bluuebunny/crossref_metadata_2025 huggingface dataset:
Managing Epidemic Prevention Activities for Public Preschools’ Children
Authors: Cao Xuan Thi Thanh
Published: September 2021

ABSTRACT Preschool education is an important aspect of education for all children, with a focus on improving the quality of health care and epidemic prevention for preschoolers. 252 Vietnamese preschool school respondents (21 personnel, 105 teachers and six medical workers) participated. The participants completed a self-administered survey and examined elements for the management of epidemic prevention for children in public preschools. A survey was conducted at seven public preschools in Binh Chanh District, Ho Chi Minh City. The findings indicate that regular training and organization are essential for preventing epidemics in youngsters. It is important to note that school authorities and people outside the school, who are always mindful of the importance of infectious disease prevention for children, note this policy change’s benefit for children in preschool. Because it attracts their attention and motivates young parents to make sure their children avoid disease and remain healthy while participating in school activities and extracurricular activities, like play, work, and study.
Dynamics of Adaptive Change in Human Vestibulo-Ocular Reflex Direction
Authors: Khater T.T. , Baker J.F. , Peterson B.W.
Published: September 2021

Adaptive modification of vestibulo-ocular reflex (VOR) direction was characterized in humans by recording vertical and horizontal VOR eye movements during horizontal rotations in darkness at frequencies of 0.05 to 1 Hz before and after exposure to a VOR direction adaptation procedure. This procedure paired yaw horizontal vestibular rotation at 0.25 Hz with synchronous pitch vertical optokinetic motion. Saccades were removed from eye position records and VOR gain and phase were recorded. With an onset time constant of 36 min, the VOR measured during horizontal rotation in complete darkness acquired a vertical component in phase with the optokinetic stimulus presented during adaptation. The amplitude of this newly acquired vertical VOR component was maximal during rotation at the frequency of adaptation; at other frequencies, the amplitude was lower, but still significant. Unlike VOR direction adaptation in cats, the phase of the adaptive VOR component in humans did not show significant leads or lags at test frequencies below or above the adaptation frequency. These data suggest that, like the cat, the human VOR can be directionally adapted, and the pathways involving the adaptive component of the VOR are frequency specific.
Suppression of Optokinetic Velocity Storage in Humans by Static Tilt in Pitch
Authors: Lafortune S.H. , Ireland D.J. , Jell R.M.
Published: September 2021

The effects of static tilts about the pitch axis on human horizontal optokinetic afternystagmus OKAN (HOKAN) were examined. Static tilts in pitch produced tilt-dependent HOKAN suppression. The slow decay (indirect pathway) component (coefficient C and long time constant 1/D) of the two-component model for OKAN was significantly reduced, while the short decay (direct pathway) component (coefficient A and short time constant 1/B) remained invariant as angle of tilt was increased. These results provide further evidence that otolith organ activity can couple to horizontal velocity storage in humans; in accordance with models proposed in the literature.
Age-Related Changes in Human Vestibulo-Ocular Reflexes: Sinusoidal Rotation and Caloric Tests
Authors: Peterka R.J. , Black F.O. , Schoenhoff M.B.
Published: September 2021

The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 y. The effects of aging on VOR dynamics and parameter distributions that describe VOR responses to caloric and to sinusoidal rotational stimuli were determined in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others that showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 y. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR.
Age-Related Changes in Human Vestibulo-Ocular and Optokinetic Reflexes: Pseudorandom Rotation Tests
Authors: Peterka R.J. , Black F.O. , Schoenhoff M.B.
Published: September 2021

The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 y. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters that describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year.
Age-Related Changes in Human Posture Control: Sensory Organization Tests
Authors: Peterka R.J. , Black F.O.
Published: September 2021

Postural control was measured in 214 human subjects ranging in age from 7 to 81 y. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were normal, altered (by rotating the visual surround and support surface in proportion to the subject’s sway), or vision eliminated (eyes closed). No age-related increase in postoral sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age-related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older tban about 55 y showed the largest sway increases. Subjects younger than about 15 y were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues, whereas younger subjects had more difficulty with altered somatosensory cues.
Eye-Head Movement Coordination: Vestibulo-Ocular Reflex Suppression with Head-Fixed Target Fixation1
Authors: Vercher Jean-Louis , Gauthier Gabriel M.
Published: September 2021

To maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counter-rotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the optokinetic reflex. A problem of importance relates to the value of the so-called intrinsic gain of the VOR (VORG) in man, and how this gain is modulated to provide appropriate eye movements. We have studied these problems in two situations: 1. fixation of a stationary object of the visual space while the head moves; 2. fixation of an object moving with the head. These two situations were compared to a basic condition in which no visual target was allowed in order to induce “pure” VOR. Eye movements were recorded in seated subjects during stationary sinusoidal and transient rotations around the vertical axis. Subjects were in total darkness (DARK condition) and involved in mental arithmetic. Alternatively, they were provided with a small foveal target, either fixed with respect to earth (earth-fixed target: EFT condition), or moving with them (chair-fixed-target: CFT condition). The stationary rotation experiment was used as baseline for the ensuing experiment and yielded control data in agreement with the literature. In all 3 visual conditions, typical responses to transient rotations were rigorously identical during the first 200 ms. They showed, sequentially, a 16-ms delay of the eye behind the head and a rapid increase in eye velocity during 75 to 80 ms, after which the average VORG was 0.9 ± 0.15. During the following 50 to 100 ms, the gain remained around 0.9 in all three conditions. Beyond 200 ms, the VORG remained around 0.9 in DARK and increased slowly towards 1 or decreased towards zero in the EFT and CFT conditions, respectively. The time-course of the later events suggests that visual tracking mechanisms came into play to reduce retinal slip through smooth pursuit, and position error through saccades. Our data also show that in total darkness VORG is set to 0.9 in man. Lower values reported in the literature essentially reflect predictive properties of the vestibulo-ocular mechanism, particularly evident when the input signal is a sinewave.
The Effect of Treatment on Eye-Head Coordination in Parkinson’s Disease1
Authors: Hansen H.C. , Gibson J.M. , Zangemeister W.H. , Kennardt C.
Published: September 2021

Eye-head movements to target steps of amplitude 3.75∘ to 30∘ were analyzed in 9 untreated patients with idiopathic Parkinson’s disease. Testing was performed before and after the introduction of a dopamimetic drug (L-dopa or bromocriptine) and compared with 9 normal controls. The patients showed a significantly greater scatter of mean head latencies prior to treatment, although their mean latencies were not significantly prolonged. When compared to controls, the patients’ head movements were of reduced peak velocity and gain. Treatment resulted in an improvement of gain but not velocity. Analysis of the frequency of gaze types showed no significant effect of treatment.
Guinea Pig Vestibular Type I Hair Cells Can Show Reversible Shortening
Authors: Lapeyre Pascale N.M. , Cazals Yves
Published: September 2021

Guinea pig isolated vestibular type I hair cells (VIHCs) were recently reported by our group to respond to high [KCl] solutions by an irreversible tilt of their neck region and sometimes by a sustained shortening and swelling. A possible osmotic contribution to these shape changes was investigated by substituting gluconate (G) for chloride in the test solution, so as to minimize water influx, and also by changing the osmotic pressure of the extracellular solution. For comparison, similar experiments were also undertaken on cochlear outer hair cells (OHCs). Utricular and ampullar type I hair cells were more difficult to isolate than OHCs and, like them, responded to an isotonic high [KCl] solution by a sustained shortening and widening, which were found to be reversible for most cells when rinsed with the control solution. In a high [KG] solution, all OHCs showed a shortening reversible in the test solution; among the VIHCs tested, two-thirds presented a slight sustained shortening without widening and a third showed a spontaneously reversible shortening, particularly at the neck level. VIHCs exposed to a high [N-methyl-D-glucamine chloride] solution, this impermeant cation replacing K+ for control, presented only a slight sustained shortening. In response to osmotic changes of the bathing medium, both VIHCs and OHCs showed a sustained shortening or elongation (the latter to a lesser degree) for hypo- and hyperosmotic solutions, respectively. The VIHCs and OHCs that presented a reversible shortening in a high [KG] solution widened concomitantly with their shortening, but to a smaller extent compared with what was observed in a high [KCl] solution, and this diameter increase was reversible in the test solution, unlike the widening observed in a hypotonic solution. These results show that a reversible shortening occurred for some VIHCs; they also indicate the involvement of two components in the KCl-induced response: one osmotic and another potassium-dependent.
Visual-Vestibular Interaction with Telescopic Spectacles
Authors: Demer J.L. , Goldberg J. , Porter F.I. , Jenkins H.A. , Schmidt K.
Published: September 2021

Vestibularly and visually driven eye movements interact to compensate for head movements to maintain the necessary retinal image stability for clear vision. The wearing of highly magnifying telescopic spectacles requires that such compensatory visual-vestibular interaction operate in a quantitative regime much more demanding than that normally encountered. We employed electro-oculography to investigate the effect of wearing of 2×, 4×, and 6× binocular telescopic spectacles on visual-vestibular interactions during sinusoidal head rotation in 43 normal subjects. All telescopic spectacle powers produced a large, immediate increase in the gain (eye velocity/head velocity) of compensatory eye movements, called the visual-vestibulo-ocular reflex (VVOR). However, the amount of VVOR gain augmentation became limited as spectacle magnification and the amplitude of head velocity increased. Optokinetic responses during wearing of telescopic spectacles exhibited a similar nonlinearity with respect to stimulus amplitude and spectacle magnification. Computer simulation was used to demonstrate that the nonlinear response of the VVOR with telescopic spectacles is a result of nonlinearities in visually guided tracking movements. Immediate augmentation of VVOR gain by telescopic spectacles declined significantly with increasing age in the subject pool studied. Presentation of unmagnified visual field peripheral to the telescopic spectacles reduced the immediate VVOR gain-enhancing effect of central magnified vision. These results imply that the VVOR may not be adequate to maintain retinal image stability during head movements when strongly magnifying telescopic spectacles are worn.
Perception of Horizontal Head and Trunk Rotation in Patients with Loss of Vestibular Functions
Authors: Heimbrand S. , Müller M. , Schweigart G. , Mergner T.
Published: September 2021

