scholarly journals How do red-eyed treefrog embryos sense motion in predator attacks? Assessing the role of vestibular mechanoreception

2019 ◽  
Author(s):  
Julie Jung ◽  
Su J. Kim ◽  
Sonia M. Pérez Arias ◽  
James G. McDaniel ◽  
Karen M. Warkentin
Keyword(s):  
Vestibular System ◽  
Vestibular Function ◽  
Developmental Period ◽  
Limiting Factor ◽  
Environmental Cues ◽  
Physical Disturbance ◽  
Agalychnis Callidryas ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

ABSTRACTThe widespread ability to alter hatching timing in response to environmental cues can serve as a defense against threats to eggs. Arboreal embryos of red-eyed treefrogs, Agalychnis callidryas, hatch up to 30% prematurely to escape predation. This escape-hatching response is cued by physical disturbance of eggs during attacks, including vibrations or motion, and thus depends critically on mechanosensory ability. Predator-induced hatching appears later in development than flooding-induced, hypoxia-cued hatching; thus, its onset is not constrained by the development of hatching ability. It may, instead, reflect the development of mechanosensor function. We hypothesize that vestibular mechanoreception mediates escape-hatching in snake attacks, and that the developmental period when hatching-competent embryos fail to flee from snakes reflects a sensory constraint. We assessed the ontogenetic congruence of escape-hatching responses and an indicator of vestibular function, the vestibulo-ocular reflex (VOR), in three ways. First, we measured VOR in two developmental series of embryos 3–7 days old to compare with the published ontogeny of escape success in attacks. Second, during the period of greatest variation in VOR and escape success, we compared hatching responses and VOR across sibships. Finally, in developmental series, we compared the response of individual embryos to a simulated attack cue with their VOR. The onset of VOR and hatching responses were largely concurrent at all three scales. Moreover, latency to hatch in simulated attacks decreased with increasing VOR. These results are consistent with a key role of the vestibular system in the escape-hatching response of A. callidryas embryos to attacks.Red-eyed treefrogs’ hatching responses to predator attacks, vibration playbacks, and egg-jiggling appear when vestibular function develops. Ear development may be a key limiting factor in the onset of mechanosensory-cued hatching.

scholarly journals Finding a Balance: A Systematic Review of the Biomechanical Effects of Vestibular Prostheses on Stability in Humans

2020 ◽  
Vol 5 (2) ◽  
pp. 23
Author(s):  
Felix Haxby ◽  
Mohammad Akrami ◽  
Reza Zamani
Keyword(s):  
Vestibular System ◽  
Postural Sway ◽  
Vestibular Function ◽  
Vestibular Stimulation ◽  
Significant Heterogeneity ◽  
Vestibular Loss ◽  
Ocular Reflex ◽  
Gait Characteristics ◽  
Vestibulo Ocular Reflex ◽  
Meta Analyses

The vestibular system is located in the inner ear and is responsible for maintaining balance in humans. Bilateral vestibular dysfunction (BVD) is a disorder that adversely affects vestibular function. This results in symptoms such as postural imbalance and vertigo, increasing the incidence of falls and worsening quality of life. Current therapeutic options are often ineffective, with a focus on symptom management. Artificial stimulation of the vestibular system, via a vestibular prosthesis, is a technique being explored to restore vestibular function. This review systematically searched for literature that reported the effect of artificial vestibular stimulation on human behaviours related to balance, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. A total of 21 papers matched the inclusion criteria of the literature search conducted using the PubMed and Web of Science databases (February 2019). The populations for these studies included both healthy adults and patients with BVD. In every paper, artificial vestibular stimulation caused an improvement in certain behaviours related to balance, although the extent of the effect varied greatly. Various behaviours were measured such as the vestibulo-ocular reflex, postural sway and certain gait characteristics. Two classes of prosthesis were evaluated and both showed a significant improvement in at least one aspect of balance-related behaviour in every paper included. No adverse effects were reported for prostheses using noisy galvanic vestibular stimulation, however, prosthetic implantation sometimes caused hearing or vestibular loss. Significant heterogeneity in methodology, study population and disease aetiology were observed. The present study confirms the feasibility of vestibular implants in humans for restoring balance in controlled conditions, but more research needs to be conducted to determine their effects on balance in non-clinical settings.

Implications of Ewald's Second Law for the Evaluation of Vestibular Function

1979 ◽  
Vol 87 (4) ◽  
pp. 453-458 ◽  
Author(s):  
Young S. Kim ◽  
Clifford G. Y. Lau ◽  
Herman A. Jenkins ◽  
Vicente Honrubia
Keyword(s):  
Vestibular System ◽  
Semicircular Canal ◽  
Piecewise Linear ◽  
Vestibular Function ◽  
Second Law ◽  
Horizontal Semicircular Canal ◽  
Transfer Characteristics ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Ewald’S Second Law

