Introductory survey

1960 ◽  
Vol 152 (946) ◽  
pp. 1-2
Keyword(s):  
Sense Organ ◽  
Angular Acceleration ◽  
Organ Of Corti ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Otolith Organs ◽  
Gravitational Acceleration ◽  
System A ◽  
History Of ◽  
Food Vacuoles

When we speak of the ear we associate it primarily with hearing. In our symposium today we shall, however, not be exclusively concerned with hearing in aquatic animals; and this has to do with the evolutionary history of the ear. Even in its most highly evolved form the ear is still a dual- or better-to-say a triple-purpose sense organ. In it are combined receptors for angular acceleration (the semicircular canals) for linear, including gravitational, acceleration (the otolith organs) and an organ for the accurate frequency analysis of sound (the organ of Corti in the cochlea). The otolith organs, are by dint of their particular design capable of signalling oscillatory changes in linear acceleration manifesting themselves as vibration or as sound in the widest meaning of the term. The functional association between reception of gravitational and vibrational stimuli, between balance and hearing is, phylogenetically speaking, a very old story. It begins probably with the emergence of the living cell. There exist inhomogeneities in density in the form of various cell inclusions, such as food vacuoles, etc., in an otherwise gravitationally or vibrationally ‘transparent’ cytoplasmic system. A density of two or three times that of water is sufficient to give pivotal importance to such cell inclusions making them capable of acting as internal points of reference for the perception of accelerational changes by the pressure-sensitive surrounding cytoplasm. This, on the multicellular level of organization, is the functional principle of the invertebrate statocyst.

Introduction

2016 ◽  
Author(s):  
Robert W. Baloh
Keyword(s):  
Inner Ear ◽  
Angular Acceleration ◽  
Organ Of Corti ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Positional Vertigo ◽  
Linear Movement ◽  
The Brain ◽  
Simple Bedside ◽  
Paroxysmal Positional Vertigo

The inner ear contains three major sensory receptors: the crista of the semicircular canals for sensing angular acceleration, the macule of the utricle and saccule for sensing linear acceleration, and the organ of Corti of the cochlea for sensing sound. Vertigo is an illusion of movement—usually spinning or turning but occasionally linear movement or tilt. Abnormalities of the inner ear or its connections in the brain cause an illusion of movement—vertigo. Benign paroxysmal positional vertigo (BPPV) is by far the most common cause of vertigo. Sudden violent spells of spinning are triggered by a change in position, such as turning over in bed, getting in and out of bed, and extending the head back to look up. This book tells the story of how the cause of BPPV was discovered and how a simple bedside cure was developed.

scholarly journals Convergence of linear acceleration and yaw rotation signals on non-eye movement neurons in the vestibular nucleus of macaques

2018 ◽  
Vol 119 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Shawn D. Newlands ◽  
Ben Abbatematteo ◽  
Min Wei ◽  
Laurel H. Carney ◽  
Hongge Luan
Keyword(s):  
Eye Movement ◽  
Multisensory Integration ◽  
Vestibular Nucleus ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Vestibular Nuclei ◽  
Otolith Organs ◽  
Angular Rotation ◽  
Sensory Signals ◽  
Nonlinear Integration

Roughly half of all vestibular nucleus neurons without eye movement sensitivity respond to both angular rotation and linear acceleration. Linear acceleration signals arise from otolith organs, and rotation signals arise from semicircular canals. In the vestibular nerve, these signals are carried by different afferents. Vestibular nucleus neurons represent the first point of convergence for these distinct sensory signals. This study systematically evaluated how rotational and translational signals interact in single neurons in the vestibular nuclei: multisensory integration at the first opportunity for convergence between these two independent vestibular sensory signals. Single-unit recordings were made from the vestibular nuclei of awake macaques during yaw rotation, translation in the horizontal plane, and combinations of rotation and translation at different frequencies. The overall response magnitude of the combined translation and rotation was generally less than the sum of the magnitudes in responses to the stimuli applied independently. However, we found that under conditions in which the peaks of the rotational and translational responses were coincident these signals were approximately additive. With presentation of rotation and translation at different frequencies, rotation was attenuated more than translation, regardless of which was at a higher frequency. These data suggest a nonlinear interaction between these two sensory modalities in the vestibular nuclei, in which coincident peak responses are proportionally stronger than other, off-peak interactions. These results are similar to those reported for other forms of multisensory integration, such as audio-visual integration in the superior colliculus. NEW & NOTEWORTHY This is the first study to systematically explore the interaction of rotational and translational signals in the vestibular nuclei through independent manipulation. The results of this study demonstrate nonlinear integration leading to maximum response amplitude when the timing and direction of peak rotational and translational responses are coincident.