In patients with loss of vestibular functions, we studied psychophysically the self-motion perception for ‘trunk in space’ and ‘head in space’ during various combinations of horizontal head and trunk rotation in the dark. The results were compared to those of normal subjects. For their ‘trunk in space’ perception, the subjects relied on their internal image of space, derived from the vestibular receptors in the head, and referred their trunk to this as a reference by adding to it a nuchal trunk-to-head signal. The patients, by contrast, always considered the trunk as stationary. Obviously because they were devoid of any space cues, they abandoned or suppressed a neck contribution to their ‘trunk in space’ perception, which, in fact, would yield an erroneous perception in almost all conditions in the dark. Both the patients and the subjects based their ‘head in space’ perception on their internal representation of ‘trunk in space’ and added to this a nuchal head-to-trunk signal. However, the patients’ head-to-trunk signal, unlike that of the subjects, was considerably larger than the actual head-to-trunk rotation at low stimulus frequency. We relate this finding to some unconscious modification of their neck muscle activity during passive head rotation. It appears that the patients’ gain of the neck input per se is not increased, but rather that subsets of this input are modified according to the particular function they serve.
Influence of Visual, Vestibular, Cervical, and Somatosensory Tilt Information on Ocular Rotation and Perception of the Horizontal
Authors: de Graaf Bernd , Bekkering Harold , Erasmus Corrie , Bles Willem
Published: September 2021

By combining a tilting chair and a tilting room we investigated the subjective horizontal (SH) and ocular counterrotation (OCR) as a function of body tilt, trunk tilt, and tilt of a visual frame. Significant influences of (isolated or combined) vestibular and visual information were found, but no influence of neck proprioception. A second and similar experiment, however, now conducted with subjects devoid of labyrinthine function, suggested a contribution of the neck as well as of somatosensory origin. This made a reinter-pretation of our data for normal subjects possible.
Context-Specific Adaptation of the Gain of the Vestibulo-Ocular Reflex in Humans
Authors: Shelhamer M. , Robinson D.A. , Tan H.S.
Published: September 2021

Previous experiments show that altered visual feedback can change VOR gain. Such changes also presumably occur when eyeglasses are donned and doffed, or when bifocals are worn. In these cases, a nonvisual cue accompanies the required gain adjustment (frames on/off for eyeglasses, looking up/down for bifocals). We set out to show that a subject can establish two VOR gains, and to determine if one of the associated nonvisual cues alone is sufficient to subsequently determine which gain to employ. Each of three subjects sat in a rotating chair inside an OKN drum during 2 hours of sinusoidal rotation at 0.2 Hz, 30∘/s peak. For 10 minutes the chair and drum counterrotated, driving VOR gain toward 1.7, while subjects looked up 20∘. Chair and drum were then coupled for 10 minutes, driving gain toward zero, during which subjects looked down 20∘. This sequence was repeated for 2 hours. Immediately thereafter, VOR gains were measured while subjects looked alternately up and down, using 20∘ to 40∘ step rotations. A fixation target, presented before and after each step, provided accurate gain determination by measuring the size of the re-fixation saccade. Results show a consistent reduced VOR gain looking downward (average 6%) and increased gain looking upward (average 8%). We conclude that humans carn adjust their VOR gain dependent on a situational context; we speculate that this context can take many forms.
Predictive Mechanisms of Head-Eye Coordination and Vestibulo-Ocular Reflex Suppression in Humans
Authors: Barnes G.R. , Grealy M.A.
Published: September 2021

