twofold. First, examine whether the right and left VOR gains can be synchronously adapted in opposing directions. Second, to investigate whether the adaptation context transfers between both sides. Three separate VOR adaptation sessions were randomized such that the VOR was adapted Up-bilaterally, Down-bilaterally, or Mixed (one side up, opposite side down). Ten healthy subjects completed the study. Subjects were tested while seated upright, 1 meter in front of a wall in complete dark. Each subject made active (self-generated) head impulse rotations for 15 min while viewing a gradually increasing amount of retinal slip. VOR training demand changed by 10% every 90 s. The VOR changed significantly for all training conditions. No significant differences in the magnitude of VOR gain changes between training conditions were found. The human VOR can be simultaneously driven in opposite directions. The similar magnitude of VOR gain changes across training conditions suggests functionally independent VOR circuits for each side of head rotation that mediate simultaneous and opposing VOR adaptations. NEW & NOTEWORTHY Our results indicate that humans have the adaptive capacity for concurrent and opposing directions of vestibulo-ocular reflex (VOR) motor learning. Context specificity of VOR adaptation is dependent on the error signal being unilateral or bilateral, which we illustrate via a lack of VOR gain transfer using unique adaptive demands.
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Affiliation(s)
- Yoav Gimmon
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Americo A. Migliaccio
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Christopher J. Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - William V. C. Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
| | - Michael C. Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Muntaseer Mahfuz M, Schubert MC, Figtree WVC, Todd CJ, Migliaccio AA. Human Vestibulo-Ocular Reflex Adaptation Training: Time Beats Quantity. J Assoc Res Otolaryngol 2018; 19:729-739. [PMID: 30251187 DOI: 10.1007/s10162-018-00689-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/04/2018] [Indexed: 01/08/2023] Open
Abstract
The vestibulo-ocular reflex (VOR) is the main gaze stabilising system during rapid head movements. The VOR is highly plastic and its gain (eye/head velocity) can be increased via training that induces an incrementally increasing retinal image slip error signal to drive VOR adaptation. Using the unilateral incremental VOR adaptation technique and horizontal active head impulses as the vestibular stimulus, we sought to determine the factors important for VOR adaptation including: the total training time, ratio and number of head impulses to each side (adapting and non-adapting sides; the adapting side was pseudo-randomised left or right) and exposure time to the visual target during each head impulse. We tested 11 normal subjects, each over 5 separate sessions and training protocols. The basic training protocol (protocol one) consisted of unilateral incremental VOR adaptation training lasting 15 min with the ratio of head impulses to each side 1:1. Each protocol varied from the basic. For protocol two, the ratio of impulses were in favour of the adapting side by 2:1. For protocol three, all head impulses were towards the adapting side and the training only lasted 7.5 min. For protocol four, all impulses were towards the adapting side and lasted 15 min. For protocol five, all head impulses were to the adapting side and the exposure time to the visual target during each impulse was doubled. We measured the active and passive VOR gains before and after the training. Albeit with small sample size, our data suggest that the total training time and the visual target exposure time for each head impulse affected adaptation, whereas the total number and repetition rate of head impulses did not. These data have implications for vestibular rehabilitation, suggesting that quality and duration of VOR adaptation exercises are more important than rapid repetition of exercises.
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Affiliation(s)
- M Muntaseer Mahfuz
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia
- University of New South Wales, Sydney, NSW, 2033, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia
- University of New South Wales, Sydney, NSW, 2033, Australia
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia
- University of New South Wales, Sydney, NSW, 2033, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia.
- University of New South Wales, Sydney, NSW, 2033, Australia.
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.
