bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Predictive and Nonpredictive Ocular Pursuit Under Active and Passive Stimulation Conditions in Humans
Authors: Ohashi Naoki , Barnes Graham
Published: December 2019

A technique has been developed for the comparison of predictive and nonpredictive ocular pursuit in human subjects, with the objective of estimating the contribution made by predictive processes to the normal pursuit response. Subjects were presented with a target moving at constant velocity in the horizontal plane and instructed to actively pursue the target or to passively stare at it. In the predictive mode (PRD), a step-ramp stimulus with velocity ranging from 12.5 to 50°/s was presented at regular intervals of 1.728 s, in alternating directions, with target exposure durations (PD) that varied from 80 to 640 ms. In the interval between presentations, subjects were in complete darkness. In the nonpredictive mode (RND), similar step–ramp stimuli were presented but with randomized direction and timing of target exposure. In the nonpredictive mode, during both active and passive stimulation, the smooth component of eye velocity was initiated after a mean delay of 125 ms. In the predictive mode, eye velocity started to build up well before target onset, even during passive stimulation. It was found that the time of initiation of this anticipatory response was closely associated with the time at which the target would have changed direction even though the target could not be seen at this time. Eye velocity measured 100 ms after target onset was negligible in the nonpredictive mode, whereas in the predictive mode, it progressively increased with target velocity, reaching a maximum of 18°/s when target velocity was 50°/s and PD was greater than 240 ms. Examination of the difference in the eye velocity trajectories for the predictive and nonpredictive modes indicated that the greatest contribution of prediction occurred approximately 150 ms after target onset and its effects were evident in the predictive response for at least 300 ms. This effect was reflected in the reaction time between target onset and the occurrence of peak eye velocity. In the nonpredictive mode, this progressively increased from 250 ms to 400 ms as PD increased from 80 to 640 ms, whereas in the predictive mode peak velocity occurred an average of 50 ms earlier for all values of PD. The results demonstrate the significant contribution that predictive processes make to normal ocular pursuit behavior and the importance of timing control in this process. They also indicate that this process is not dependent on volitional control, but can be seen as an automatized response during passive stimulation.
Phase-Shifted Direction Adaptation of the Vestibulo-Ocular Reflex in Cat
Authors: Powell K.D. , Peterson B.W. , Baker J.F.
Published: December 2019

The ability of the vestibulo-ocular reflex (VOR) to alter the phase of the motor output relative to the sensory input is examined. Alert cats were trained for 2 h with 0.25 Hz sinusoidal horizontal vestibular and vertical optokinetic rotational stimuli. In each experiment the optokinetic training stimulus was phase shifted by 0°, +45°, −45°, or 90° from the vestibular stimulus. Vertical and horizontal eye movements were measured during horizontal rotations in darkness before and after the training procedure. Phase-advance experiments (+45°) produced an adaptive vertical VOR with a mean phase of +28°. After phase-delay experiments (−45°), the adapted VOR had a mean phase of −19°. The peak adaptive change in VOR gain was at or near the 0.25 Hz training frequency in each experimental group, but the gain depended in a complex manner on the testing frequency and the degree of phase shift of the training stimulus. Training with a 45° phase-delayed optokinetic stimulus produced an adaptive vertical VOR with a gain that was relatively higher at frequencies below the training stimulus than at those that were above. Training with a 45° phase-advanced optokinetic stimulus produced an adaptive vertical VOR with a gain that was higher at frequencies above the training frequency than at those that were below. During training with a phase-shifted optokinetic stimulus, adjustment of the relative efficacies of two neural pathways, a velocity pathway and an integrating pathway, could account for gain dependence on testing frequency and phase shift. This was corroborated by a model of the VOR that incorporates parallel velocity and integrating pathways. Data from 45° phase advances were fit by increasing the gain of the velocity versus integrating pathway, whereas 45° phase delay data were fit by decreasing the gain of the direct versus integrating pathway. The models altered the time constants of either the common oculomotor integrator or the velocity storage mechanism.
Influence of Otolith Organs, Semicircular Canals, and Neck Afferents on Post-Rotatory Nystagmus
Authors: Koizuka Izumi , Schor Robert H. , Furman Joseph M.
Published: December 2019