Head and eye movements of human subjects have been recorded during head-free pursuit in the horizontal plane of a target executing sinusoidal motion at a frequency of 0.26 to 0.78 Hz and a peak velocity of ±96∘/s. The target was not presented continuously but was exposed for brief durations of 120 to 320 ms as it passed through the centre of the visual field at peak velocity. This technique allowed the timing of each response to be assessed in relation to the onset of target appearance. During the first 3 to 4 target presentations, there was a progressive buildup of both head velocity and the smooth component of gaze velocity, while, simultaneously, the responses became more phase-advanced with respect to target onset. In the steady state, similar temporal response trajectories were observed for head and gaze velocity, which were initiated approximately 500 ms prior to target on-set, rose to a peak that increased with the duration of target exposure, and then decayed with a time constant of 0.5 to 1 s. Whenever the target failed to appear as expected, the gaze and head velocity trajectories continued to be made, indicating that predictive suppression of the vestibulo-ocular reflex (VOR) was taking place in darkness. In a further experiment, subjects attempted to suppress the VOR during whole body oscillation at 0.2 or 0.4 Hz on a turntable by fixating, a head-fixed target that appeared for 10 to 160 ms at the time of peak head velocity. Again, VOR suppression was initiated prior to target appearance in the same manner as for natural head movements, and when the target suddenly disappeared but rotation continued, predictive VOR suppression was observed in darkness. The similarity of these predictive effects to those obtained previously for head-fixed pursuit provides further support for the hypothesis that both pursuit and visual suppression of the VOR are controlled primarily by identical visual feedback mechanisms.
The Influence of Age on Susceptibility to Motion Sickness in Monkeys1
Authors: Cheung B.S.K. , Money K.E.
Published: September 2021

A longitudinal study on the effects of age on the susceptibility to motion sickness in the squirrel monkey was carried out over a lO-year period (1982 to 1991). The typical life span of squirrel monkeys is 15 years. Ten mature male squirrel monkeys of the Bolivian subspecies were found to be susceptible to motion sickness induced by a combination of vertical oscillation at 0.5 Hz and rotation in the horizontal plane at 25 rotations per minute (RPM) in a visually unrestricted environment. Signs of motion sickness were quantified according to a rating scale based on Graybiel’s diagnostic criteria. Latency to vomiting/retching and severity of sickness obtained from year 1 (baseline), 3, 5, 7 and 10 were subjected to repeated-measures design analysis. There were no significant differences in the susceptibility level (as measured by latency to vomiting/retching and cumulative sickness scores) in the monkeys throughout the 10-year period. The habituation to 7 consecutive daily exposures remained the same throughout the same period. We conclude that, in the squirrel monkeys from maturity to near the end of their life span, there is no change in susceptibility to motion sickness with aging.
Visual-Vestibular Interaction in Humans During Active and Passive, Vertical Head Movement1
Authors: Demer Joseph L. , Oas John G. , Baloh Robert W.
Published: September 2021

We studied visual-vestibular interaction (VVI) in 9 normal human subjects using active and passive vertical head rotations. Gain and phase of the vertical vestibulo-ocular reflex (VOR) and visually enhanced vestibulo-ocular reflex (VVOR) were measured for single frequency sinusoidal motion, as well as for sinusoidal motion of continuously increasing frequency, over the range of 0.4 to 4.0 Hz. In addition to measurement of VVOR during normal vision, telescopic spectacles having a magnification of 1.9× were used to challenge VVI to facilitate measurement of visual enhancement of VOR gain. In the mid-frequency range (1.6 to 2.4 Hz), the active VOR exhibited gain closer to compensatory than did the passive VOR; at other frequencies, active and passive VOR gains were similar. VVOR gain during normal vision was compensatory for both active and passive motion throughout the frequency range tested. VVOR gain with 1.9× telescopic spectacles was greater than VOR gain at all frequencies tested, including up to 3.2 Hz for passive bead movements, and up to 4.0 Hz for active head movement. However, gain enhancement with telescopic spectacles was consistently greater during active than during passive head movement. Phase errors for the VOR and VVOR were small under all testing conditions. Although active VOR and VVOR were directionally symmetrical, gain of upward slow phases differed from that of downward slow phases for passive VOR and VVOR in a manner depending on rotational frequency. For both active and passive testing, gain and phase values obtained during swept frequency rotations were similar to those obtained during single frequency sinusoidal testing. These data indicate that VVI can enhance gain of the passive vertical VOR even at frequencies above what is usually considered to be the upper limit of visual pursuit tracking. The additional enhancement observed during active bead movements at these high frequences is attributable to use of efference copy of the skeletal motor command to neck musculature.
Three Dimensional Eye Movements of Squirrel Monkeys Following Postrotatory Tilt
Authors: Merfeld Daniel M. , Young Laurence R. , Paige Gary D. , Tomko David L.
Published: September 2021

Three-dimensional squirrel monkey eye movements were recorded during and immediately following rotation around an earth-vertical yaw axis (160∘/s steady state, 100∘/s2 acceleration and deceleration). To study interactions between the horizontal angular vestibulo-ocular reflex (VOR) and head orientation, postrotatory VOR alignment was changed relative to gravity by tilting the head out of the horizontal plane (pitch or roll tilt between 15∘ and 90∘) immediately after cessation of motion. Results showed that in addition to post rotatory horizontal nystagmus, vertical nystagmus followed tilts to the left or right (roll), and torsional nystagmus followed forward or backward (pitch) tilts. When the time course and spatial orientation of eye velocity were considered in three dimensions, the axis of eye rotation always shifted toward alignment with gravity, and the postrotatory horizontal VOR decay was accelerated by the tilts. These phenomena may reflect a neural process that resolves the sensory conflict induced by this postrotatory tilt paradigm.
Adaptation of the Vestibulo-Ocular Reflex with the Head in Different Orientations and Positions Relative to the Axis of Body Rotation
Authors: Tiliket Caroline , Shelhamer Mark , Tan H. Stevie , Zee David S.
Published: September 2021

