scholarly journals Effect of Intensity Level and Speech Stimulus Type on the Vestibulo-Ocular Reflex

2019 ◽  
Vol 30 (09) ◽  
pp. 792-801 ◽  
Author(s):  
Mary Easterday ◽  
Patrick N. Plyler ◽  
James D. Lewis ◽  
Steven M. Doettl
Keyword(s):  
Repeated Measures ◽  
Vestibular Nuclei ◽  
Auditory Stimulation ◽  
Broadband Noise ◽  
Speech Stimulus ◽  
Intensity Level ◽  
Acoustic Reflex ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Acoustic Reflex Threshold

AbstractAccurate vestibulo-ocular reflex (VOR) measurement requires control of extravestibular suppressive factors such as visual fixation. Although visual fixation is the dominant suppressor and has been extensively studied, the mechanisms underlying suppression from nonvisual factors of attention and auditory stimulation are less clear. It has been postulated that the nonvisual suppression of the VOR is the result of one of two mechanisms: (1) activation of auditory reception areas excites efferent pathways to the vestibular nuclei, thus inhibiting the VOR or (2) cortical modulation of the VOR results from directed attention, which implies a nonmodality-specific process.The purpose of this research was to determine if the VOR is affected by the intensity level and/or type of speech stimulus.A repeated measures design was used. The experiment was single-blinded.Participants included 17 adults (14 females, three males) between the ages of 18–34 years who reported normal oculomotor, vestibular, neurological, and musculoskeletal function.Each participant underwent slow harmonic acceleration testing in a rotational chair. VOR gain was assessed at 0.02, 0.08, and 0.32 Hz in quiet (baseline). VOR gain was also assessed at each frequency while a forward running speech stimulus (attentional) or a backward running speech stimulus (nonattentional) was presented binaurally via insert earphones at 42, 62, and 82 dBA. The order of the conditions was randomized across participants. VOR difference gain was calculated as VOR gain in the auditory condition minus baseline VOR gain. To evaluate auditory efferent function, the medial olivocochlear reflex (MOCR) was assayed using transient-evoked otoacoustic emissions (right ear) measured in the presence and absence of broadband noise (left ear). Contralateral acoustic reflex thresholds were also assessed using a broadband noise elicitor. A three-way repeated measures analysis of variance was conducted to evaluate the effect of frequency, intensity level, and speech type on VOR difference gain. Correlations were conducted to determine if difference gain was related to the strength of the MOCR and/or to the acoustic reflex threshold.The analysis of variance indicated that VOR difference gain was not significantly affected by the intensity level or the type of speech stimulus. Correlations indicated VOR difference gain was not significantly related to the strength of the MOCR or the acoustic reflex threshold.The results were in contrast to previous research examining the effect of auditory stimulation on VOR gain as auditory stimulation did not produce VOR suppression or enhancement for most of the participants. Methodological differences between the studies may explain the discrepant results. The removal of an acoustic target from space to attend to may have prevented suppression or enhancement of the VOR. Findings support the hypothesis that VOR gain may be affected by cortical modulation through directed attention rather than due to activation of efferent pathways to the vestibular nuclei.

Factors Influencing the Acoustic-Immittance Characteristics of the Acoustic Reflex

1979 ◽  
Vol 22 (3) ◽  
pp. 480-499 ◽  
Author(s):  
Richard H. Wilson
Keyword(s):  
Middle Ear ◽  
Sound Pressure ◽  
Broadband Noise ◽  
Intensity Level ◽  
Ear Canal ◽  
Acoustic Reflex ◽  
Impedance Characteristics ◽  
Reflex Threshold ◽  
Acoustic Reflex Threshold ◽  
Tonal Stimuli

