scholarly journals Semicircular canal plane head impulses detect absent function of individual semicircular canals

Brain ◽  
1998 ◽  
Vol 121 (4) ◽  
pp. 699-716 ◽  
Author(s):  
P. Cremer
Keyword(s):  
Semicircular Canal ◽  
Semicircular Canals ◽  
Head Impulses

Head impulses reveal loss of individual semicircular canal function

1999 ◽  
Vol 9 (3) ◽  
pp. 173-180
Author(s):  
S.T. Aw ◽  
G.M. Halmagyi ◽  
R.A. Black ◽  
I.S. Curthoys ◽  
R.A. Yavor ◽  
...  
Keyword(s):  
Semicircular Canal ◽  
Three Dimensional ◽  
Semicircular Canals ◽  
Normal Subjects ◽  
Three Dimensions ◽  
Posterior Canal ◽  
Head Velocity ◽  
Ocular Reflex ◽  
Vestibular Ocular Reflex ◽  
Head Impulses

We studied individual semicircular canal responses in three dimensions to high-acceleration head rotations (“head impulses”) in subjects with known surgical lesions of the semicircular canals, and compared their results to those of normal subjects. We found that vestibular-ocular reflex (VOR) gains at close to peak head velocity in response to yaw, pitch and roll impulses were reliable indicators of semicircular canal function. When compared to normals, lateral canal function showed a 70–80% gain at peak of yaw head velocity during ipsilesional yaw impulses. After the loss of one vertical canal function there was a 30–50% and torsional VOR gain in response to ipsilesional pitch and roll impulses respectively. Bilateral deficits in anterior or posterior canal function resulted in a 80–90% impulses, while the loss of ipsilateral anterior and posterior canal functions will result in a 80–90% ipsilesional roll impulses. Three-dimensional vector analysis and animation of the VOR responses in a unilateral vestibular deafferented subject to yaw, pitch and roll impulses further demonstrated the deficits in magnitude and direction of the VOR responses following the loss of unilateral lateral, anterior and posterior canal functions.

Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-Driven Tilt Responses

2002 ◽  
Vol 87 (3) ◽  
pp. 1635-1640 ◽  
Author(s):  
Dora E. Angelaki ◽  
Shawn D. Newlands ◽  
J. David Dickman
Keyword(s):  
Eye Movements ◽  
Semicircular Canal ◽  
Translational Motion ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Lateral Motion ◽  
Functional Interaction ◽  
Gaze Stabilization ◽  
Theoretical Evidence ◽  
Ocular System

Growing experimental and theoretical evidence suggests a functional synergy in the processing of otolith and semicircular canal signals for the generation of the vestibulo-ocular reflexes (VORs). In this study we have further tested this functional interaction by quantifying the adaptive changes in the otolith-ocular system during both rotational and translational movements after surgical inactivation of the semicircular canals. For 0.1–0.5 Hz (stimuli for which there is no recovery of responses from the plugged canals), pitch and roll VOR gains recovered during earth-horizontal (but not earth-vertical) axis rotations. Corresponding changes were also observed in eye movements elicited by translational motion (0.1–5 Hz). Specifically, torsional eye movements increased during lateral motion, whereas vertical eye movements increased during fore-aft motion. The findings indicate that otolith signals can be adapted according to a compromised strategy that leads to improved gaze stabilization during motion. Because canal-plugged animals permanently lose the ability to discriminate gravitoinertial accelerations, adapted animals can use the presence of gravity through otolith-driven tilt responses to assist gaze stabilization during earth-horizontal axis rotations.

The functional allometry of semicircular canals, fins, and body dimensions in the juvenile centrarchid fish, Lepomis gibbosus (L.)

Development ◽  
1973 ◽  
Vol 29 (3) ◽  
pp. 721-743
Author(s):  
Howard C. Howland ◽  
Joseph Masci
Keyword(s):  
Body Mass ◽  
Semicircular Canal ◽  
Semicircular Canals ◽  
Lepomis Gibbosus ◽  
Swimming Velocity ◽  
Body Dimensions ◽  
Moments Of Inertia ◽  
Significant Difference ◽  
Vertical Semicircular Canal ◽  
Vertical Semicircular Canals

