scholarly journals The Mechanics of the Growing Semicircular Canal

1973 ◽  
Vol 58 (2) ◽  
pp. 351-366
Author(s):  
J. H. TEN KATE
Keyword(s):  
Angular Velocity ◽  
Body Length ◽  
Semicircular Canal ◽  
Angular Acceleration ◽  
Radius Of Curvature ◽  
Sensitivity Factor ◽  
Growth Effects ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Factor G

1. The motion of the endolymph in the semicircular canal is described with the aid of a linear second-order system, comprising the applied angular acceleration and the linear displacement, the linear velocity and the linear acceleration of the endolymph. 2. A sensitivity factor G for angular velocity is derived and expressed in the dimensions of the semicircular canal. 3. The sensitivity factor G of the semicircular canal proves to be consistent with the equivalent sensitivity factor of a more sophisticated hydrodynamic model of these canals. 4. The sensitivity of the growing semicircular canal is defined to be G/hc2, independent of the pike's size. Threshold angular velocities for the vestibulo-ocular reflex of 27 pike between 4 and 50 cm bodylength are in agreement with this assumption. 5. At threshold stimulation with an angular velocity of 2°/sec the radius of curvature Rc of the cupula is calculated to be 220±48 cm. 6. At the threshold angular velocity γ = 2°/sec the deviation of sensory hairs 5 µm long is assessed to be between 0.06 Å and 1 Å. 7. Young's modulus of elasticity for the cupular substance is found to be between 0.35 x 103 dyne/cm2 and 1.85 x 103 dyne/cm2 (on the basis of a circular bending for the cupula). 8. Characteristics of the model of the growing semicircular canal are calculated for pike with body length between 5 and 100 cm. 9. Observed growth effects of the pike's vestibulo-ocular reflex arc are correlated to the growth effects calculated on basis of the model for the growing semicircular canal. 10. The pike possesses the same degree of vestibulo-ocular compensation in the high-frequency range (2 radians/sec ≤ ω < 7 radians/sec) of angular oscillations during its whole life (11 observations of pike of body length 4-56 cm).

Vestibulo-Ocular Response of Human Subjects Seated in a Pivoting Support System During 3 Gz Centrifuge Stimulation

1995 ◽  
Vol 5 (5) ◽  
pp. 331-347
Author(s):  
B.J. McGrath ◽  
F.E. Guedry ◽  
C.M. Oman ◽  
A.H. Rupert
Keyword(s):  
Angular Velocity ◽  
Spatial Orientation ◽  
Human Subjects ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Slow Phase ◽  
Ocular Reflex ◽  
Vertical Linear Acceleration ◽  
Acceleration And Deceleration ◽  
Vestibulo Ocular Reflex

The vestibulo-ocular reflex (VOR) and spatial orientation perceptions were recorded in 15 subjects during 3 Gz centrifuge runs. These data were obtained to study two issues: (1) to gain insight into reports of asymmetrical disorientation and disturbance during acceleration and deceleration of centrifuge runs like those used to train pilots on the procedures to counteract G-induced loss of consciousness (G-LOC); (2) to study the effects of sustained vertical linear acceleration on the vestibular system. The centrifuge angular velocity profile consisted of a 19 s angular acceleration to 3 Gz that was sustained for 5 min during a period of constant angular velocity, and a 19 s deceleration to 1 Gz. The runs were repeated three times with the subject facing the motion and three times with the subject’s back to the motion. The VOR and spatial orientation perceptions from the eight subjects who completed all six runs were analyzed. The total VOR response during acceleration and deceleration was composed of interacting angular (AVOR) and linear components (LVOR). Asymmetries in pitch orientation perception between centrifuge acceleration and deceleration were not matched by asymmetries in the total VOR slow phase velocity. During the constant velocity high-G phase of the run, sustained up-beating LVOR (Lz nystagmus) was present in 14 of the 15 subjects. Significant individual differences in Lz nystagmus were found, but the maximum Lz response in our 15 subjects was probably of insufficient magnitude to degrade visual scan of cockpit instruments. Mean magnitudes ranged from 0 to 10 deg/s at 90 s from onset of centrifuge run.

