scholarly journals Determinants of Spatial and Temporal Coding by Semicircular Canal Afferents

2005 ◽  
Vol 93 (5) ◽  
pp. 2359-2370 ◽  
Author(s):  
Stephen M. Highstein ◽  
Richard D. Rabbitt ◽  
Gay R. Holstein ◽  
Richard D. Boyle
Keyword(s):  
Angular Velocity ◽  
Hair Cell ◽  
Time Integration ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Ionic Currents ◽  
Temporal Coding ◽  
Corner Frequency ◽  
Low Frequencies ◽  
Afferent Fibers

The vestibular semicircular canals are internal sensors that signal the magnitude, direction, and temporal properties of angular head motion. Fluid mechanics within the 3-canal labyrinth code the direction of movement and integrate angular acceleration stimuli over time. Directional coding is accomplished by decomposition of complex angular accelerations into 3 biomechanical components—one component exciting each of the 3 ampullary organs and associated afferent nerve bundles separately. For low-frequency angular motion stimuli, fluid displacement within each canal is proportional to angular acceleration. At higher frequencies, above the lower corner frequency, real-time integration is accomplished by viscous forces arising from the movement of fluid within the slender lumen of each canal. This results in angular velocity sensitive fluid displacements. Reflecting this, a subset of afferent fibers indeed report angular acceleration to the brain for low frequencies of head movement and report angular velocity for higher frequencies. However, a substantial number of afferent fibers also report angular acceleration, or a signal between acceleration and velocity, even at frequencies where the endolymph displacement is known to follow angular head velocity. These non-velocity-sensitive afferent signals cannot be attributed to canal biomechanics alone. The responses of non-velocity-sensitive cells include a mathematical differentiation (first-order or fractional) imparted by hair-cell and/or afferent complexes. This mathematical differentiation from velocity to acceleration cannot be attributed to hair cell ionic currents, but occurs as a result of the dynamics of synaptic transmission between hair cells and their primary afferent fibers. The evidence for this conclusion is reviewed below.

scholarly journals Rotation Experiments with Blind Goldfish

1957 ◽  
Vol 34 (2) ◽  
pp. 259-275
Author(s):  
F. R. HARDEN JONES
Keyword(s):  
Angular Velocity ◽  
Centrifugal Force ◽  
Constant Velocity ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Mechanical Stimulus ◽  
Constant Angular Velocity ◽  
Water Current

1. Blind goldfish react to rotation at constant angular velocity by swimming against the direction of rotation so as to maintain, on the whole, the same orientation or bearing relative to earth. 2. The lowest angular velocity to which the fish appear to react is below 10°/sec. For the best performers the threshold is about 3°/sec. 3. The stimulus to which the fish responds is not one of contact, initial swirl or water current (when the turntable gets under way), variation in turntable velocity or centrifugal force. 4. The semicircular canals are probably the sensory channels through which a fish is able to detect rotation at constant velocity and the mechanical stimulus to which it responds is probably an angular acceleration. How the fish becomes aware of angular accelerations during rotation at constant velocity is not yet understood.

Kinematics of rotation in place during defense turning in the crayfish Procambarus clarkii

2001 ◽  
Vol 204 (3) ◽  
pp. 471-486 ◽  
Author(s):  
N. Copp ◽  
M. Jamon
Keyword(s):  
Angular Velocity ◽  
Procambarus Clarkii ◽  
Angular Acceleration ◽  
The Body ◽  
Simple Variation ◽  
Freely Behaving ◽  
Leg Motion ◽  
Two Phases ◽  
Analysis System ◽  
Final Orientation

The kinematic patterns of defense turning behavior in freely behaving specimens of the crayfish Procambarus clarkii were investigated with the aid of a video-analysis system. Movements of the body and all pereiopods, except the chelipeds, were analyzed. Because this behavior approximates to a rotation in place, this analysis extends previous studies on straight and curve walking in crustaceans. Specimens of P. clarkii responded to a tactile stimulus on a walking leg by turning accurately to face the source of the stimulation. Angular velocity profiles of the movement of the animal's carapace suggest that defense turn responses are executed in two phases: an initial stereotyped phase, in which the body twists on its legs and undergoes a rapid angular acceleration, followed by a more erratic phase of generally decreasing angular velocity that leads to the final orientation. Comparisons of contralateral members of each pair of legs reveal that defense turns are affected by changes in step geometry, rather than by changes in the timing parameters of leg motion, although inner legs 3 and 4 tend to take more steps than their outer counterparts during the course of a response. During the initial phase, outer legs 3 and 4 exhibit larger stance amplitudes than their inner partners, and all the outer legs produce larger stance amplitudes than their inner counterparts during the second stage of the response. Also, the net vectors of the initial stances, particularly, are angled with respect to the body, with the power strokes of the inner legs produced during promotion and those of the outer legs produced during remotion. Unlike straight and curve walking in the crayfish, there is no discernible pattern of contralateral leg coordination during defense turns. Similarities and differences between defense turns and curve walking are discussed. It is apparent that rotation in place, as in defense turns, is not a simple variation on straight or curve walking but a distinct locomotor pattern.