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Mahfuz MM, Schubert MC, Figtree WVC, Todd CJ, Migliaccio AA. Human Vestibulo-Ocular Reflex Adaptation: Consolidation Time Between Repeated Training Blocks Improves Retention. J Assoc Res Otolaryngol 2018; 19:601-610. [PMID: 30120621 DOI: 10.1007/s10162-018-00686-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
We sought to determine if separating vestibulo-ocular reflex (VOR) adaptation training into training blocks with a consolidation (rest) period in between repetitions would result in improved VOR adaptation and retention. Consolidation of motor learning refers to the brain benefitting from a rest period after prior exposure to motor training. The role of consolidation on VOR adaptation is unknown, though clinicians often recommend rest periods as a part of vestibular rehabilitation. The VOR is the main gaze stabilising system during rapid head movements. The VOR is highly plastic and its gain (eye/head velocity) can be increased via training that induces an incrementally increasing retinal image slip error signal to drive VOR adaptation. The unilateral incremental adaptation technique typically consists of one 15-min training block leading to an increase in VOR gain of ~ 10 % towards the training side. We tested nine normal subjects, each over six separate sessions/days. Three training protocols/sessions were 5 min each (1 × 5-min training) and three training protocols/sessions were 55 min each. Each 55-min protocol comprised 5-min training, 20-min rest, 5-min training, 20-min rest, 5-min training (3 × 5-min training). Active and passive VOR gains were measured before and after training. For training with consolidation breaks, VOR gain retention was measured over 1 h. The VOR gain increase after 1 × 5-min training was 3.1 ± 2.1 % (P < 0.01). One might expect that repeating this training three times would result in × 3 total increase of 9.3 %; however, the gain increase after 3 × 5-min training was only 7.1 ± 2.8 % (P < 0.001), suggesting that consolidation did not improve VOR adaptation for our protocols. However, retention was improved by the addition of consolidation breaks, i.e. gains did not decrease over 1 h (P = 0.43). These data suggest that for optimal retention VOR adaptation exercises should be performed over shorter repeated blocks.
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Affiliation(s)
- M Muntaseer Mahfuz
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia.
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia.
- Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.
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Todd CJ, Hubner PP, Hubner P, Schubert MC, Migliaccio AA. StableEyes—A Portable Vestibular Rehabilitation Device. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1223-1232. [DOI: 10.1109/tnsre.2018.2834964] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Mahfuz MM, Schubert MC, Figtree WVC, Todd CJ, Khan SI, Migliaccio AA. Optimal Human Passive Vestibulo-Ocular Reflex Adaptation Does Not Rely on Passive Training. J Assoc Res Otolaryngol 2018; 19:261-271. [PMID: 29464411 DOI: 10.1007/s10162-018-0657-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 02/08/2018] [Indexed: 10/18/2022] Open
Abstract
The vestibulo-ocular reflex (VOR) is the main vision-stabilising system during rapid head movements in humans. A visual-vestibular mismatch stimulus can be used to train or adapt the VOR response because it induces a retinal image slip error signal that drives VOR motor learning. The training context has been shown to affect VOR adaptation. We sought to determine whether active (self-generated) versus passive (externally imposed) head rotation vestibular training would differentially affect adaptation and short-term retention of the active and passive VOR responses. Ten subjects were tested, each over six separate 1.5-h sessions. We compared active versus passive head impulse (transient, rapid head rotations with peak velocity ~ 150 °/s) VOR adaptation training lasting 15 min with the VOR gain challenged to increment, starting at unity, by 0.1 every 90 s towards one side only (this adapting side was randomised to be either left or right). The VOR response was tested/measured in darkness at 10-min intervals, 20-min intervals, and two single 60-min interval sessions for 1 h post-training. The training was active or passive for the 10- and 20-min interval sessions, but only active for the two single 60-min interval sessions. The mean VOR response increase due to training was ~ 10 % towards the adapting side versus ~2 % towards the non-adapting side. There was no difference in VOR adaptation and retention between active and passive VOR training. The only factor to affect retention was exposure to a de-adaptation stimulus. These data suggest that active VOR adaptation training can be used to optimally adapt the passive VOR and that adaptation is completely retained over 1 h as long as there is no visual feedback signal driving de-adaptation.
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Affiliation(s)
- M Muntaseer Mahfuz
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Michael C Schubert
- Department of Otolaryngology-Head and Neck Surgery, Laboratory of Vestibular NeuroAdaptation, Johns Hopkins University, Baltimore, MD, 21205, USA.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Serajul I Khan
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, NSW, 2031, Australia. .,University of New South Wales, Sydney, NSW, 2033, Australia. .,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA. .,Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, NSW, 2031, Australia.