We investigated the influence of static head orientation and position, relative to the axis of body rotation, upon vestibular adaptation. With the head centered, displaced anterior to the axis of body rotation, or tilted 40∘ to 45∘ in roll or pitch, the gain of the vestibulo-ocular reflex (VOR) was trained (to go either up or down) for one hour using artificial manipulation of the visual surround to produce a visual-vestibular mismatch. Before and after each training session, the VOR was measured in darkness with the head in the training as well as in several non-training positions. We found that transfer of VOR adaptation to non-training positions was almost complete when comparing head eccentric versus head-centered rotations. For tilts, however, transfer of VOR learning was far less complete suggesting that static otolith signals provide a strong contextual cue that gates the expression of an adaptive VOR response. Finally, following training to increase than VOR, gain was greater for centripetally than centrifugally directed slow phases. Centripetally directed postsaccadic drift also developed. These fundings imply that the gain increase paradigm also leads to abnormal function of the velocity-to-position neural integrator, which holds eccentric positions of gaze.
Axial Synergies Under Microgravity Conditions
Authors: Massion J. , Gurfinkel V. , Lipshits M. , Obadia A. , Popov K.
Published: September 2021

Fast forward and backward upper trunk movements were analyzed and compared under microgravity and under preflight and postflight conditions. The kinematic analysis showed that the upper trunk movements were accompanied by hip and knee movements in the opposite direction both under microgravity and under normal gravitational conditions. This suggests that the center of mass position with respect to the feet is still regulated under microgravity when the feet are attached to the floor. The EMG analysis during backward movements shows that under preflight conditions a set of muscles (ErSp, BF, Sol) in the back of the body are activated early on. Under microgravity, the early Sol activation was replaced by an early TA activation, which was still present at the first postflight recording and was then replaced by the early Sol activation observed under preflight conditions. This finding shows that the EMG pattern underlying the axial synergies is flexible and that adaptive changes take place both under microgravity and after return to Earth.
Crucial Effects of Weightlessness on Human Orientation
Authors: Mittelstaedt H. , Glasauer S.
Published: September 2021

This contribution examines the consequences of two remarkable experiences of subjects in weightlessness, 1) the missing of sensations of trunk tilt and of the respective concomitant reflexes when the head is tilted with respect to the trunk, and 2) the persistence of a perception of “up” and “down,” that is, of the polarity of the subjective vertical (SV) in the absence of, as well as in contradiction to, visual cues. The first disproves that the necessary head-to-trunk coordinate transformation be achieved by adding representations of the respective angles gained by utricles and neck receptors, but corroborates an extant model of cross-multiplication of utricular, saccular, and neck receptor components. The second indicates the existence of force-independent components in the determination of the SV. Although the number of subjects is still small and experimental conditions are not as homogeneous as desired, measurements and/or reports on the ground, in parabolic, and in space flight point to the decisive role of the saccular z-bias, that is, of a difference of the mean resting discharges of saccular units polarized in the rostrad and the caudad (±z-) direction.
Horizontal Angular VOR, Nystagmus Dumping, and Sensation Duration in Spacelab SLS-1 Crewmembers
Authors: Oman C.M. , Balkwill M.D.
Published: September 2021

In 1 G, the apparent time constant (Td) of postrotatory SPV decay with the head tilted face down is 55% of that with head erect (Te). This phenomenon is called “nystagmus dumping” and has been attributed to G effects on VOR velocity storage. Similarly, postrotatory sensation duration with head tilted (Dd) is 32% of that when head erect (De). In parabolic flight, Te and De are 70% of 1-G values, but a pitch back dumping movement produces no further change. Te, Td, and Dd have not previously been measured in orbital flight. VOR and sensation duration was tested in 4 crewmembers in 4 preflight, 1 inflight (days 4 or 5) and 4 post flight sessions. Bitemporal EOG was recorded with eyes open in darkness. Instructions were to “gaze straight ahead,” and indicate when “rotation sensation disappears or becomes ambiguous”. Subjects were rotated CW and CCW head erect for 1 min at 120∘/s, stopped, and EOG was recorded for another 1 min. This procedure was then used to study dumping, except that immediately after chair stop, subjects pitched their head forward 90∘. SPV was calculated using order statistic filtering, and dropouts removed using an iterative model fitting method. Te and Td were determined by logarithmic linear regression of mean SPV for each subject. In orbit 90∘ pitch movement produced rapid subjective dumping, but not nystagmus dumping. Dd was noticeably shorter (“almost instantaneous”) compared in preflight Dd. Te and Td in orbit were similar to preflight Te for 3/4 subjects (rather than to preflight Td as expected). No consistent VOR gain changes were seen in orbit. Although Te is known to decrease acutely in parabolic flight, a longer time constant was measured in 3/4 subjects after 4-5 days adaptation to weightlessness, suggesting a return of angular velocity storage.
Interactions Within and Between the Spatial Senses
Authors: Howard Ian P.
Published: September 2021