1. The ontogenetic allometry of radii of curvature and the tube radii of the semicircular canals of approximately 85 juvenile (2–20 g) centrarchids of the species Lepomis gibbosus (L.) was investigated. The radii of curvature of the semicircular canals have different allometries; these arefor the anterior vertical, posterior vertical and horizontal canals respectively. The differences in growth exponents between the anterior and posterior vertical semicircular canals and between the anterior vertical and horizontal semicircular canals were statistically significant (P < 0·02 and P < 0·05 respectively). 2. Body mass and standard length were almost equally good predictors of the radii of curvature of the anterior vertical semicircular canals, but body mass was the better predictor of the radii of curvature of the posterior vertical and horizontal semicircular canals, as judged by the magnitude of the mean squares about the logarithmic regressions of radii on length and mass. 3. By measuring and estimating the area moments of the fins of the fish, the moments of inertia about various axes and the allometry of the characteristic swimming velocity of the fish, we attempted to account for the magnitude and direction of the differences in allometric growth exponents of the radii of curvature of the semicircular canals. Unexplained by our best estimate of growth exponents was the very high value observed for the posterior vertical semicircular canals. 4. No significant correlation could be found between the residuals of the major dimensions of the posterior vertical semicircular canals and those of body width or depth once the influence of body mass was removed. This finding suggests the rejection of the hypothesis that the allometry of this semicircular canal is simply correlated with overall body expansion in its plane. 5. The discrepancies between our predictions and observations of growth exponents could be explained by a gradual increase of the spring constant of the semicircular canals on the order ofthough they may also be due to other factors neglected in our model, e.g. the allometry of the added mass of the fish. 6. No evidence suggested that the shape of the semicircular canals was altered over the size range of the fish we studied. However, among the fins of the fish and the major body dimensions, only the width and the depth of the fish exhibited growth constants that did not differ significantly from each other. 7. We computed the effective toroidal radii of the non-toroidal-shaped vertical semicircular canals and found that the equivalent toroidal radius of the anterior vertical semicircular canal was consistently greater than that of the posterior vertical semicircular canal. This difference is explicable on the basis of the different moments of inertia of the animal about axes through the center of gravity and parallel to the axes of the semicircular canals. 8. We computed the allometry of the ratios R̄/r2 for all three semicircular canals and found in accordance with the prediction of Jones & Spells that they did not differ significantly from zero. 9. The allometry of the outer tube radii of the several semicircular canals was determined, and, while there was no significant difference in the growth exponents of the tube radii, it was noted that the tube radius of the horizontal semicircular canal was consistently and significantly smaller than that of the vertical semicircular canal. We suggested that this difference might be due to the broader range of frequencies that the fish experienced about its yaw axis. 10. Taken as a whole the data and calculations of this paper generally support the theory that the dimensions of the semicircular canals and the ontogenetic changes in them attune the semicircular canals to the angular frequency spectra that the fish experience about their axes.

scholarly journals Biomechanical Analysis of Angular Motion in Association with Bilateral Semicircular Canal Function

2019 ◽  
Author(s):  
Shuang Shen ◽  
Fei Zhao ◽  
Zhaoyue Chen ◽  
Qingyin Zheng ◽  
Shen Yu ◽  
...  
Keyword(s):  
Theoretical Approach ◽  
Semicircular Canal ◽  
Amplitude Ratio ◽  
Semicircular Canals ◽  
Vestibular Dysfunction ◽  
Angular Motion ◽  
Biomechanical Analysis ◽  
Fe Model ◽  
Healthy Human ◽  
Horizontal Semicircular Canal

AbstractThe aim of this study was to develop a finite element (FE) model of bilateral human semicircular canals (SCCs) in order to simulate and analyze the complex fluid-structural interaction between the endolymph and cupulae by calculating the degree of cupular expansion and the cupular deflection. The results showed that cupular deflection responses were consistent with Ewald’s II law, whereas each pair of bilateral cupulae simultaneously expanded or compressed to the same degree. In addition, both the degree of cupular expansion and cupular deflection can be expressed as the solution of forced oscillation during head sinusoidal rotation, and the amplitude of cupular expansion was approximately two times greater than that of cupular deflection. Regarding the amplitude-frequency and phase-frequency characteristics, the amplitude ratios among the horizontal semicircular canal (HC) cupular expansion, the anterior semicircular canal (AC) cupular expansion, and the posterior semicircular canal (PC) cupular expansion was constant at 1:0.82:1.62, and the phase differences among them were constant at 0 or 180 degrees at the frequencies of 0.5 to 6 Hz. However, both the amplitude ratio and the phase differencies of the cupular deflection incresed nonlinearly with the increase of frequency and tended to be constant at the frequency band between 2 and 6 Hz. The results indicate that the responses of cupular expansion might only be related to the mass and rigidity of three cupulae and the endolymph, but the responses of cupular deflection are related to the mass, rigidity, or damping of them, and these physical properties would be affected by vestibular dysfunction. Therefore, both the degree of cupular expansion and cupular deflection should be considered important mechanical variables for induced neural signals. Such a numerical model can be further built to provide a useful theoretical approach for exploring the biomechanical nature underlying vestibular dysfunction.Statement of significanceBy taking the advantage of the torsional pendulum model and the FE model, a healthy human vestibular SCCs was developed to investigate the angular motion in association with SCC function. As a result, the responses of cupular expansion and deflection during head horizontal sinusoidal rotation were analyzed for the first time, showing quantitative correlation to the eye movement due to the vestibular ocular reflex (VOR) pathway. These responses play important roles in the cupular mechano-electrical transduction process. The significant outcome derived from this study provides a useful theoretical approach for further exploring the biomechanical nature underlying vestibular dysfunction.