Functions of separate sensory receptors of nonauditory labyrinth of the cat

1962 ◽  
Vol 202 (6) ◽  
pp. 1211-1220 ◽  
Author(s):  
Kenneth E. Money ◽  
John W. Scott
Keyword(s):  
Intact Animal ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
The Other ◽  
Sensory Receptors ◽  
Vestibular Tests ◽  
Normal Orientation ◽  
Angular Displacements ◽  
Vertical Semicircular Canals

A technique for plugging individual semicircular canals of cats was developed, and it was established that the plugging of a semicircular canal completely blocked its receptivity without influencing the functions of the other vestibular receptors. It was found that cats with all six semicircular canals plugged were lacking all sensitivity to angular acceleration, but they retained normal responses to linear acceleration. Results of several vestibular tests led to the conclusion that the vertical semicircular canals initiate corrections for fast angular displacements from the normal orientation when the displacements are about horizontal axes and that the otoliths initiate corrections for slow angular displacements about horizontal axes. In tests of single horizontal canals, the durations of postrotatory nystagmus were the same after rotations in opposite directions. It was concluded that in the intact animal both horizontal semicircular canals contribute equally to reception of angular acceleration in both directions.

A comparative study of the responses of isolated first-order semicircular canal afferents to angular and linear acceleration, analysed in the time and frequency domains

1978 ◽  
Vol 202 (1148) ◽  
pp. 313-338 ◽  
Keyword(s):  
Angular Acceleration ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Basic Mechanism ◽  
Considerable Proportion ◽  
Time Constants ◽  
First Order ◽  
Elasmobranch Fishes ◽  
The Time Domain ◽  
Head Positions

The experiments reported here represent a study of the responses of semicircular canals in the isolated surviving labyrinth of elasmobranch fishes, with special reference to their sensitivity to linear acceleration, including positional stimuli, in comparison with their 'classical ’ function as inertial angular accelerometers. Responses to angular velocity steps, to step changes in position (linear acceleration steps), and responses to sinusoidal stimuli were analysed in the time domain or in the frequency domain respectively. In this investigation the existence of peripheral adaptation and the associated time constants were taken into account. It was found that the time constants and phase aspects of the res­ponses to angular and linear acceleration stimuli are consistently com­parable. This is believed to point to similarities in the basic mechanism of both types of canal response. It is suggested, therefore, that the sensitivity of semicircular canals to linear acceleration, referred to in this paper as the ‘Ledoux effect’, originates within the cupula-endolymph system in a manner fundamentally similar to that governing the inertial responses to angular acceleration. Although a considerable proportion of the canal-controlled first-order neurons studied responded to positional stimuli, no predictable and directionally fixed relation was found to exist between head positions and response levels. This suggests that differences in density as between cupula and endolymph, considered to be the cause of the positional responses, must be assumed to be subject to fluctuation both in sign and magnitude. We conclude that it is, therefore, doubtful whether the Ledoux effect falls within the range of ‘normal’ canal function in the control of posture and movement. Nevertheless, its existence cannot be discounted in the qualitative and quantitative analysis of vestibular responses, and, especially, in the differential diagnosis of malfunction in the field of clinical otology. Work along similar lines on higher vertebrates is discussed in the context of the reported results.