Measurements of the aural acoustic-immittance (admittance and impedance) characteristics of the middle-ear transmission system in humans during the quiescent (static) and reflexive states were made (N = 36) utilizing a signal-averaging technique. Three pure tones (750, 1000, and 2000 Hz) and broadband noise stimuli elicited the acoustic reflex in 2-dB steps at sound-pressure levels from 84–116 dB (tones) and 66–116 dB (noise) during ascending- and descending-intensity level runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an admittance meter. A computer corrected for the ear-canal volume utilizing measurements made at ear-canal pressures of 0 and −350 daPa and then converted the conductance and susceptance values into admittance and impedance units. The results were reported in absolute and relative immittance units, including components, as a function of both stimulus sound-pressure level and intensity level above the acoustic-reflex threshold. The static immittance of the middle ear changed nonlinearly over time to lower admittance or higher impedance values. The influence of this static-immittance shift on the reflex magnitude was discussed. The largest mean reflex magnitude and the slowest rate of growth were observed with broadband noise, although eight of the 36 subjects demonstrated the largest reflex magnitude in response to one or more of the tonal stimuli. Although static-immittance values and acoustic-reflex thresholds were poorly correlated, the reflex magnitudes were proportional to static immittance. The variability of the reflex measures was similar to the variability of the static-immittance values. Finally, bi-directional changes in resistance during the reflexive state were observed and discussed.

Spatial orientation of the angular vestibulo-ocular reflex

1999 ◽  
Vol 9 (3) ◽  
pp. 163-172
Author(s):  
Bernard Cohen ◽  
Susan Wearne ◽  
Mingjia Dai ◽  
Theodore Raphan
Keyword(s):  
Spatial Orientation ◽  
Optokinetic Nystagmus ◽  
Vestibular Nuclei ◽  
Velocity Storage ◽  
Gravitational Acceleration ◽  
Ocular Reflex ◽  
Eye Rotation ◽  
Slow Velocity ◽  
Vestibulo Ocular Reflex ◽  
Vector Sum

During vestibular nystagmus, optokinetic nystagmus (OKN), and optokinetic afternystagmus (OKAN), the axis of eye rotation tends to align with the vector sum of linear accelerations acting on the head. This includes gravitational acceleration and the linear accelerations generated by translation and centrifugation. We define the summed vector of gravitational and linear accelerations as gravito-inertial acceleration (GIA) and designate the phenomenon of alignment as spatial orientation of the angular vestibuloocular reflex (aVOR). On the basis of studies in the monkey, we postulated that the spatial orientation of the aVOR is dependent on the slow (velocity storage) component of the aVOR, not on the short latency, compensatory aVOR component, which is in head-fixed coordinates. Experiments in which velocity storage was abolished by midline medullary section support this postulate. The velocity storage component of the aVOR is likely to be generated in the vestibular nuclei, and its spatial orientation was shown to be controlled through the nodulus and uvula of the vestibulo-cerebellum. Separate regions of the nodulus/uvula appear to affect the horizontal and vertical/torsional components of the response differently. Velocity storage is weaker in humans than in monkeys, but responds in a similar fashion in both species. We postulate that spatial orientation of the aVOR plays an important role in aligning gaze with the GIA and in maintaining balance during angular locomotion.

Anterior canal neurons in cat vestibular nuclei have large phase leads during low frequency vertical axis pitch

2007 ◽  
Vol 16 (6) ◽  
pp. 245-256
Author(s):  
Sandra C. Brettler ◽  
James F. Baker
Keyword(s):  
Low Frequency ◽  
Vertical Axis ◽  
Vestibular Nuclei ◽  
Whole Body ◽  
Posterior Canal ◽  
Spatial Sensitivity ◽  
Ocular Reflex ◽  
Vestibular Afferents ◽  
Vestibulo Ocular Reflex ◽  
Anterior Canal