The duration of post-rotatory nystagmus is known to be shortened by head tilt, a phenomenon that has been attributed to rapid discharge of the velocity storage mechanism. The relative importance of the various sensory signals associated with post-rotatory head tilt is unknown. Using both earth-vertical axis and off-vertical axis rotation, we investigated this issue in humans by combining sudden termination of constant velocity rotation with several post-rotatory maneuvers that stimulated combinations of otolith organ, somatosensory, and vertical semicircular canal afferents. Results indicated that horizontal post-rotatory nystagmus was shortened by maneuvers that move the head from upright to off-vertical and by cessation of dynamic otolith stimuli. Somatosensory, neck afferent, and transient vestibular stimulation had no consistent effect. We conclude that tilt suppression of postrotatory nystagmus and the short time constant following off-vertical axis rotation is primarily a function of otolith influence on the velocity storage system.
“Torso Rotation” Experiments; 2: Gaze Stability During Voluntary Head Movements Improves with Adaptation to Motion Sickness
Authors: Bouyer L.J.G. , Watt D.G.D.
Published: December 2019

Following a 30-minute exposure to an unusual motor strategy called “Torso Rotation” (TR), the signs and symptoms of motion sickness appear along with perceptual illusions during movement, gaze and postural instability, and a significantly reduced vestibulo-ocular response (VOR) gain. With repeated exposure to TR, motion sickness symptoms disappear and gaze instability seems reduced, but without any concomitant change in VOR gain. Is the reduction in gaze instability a perceptual illusion or a real, measurable phenomenon? Velocity gain (eye velocity/head velocity) was evaluated during voluntary head shaking in the light over the frequency range 0.3 to 3.0 Hz. A significant improvement was seen after 3 days of testing (P<0.01). Furthermore, the time course of improvement in gaze stability was correlated with the loss of motion sickness symptoms reported in the previous study (1). We suggest that adaptation to motion sickness could be related to an overall change in sensorimotor strategy, perhaps including a de-emphasis of a vestibular reference.
Effects of Different Treatments on Postural Performance in Patients with Cervical Root Compression1
Authors: Persson Liselott , Karlberg Mikael , Magnusson Måns
Published: December 2019

Patients with cervical root compression were used as a “model” to investigate the possible importance of neck disorders and cervical sensory information in postural control. We assessed postural performance with posturography before and after treatment in 71 consecutive patients with MRI-verified cervical root compression without medullary compression. The patients were randomized to surgery (n=22), physiotherapy (n=24) or treatment with cervical collars (n=25). There were no differences in postural performance or pain intensity between the groups before treatment. After treatment, the surgery group manifested significantly improved postural performance and reduced neck pain scores, as compared to the two conservative treatment groups, and their postural performance had improved to the same level manifested by healthy controls. The conservative treatment groups manifested no consistent significant changes in postural performance or pain scores. Decreased muscular tension due to reduction of cervical pain after surgery and normalization of cervical proprioception are suggested as possible explanations of the improved postural control.
Measuring Eye Movements During Locomotion: Filtering Techniques for Obtaining Velocity Signals From a Video-based Eye Monitor
Authors: Das Vallabh E. , Thomas Cecil W. , Zivotofsky Ari Z. , Leigh R. John
Published: December 2019

Video-based eye-tracking systems are especially suited to studying eye movements during naturally occurring activities such as locomotion, but eye velocity records suffer from broad band noise that is not amenable to conventional filtering methods. We evaluated the effectiveness of combined median and moving-average filters by comparing prefiltered and postfiltered records made synchronously with a video eye-tracker and the magnetic search coil technique, which is relatively noise free. Root-mean-square noise was reduced by half, without distorting the eye velocity signal. To illustrate the practical use of this technique, we studied normal subjects and patients with deficient labyrinthine function and compared their ability to hold gaze on a visual target that moved with their heads (cancellation of the vestibulo-ocular reflex). Patients and normal subjects performed similarly during active head rotation but, during locomotion, patients held their eyes more steadily on the visual target than did subjects.
Modification of Vertical OKN and Vertical OKAN Asymmetry in Humans During Parabolic Flight
Authors: Wei Gang , Lafortune-Kahane Sylviane , Ireland Desmond , Jell Ralph
Published: December 2019