Mathematical Models of Control Systems of Angular Speed of Steam Turbines for Diagnostic Tests of Automatic and Mechatronic Devices

2013 ◽  
Vol 198 ◽  
pp. 519-524
Author(s):  
Grzegorz Redlarski ◽  
Janusz Piechocki ◽  
Mariusz Dąbkowski
Keyword(s):  
Angular Velocity ◽  
Power System ◽  
Control Systems ◽  
Working Conditions ◽  
Diagnostic Tests ◽  
Angular Acceleration ◽  
Angular Speed ◽  
Physical Parameters ◽  
Steam Turbines ◽  
Parallel Operation

In many automatics and mechatronics systems accurate modeling of several physical processes is needed. In power system, one of these is the process of control of angular velocity of power blocks during their connection to parallel operation. This process is extremely dynamic and the response of control system results from continuous changes in many physical parameters (temperature, pressure and flow of the working medium, etc.). An accuracy of modeling this process influences int. al. on: quality of the automatic synchronizer diagnostic tests in the laboratory, as well as the possibility of evaluation of prospects for connection process in the power system, without the automatic synchronizer [. Automatics systems used for research and diagnosis of automatic synchronizers are known in the literature as and simulators [2, . To impose similar to real working conditions, it is required to implement an appropriate models of control systems. One of such models, representative for the larger population of objects, is model of control systems of angular velocity. Currently used models, e.g. [3, 4, 5, , allow to approximate the response of real object, or to impose higher restricted conditions of work, for example: related to the angular acceleration dω/dt, the size of overshoots and decay time of transitional characteristics, while accurate modeling the real working conditions using them is not possible. Furthermore, their use requires knowledge of the (often difficult to access) object parameters and time-consuming selection of manual procedure of certain substitute settings, occurring in these models. To eliminate inconveniences mentioned above, in the paper the proposal and mathematical modeling procedure is presented, which allow to obtain much more accurate transitional characteristics of real objects.

Gyroscope-Free Link Parameter Measurement Using Accelerometers and Magnetometer

2014 ◽  
Author(s):  
Vishesh Vikas ◽  
Carl D. Crane
Keyword(s):  
Angular Velocity ◽  
Joint Angle ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Parameter Measurement ◽  
Joint Angles ◽  
Symmetry Constraint ◽  
Estimation Techniques ◽  
Angular Velocities ◽  
Joint Parameters

Knowledge of joint angles, angular velocities is essential for control of link mechanisms and robots. The estimation of joint angles and angular velocity is performed using combination of inertial sensors (accelerometers and gyroscopes) which are contactless and flexible at point of application. Different estimation techniques are used to fuse data from different inertial sensors. Bio-inspired sensors using symmetrically placed multiple inertial sensors are capable of instantaneously measuring joint parameters (joint angle, angular velocities and angular acceleration) without use of any estimation techniques. Calibration of inertial sensors is easier and more reliable for accelerometers as compared to gyroscopes. The research presents gyroscope-less, multiple accelerometer and magnetometer based sensors capable of measuring (not estimating) joint parameters. The contribution of the improved sensor are four-fold. Firstly, the inertial sensors are devoid of symmetry constraint unlike the previously researched bio-inspired sensors. However, the accelerometer are non-coplanarly placed. Secondly, the accelerometer-magnetometer combination sensor allows for calculation of a unique rotation matrix between two link joined by any kind of joint. Thirdly, the sensors are easier to calibrate as they consist only of accelerometers. Finally, the sensors allow for calculation of angular velocity and angular acceleration without use of gyroscopes.

WDR1 expression in the normal and noise-damaged chick vestibule

2008 ◽  
Vol 17 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Myung Whan Suh ◽  
Dong Hoon Shin ◽  
Ho Sun Lee ◽  
Ji Yeong Park ◽  
Chong Sun Kim ◽  
...  
Keyword(s):  
Hair Cell ◽  
Semicircular Canals ◽  
Normal Group ◽  
Hair Cell Regeneration ◽  
Rt Pcr ◽  
Wd40 Repeat ◽  
Cochlear Hair Cells ◽  
Repeat Protein ◽  
Acoustic Overstimulation ◽  
Before And After