Torsional vestibulo-ocular reflex during whole-body oscillation in the upright and the supine position: II. Responses in patients after vestibular neuritis

2004 ◽  
Vol 14 (4) ◽  
pp. 353-359
Author(s):  
A. Schmid-Priscoveanu ◽  
A.A. Kori ◽  
D. Straumann
Keyword(s):  
Supine Position ◽  
Semicircular Canal ◽  
Low Frequency ◽  
Phase Changes ◽  
Vestibular Neuritis ◽  
Whole Body ◽  
Healthy Human ◽  
Phase Lead ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

In a recent study we demonstrated that otolith input modifies the torsional angular vestibulo-ocular reflex (torVOR) of healthy human subjects: Compared to turntable oscillations in supine position, oscillations in upright position increased the gain of torVOR by 0.1 and cancelled the phase lead originating from low-frequency semicircular canal signals. We asked whether these otolith-related changes of torVOR are still present in patients after vestibular neuritis (VN). Eight patients were sinusoidally oscillated about their naso-occipital axis in supine (canal-only stimulation) and upright (canal-and-otolith stimulation) position. Three-dimensional eye movements were recorded with dual search coils. The patients showed similar otolith-related gain and phase changes of the torVOR as healthy subjects: the gain increased by about 0.1 (p < 0.05) and the low-frequency phase lead from semicircular canal signals was abolished. These results indicate that otolith function after VN is still sufficient to interact with semicircular canal signals to optimize torsional gaze stabilization when the head is upright.

The human horizontal vestibulo-ocular reflex during combined linear and angular acceleration

1997 ◽  
Vol 114 (2) ◽  
pp. 304-320 ◽  
Author(s):  
Benjamin T. Crane ◽  
Erik S. Viirre ◽  
J. L. Demer
Keyword(s):  
Angular Acceleration ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

The click-evoked vestibulo-ocular reflex in superior semicircular canal dehiscence

Neurology ◽  
2003 ◽  
Vol 60 (7) ◽  
pp. 1172-1175 ◽  
Author(s):  
G.M. Halmagyi ◽  
L. A. McGarvie ◽  
S. T. Aw ◽  
R. A. Yavor ◽  
M. J. Todd
Keyword(s):  
Semicircular Canal ◽  
Superior Semicircular Canal Dehiscence ◽  
Superior Semicircular Canal ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Canal Dehiscence

Click-evoked vestibulo-ocular reflex

Neurology ◽  
2006 ◽  
Vol 66 (7) ◽  
pp. 1079-1087 ◽  
Author(s):  
S. T. Aw ◽  
M. J. Todd ◽  
G. E. Aw ◽  
J. S. Magnussen ◽  
I. S. Curthoys ◽  
...  
Keyword(s):  
Semicircular Canal ◽  
Rotation Axis ◽  
Head Orientation ◽  
Superior Canal Dehiscence ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Vestibulo Ocular Reflex ◽  
Low Threshold ◽  
Canal Dehiscence ◽  
Click Polarity