Horizontal Rotation Responses of Medullary Reticular Neurons in the Decerebrate Cat1

1995 ◽  
Vol 5 (3) ◽  
pp. 223-228
Author(s):  
Robert H. Schor ◽  
Bill J. Yates
Keyword(s):  
Spinal Cord ◽  
Reticular Formation ◽  
Semicircular Canal ◽  
Semicircular Canals ◽  
Response Dynamics ◽  
Medullary Reticular Formation ◽  
Decerebrate Cat ◽  
Reticular Neurons ◽  
Semicircular Canal Afferents

This study examines the response of neurons in the medullary reticular formation of the decerebrate cat to sinusoidal yaw rotations in the plane of the horizontal semicircular canals. Responsive neurons that could be antidromically activated from the spinal cord appeared to be less sensitive to the rotary stimulus than the rest of the population of responsive neurons. Most neurons had response dynamics similar to those of semicircular canal afferents.

Semicircular canal and saccular influence on the subjective visual horizontal during gondola centrifugation

1999 ◽  
Vol 9 (5) ◽  
pp. 347-357
Author(s):  
A. Tribukait
Keyword(s):  
Semicircular Canal ◽  
Semicircular Canals ◽  
Central Position ◽  
Otolith Organs ◽  
Force Vector ◽  
Time Constants ◽  
Storage Mechanism ◽  
Spatial Disorientation ◽  
Gravitoinertial Force ◽  
Vertical Semicircular Canals

Measurements of the subjective visual horizontal (SVH) were performed in 11 healthy test persons during an increase of the resultant gravitoinertial force vector in a large swing-out gondola centrifuge. Three levels of hypergravity (1.5g, 2.0g, 2.5g) were used, each with a duration of 4 minutes and with 1–2 minute pauses at 1.0g in between. The direction of the resultant gravitoinertial force vector was always parallel with the head and body length axis. Hence, there was no roll stimulus to the otolith organs. The swing-out of the gondola during acceleration, however, is sensed by the vertical semicircular canals as a change in roll head position, thus creating an otolith-semicircular canal conflict. After acceleration of the centrifuge there was a tilt of the SVH relative to the resultant gravitoinertial horizontal. This tilt gradually decayed during the 4-minute period of recordings. For a subgroup of seven test subjects who had completely normal ENG-recordings in 1g environment, the initial offset of SVH and the time constants for exponential decay were determined for each g level; initial offsets: 9 . 9 ∘ (1.5g), 7 . 7 ∘ (2.0g), 6 . 1 ∘ (2.5g); time constants: 89s (1.5g), 74s (2.0g), 37s (2.5g). The offset of SVH is interpreted as being the result of mainly the stimulus to the vertical semicircular canals during acceleration of the centrifuge. The slow decay, however, does not correspond to the dynamics of the semicircular canal system, and is suggested to reflect some kind of central position storage mechanism. A smaller offset and more rapid decay for the higher g loads may be explained by an increasing dominance of graviceptive input, presumably from the saccules. In conclusion, these results might suggest the role of the vertical semicircular canals as well as the sacculus in the formation of SVH. They may also have relevance with regard to the spatial disorientation problem in aviators.

Role of Muscle Pulleys in Producing Eye Position-Dependence in the Angular Vestibuloocular Reflex: A Model-Based Study

2000 ◽  
Vol 84 (2) ◽  
pp. 639-650 ◽  
Author(s):  
Matthew J. Thurtell ◽  
Mikhail Kunin ◽  
Theodore Raphan
Keyword(s):  
Initial Period ◽  
Semicircular Canals ◽  
Pulse Signal ◽  
Eye Position ◽  
Vestibuloocular Reflex ◽  
Primary Position ◽  
Head Velocity ◽  
Model Based ◽  
Head Impulses ◽  
Eye Velocity