The significance of Ewald's second law in the evaluation of the vestibulo-ocular reflex (VOR) was Investigated using the transfer characteristics of the vestibular and VOR systems in normal rabbits and rabbits in which one horizontal semicircular canal had been blocked. The transfer characteristics of the vestibular system were derived from the experimental results reported by Goldberg and Fernandez in 1971. A comparison was made of the properties of the bilateral and monolateral VOR systems with the predictions of a piecewise linear model of the vestibular system. The data received quantitatively collaborate the prediction of Ewald's second law as ft applies to the VOR responses.

scholarly journals A review on screening tests for vestibular disorders

2019 ◽  
Vol 122 (1) ◽  
pp. 81-92 ◽  
Author(s):  
Helen S. Cohen
Keyword(s):  
Vestibular System ◽  
Epidemiological Studies ◽  
Screening Tests ◽  
Clinical Test ◽  
Clinical Use ◽  
Ocular Reflex ◽  
System A ◽  
Screening Battery ◽  
Vestibulo Ocular Reflex ◽  
Romberg Test

Although many studies have reported on tests of the vestibular system a valid and reliable, evidence-based screening battery for easy clinical use remains elusive. Many screening tests attempt to assess the vestibulo-ocular reflex. Therefore, head shaking, the Dix-Hallpike maneuver, the supine roll test, and head impulse tests are discussed. Other tests address the spatial orientation functions of the vestibular system, such as the Bucket Test and the Fukuda Stepping test. Still, other tests are based on the known correlates with balance skills, both static and dynamic, such as tandem walking and the modern variation of the Romberg test, the modified Clinical Test of Sensory Interaction and Balance. This review provides a critical overview of the literature on some of these tests and their value for clinical use and in epidemiological studies.

Comparison of Horizontal and Vertical Dynamic Visual Acuity in Patients with Vestibular Dysfunction and Nonvestibular Dizziness

2007 ◽  
Vol 18 (03) ◽  
pp. 236-244 ◽  
Author(s):  
Richard A. Roberts ◽  
Richard E. Gans
Keyword(s):  
Visual Acuity ◽  
Head Movement ◽  
Vestibular Function ◽  
Vestibular Dysfunction ◽  
Common Symptom ◽  
Dynamic Visual Acuity ◽  
Blurred Vision ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Horizontal Head

Blurred vision with head movement is a common symptom reported by patients with vestibular dysfunction affecting the vestibulo-ocular reflex (VOR). Impaired VOR can be measured by comparing visual acuity in which there is no head movement to visual acuity obtained with head movement. A previous study demonstrated that dynamic visual acuity (DVA) testing using vertical head movement revealed deficits in impaired VOR. There is evidence that horizontal head movement is more sensitive to impaired VOR. The objective of this investigation was to compare horizontal and vertical DVA in participants with normal vestibular function (NVF), impaired vestibular function (IVF), and participants with nonvestibular dizziness (NVD). Participants performed the visual acuity task in a baseline condition with no movement and also in two dynamic conditions, horizontal head movement and vertical head movement. Horizontal DVA was twice as sensitive to impaired VOR than vertical DVA. Results suggest that horizontal volitional head movement should be incorporated into tasks measuring functional deficits of impaired VOR. Una visión borrosa con los movimientos de la cabeza es un síntoma común reportado por los pacientes con una disfunción vestibular que afecta el reflejo vestíbulo-ocular (VOR). La alteración en el VOR puede ser medida comparando la aguda visual no acompañada de movimientos de la cabeza, con la aguda visual obtenida con movimientos cefálicos. Un estudio previo demostró que la prueba de aguda visual dinámica (DVA) usando movimiento vertical de la cabeza revelaba deficiencias relacionados con un VOR alterado. Existe evidencia que el movimiento cefálico horizontal es más sensible a un VOR alterado. El objetivo de esta investigación fue comparar el DVA horizontal y vertical en participantes con funcional vestibular normal (NVF), con función vestibular alterada (IVF) y en sujetos con mareo no vestibular (NVD). Los participantes realizaron sus tareas de agudeza visual en una condición basal, sin movimiento, y también en dos condiciones dinámicas, con movimientos de cabeza horizontales y verticales. El DVA horizontal fue dos veces más sensible a un VOR alterado que el DVA vertical. Los resultados sugieren que los movimientos volitivos horizontales de la cabeza deben incorporarse en las tareas que midan deficiencias funcionales con un VOR alterado.

scholarly journals Relation Between Perception of Vertical Axis Rotation and Vestibulo-Ocular Reflex Symmetry

1992 ◽  
Vol 2 (1) ◽  
pp. 59-69
Author(s):  
Robert J. Peterka ◽  
Martha S. Benolken
Keyword(s):  
Measurement Errors ◽  
Rotational Velocity ◽  
Vestibular Function ◽  
Vertical Axis ◽  
Perceptual Bias ◽  
Common Source ◽  
Ocular Reflex ◽  
Small Constant ◽  
Vestibulo Ocular Reflex ◽  
Axis Rotation

Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in a subject’s perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function that could be of either central or peripheral origin. Deviations from perfect vestibulo-ocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. We looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflexive and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests in the same subjects of both perceptual bias and VOR symmetry were well correlated.

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