This paper reviews five types of interaction between sources of spatial information within and between sense organs; 1) nested, 2) opponent, 3) comparison, 4) covariation, and 5) multicue interactions. Efference copy is treated as a type of sensory input. Examples of each type of interaction are provided, with an emphasis on visual-vestibular interactions. In the first type of interaction, inputs from nested sensory systems are summed like vectors. For instance, the ,3-D vector sum of inputs from the joints and muscle spindles of the arm allows one to judge the position of the hand. In the second type, inputs from opponent systems are combined to form a signed difference signal with respect to a norm. For instance, the push-pull linkage between the vestibular organs on the two sides of the head provides the signal for head rotation. The third type involves comparisons based on the detection of differences between stimuli presented to different regions of the same sense organ or to distinct sense organs. The fourth type involves the extraction of products or ratios between stimuli used in the detection of invariant high-level features. For instance, the linear size of an object can be derived from the constant product of the distance of the object and the size of its image. Similar systems are used to scale the response to one stimulus feature with respect to a second feature. For instance, vestibular inputs evoking eye nystagmus are scaled by viewing distance. Judgments based on an of the above mechanisms are relational, meaning that they require information from several sources. The fifth type involves multicue systems in which alternative cues are available for the same judgment. The cues are sometimes combined as a weighted mean. For instance, the direction of an object is derived from the mean position of the images in the two eyes, or a judgment of the rotation of the body may be based on combined inputs from the vestibular system and from visual motion. For distinct types of cue, averaging is less common than cue dominance, dissociation, or cue reinterpretation.
Importance of the vestibular system in visually induced nausea and self-vection
Authors: Johnson Walter H. , Sunahara Fred A. , Landolt Jack P.
Published: September 2021

The objective of this study was to determine the importance, if any, of the non-auditory labyrinth of the inner ear in visually induced nausea and self-vection in subjects exposed to a moving visual field with and without concomitant pitching head movements. Subjects teated were 15 normals, 18 unilateral labyrinthectomies and 6 bilateral labyrinthectomies. The findings show a higher incidence of pseudo-Coriolis induced nausea in normal subjects compared to unilateral and bilateral labyrinthectomized subjects. When the subjects were exposed to the moving visual field only (no head movement), pronounced self-vection occurred in all subjects, but with earlier onset in the bilateral labyrinthine defective subjects as compared to normal and unilateral defective subjects. The subjective intensities of self-vections reported by labyrinth-defectives were much more pronounced as compared to normal subjects, and it is apparent that visual input in these subjects achieves much more importance in maintaining compensatory eye movements, and the gain of neck reflexes is enhanced. The findings that visual stimulation is more effective in producing the disabling effects after labyrinthine destruction could possibly be explained by enhancement of vision after loss of labyrinthine sensory input, and the gain in neck reflexes is also enhanced after labyrinthectomy.
Subjective visual vertical in peripheral unilateral vestibular diseases*
Authors: Vibert D. , Häusler R. , Safran A.B.
Published: September 2021

In humans, the perception of vertical is provided by input from various sensorineural organs and pathways: vision, eye-movements, and proprioceptive and vestibular cues, particularly from the otolithic organs and graviceptive pathways. Well known in several types of brainstem lesions, subjective visual vertical (SVV) abnormalities may also be observed after peripheral vestibular lesions, such as surgical deafferentation, with a deviation directed toward the operated ear. Subjective visual vertical abnormalities are presumably related to a lesion of the otolithic organs and/or to changes in the afferent graviceptive pathways. The goal of this prospective study was to measure the SVV and to define the influence of the otolithic organs in patients suffering from various types of peripheral vestibular diseases: unilateral sudden cochleo-vestibular loss, so-called “viral labyrinthitis” (VL), sudden idiopathic unilateral peripheral vestibular loss, so-called “vestibular neuritis” (Ne). Data were compared with findings after unilateral surgical deafferentations such as vestibular neurectomy (VN) and labyrinthectomy (Lab). Subjective visual vertical was measured with a binocular test (vertical frame) and a monocular test (Maddox rod). In all patients, after VN and Lab, the SVV showed a 10 – 30 ∘ tilt with the vertical frame (N: 0 ± 2 ∘ ), 5 – 15 ∘ with the Maddox rod (N: 0 ± 4 ∘ ). With the vertical frame, SVV was tilted > 2 ∘ in VL (47%) VL (41%) Our results demonstrate that SVV is frequently tilted in acute peripheral vestibulopathies such as VL and Ne. These findings suggest that otolithic function is implicated in the deficit depending on the extent and/or the localisation of the peripheral vestibular lesion.
Somatosensory cuing of head-only rotational testing
Authors: Furman Joseph M. , Durrant John D.
Published: September 2021