It is well established that the head and eye velocity axes do not always align during compensatory vestibular slow phases. It has been shown that the eye velocity axis systematically tilts away from the head velocity axis in a manner that is dependent on eye-in-head position. The mechanisms responsible for producing these axis tilts are unclear. In this model-based study, we aimed to determine whether muscle pulleys could be involved in bringing about these phenomena. The model presented incorporates semicircular canals, central vestibular pathways, and an ocular motor plant with pulleys. The pulleys were modeled so that they brought about a rotation of the torque axes of the extraocular muscles that was a fraction of the angle of eye deviation from primary position. The degree to which the pulleys rotated the torque axes was altered by means of a pulley coefficient. Model input was head velocity and initial eye position data from passive and active yaw head impulses with fixation at 0°, 20° up and 20° down, obtained from a previous experiment. The optimal pulley coefficient required to fit the data was determined by calculating the mean square error between data and model predictions of torsional eye velocity. For active head impulses, the optimal pulley coefficient varied considerably between subjects. The median optimal pulley coefficient was found to be 0.5, the pulley coefficient required for producing saccades that perfectly obey Listing's law when using a two-dimensional saccadic pulse signal. The model predicted the direction of the axis tilts observed in response to passive head impulses from 50 ms after onset. During passive head impulses, the median optimal pulley coefficient was found to be 0.21, when roll gain was fixed at 0.7. The model did not accurately predict the alignment of the eye and head velocity axes that was observed early in the response to passive head impulses. We found that this alignment could be well predicted if the roll gain of the angular vestibuloocular reflex was modified during the initial period of the response, while pulley coefficient was maintained at 0.5. Hence a roll gain modification allows stabilization of the retinal image without requiring a change in the pulley effect. Our results therefore indicate that the eye position–dependent velocity axis tilts could arise due to the effects of the pulleys and that a roll gain modification in the central vestibular structures may be responsible for countering the pulley effect.

Multiple dehiscence of semicircular canals

2006 ◽  
Vol 121 (1) ◽  
pp. 80-82 ◽  
Author(s):  
D Rajenderkumar ◽  
K L Farrell ◽  
R M Alles ◽  
L Savy
Keyword(s):  
Current Literature ◽  
Semicircular Canal ◽  
Semicircular Canals ◽  
Superior Semicircular Canal ◽  
Uncommon Condition

Dehiscence of the semicircular canal is an uncommon condition and has been reported to involve the roof of the superior semicircular canal. We describe a case with dehiscence of four semicircular canals and in areas not involving the roof of the superior semicircular canal. Features that assist the diagnosis of this condition are reviewed, along with the current literature.

scholarly journals Pulsed Infrared Stimulation of Vertical Semicircular Canals Evokes Cardiovascular Changes in the Rat

2021 ◽  
Vol 12 ◽  
Author(s):  
Darrian Rice ◽  
Giorgio P. Martinelli ◽  
Weitao Jiang ◽  
Gay R. Holstein ◽  
Suhrud M. Rajguru
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Semicircular Canal ◽  
Parasympathetic Nervous System ◽  
Semicircular Canals ◽  
Whole Body ◽  
Experimental Session ◽  
Otolith Organs ◽  
Vertical Semicircular Canals ◽  
Stimulation Of

A variety of stimuli activating vestibular end organs, including sinusoidal galvanic vestibular stimulation, whole body rotation and tilt, and head flexion have been shown to evoke significant changes in blood pressure (BP) and heart rate (HR). While a role for the vertical semicircular canals in altering autonomic activity has been hypothesized, studies to-date attribute the evoked BP and HR responses to the otolith organs. The present study determined whether unilateral activation of the posterior (PC) or anterior (AC) semicircular canal is sufficient to elicit changes in BP and/or HR. The study employed frequency-modulated pulsed infrared radiation (IR: 1,863 nm) directed via optical fibers to PC or AC of adult male Long-Evans rats. BP and HR changes were detected using a small-animal single pressure telemetry device implanted in the femoral artery. Eye movements evoked during IR of the vestibular endorgans were used to confirm the stimulation site. We found that sinusoidal IR delivered to either PC or AC elicited a rapid decrease in BP and HR followed by a stimulation frequency-matched modulation. The magnitude of the initial decrements in HR and BP did not correlate with the energy of the suprathreshold stimulus. This response pattern was consistent across multiple trials within an experimental session, replicable, and in most animals showed no evidence of habituation or an additive effect. Frequency modulated electrical current delivered to the PC and IR stimulation of the AC, caused decrements in HR and BP that resembled those evoked by IR of the PC. Frequency domain heart rate variability assessment revealed that, in most subjects, IR stimulation increased the low frequency (LF) component and decreased the high frequency (HF) component, resulting in an increase in the LF/HF ratio. This ratio estimates the relative contributions of sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) activities. An injection of atropine, a muscarinic cholinergic receptor antagonist, diminished the IR evoked changes in HR, while the non-selective beta blocker propranolol eliminated changes in both HR and BP. This study provides direct evidence that activation of a single vertical semicircular canal is sufficient to activate and modulate central pathways that control HR and BP.

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