Characteristics of human vertical optokinetic nystagmus (OKN) and afternystagmus (OKAN) were examined by ISCAN imaging system on the ground and on board NASA's KC-135 aircraft in a parabolic flight study. The aircraft produced alternating periods of micro- (ca. 10−2 G) and hyper- (ca. 1.8 G) gravitoinertial forces. Each phase lasted approximately 20 to 25 s. As compared to the baseline data on the ground, there was a significant increase of downward OKN/OKAN, whereas the upward OKN/OKAN did not change significantly in either micro-or hyper-G. As a consequence, the asymmetry of vertical OKN/OKAN, normally seen on the ground, was lost. It is postulated that the increase of downward OKN/OKAN in non-1-G conditions was governed by two different mechanisms. In micro-G, the normal inhibition effect in 1 G on the downward eye movement mediated by otolith organ activity to vertical velocity storage was removed. In hyper-G, downward OKN/OKAN was facilitated by augmented otolith-ocular reflex because of increased gravitoinertial force, so as to produce enhanced compensatory downward eye movement.
Three-Dimensional Baselines for Perceived Self-Motion During Acceleration and Deceleration in a Centrifuge
Authors: Holly Jan E.
Published: December 2019

Three-dimensional motion trajectories were computed, representing the motions that would be perceived by a perfect processor of acceleration information during the acceleration and deceleration stages of a centrifuge run. These motions serve as “baselines” for perceived self-motion in a centrifuge, and depend on the initial perception of orientation and velocity immediately preceding the acceleration and immediately preceding the deceleration. The baselines show that a perfect processor of acceleration information perceives self-motion during centrifuge deceleration significantly differently from self-motion during centrifuge acceleration, despite the fact that the angular accelerations have equal magnitude (with opposite direction). At the same time, the baselines can be compared with subjects' reported perceptions to highlight limitations of the nervous system; limitations and peculiarities of the nervous system are identified as deviations from a baseline. As a result, peculiarities of the nervous system are held responsible for any perception of pitch or roll angular velocity or change in tilt of the body-horizontal plane of motion during the centrifuge run. On the other hand, baselines explain perception of tilt position during deceleration, linear velocity, possible lack of significant linear velocity during deceleration, and yaw angular velocity, including on-axis angular velocity during centrifuge deceleration. The results lead to several experimental questions.
Aging and the Human Vestibular Nucleus
Authors: Lopez Ivan , Honrubia Vicente , Baloh Robert W.
Published: December 2019

Degenerative changes during aging have been identified in the inner ear and in the vestibular nerve, but not in the human vestibular nuclear complex (VNC). Therefore, the purpose of this study was to document quantitative morphometric changes within the VNC in humans as a function of age. The VNC of normal human subjects was examined for age-related changes using computer-based microscopy. Neuronal counts, nuclear volume, neuronal density, and nuclear length of the 4 vestibular nuclei were determined in 15 normal people, age 40 to 93 years. Based on a linear model, there was approximately a 3% neuronal loss per decade from age forty to ninety. VNC volume and neuronal density also decreased significantly with age, although to a lesser degree than did the number of neurons. Neuronal loss as a percentage of the total number of neurons was greatest in the superior vestibular nucleus and least in the medial vestibular nucleus. Despite the overall loss of neurons, the number of giant neurons (>500μm2) increased in older people. This increase in giant neurons could be traced to the accumulation of lipofuscin deposits in the cell somata. The overall rate of neuronal loss with aging in the VNC is comparable to that previously observed in hair cells, primary vestibular neurons, and cerebellar Purkinje cells, but is in contrast to prior report of no age-related loss of neurons in other brain stem nuclei.
Difference in Quick Phases Induced by Horizontal and Vertical Vestibular Stimulations: Role of the Otolithic Input
Authors: Pettorossi V.E. , Errico P. , Ferraresi A.
Published: December 2019

