scholarly journals Exploring the biomechanical responses of human cupula by numerical analysis of temperature experiments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiang Wu ◽  
Shen Yu ◽  
Shuang Shen ◽  
Wenlong Liu
Keyword(s):  
Numerical Simulation ◽  
Elastic Modulus ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Temperature Characteristic ◽  
Slow Phase ◽  
Vestibular Diseases ◽  
Slow Phase Velocity ◽  
Biomechanical Responses ◽  
Vestibular Receptor

AbstractThe vestibular receptor of cupula acts an important role in maintaining body balance. However, the cupula buried in the semicircular canals (SCCs) will be destroyed if it is detached from the relevant environment. The mechanical properties of human cupula still remain ambiguous. In this paper, we explored the cupula responses changing with temperature by experiments and numerical simulation of SCCs model. We obtained 3 volunteers’ nystagmus induced by constant angular acceleration when the temperature of volunteers’ SCCs was 36 °C and 37 °C respectively. The slow-phase velocity of 3 volunteers decreased by approximately 3°/s when the temperature of SCCs reduced by 1 °C, which corresponded to the reduction of cupula deformation by 0.3–0.8 μm in the numerical model. Furthermore, we investigated the effects of the variation of endolymphatic properties induced by temperature reduction on cupula deformation through numerical simulation. We found that the decrease of cupula deformation was not caused by the change of endolymphatic properties, but probably by the increase of cupula’s elastic modulus. With the temperature reducing by 1 °C, the cupula’s elastic modulus may increase by 6–20%, suggesting that the stiffness of cupula is enhanced. This exploration of temperature characteristic of human cupula promotes the research of alleviating vestibular diseases.

scholarly journals Exploring the Mechanical Properties of Human Cupula by Numerical Analysis of Temperature Experiments

2021 ◽  
Author(s):  
Xiang Wu ◽  
Shen Yu ◽  
Shuang Shen ◽  
Wenlong Liu
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Elastic Modulus ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Temperature Characteristic ◽  
Slow Phase ◽  
Vestibular Diseases ◽  
Slow Phase Velocity ◽  
Vestibular Receptor

Abstract The vestibular receptor of cupula acts an important role in maintaining body balance. However, the cupula buried in the semicircular canals (SCCs) will be destroyed if it is detached from the relevant environment. The mechanical properties of human cupula still remain ambiguous. In this paper, we explored the cupula’s elastic modulus changing with temperature by experiments and numerical simulation of SCCs model. We obtained 3 volunteers’ nystagmus induced by constant angular acceleration when the temperature of volunteers’ SCCs was 36℃ and 37℃ respectively. The slow-phase velocity of 3 volunteers decreased by approximately 3°/s when the temperature of SCCs reduced by 1℃, which corresponded to the reduction of cupula deformation by 0.3–0.8 µm in the numerical model. Furthermore, we investigated the effects of the variation of endolymphatic properties induced by temperature reduction on cupula deformation through numerical simulation. We found that the decrease of cupula deformation was not caused by the change of endolymphatic properties, but probably by the increase of cupula’s elastic modulus. With the temperature reducing by 1℃, the cupula’s elastic modulus may increase by 6%-20%, suggesting that the stiffness of cupula is enhanced. This exploration of temperature characteristic of human cupula promotes the research of alleviating vestibular diseases.

Ictal downbeat nystagmus in Ménière disease

Neurology ◽  
2020 ◽  
Vol 95 (17) ◽  
pp. e2409-e2417
Author(s):  
Sun-Uk Lee ◽  
Hyo-Jung Kim ◽  
Jeong-Yoon Choi ◽  
Ji-Soo Kim
Keyword(s):  
Semicircular Canals ◽  
Vestibular Evoked Myogenic Potentials ◽  
Slow Phase ◽  
Downbeat Nystagmus ◽  
Meniere Disease ◽  
Head Impulse ◽  
Slow Phase Velocity ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Menière Disease

ObjectiveTo determine the mechanism of ictal downbeat nystagmus in Ménière disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between patients with (n = 7) and without (n = 70) downbeat nystagmus during attacks of MD.MethodsWe retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack.ResultsPure or predominant downbeat nystagmus was observed in 7 patients (9%) with unilateral MD during the attacks. All 7 patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s (median 5.4, interquartile range 3.7–8.5). All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n = 4) or in the affected ear (n = 3). Cervical VEMPs were decreased in the affected (n = 2) or both ears (n = 2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p < 0.001), while the gains for other semicircular canals did not differ between the groups.ConclusionDownbeat nystagmus may be observed during attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.

scholarly journals Alexander's Law During High-Speed, Yaw-Axis Rotation: Adaptation or Saturation?