Vestibulo-ocular and second-order neurons in medial and superior vestibular nuclei of alert cats were identified by antidromic and orthodromic electrical stimulation, and their responses to whole body rotations were recorded in the dark. Neurons that had spatial sensitivity most closely aligned with the anterior canal (anterior canal neurons) were compared with neurons that had spatial sensitivity most closely aligned with the posterior canal (posterior canal neurons). Responses were recorded during low frequency earth-horizontal axis pitch rotations in the normal upright posture, and during earth-vertical axis pitch with the head and body lying on the left side. During upright pitch, response phases of anterior canal neurons slightly lagged those of posterior canal neurons or primary vestibular afferents, as previously reported. During on-side pitch, anterior canal neurons showed far greater phase leads with respect to head velocity than posterior canal neurons, primary vestibular afferents, or previously reported vestibulo-ocular reflex eye movements. These results provide challenges for vestibulo-ocular reflex models to incorporate central mechanisms for phase leads among the inputs to anterior canal neurons and to explain how the anterior canal neuron signals reported here combine with other signals to produce observed vestibulo-ocular reflex behavior.

Temporal Integration of the Contralateral Acoustic Reflex Threshold for a 1000 Hz Tonal Activator and Its Age-Related Changes

2009 ◽  
Vol 20 (04) ◽  
pp. 225-228 ◽  
Author(s):  
Michele B. Emmer ◽  
Shlomo Silman ◽  
Carol A. Silverman ◽  
Harry Levitt
Keyword(s):  
Temporal Integration ◽  
Age Effect ◽  
Broadband Noise ◽  
Hearing Level ◽  
Acoustic Reflex ◽  
Hearing Sensitivity ◽  
Age Related ◽  
Main Effect ◽  
Reflex Threshold ◽  
Acoustic Reflex Threshold

Background: Previous research has noted an age effect on the temporal integration of the acoustic reflex for a noise activator. Purpose: To determine whether the age effect earlier noted for a noise activator will be noted for a tonal activator. Research Design: Comparison of ARTs of younger and older groups at activating stimulus durations of 12, 25, 50, 100, 200, 300, 500, and 1000 msec. Study Sample: Two groups of adults with normal-hearing sensitivity: one group of 20 young adults (ten males and ten females, ages 18–29 years, with a mean age of 24 years) and one group of 20 older adults (ten males and ten females, ages 59–75 years, with a mean age of 67.5 years). Results: A significant main effect for duration was obtained. That is, as the duration increased, the acoustic reflex threshold for the 1000 Hz tonal activator decreased. The interactions of duration × age group and duration × hearing level were not significant. There was a nonsignificant main effect (p = .889) for the between-subjects factor of age. Conclusion: Results contradict the findings for broadband noise.

scholarly journals Evaluation of Interexaminer Variability in Video Head Impulse Test Results

2020 ◽  
Vol 31 (08) ◽  
pp. 613-619
Author(s):  
Başak Mutlu ◽  
Sıdıka Cesur ◽  
Merve Torun Topçu ◽  
Cennet Reyyan Geçici ◽  
Öyküm Esra Aşkın ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Semicircular Canals ◽  
Head Impulse Test ◽  
Video Head Impulse Test ◽  
Head Impulse ◽  
Lateral Canal ◽  
Ocular Reflex ◽  
Left Posterior ◽  
Vestibulo Ocular Reflex ◽  
The Right

Abstract Objective The video head impulse test (vHIT) is a diagnostic tool to assess the function of the semicircular canals and branches of the vestibular nerve. The aim of this study was to analyze the interexaminer variability of vHIT results in healthy subjects. Materials and Methods A total of 21 healthy participants were included in the study. vHIT responses were collected by four clinicians. Variability of the vHIT results between examiners was analyzed statistically. Results The vestibulo-ocular reflex (VOR) velocity regression values were from 0.99 to 1.09 degrees per second for the lateral canals. For the vertical canals, VOR velocity regression values were from 0.87 to 1.21 degrees per second. According to repeated measures analysis of variance, the normality assumptions for the velocity regression of the left lateral canal (p = 0.002) and the right anterior canal (p < 0.01) were met and the differences were statistically significant. The normality assumptions were not met for 40, 60, and 80 ms median gain of the right lateral canal (p = 0.016, p = 0.038, and p = 0.001, respectively); 40 and 60 ms median gain of the left lateral canal (p < 0.001 and p = 0.008, respectively); and the velocity regression of the left posterior canal (p < 0.00). These differences were found to be statistically significant by using the Friedman test. Conclusion The interexaminer differences of the VOR gain values for the vHIT were statistically significant. Serial vHIT testing should be performed by the same examiner to reduce the effects of interexaminer variability.