Quick phases (QPs) induced by horizontal and vertical sinusoidal vestibular stimulations were studied in rabbits, cats, and humans. In all the animals, large and frequent horizontal QPs were observed following yaw stimulation in prone position. By contrast, QPs were almost absent during roll stimulation in rabbits, and they were small and oblique during pitch stimulation in cats and humans. As a result of these differences, the range of gaze displacement induced by vestibular stimulations was greater in the horizontal plane than in the vertical one. We also found that the trajectory of the QPs in rabbits was kept horizontal even when the yaw rotation was off vertical axis of ±45° in the sagittal plane. Moreover, in the rabbit, the rare horizontal QPs induced by roll stimulation did not change their orientation at various pitch angles of roll stimulation axis. The QPs were also analyzed following roll stimulation of the rabbit in supine position. In this condition, in which the otolithic receptors were activated in the opposite way compared to prone position, large vertical QPs were elicited. We concluded that these results provide evidence that the otolithic signal plays a role in controlling occurrence and trajectory orientation of the QPs.
Kinematic Analysis of Locomotion in Unilateral Vestibular Neurectomized Cats
Authors: Lacour Michel , Sun Jiurong , Harlay Françoise
Published: December 2019

The vestibular syndrome following unilateral lesion of the vestibular system and the subsequent behavioral compensation over time have been well documented in many species. However, the locomotor pattern changes and the behavioral strategies used to preserve balance have still not been described. This study was aimed at quantitatively describing posturolocomotor behavior in cats tested before and after unilateral vestibular neurectomy (UVN) by the rotating beam test, which provides locomotor tasks of various difficulty. The position of head, neck, and trunk and the trajectory of the forelimbs and hindlimbs were recorded in 5 cats by 3D motion analysis. Step length and frequency, walking velocity, and body height were computed. Results showed that normal cats adapted their locomotor patterns to the speed of beam rotation by increasing step length and/or frequency, that is, by increasing walking velocity, but without drastically changing their body posture. By contrast, UVN cats typically lowered their body centers of gravity and modified their locomotor patterns according to the locomotor task. Mean walking velocity was decreased in the low range of beam rotation as a result of smaller step length and lower frequency, and it was increased in the high range by opposite effects on these step cycle parameters. Modifications of the locomotor parameters were a function of the direction of beam rotation, showing significant reduction of step length, frequency, and velocity in the low range of counterclockwise compared to clockwise beam rotation, that is, during rotations toward the lesioned side. Phase plane plots of foot linear velocity with respect to foot linear displacement along the horizontal longitudinal axis displayed two different limit cycles, adapted to easy (low range of beam rotation) and more difficult (high range of rotation) walking conditions, in the normal cat. These dynamic profiles of the trajectories of the limbs during the step cycle were not greatly modified after vestibular lesion, but the phase plane typically observed in the high range for the normals was also found in the low range for the UVN cats. Thus, locomotor equilibrium function in the cat is strongly impaired following UVN, but locomotor balance can still be achieved in the UVN cats by the development of adaptive posturolocomotor strategies compensating for the lack of vestibular inputs.
Visual Object Localization through Vestibular and Neck Inputs. 1: Localization with Respect to Space and Relative to the Head and Trunk Mid-Sagittal Planes
Authors: Maurer C. , Kimmig H. , Trefzer A. , Mergner T.
Published: December 2019