2020 ◽  
Vol 11 ◽  
Author(s):  
Claudia Lädrach ◽  
David S. Zee ◽  
Thomas Wyss ◽  
Wilhelm Wimmer ◽  
Athanasia Korda ◽  
...  
Keyword(s):  
Eye Movements ◽  
Phase Velocity ◽  
High Speed ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Normal Subjects ◽  
Vestibular Nuclei ◽  
Slow Phase ◽  
Slow Phase Velocity ◽  
Alexander’S Law

Objective: Alexander's law (AL) states the intensity of nystagmus increases when gaze is toward the direction of the quick phase. What might be its cause? A gaze-holding neural integrator (NI) that becomes imperfect as the result of an adaptive process, or saturation in the discharge of neurons in the vestibular nuclei?Methods: We induced nystagmus in normal subjects using a rapid chair acceleration around the yaw (vertical) axis to a constant velocity of 200°/second [s] and then, 90 s later, a sudden stop to induce post-rotatory nystagmus (PRN). Subjects alternated gaze every 2 s between flashing LEDs (right/left or up/down). We calculated the change in slow-phase velocity (ΔSPV) between right and left gaze when the lateral semicircular canals (SCC) were primarily stimulated (head upright) or, with the head tilted to the side, stimulating the vertical and lateral SCC together.Results: During PRN AL occurred for horizontal eye movements with the head upright and for both horizontal and vertical components of eye movements with the head tilted. AL was apparent within just a few seconds of the chair stopping when peak SPV of PRN was reached. When slow-phase velocity of PRN faded into the range of 6–18°/s AL could no longer be demonstrated.Conclusions: Our results support the idea that AL is produced by asymmetrical responses within the vestibular nuclei impairing the NI, and not by an adaptive response that develops over time. AL was related to the predicted plane of eye rotations in the orbit based on the pattern of SCC activation.

Spatial Orientation of Caloric Nystagmus in Semicircular Canal-Plugged Monkeys

2002 ◽  
Vol 88 (2) ◽  
pp. 914-928 ◽  
Author(s):  
Yasuko Arai ◽  
Sergei B. Yakushin ◽  
Bernard Cohen ◽  
Jun-Ichi Suzuki ◽  
Theodore Raphan
Keyword(s):  
Phase Velocity ◽  
Spatial Orientation ◽  
Velocity Vector ◽  
Semicircular Canals ◽  
Velocity Storage ◽  
Slow Phase ◽  
Coordinate Frame ◽  
Slow Phase Velocity ◽  
Caloric Nystagmus ◽  
Eye Velocity

We studied caloric nystagmus before and after plugging all six semicircular canals to determine whether velocity storage contributed to the spatial orientation of caloric nystagmus. Monkeys were stimulated unilaterally with cold (≈20°C) water while upright, supine, prone, right-side down, and left-side down. The decline in the slow phase velocity vector was determined over the last 37% of the nystagmus, at a time when the response was largely due to activation of velocity storage. Before plugging, yaw components varied with the convective flow of endolymph in the lateral canals in all head orientations. Plugging blocked endolymph flow, eliminating convection currents. Despite this, caloric nystagmus was readily elicited, but the horizontal component was always toward the stimulated (ipsilateral) side, regardless of head position relative to gravity. When upright, the slow phase velocity vector was close to the yaw and spatial vertical axes. Roll components became stronger in supine and prone positions, and vertical components were enhanced in side down positions. In each case, this brought the velocity vectors toward alignment with the spatial vertical. Consistent with principles governing the orientation of velocity storage, when the yaw component of the velocity vector was positive, the cross-coupled pitch or roll components brought the vector upward in space. Conversely, when yaw eye velocity vector was downward in the head coordinate frame, i.e., negative, pitch and roll were downward in space. The data could not be modeled simply by a reduction in activity in the ipsilateral vestibular nerve, which would direct the velocity vector along the roll direction. Since there is no cross coupling from roll to yaw, velocity storage alone could not rotate the vector to fit the data. We postulated, therefore, that cooling had caused contraction of the endolymph in the plugged canals. This contraction would deflect the cupula toward the plug, simulating ampullofugal flow of endolymph. Inhibition and excitation induced by such cupula deflection fit the data well in the upright position but not in lateral or prone/supine conditions. Data fits in these positions required the addition of a spatially orientated, velocity storage component. We conclude, therefore, that three factors produce cold caloric nystagmus after canal plugging: inhibition of activity in ampullary nerves, contraction of endolymph in the stimulated canals, and orientation of eye velocity to gravity through velocity storage. Although the response to convection currents dominates the normal response to caloric stimulation, velocity storage probably also contributes to the orientation of eye velocity.

Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. II Spatiotemporal properties of the adapted slow-phase eye velocity

1996 ◽  
Vol 76 (5) ◽  
pp. 2954-2971 ◽  
Author(s):  
D. E. Angelaki ◽  
B. J. Hess
Keyword(s):  
Phase Velocity ◽  
Semicircular Canals ◽  
Response Amplitude ◽  
Slow Phase ◽  
Response Properties ◽  
Slow Phase Velocity ◽  
The Right ◽  
Head Positions ◽  
Eye Velocity ◽  
Over Time

1. The ability of the vestibuloocular reflex (VOR) to undergo adaptive modification after selective changes in the peripheral vestibular system was investigated in rhesus monkeys by recording three-dimensional eye movements before and after inactivation of selective semicircular canals. In the preceding paper we showed that the horizontal VOR gain evoked by passive yaw oscillations after lateral semicircular canal inactivation recovers gradually over time in a frequency-specific manner. Here we present the spatial tuning of the adapted slow-phase eye velocity and describe its spatiotemporal properties as a function of time after canal inactivation. 2. The spatial organization of the VOR was investigated during oscillations at different head positions in the pitch, roll, and yaw planes, as well as in the right anterior/left posterior and left anterior/right posterior canal planes. Acutely after bilateral inactivation of the lateral semicircular canals, a small horizontal response could still be elicited that peaked during rotations in pitched head positions that would maximally stimulate vertical semicircular canals. In addition, the phase of horizontal slow-phase velocity abruptly reversed through 180 degrees at positions close to upright, similarly to torsional slow-phase velocity. These spatial response properties suggest that the small, residual horizontal response components that are present acutely after plugging of both lateral canals originate from vertical semicircular canal signals. 3. As the horizontal response amplitude increased over time, consistent changes were also observed in the spatiotemporal tuning of horizontal slow-phase velocity. 1) The spatiotemporal response properties of horizontal slow-phase velocity acquired noncosine tuning characteristics, primarily in the pitch plane, in the right anterior/left posterior and left anterior/right posterior canal planes. Accordingly, horizontal response amplitude was nonzero during rotation in any head position in these planes and response phase varied significantly as a function of head orientation. 2) The peak horizontal response amplitude shifted spatially over time, such that 5–10 mo after plugging it was maximal during rotations at head positions close to upright. 4. In parallel to these unique spatiotemporal response properties characterizing the adapted horizontal VOR, torsional slow-phase velocity also exhibited small spatiotemporal changes after lateral canal inactivation that tended to precede in time the changes associated with the horizontal response components. In contrast, vertical slow-phase velocity in the plugged animals was unaltered and continued to be characterized by cosine-tuned spatial properties in three dimensions. 5. Recovery of the horizontal response gain during yaw oscillations in upright position, as well as the unique, noncosine spatiotemporal characteristics of the adapted horizontal VOR, were also observed in an animal with all but one vertical semicircular canals inactivated. There was, however, no sign of VOR gain recovery up to 2 mo after all semicircular canals were inactivated. These results suggest that the observed recovery of horizontal VOR is at least partly due to signals originating from the remaining intact vertical canal(s). Even in the presence of a single intact vertical canal, the improvement in horizontal gaze stability is at least partly restored through spatiotemporal changes in the processing of vestibuloocular signals that improve the gain and spatial tuning of horizontal VOR at the expense of temporal response properties.

Vestibular Function and Motion Sickness Susceptibility: Videonystagmographic Evidence From Oculomotor and Caloric Tests

2020 ◽  
Vol 29 (2) ◽  
pp. 188-198
Author(s):  
Cynthia G. Fowler ◽  
Margaret Dallapiazza ◽  
Kathleen Talbot Hadsell
Keyword(s):  
Phase Velocity ◽  
Motion Sickness ◽  
Repeated Measures ◽  
Short Form ◽  
Vestibular Function ◽  
Slow Phase ◽  
Test Results ◽  
Normal Range ◽  
Slow Phase Velocity ◽  
Caloric Tests