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Muntaseer Mahfuz M, Schubert MC, Todd CJ, Figtree WVC, Khan SI, Migliaccio AA. The Effect of Visual Contrast on Human Vestibulo-Ocular Reflex Adaptation. J Assoc Res Otolaryngol 2017; 19:113-122. [PMID: 29110135 DOI: 10.1007/s10162-017-0644-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 10/17/2017] [Indexed: 10/18/2022] Open
Abstract
The vestibulo-ocular reflex (VOR) is the main retinal image stabilising mechanism during rapid head movement. When the VOR does not stabilise the world or target image on the retina, retinal image slip occurs generating an error signal that drives the VOR response to increase or decrease until image slip is minimised, i.e. VOR adaptation occurs. Visual target contrast affects the human smooth pursuit and optokinetic reflex responses. We sought to determine if contrast also affected VOR adaptation. We tested 12 normal subjects, each over 16 separate sessions. For sessions 1-14, the ambient light level (lx) during adaptation training was as follows: dark, 0.1, 0.2, 0.3, 0.5, 0.7, 1, 2, 8, 16, 32, 64, 128 and 255 lx (light level for a typical room). For sessions 15-16, the laser target power (related to brightness) was halved with ambient light at 0 and 0.1 lx. The adaptation training lasted 15 min and consisted of left/right active head impulses. The VOR gain was challenged to increment, starting at unity, by 0.1 every 90 s for rotations to the designated adapting side and fixed at unity towards the non-adapting side. We measured active and passive VOR gains before and after adaptation training. We found that for both the active and passive VOR, there was a significant increase in gain only towards the adapting side due to training at contrast level 1.5 k and above (2 lx and below). At contrast level 261 and below (16 lx and above), adaptation training resulted in no difference between adapting and non-adapting side gains. Our modelling suggests that a contrast threshold of ~ 1000, which is 60 times higher than that provided by typical room lighting, must be surpassed for robust active and passive VOR adaptation. Our findings suggest contrast is an important factor for adaptation, which has implication for rehabilitation programs.
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Affiliation(s)
- M Muntaseer Mahfuz
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Christopher J Todd
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
| | - William V C Figtree
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia
| | - Serajul I Khan
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2033, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Cnr Barker Street & Easy Street, Randwick, Sydney, NSW, 2031, Australia. .,University of New South Wales, Sydney, NSW, 2033, Australia. .,Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, 21205, USA.
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16
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Abstract
OBJECTIVE The angular vestibulo-ocular reflex (aVOR) is known to be influenced by factors such as arousal and cognition during traditional vestibular function testing. However, the inherent variability of the aVOR to head impulse testing has not been explicitly examined. The purpose of this study was to determine the variability of the aVOR to active and passive head impulses using the gold standard scleral search coil method to record head and eye rotation. STUDY DESIGN Descriptive. SETTING Tertiary referral center. PATIENTS Twenty six healthy control subjects agreed to active and passive horizontal head impulse testing on at least two separate sessions from two unique institutions. An additional 27 individuals with cochlear implantation (CI) underwent passive horizontal and vertical semicircular canal plane head impulse testing. Test sessions were separated from 3 to 210 days in the normal subjects and from 49 to 537 days in the subjects with CI. MAIN OUTCOME MEASURE(S) Reliability of the angular VOR gain (eye velocity/head velocity) over time. RESULTS In the healthy control subjects, there was no difference in aVOR gain between right and left ears, between session one and session two, or between active (self-generated, 0.99 ± 0.08) or passive (imposed, 1.0 ± 0.08) head impulses. In the patients, we also found the aVOR gain very stable over time. However, the aVOR gains of the patients were different across the semicircular canal planes tested (p < 0.001) with the four vertical semicircular canals having lower aVOR gains than the two horizontal canals. CONCLUSIONS Our data suggest the aVOR gain is quite stable when tested across unique days in healthy controls and patients with auditory-only inner ear pathology.
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Anson ER, Kiemel T, Carey JP, Jeka JJ. Eye Movements Are Correctly Timed During Walking Despite Bilateral Vestibular Hypofunction. J Assoc Res Otolaryngol 2017; 18:591-600. [PMID: 28593438 DOI: 10.1007/s10162-017-0626-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 05/15/2017] [Indexed: 12/12/2022] Open
Abstract
Individuals with bilateral vestibular hypofunction (BVH) often report symptoms of oscillopsia (the perception that the world is bouncing or unstable) during walking. Efference copy/proprioception contributes to locomotion gaze stability in animals, sometimes inhibiting the vestibulo-ocular reflex (VOR). Gaze stability requires both adequate eye velocity and appropriate timing of eye movements. It is unknown whether eye velocity (VOR gain), timing (phase), or both are impaired for individuals with BVH during walking. Identifying the specific mechanism of impaired gaze stability can better inform rehabilitation options. Gaze stability was measured for eight individuals with severe BVH and eight healthy age- and gender-matched controls while performing a gaze fixation task during treadmill walking. Frequency response functions (FRF) were calculated from pitch eye and head velocity. A one-way ANOVA was conducted to determine group differences for each frequency bin of the FRF. Pearson correlation coefficients were calculated to determine the relationship between the real and imaginary parts of the FRF and the Oscillopsia Visual Analog Scale (oVAS) scores. Individuals with BVH demonstrated significantly lower gains than healthy controls above 0.5 Hz, but their phase was ideally compensatory for frequencies below 3 Hz. Higher oVAS scores were correlated with lower gain. Individuals with BVH demonstrated ideal timing for vertical eye movements while walking despite slower than ideal eye velocity when compared to healthy controls. Rehabilitation interventions focusing on enhancing VOR gain during walking should be developed to take advantage of the intact timing reported here. Specifically, training VOR gain while walking may reduce oscillopsia severity and improve quality of life.