Object localization in space signals in the absence of an external reference (visual, auditory, haptic) involves a signal of the head in space (vestibular). The present study asks whether signals of body position relative to the support surface (proprioceptive) are involved as well, by investigating the role of vestibular-neck interaction (dissociating head and trunk position). Normal human subjects saw a light spot (object) and continuously nulled displacement steps of the spot. They did so before and after vestibular and/or neck rotational stimulation in the horizontal plane, reproducing a predesignated object localization in space (i), relative to the head mid-sagittal (ii), and relative to the trunk mid-sagittal (iii). The predominant frequency contained in the stimuli was varied (0.05, 0.1, and 0.4 Hz). (I) Object localization in space upon whole-body rotation (vestibular stimulus) at high frequency was veridical, whereas that at low frequency fell short. Almost identical results were obtained for trunk rotation about the stationary head (neck stimulus). In contrast, when combining the stimuli in the form of head rotation on the stationary trunk, the results were veridical, independent of stimulus frequency. Additional findings obtained with a large variety of vestibular-neck stimulus combinations suggest a linear summation of vestibular and neck signals. (II) Object localization with respect to the head was approximately veridical, being independent of vestibular and neck stimulation. However, this only applied if subjects were not biased by a head-in-space motion illusion of neck origin. (III) Object localization with respect to the trunk was veridical in all conditions tested. The findings support a recently developed concept, according to which humans evaluate the kinematic state of a visual object in space by (a) relating it to that of the body support by means of an essentially ideal proprioceptive coordinate transformation, and (b) relating, in turn, the kinematic state of the support to a vestibularly derived notion of space, using a proprioceptive coordinate transformation that “knows” the vestibular transfer characteristics. One important aspect is that object localization in space always is veridical during head and trunk rotation relative to a stationary support (for example, the ground) despite non-ideal vestibular transfer characteristics. Additional findings in patients with chronic loss of vestibular function confirm this concept.
Do Infants Have Motor Responses to Sudden Surface Rotations in Prone Position?
Authors: Hirschfeld H.
Published: December 2019

This study investigated whether sudden rotation of the support surface (platform) triggers motor responses similar to reactions to sudden free fall in infants at very early age (2 to 5 weeks). Ten infants in prone position were exposed to sudden head-down rotation (mimicking the falling phase) and head-up rotation of the platform (mimicking landing phase) of 4° or 6° amplitude and 35°/s velocity while EMGs and kinematics were recorded from the neck, trunk, and right arm. One infant, reassessed at 13 weeks, and one adult were tested for complementary developmental information. Sudden downward acceleration of the platform, induced either during head-down rotation or during the deceleration phase of head-up rotation, indeed mimicked falling and evoked in infants two-peaked EMG responses in the neck, trunk, and arm muscles, lasting in the latter over several hundred milliseconds. The activation pattern showed similarities to the adult and 13-week-old control subjects. The results suggested that the first burst may be ascribed to cutaneous pressure changes at the body and to vestibular signals triggering a startle-like response, whereas the second burst of the pattern in the arm is likely a candidate for an early substrate of the landing response normally seen during later stages of motor development. Head control appeared to be related more to its position with respect to the orientation of the trunk rather than to space in the infants and in the adult and might be due to the experimental paradigm, in which the surface accelerated away from the body and not, as during normal falling, when the body accelerates toward the support surface.
Interaction of Semicircular Canal Stimulation with Carotid Baroreceptor Reflex Control of Heart Rate
Authors: Convertino Victor A.
Published: December 2019

The carotid-cardiac baroreflex contributes to the prediction of orthostatic tolerance; experimental attenuation of the reflex response leads to orthostatic hypotension in humans and animals. Anecdotal observations indicate that rotational head movements about the vertical axis of the body can also induce orthostatic bradycardia and hypotension through increased parasympathetic activity. We therefore measured the chronotropic response to carotid baroreceptor stimulation in 12 men during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that stimulation of the semicircular canals associated with head movements in the yaw plane inhibits cardioacceleration through a vagally mediated baroreflex. Carotid-cardiac baroreflex response was assessed by plotting R-R intervals (ms) at each of 8 neck pressure steps with their respective carotid distending pressures (mmHg). Calculated baroreflex gain (maximal slope of the stimulus-response relationship) was measured under 4 experimental conditions: 1) sinusoidal whole-body yaw rotation of the subject in the dark without visual fixation (combined vestibular-oculomotor stimulation); 2) yaw oscillation of the subject while tracking a small head-fixed light moving with the subject (vestibular stimulation without eye movements); 3) subject stationary while fixating on a small light oscillating in yaw at the same frequency, peak acceleration, and velocity as the chair (eye movements without vestibular stimulation); and 4) subject stationary in the dark (no eye or head motion). Head motion alone and with eye movement reduced baseline baroreflex responsiveness to the same stimulus by 30%. Inhibition of cardioacceleration during rotational head movements may have significant impact on functional performance in aerospace environments, particularly in high-performance aircraft pilots during high angular acceleration in aerial combat maneuvers or in astronauts upon return from spaceflight who already have attenuated baroreflex functions.
Examination of Two Methods for Statistical Analysis of Data with Magnitude and Direction Emphasizing Vestibular Research Applications
Authors: Calkins D.S.
Published: December 2019