The Vestibular Sense

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Inner Ear ◽  
Vestibular System ◽  
Alcohol Intoxication ◽  
Conscious Experience ◽  
Head Tilt ◽  
Angular Acceleration ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Movements ◽  
Age Related

The vestibular system contains semicircular canals that respond to angular acceleration and otoconial organs that respond to linear acceleration of the head. Information is sent to the motor system and, under normal circumstances, does not lead to conscious perception. Yet damage to the vestibular system can result in disequilibrium or vertigo, disturbing perceptions that dominate conscious experience. The shared residence of the cochlear and vestibular end organs in the inner ear can give rise to inner ear disorders such as Ménière’s disease. The effect of gravity on the otoconial masses in the sacculus and utriculus enable detection of static head tilt. Age-related disequilibrium, benign paroxysmal positional vertigo, motion sickness, and alcohol intoxication–induced vertigo are explained. How natural head movements elicit combined canal and otoconial organ responses is described. Finally, the dependence of posture and gaze on vestibular inputs is introduced as a segue to the next chapter.

Neural Processing of Gravito-Inertial Cues in Humans. I. Influence of the Semicircular Canals Following Post-Rotatory Tilt

2000 ◽  
Vol 84 (4) ◽  
pp. 2001-2015 ◽  
Author(s):  
L. H. Zupan ◽  
R. J. Peterka ◽  
D. M. Merfeld
Keyword(s):  
Eye Movements ◽  
Information Integration ◽  
Constant Velocity ◽  
Gravitational Force ◽  
Inertial Force ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Orientation ◽  
Otolith Organs ◽  
Sensory Cues

Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90° in darkness to one of eight different evenly spaced final orientations, a so-called “dumping” protocol. Three speeds (200, 100, and 50°/s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200°/s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so-called “barbecue” protocol. The GIF resolution hypothesis predicts that post-rotatory horizontal VOR eye movements for both protocols should include an “induced” VOR component, compensatory to an interaural estimate of linear acceleration, even though no true interaural linear acceleration is present. The GIF resolution hypothesis accurately predicted VOR and induced VOR dependence on rotation direction, rotation speed, and head orientation. Alternative hypotheses stating that frequency segregation may discriminate tilt from translation or that the post-rotatory VOR time constant is dependent on head orientation with respect to the GIF direction did not predict the observed VOR for either experimental protocol.

scholarly journals Proteomics and the Inner Ear

2001 ◽  
Vol 17 (4) ◽  
pp. 259-270 ◽  
Author(s):  
Isolde Thalmann
Keyword(s):  
Inner Ear ◽  
Calcium Binding ◽  
Angular Acceleration ◽  
Organ Of Corti ◽  
Semicircular Canals ◽  
Frequency Discrimination ◽  
Receptor System ◽  
Perilymphatic Fistula ◽  
Proteomics Approach

The inner ear, one of the most complex organs, contains within its bony shell three sensory systems, the evolutionary oldest gravity receptor system, the three semicircular canals for the detection of angular acceleration, and the auditory system - unrivaled in sensitivity and frequency discrimination. All three systems are susceptible to a host of afflictions affecting the quality of life for all of us. In the first part of this review we present an introduction to the milestones of inner ear research to pave the way for understanding the complexities of a proteomics approach to the ear. Minute sensory structures, surrounded by large fluid spaces and a hard bony shell, pose extreme challenges to the ear researcher. In spite of these obstacles, a powerful preparatory technique was developed, whereby precisely defined microscopic tissue elements can be isolated and analyzed, while maintaining the biochemical state representative of thein vivoconditions. The second part consists of a discussion of proteomics as a tool in the elucidation of basic and pathologic mechanisms, diagnosis of disease, as well as treatment. Examples are the organ of Corti proteins OCP1 and OCP2, oncomodulin, a highly specific calcium-binding protein, and several disease entities, Meniere's disease, benign paroxysmal positional vertigo, and perilymphatic fistula.