Background: An enlarged, low-threshold click-evoked vestibulo-ocular reflex (VOR) can be averaged from the vertical electro-oculogram in a superior canal dehiscence (SCD), a temporal bone defect between the superior semicircular canal and middle cranial fossa.Objective: To determine the origin and quantitative stimulus–response properties of the click-evoked VOR.Methods: Three-dimensional, binocular eye movements evoked by air-conducted 100-microsecond clicks (110 dB normal hearing level, 145 dB sound pressure level, 2 Hz) were measured with dual-search coils in 11 healthy subjects and 19 patients with SCD confirmed by CT imaging. Thresholds were established by decrementing loudness from 110 dB to 70 dB in 10-dB steps. Eye rotation axis of click-evoked VOR computed by vector analysis was referenced to known semicircular canal planes. Response characteristics were investigated with regard to enhancement using trains of three to seven clicks with 1-millisecond interclick intervals, visual fixation, head orientation, click polarity, and stimulation frequency (2 to 15 Hz).Results: In subjects and SCD patients, click-evoked VOR comprised upward, contraversive-torsional eye rotations with onset latency of approximately 9 milliseconds. Its eye rotation axis aligned with the superior canal axis, suggesting activation of superior canal receptors. In subjects, the amplitude was less than 0.01°, and the magnitude was less than 3°/second; in SCD, the amplitude was up to 60 times larger at 0.66°, and its magnitude was between 5 and 92°/second, with a threshold 10 to 40 dB below normal (110 dB). The click-evoked VOR magnitude was enhanced approximately 2.5 times with trains of five clicks but was unaffected by head orientation, visual fixation, click polarity, and stimulation frequency up to 10 Hz; it was also present on the surface electro-oculogram.Conclusion: In superior canal dehiscence, clicks evoked a high-magnitude, low-threshold, 9-millisecond-latency vestibulo-ocular reflex that aligns with the superior canal, suggesting superior canal receptor hypersensitivity to sound.

The human horizontal vestibulo-ocular reflex during combined linear and angular acceleration

1997 ◽  
Vol 117 (1) ◽  
pp. 178-178
Author(s):  
Benjamin T. Crane ◽  
Erik S. Viirre ◽  
J. L. Demer
Keyword(s):  
Angular Acceleration ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

Some Dimensions of the Angular Acceleration Receptor Systems of Cephalopods

1984 ◽  
Vol 64 (1) ◽  
pp. 55-79 ◽  
Author(s):  
Linda Maddock ◽  
J. Z. Young
Keyword(s):  
Angular Velocity ◽  
Frequency Band ◽  
Deep Sea ◽  
Horizontal Plane ◽  
Angular Acceleration ◽  
The Body ◽  
The Other ◽  
Radius Of Curvature ◽  
Internal Radius ◽  
Neutrally Buoyant

The shapes and dimensions of the statocysts of cephalopods have been measured and compared with the semi-circular canals of vertebrates. The cavities grow much more slowly than the body as a whole, but there are knobs, anticristae, which restrict the cavity, and these grow relatively faster. This ensures that the flow of endolymph across the cupulae remains small. Where the liquid is constrained within canals the radius of curvature of the whole canal, R, is similar to that of fishes, whereas its internal radius, r, is twice as large in non-buoyant and four times as large in deep-sea buoyant cephalopods as in fishes of similar size. As in fishes the restriction is greatest in the horizontal plane, providing for operation at higher frequencies in turning about the yaw axis.The statocysts of seven species of Loligo all have similar proportions. The largest individuals of 16 genera of non-buoyant squids also have these same relative dimensions. The statocyst of Sepia is more like that of non-buoyant than of other buoyant cephalopods but yet differs significantly from that of Loligo at all sizes. On the other hand 21 genera of squids known to be neutrally buoyant are very different. Their statocysts are often larger than in the non-buoyant forms and there is less restriction of the cavity by anticristae. The greater flow of endolymph acting across the cupulae presumably provides greater sensitivity at the lower frequencies of turning of these deep-sea animals.The data suggest that the cristae of the cephalopod statocyst may operate in the frequency band where they act as angular accelerometers whereas the vertebrate semi-circular canals operate at higher frequencies as angular velocity meters.

Response of the Human Vestibulo-Ocular Reflex System to Constant Angular Acceleration

ORL ◽  
1983 ◽  
Vol 45 (3) ◽  
pp. 130-142 ◽  
Author(s):  
L.J.J.M. Boumans ◽  
M. Rodenburg ◽  
A.J.J. Maas
Keyword(s):  
Angular Acceleration ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Reflex System
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