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Affiliation(s)
- Eric R Anson
- Department of Otolaryngology Head and Neck Surgery and the David M. Rubinstein Hearing Center, Johns Hopkins School of Medicine, Baltimore, MD, USA. .,Johns Hopkins Outpatient Center, 601 N. Caroline Street, Ste 6030D, Baltimore, MD, 21287, USA.
| | - Tim Kiemel
- Kinesiology Department, University of Maryland, College Park, MD, USA
| | - John P Carey
- Department of Otolaryngology Head and Neck Surgery and the David M. Rubinstein Hearing Center, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - John J Jeka
- Department of Kinesiology, Temple University, Philadelphia, 19122, PA, United States.,Department of Bioengineering, Temple University, Philadelphia, PA, USA.,Shriners Hospital for Children, Philadelphia, PA, USA
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Khan SI, Hübner PP, Brichta AM, Smith DW, Migliaccio AA. Aging reduces the high-frequency and short-term adaptation of the vestibulo-ocular reflex in mice. Neurobiol Aging 2017; 51:122-131. [PMID: 28063365 DOI: 10.1016/j.neurobiolaging.2016.12.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Serajul I Khan
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia; University of New South Wales, Sydney, New South Wales, Australia
| | - Patrick P Hübner
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia; University of New South Wales, Sydney, New South Wales, Australia
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
| | - Doug W Smith
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, Australia
| | - Americo A Migliaccio
- Balance and Vision Laboratory, Neuroscience Research Australia, Sydney, New South Wales, Australia; University of New South Wales, Sydney, New South Wales, Australia; Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA.
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Anson ER, Bigelow RT, Carey JP, Xue QL, Studenski S, Schubert MC, Weber KP, Agrawal Y. Aging Increases Compensatory Saccade Amplitude in the Video Head Impulse Test. Front Neurol 2016; 7:113. [PMID: 27486430 PMCID: PMC4947583 DOI: 10.3389/fneur.2016.00113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/05/2016] [Indexed: 11/16/2022] Open
Abstract
Objective Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR) gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade characteristics varied as a function of age, independent of semicircular canal function as quantified by VOR gain. Methods Horizontal VOR gain was measured in 243 participants age 27–93 from the Baltimore Longitudinal Study of Aging using video head impulse testing. Latency and amplitude of the first saccade (either covert – occurring during head impulse, or overt – occurring following head impulse) were measured for head impulses with compensatory saccades (n = 2230 head impulses). The relationship between age and saccade latency, as well as the relationship between age and saccade amplitude, were evaluated using regression analyses adjusting for VOR gain, gender, and race. Results Older adults (mean age 75.9) made significantly larger compensatory saccades relative to younger adults (mean age 45.0). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory covert saccade (β = 0.015, p = 0.008). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory overt saccade (β = 0.02, p < 0.001). Compensatory saccade latencies did not vary significantly by age. Conclusion We observed that aging increases the compensatory catch-up saccade amplitude in healthy adults after controlling for VOR gain. Size of compensatory saccades may be useful in addition to VOR gain for characterizing vestibular function in aging adults.
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Affiliation(s)
- Eric R Anson
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - Robin T Bigelow
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - John P Carey
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - Quan-Li Xue
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Stephanie Studenski
- Longitudinal Studies Section, National Institute on Aging , Baltimore, MD , USA
| | - Michael C Schubert
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA
| | - Konrad P Weber
- Department of Neurology, University Hospital Zurich, University of Zurich, Zurich, Switzerland; Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Yuri Agrawal
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA
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