Purpose Motion sickness (MS) is a common condition that affects millions of individuals. Although the condition is common and can be debilitating, little research has focused on the vestibular function associated with susceptibility to MS. One causal theory of MS is an asymmetry of vestibular function within or between ears. The purposes of this study, therefore, were (a) to determine if the vestibular system (oculomotor and caloric tests) in videonystagmography (VNG) is associated with susceptibility to MS and (b) to determine if these tests support the theory of an asymmetry between ears associated with MS susceptibility. Method VNG was used to measure oculomotor and caloric responses. Fifty young adults were recruited; 50 completed the oculomotor tests, and 31 completed the four caloric irrigations. MS susceptibility was evaluated with the Motion Sickness Susceptibility Questionnaire–Short Form; in this study, percent susceptibility ranged from 0% to 100% in the participants. Participants were divided into three susceptibility groups (Low, Mid, and High). Repeated-measures analyses of variance and pairwise comparisons determined significance among the groups on the VNG test results. Results Oculomotor test results revealed no significant differences among the MS susceptibility groups. Caloric stimuli elicited responses that were correlated positively with susceptibility to MS. Slow-phase velocity was slowest in the Low MS group compared to the Mid and High groups. There was no significant asymmetry between ears in any of the groups. Conclusions MS susceptibility was significantly and positively correlated with caloric slow-phase velocity. Although asymmetries between ears are purported to be associated with MS, asymmetries were not evident. Susceptibility to MS may contribute to interindividual variability of caloric responses within the normal range.

Visually evoked slow eye movements, visual-vestibular interaction, and infratentorial lesions

1983 ◽  
Vol 91 (1) ◽  
pp. 76-80 ◽  
Author(s):  
Carsten Wennmo ◽  
Nils Gunnar Henriksson ◽  
Bengt Hindfelt ◽  
Ilmari PyykkÖ ◽  
MÅNs Magnusson
Keyword(s):  
Eye Movements ◽  
Phase Velocity ◽  
Brain Stem ◽  
Smooth Pursuit ◽  
Maximum Velocity ◽  
Slow Phase ◽  
Slow Phase Velocity ◽  
Velocity Gain ◽  
Visual Vestibular Interaction ◽  
Slow Eye Movements

The maximum velocity gain of smooth pursuit and optokinetic, vestibular, and optovestibular slow phases was examined in 15 patients with pontine, 10 with medullary, 10 with cerebellar, and 5 with combined cerebello — brain stem disorders. Marked dissociations were observed between smooth pursuit and optokinetic slow phases, especially in medullary disease. A cerebellar deficit enhanced slow phase velocity gain during rotation in darkness, whereas the corresponding gain during rotation in light was normal.

Numerical Simulation on the Temperature Characteristics of Indirect Air Cooling System

2015 ◽  
Vol 741 ◽  
pp. 536-540
Author(s):  
Xiao Zhi Qiu ◽  
Yan Ming Zhao ◽  
Bao Hua Huang ◽  
Wei Xu
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Cooling System ◽  
System Change ◽  
Temperature Characteristic ◽  
Air Cooling ◽  
Ansys Software ◽  
System A ◽  
Air Cooling System ◽  
Simulation Results

Based on the analysis of indirect air cooling system, a numerical simulation model of indirect air cooling system was constructed by ANSYS software. According to the different wind speed condition, the temperature characteristic of indirect air cooling system was analyzed. The simulation results show that with the increase of wind speed, the ventilation and heat release of the indirect air cooling system change greatly. It provides a theoretical basis for the design of the wind-proof device of indirect air cooling system.

Monocular Nystagmic Responses to Caloric Stimulation

1979 ◽  
Vol 88 (1) ◽  
pp. 79-85 ◽  
Author(s):  
James W. Wolfe
Keyword(s):  
Phase Velocity ◽  
Rhesus Monkeys ◽  
Cold Water ◽  
Normal Subjects ◽  
Closed Circuit ◽  
Slow Phase ◽  
Vestibular Nystagmus ◽  
Differential Activation ◽  
Slow Phase Velocity ◽  
Left And Right

Twenty-five normal subjects and 173 clinical patients received standard bithermal caloric testing. Vestibular nystagmus was evaluated for cumulative slow phase velocity from the summated horizontal eye recording and independent recording of the left and right eye. These data revealed that cold water stimulation produced more intense activation of the ipsilateral eye. Simultaneous closed-circuit video and D.C. electro-oculographic recordings from eight normal rhesus monkeys in response to cold water irrigations confirmed the fact that this stimulus leads to differential activation of the extraocular muscles. A possible explanation for this finding is discussed.

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