When the dependent (or response) variable response variable in an experiment has direction and magnitude, one approach that has been used for statistical analysis involves splitting magnitude and direction and applying univariate statistical techniques to the components. However, such treatment of quantities with direction and magnitude is not justifiable mathematically and can lead to incorrect conclusions about relationships among variables and, as a result, to flawed interpretations. This note discusses a problem with that practice and recommends mathematically correct procedures to be used with dependent variables that have direction and magnitude for 1) computation of mean values, 2) statistical contrasts of and confidence intervals for means, and 3) correlation methods.
An Earth-Stationary Perceived Visual Scene During Roll and Yaw Motions in a Flight Simulator
Authors: van der Steen F.A.M.
Published: December 2019

A flight simulator was used for two experiments to determine the amplitude combinations of visual scene motion (with respect to the observer) and inertial body motion (with respect to an earth-fixed frame) that provide the perception of an earth-stationary visual scene and realistic simulated self-motion. In the first experiment, this range was determined for simulated self-motion about the longitudinal body axis, while in the second, self-motion about the vertical body axis was considered. Both the inertial and the visual motions consisted of 0.75 s accelerations, followed by 1.50 s decelerations, and 0.75 s accelerations. The visual scene acceleration amplitude, W, was fixed at either 0, 2, 4, 8, or 12°/s2 while the inertial acceleration amplitude, I, was varied by a staircase procedure. Following the visual and inertial motions, the subjects pushed a button when they perceived the scene to be not earth-stationary. At each visual scene acceleration amplitude, the lower and upper inertial threshold amplitudes were determined, which bounded the range in which the visual scene was perceived to be earth-stationary. The lower and upper inertial thresholds were defined as the inertial motion amplitudes for which the inertial stimulations were too small or too large, respectively, to provide the perception of an earth-stationary visual scene. The lower inertial thresholds were determined for W=2 through W=12°/s2 and were found to be well approximated by the linear relation I=−0.37+0.60W for the roll motions tested, and I=1.1+0.33W for the yaw motions tested. The upper inertial thresholds were determined for W=0 through W=12°/s2 and were found to be well approximated by the linear relation I=2.7+1.7W for roll and I=2.2+1.4W for yaw. With the assumption that the lower and upper inertial threshold amplitudes are symmetric about the W=0 condition, the present results infer a strong nonlinearity of the thresholds near W=0.
Acute endolymphatic hydrops has no direct effect on the vestibular evoked potential in the guinea pig
Authors: Kingma C.M. , Wit H.P.
Published: December 2019

To investigate the effect of an acute endolymphatic hydrops on the functioning of the vestibular system a hydrops was created by microinjection of artificial endolymph through the basilar membrane into scala media in 10 guinea pigs. To control for the effect of perforation of the basilar membrane, the same procedure was performed in 9 other guinea pigs, but without injection of endolymph. Contralateral ears served as control ears. Vestibular evoked potentials, evoked by vertical acceleration pulses applied to the guinea pig's head, were measured in all ears before, immediately after, and 2, 4, and 5 hours after perforation/injection. Acute endolymphatic hydrops did not affect the amplitude of the VsEP immediately after injection. After 4 to 5 hours VsEP was significantly reduced in both hydrops and perforated-only ears, compared to control ears. However, no significant difference was found between VsEP of the hydrops ears and perforated-only ears. Reduction of VsEP is not caused by a direct hydromechanical effect on the vestibular system, but possibly by leakage of perilymph through the perforation hole, supporting the membrane rupture theory for Menière-attacks.
Three-dimensional reconstruction of the pigeon inner ear
Authors: Hofman R. , Segenhout J.M. , Wit H.P.
Published: December 2019