Aural Acoustic-Immittance Measurements

1981 ◽  
Vol 46 (4) ◽  
pp. 413-421 ◽  
Author(s):  
Richard H. Wilson ◽  
Janet E. Shanks ◽  
Therese M. Velde
Keyword(s):  
Sound Pressure ◽  
Broadband Noise ◽  
Intensity Level ◽  
Growth Data ◽  
Acoustic Reflex ◽  
Individual Subject ◽  
Acoustic Admittance ◽  
Sound Pressure Levels ◽  
Pure Tones ◽  
The Individual

Bilateral measurements of the aural acoustic-immittance characteristics of the middle-ear transmission systems of 48 subjects were made with an acoustic-admittance meter. The measurements, including static acoustic-immittance, acoustic-reflex thresholds, and acoustic-reflex growth functions, were made using a 220-Hz probe. The contralateral reflex data for three pure tones (500, 1000, and 2000 Hz) and for broadband noise were acquired in 2-dB steps at sound-pressure levels from 84–116 dB (tones) and 66–116 dB (noise) during ascending- and descending-intensity level runs. For all acoustic-immittance measurements, right ear and left ear comparisons were made and found not to be significantly different. The individual subject data then were expressed as the absolute differences between ears. In this manner normative inter-aural immittance differences were defined. The peak static immittance data were analyzed in terms of median inter-aural differences and upper 80% cut-off values. The 80% range for normal immittance values were smaller for a within subject versus an across subject comparison. For acoustic-reflex thresholds, a disparity between ears of >10 dB was suggested as indicative of an abnormality in the auditory mechanism. Finally, the reflex-growth data indicated mean inter-aural absolute differences that ranged to .040–.043 acoustic mmhos (300–400 acoustic ohms) at the higher reflex activator sound-pressure levels.

Mental Tasking and Caloric-Induced Vestibular Nystagmus Utilizing Videonystagmography

2016 ◽  
Vol 25 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Mary K. Easterday ◽  
Patrick N. Plyler ◽  
Steven M. Doettl
Keyword(s):  
Repeated Measures ◽  
Adult Population ◽  
Response Duration ◽  
Slow Phase ◽  
Eye Blink ◽  
Repeated Measures Design ◽  
Ocular Reflex ◽  
Significant Difference ◽  
Vestibulo Ocular Reflex ◽  
Blink Artifact

Purpose The purpose of this study was to quantify the effects of mental tasking on measures of the caloric vestibulo-ocular reflex utilizing videonystagmography as the measurement technique. Method A within-subjects repeated-measures design was utilized. Sixteen healthy adults were evaluated (13 women, 3 men; ages 19–31 years). Each participant underwent bithermal caloric irrigation at 2 separate counterbalanced visits. At 1 visit mental tasking was utilized, whereas the other visit did not utilize mental tasking. The following outcomes were measured for each visit: peak slow-phase velocity (SPV), response duration, peak SPV latency, and eye blink artifact. Results No significant difference was seen for tasking versus no tasking with peak SPV, peak latency, or response duration. A significant difference was seen for the amount of eye blink artifact, with significantly more eye blinks present for the tasking condition. Conclusions Results could indicate mental tasking does not affect the important measure of SPV. Moreover, increased eye blink artifact with tasking could obscure the clinician's ability to read the nystagmograph. However, this investigation is limited to the healthy young adult population, and more studies should be performed to corroborate the presented evidence.

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