Head-only rotational testing (HORT) is a method of assessing the vestibulo-ocular reflex (VOR) that can be performed at the bedside with inexpensive, transportable equipment. Previous studies of HORT using auditory cuing have suggested that test results are in large part independent of the method by which a subject's head is moved, that is, active versus passive. However, many subjects have difficulty moving their head at rotational frequencies of 3 Hz or greater. In an attempt to overcome this difficulty, and to learn more about HORT, we explored the possibility of providing subjects with a somatosensory, rather than an auditory cue for head movement. Somatosensory, cues were provided either by applying gentle pressure against a tightly-fitted headband or by lightly tapping on the shoulders. Our results with young, healthy subjects indicate that somatosensory cuing is an efficacious means of inducing periodic head rotation and that HORT results are unaffected by the type of cue provided. We conclude that somatosensory rather than auditory cuing may be the preferred method of performing HORT.
The influence of dynamic visual environments on postural sway in the elderly
Authors: Borger L.L. , Whitney S.L. , Redfern M.S. , Furman J.M.
Published: September 2021

Postural sway during stance has been found to be sensitive to moving visual scenes in young adults, children, and those with vestibular disease. The effect of visual environments on balance in elderly individuals is relatively unknown. The purpose of this study was to compare postural sway responses of healthy elderly to those of young subjects when both groups were exposed to a moving visual scene. Peak to peak, root mean squared, and mean velocity of the center of pressure were analyzed under conditions combining four moving scene amplitudes ( 2 . 5 ∘ , 5 ∘ , 7 . 5 ∘ , 10 ∘ ) and two frequencies of scene movement (0.1 Hz, 0.25 Hz). Each visual condition was tested with a fixed floor and sway referenced platform. Results showed that elderly subjects swayed more than younger subjects when experiencing a moving visual scene under all conditions. The elderly were affected more than the young by sway referencing the platform. The differences between the two age groups were greater at increased amplitudes of scene movement. These results suggest that elderly are more influenced by dynamic visual information for balance than the young, particularly when cues from the ankles are altered.
Further evidence for age-related deficits in human postural function
Authors: Matheson Anna J. , Darlington Cynthia L. , Smith Paul F.
Published: September 2021

Vestibular dysfunction can have a tremendous impact on an individual’s quality of life. The purpose of this paper is to determine if the level of handicap reported by individuals on the Dizziness Handicap Inventory (DHI), an inventory developed for use with individuals with complaints of dizziness symptoms, will be consistent with that reported on the Activities-specific Balance Confidence Scale (ABC), a tool developed for use with elderly individuals that attempts to assess a person’s confidence level in performing activities of daily living (ADL’s). A sample of convenience was used consisting of 71 subjects (15 males and 56 females) from a local Balance and Vestibular Clinic. The subjects ranged in age from 26 to 88 years of age. Both the DHI and the ABC were administered as part of an initial physical therapy evaluation to new patients at the clinic. A moderately strong negative correlation was found between the scores of the two inventories ( r s = − 0.6350). The results suggest that the ABC is a valid tool for use with individuals with complaints of dizziness.
Coordination of a step with a reach
Authors: Daghestani Linda , Anderson John H. , Flanders Martha
Published: September 2021

Although natural reaching behavior can easily include forward body movement, most laboratory studies of reaching have constrained the body to be stationary. Recently, however, it has been shown that normal subjects exhibit a different pattern of errors when attempting to pinpoint remembered target locations, depending on whether or not the reach includes a step. In the study of Flanders et al. [1], these errors appeared to be due to the strategy of eye/head/hand coordination which normally comes into play when the body is moving toward the target. Since the spatial positioning of the head was found to partially explain the errors in hand placement, the present study examined the movements of patients with bilateral vestibular deficits in order to further analyze the whole-body coordination. Somewhat surprisingly, the patients exhibited the same pattern of head movement and the same errors in hand placement as did the control subjects. Nevertheless, the patients' movements clearly exhibited evidence for an abnormal decomposition of elbow extension and trunk rotation. Furthermore the patients' (spatial) hand paths were significantly more curved than those of control subjects and, only in the patients, paths to remembered targets were significantly more curved than paths to visible targets. Thus for movements to remembered targets, the patients tended to move the hand to the same incorrect spatial positions as control subjects but spatiotemporal aspects of the arm and body movement differed. The results are consistent with the idea that vestibular patients are overly dependent upon visual cues, and support the hypothesis that this stepping and reaching behavior is largely dependent upon a visual reference signal.
Directional preponderance in pitch circular vection
Authors: Fushiki H. , Takata S. , Yasuda K. , Watanabe Y.
Published: September 2021