Unlike mammals, avian cochlear hair cells can regenerate after acoustic overstimulation. The WDR1 gene is one of the genes suspected to play an important role in this difference. In an earlier study, we found that the WDR1 gene is over-expressed in the chick cochlea after acoustic overstimulation. The aim of this study was to compare the expression of WDR1 before and after acoustic overstimulation in the chick vestibule. Seven-day-old chicks were divided into three groups: normal group, damage group, and regeneration group. The damage and regeneration group was exposed to 120 dB SPL white noise for 5–6 hours. The damage group was euthanized shortly after the impulse, but the regeneration group was allowed to recover for 2 days. The utricle, saccule, and the three ampullae of each semicircular canal were dissected and immunohistochemically stained with anti-WD40 repeat protein 1 antibody. For quantitative analysis, immunoreactive densities were measured and quantitative real-time RT PCR was performed. WD40 repeat protein 1 expression was elevated in all the semicircular canals and utricle, two days after an acoustic overstimulation (P = 0.001). WDR1 mRNA expression was 1.34 times higher in the regeneration group compared to the normal group, but it was not statistically significant. Exceptionally, WD40 repeat protein 1 expression did not increase in the saccule of the regeneration group. Elevated WDR1 expression in the avian vestibule may have a role in the hair cell regenerating ability as in the avian cochlea. A similar mechanism of hair cell regeneration may exist in the avian cochlea and vestibule.

Asymmetric Integration Recorded From Vestibular-Only Cells in Response to Position Transients

2002 ◽  
Vol 88 (4) ◽  
pp. 2104-2113 ◽  
Author(s):  
Sam Musallam ◽  
R. D. Tomlinson
Keyword(s):  
Angular Velocity ◽  
Firing Rate ◽  
Vestibular Nucleus ◽  
Semicircular Canals ◽  
Excitatory Postsynaptic Potential ◽  
Otolith Organs ◽  
Neural Integrator ◽  
Postsynaptic Potential ◽  
Translational Acceleration ◽  
Vestibular Pathways

Angular and translational accelerations excite the semicircular canals and otolith organs, respectively. While canal afferents approximately encode head angular velocity due to the biomechanical integration performed by the canals, otolith signals have been found to approximate head translational acceleration. Because central vestibular pathways require velocity and position signals for their operation, the question has been raised as to how the integration of the otolith signals is accomplished. We recorded responses from 62 vestibular-only neurons in the vestibular nucleus of two monkeys to position transients in the naso-occipital and interaural orientations and varying directions in between. Responses to the transients were directionally asymmetric; one direction elicited a response that approximated the integral of the acceleration of the stimulus. In the opposite direction, the cells simply encoded the acceleration of the motion. We present a model that suggests that a neural integrator is not needed. Instead a neuron with a long membrane time constant and an excitatory postsynaptic potential duration that increases with the firing rate of the presynaptic cell can emulate the observed behavior.

Research on the Kinematic Characteristics of Digging Tree Mechanism of Tree Transplanter

2014 ◽  
Vol 620 ◽  
pp. 381-387 ◽  
Author(s):  
De Jin Zhao ◽  
Yan Ling Guo ◽  
Wen Long Song
Keyword(s):  
Angular Velocity ◽  
Dynamic Simulation ◽  
Analytical Method ◽  
Angular Acceleration ◽  
Hydraulic Cylinder ◽  
Matlab Software ◽  
Kinematic Characteristics ◽  
Adams Software ◽  
Model File

In order to study the kinematic characteristics of the tree transplanter and the hydraulic cylinder, this paper established the model of the tree transplanter with the Cero2.0 software and analyzed kinematic characteristics of the hydraulic cylinder and the tree spade when the tree spade was driven by the hydraulic cylinder with the analytical method. The dynamic simulation curves of the angular velocity and the angular acceleration of the hydraulic cylinder can be obtained with the Matlab software. Then the appropriate format model file was imported into Adams software, and the angular velocity and the angular acceleration of the hydraulic cylinder were analyzed and simulated in Adams. The obtained curves in Adams software were compared with the curves obtained with the Matlab using the analytical method. The result revealed that the trends of the two ways simulation curves were consistent. The comparison showed the analytical method of kinematic characteristics of the tree transplanter and hydraulic cylinder was correct.

Kinematic Analysis of Mechanisms by the Complex Conjugate Exponential Method

1975 ◽  
Vol 97 (3) ◽  
pp. 795-799 ◽  
Author(s):  
J. A. Smith
Keyword(s):  
Angular Velocity ◽  
Closed Form ◽  
Kinematic Analysis ◽  
Angular Position ◽  
Angular Acceleration ◽  
Dynamic State ◽  
Complex Conjugate ◽  
Iterative Techniques ◽  
Numerical Example ◽  
Exponential Method

Generalized closed-form expressions are presented for the analysis of angular and path position and dynamic state properties of an n link mechanism with single or multiple prescribed input specifications. The complex conjugate concept is extensively used to formulate these explicit expressions. A numerical example of a six-bar mechanism is presented, and the closed-form expressions are used to calculate—without graphical, numerical, or iterative techniques—the angular position, angular velocity, and angular acceleration of each link.

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