Stance performance under different sensorimotor conditions in patients with post-traumatic otolith disorders

2007 ◽  
Vol 17 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Dietmar Basta ◽  
Andrew Clarke ◽  
Arne Ernst ◽  
Ingo Todt
Keyword(s):  
Otolith Organs ◽  
Test Results ◽  
Dynamic Posturography ◽  
System A ◽  
Test Conditions ◽  
Trunk Sway ◽  
History Of ◽  
Balance Deficits ◽  
Post Traumatic ◽  
And Gender

Dynamic posturography with the Equitest® system is helpful to screen patients for balance deficits, but diagnostic specificity, for otolith disorders is unknown until now. It was therefore the aim of our present paper to examine patients with a well-defined otolith disorder on the Equitest® at different test conditions while simultaneously recording trunk sway by means of the Sway Star® system. A total of 22 patients with different types of otolith disorders were included in this study. All test results of the patients were matched with respect to age and gender to controls without history of ENT diseases. The overall sensitivity of the Equitest® system in our series was only higher than 50% in 2 conditions. The results of the trunk sway recordings were significantly different between patients with a sacculo-utricular disorder and controls in all test conditions. The results suggest that a disorder of the otolith organs seems to affect especially the trunk sway to a large extent.

scholarly journals Canal and Otolith Contributions to Compensatory Tilt Responses in Pigeons

2008 ◽  
Vol 100 (3) ◽  
pp. 1488-1497 ◽  
Author(s):  
Kimberly L. McArthur ◽  
J. David Dickman
Keyword(s):  
Rotational Motion ◽  
Translational Motion ◽  
Low Frequency ◽  
Linear Acceleration ◽  
Horizontal Axis ◽  
Otolith Organs ◽  
Gravitational Acceleration ◽  
Model Combining ◽  
Linear Scheme ◽  
Head Responses

Gaze-stabilizing eye and head responses compensate more effectively for low-frequency rotational motion when such motion stimulates the otolith organs, as during earth-horizontal axis rotations. However, the nature of the otolith signal responsible for this improvement in performance has not been previously determined. In this study, we used combinations of earth-horizontal axis rotational and translational motion to manipulate the magnitude of net linear acceleration experienced by pigeons, under both head-fixed and head-free conditions. We show that phase enhancement of eye and head responses to low-frequency rotational motion was causally related to the magnitude of dynamic net linear acceleration and not the gravitational acceleration component. We also show that canal-driven and otolith-driven eye responses were both spatially and temporally appropriate to combine linearly, and that a simple linear model combining canal- and otolith-driven components predicted eye responses to complex motion that were consistent with our experimental observations. However, the same model did not predict the observed head responses, which were spatially but not temporally appropriate to combine according to the same linear scheme. These results suggest that distinct vestibular processing substrates exist for eye and head responses in pigeons and that these are likely different from the vestibular processing substrates observed in primates.

Eyes on Target: What Neurons Must do for the Vestibuloocular Reflex During Linear Motion

2004 ◽  
Vol 92 (1) ◽  
pp. 20-35 ◽  
Author(s):  
Dora E. Angelaki
Keyword(s):  
Sensory Information ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Rotation ◽  
Oculomotor System ◽  
Eye Position ◽  
Otolith Organs ◽  
Vestibuloocular Reflex ◽  
Linear Motion ◽  
Gaze Stabilization

A gaze-stabilization reflex that has been conserved throughout evolution is the rotational vestibuloocular reflex (RVOR), which keeps images stable on the entire retina during head rotation. An ethological newer reflex, the translational or linear VOR (TVOR), provides fast foveal image stabilization during linear motion. Whereas the sensorimotor processing has been extensively studied in the RVOR, much less is currently known about the neural organization of the TVOR. Here we summarize the computational problems faced by the system and the potential solutions that might be used by brain stem and cerebellar neurons participating in the VORs. First and foremost, recent experimental and theoretical evidence has shown that, contrary to popular beliefs, the sensory signals driving the TVOR arise from both the otolith organs and the semicircular canals. Additional unresolved issues include a scaling by both eye position and vergence angle as well as the temporal transformation of linear acceleration signals into eye-position commands. Behavioral differences between the RVOR and TVOR, as well as distinct differences in neuroanatomical and neurophysiological properties, raise multiple functional questions and computational issues, only some of which are readily understood. In this review, we provide a summary of what is known about the functional properties and neural substrates for this oculomotor system and outline some specific hypotheses about how sensory information is centrally processed to create motor commands for the VORs.

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