We used optokinetic stimulation (OKS) in eighteen normal adults aged 18–30 years to investigate vertical self-motion perception. In order to induce self-rotation, either a stripe pattern or a random dot pattern was projected onto the inner wall of a hemispherical dome with a diameter of 150 cm. The pattern was rotated either about the subject’s vertical axis (yaw) or about the subject’s interaural axis (pitch) for 80 s at a constant acceleration of 1 deg / s 2 . Stimuli were randomly repeated three to four times in each direction. The latency of onset as well as the perceived intensity of circular vection (CV) was measured for each stimulus presentation. CV latencies for upward rotational stimulation were significantly longer than those for downward rotational stimulation under both types of stimulus conditions. There was no significant difference in CV latency between rightward and leftward rotational stimulation. For most subjects, the magnitudes of the perceived CV for rightward rotational stimulation were equal to those for leftward rotational stimulation, whereas the magnitudes of the perceived CV for vertical stimulation showed large intersubject variability. These results provide additional evidence that fundamental differences exist between different types of self-motion. Possible explanations for the directional asymmetry in vertical perception of self-motion will also be discussed.
The dynamic gait index relates to self-reported fall history in individuals with vestibular dysfunction
Authors: Whitney S.L. , Hudak M.T. , Marchetti G.F.
Published: September 2021

The purpose of this study was to determine the relationship between gait instability and falls history in people with vestibular disorders. A total of 247 people (164 women, 83 men) participated in the study (mean age = 62.5). Falls history within the last 6 months and scores on the Dynamic Gait Index (DGI) were compared using the Mantel-Hantzel Chi-square statistic. Thirty-seven percent of all subjects reported falling within the last 6 months. Odds ratios in favor of falls with DGI scores of 19 or lower was 2.58 (95% were 2.58 times more likely to have reported a fall in the previous 6 months than subjects with scores above 19. Younger subjects (those under 65 years of age) with vestibular disorders reported more falls than persons 65 years of age or over. Younger people may be more willing to risk a fall while actively having a vestibular disorder. The DGI appears to be a good indicator of fall status in persons with vestibular disorders, regardless of age.
The effect of habituation and plane of rotation on vestibular perceptual responses
Authors: Grunfeld E.A. , Okada T. , Jáuregui-Renaud K. , Bronstein A.M.
Published: September 2021

A technique was applied to assess vestibular sensation without reference to external spatial, position cues. The stimuli were stopping responses to velocity-steps of 90 deg/s in the dark. Subjects indicated their perceived angular velocity by turning a flywheel connected to a tachogenerator. Two separate experiments were conducted. In one, subjects were rotated in yaw about an earth-vertical axis before and after prolonged rotational or visual (optokinetic) stimuli. In the second experiment, subjects were rotated in roll supine, with either the head (`roll centred') or the feet (`roll eccentric') on the axis of rotation. The two aims of the paper were to (i) examine the effect of repetitive vestibular and optokinetic stimulation on the time constant of decay of vestibular sensation in yaw; (ii) to compare vestibular sensation responses to rotation in roll both with and without the addition of a Z-axis centrifugal force. The pre-habituation sensation response in yaw decayed exponentially with a median time constant of 12.8 s. The duration of the sensation responses were significantly reduced following both prolonged vestibular and optokinetic stimulation. The reduction in vestibular responses following prolonged visual and vestibular stimuli, 1) is likely to occur in velocity storage mechanisms mediating ocular and perceptual responses, 2) may represent a mechanism for reducing the disorientating consequences of visual-vestibular conflict and 3) supports the use of optokinetic stimuli as a treatment for vestibular patients. The time constant of the sensation responses in roll was shorter and not significantly influenced by head position: 5.7 s in the head-centred position compared to 4.7 s in the eccentric head position. Therefore, perceptual as well as ocular responses to rotation in roll are determined primarily by cupula dynamics and not influenced by velocity storage.
Application of multivariate statistics to vestibular testing: Discriminating between Menière's disease and migraine associated dizziness
Authors: Dimitri P.S. , Wall C. , Oas J.G. , Rauch S.D.
Published: September 2021

Menière's disease (MD) and migraine associated dizziness (MAD) are two disorders that can have similar symptomatologies, but differ vastly in treatment. Vestibular testing is sometimes used to help differentiate between these disorders, but the inefficiency of a human interpreter analyzing a multitude of variables independently decreases its utility. Our hypothesis was that we could objectively discriminate between patients with MD and those with MAD using select variables from the vestibular test battery. Sinusoidal harmonic acceleration test variables were reduced to three vestibulo-ocular reflex physiologic parameters: gain, time constant, and asymmetry. A combination of these parameters plus a measurement of reduced vestibular response from caloric testing allowed us to achieve a joint classification rate of 91%, independent quadratic classification algorithm. Data from posturography were not useful for this type of differentiation. Overall, our classification function can be used as an unbiased assistant to discriminate between MD and MAD and gave us insight into the pathophysiologic differences between the two disorders.