Three-dimensional reconstructions of the inner ear of the pigeon (Columba livia domestica), from two-dimensional images, obtained with (conventional) light microscopy or orthogonal-plane fluorescence optical sectioning (OPFOS), are presented. The results are compared with available information on the dimensions and orientation of the semicircular canals.
Neurovestibular considerations for sub-orbital space flight: A framework for future investigation
Authors: Karmali Faisal , Shelhamer Mark
Published: December 2019

Commercial sub-orbital operators will soon offer the excitement of traveling to space to thousands of people. Based on previous experience in space flight and parabolic flight, sensorimotor disruptions in eye movements, postural stability, and motor coordination are likely in these travelers. Here we propose a framework for developing strategies to overcome these sensorimotor disruptions. We delineate how approaches should differ from those applied to orbital flight and between sub-orbital passengers and pilots based on differing frequency of flights and mission objectives. Sensorimotor adaptation is one strategy for overcoming disruptions; an important question is whether it occurs quickly enough to be of use during periods of reduced and enhanced gravity lasting less than five minutes. Data are presented showing that sensorimotor adaptation of the pitch vestibulo-ocular reflex during parabolic flight takes a few consecutive days of flying to overcome an initial disruption. We conclude with recommendations for operators and researchers to improve safety and comfort during sub-orbital o perations. We recommend using parabolic flight as a tool for pre-adapting sub-orbital passengers, along with further research into the required quantity and timing of these pre-adaptation flights and the tasks conducted during these flights. Likewise, for sub-orbital pilots, we recommend emphasizing recency of experience.
Measuring caloric response: Comparison of different analysis techniques
Authors: Mallinson A.I. , Longridge N.S. , Pace-Asciak P. , Ngo R.
Published: December 2019

Introduction: Electronystagmography (ENG) testing has been supplanted by newer techniques of measuring eye movement with infrared cameras (VNG). Most techniques of quantifying caloric induced nystagmus measure the slow phase velocity in some manner. Although our analysis is carried out by very experienced assessors, some systems have computer algorithms that have been “taught” to locate and quantify maximum responses. We wondered what differences in measurement might show up when measuring calorics using different techniques and systems, the relevance of this being that if there was a change in slow phase velocity between ENG and VNG testing when measuring caloric response, then normative data would have to be changed. There are also some subjective but important aspects of ENG interpretation which comment on the nature of the response (e.g. responses which might be “sporadic” or “scant”). Methods: Our experiment compared caloric responses in 100 patients analyzed four different ways. Each caloric was analyzed by our old ENG system, our new VNG system, an inexperienced assessor and the computer algorithm, and data was compared. Conclusions: All four systems made similar measurements but our inexperienced assessor failed to recognize responses as sporadic or scant, and we feel this is a limitation to be kept in mind in the rural setting, as it is an important aspect of assessment in complex patients. Assessment of complex VNGs should be left to an experienced assessor.
Pathophysiology of lateral semicircular canal paroxysmal positional vertigo
Authors: Vannucchi Paolo , Pecci Rudi
Published: December 2019

Objective: To study the pathophysiology of lateral semicircular canal (LSC) paroxysmal positional vertigo (PPV). Study design: Retrospective study. Methods: Between June 2004 and June 2005 we observed 471 patients with PPV. In the apogeotropic forms of LSC-PPV, we tried to transform the nystagmus into the geotropic form, either by diagnostic or therapeutic menoeuvres. If we failed, we advised barbecue rotations toward the healthy side and sleeping on the affected side. Patients were evaluated once a week until resolution. Results: 91 patients suffered LSC involvement, in 61 cases in the geotropic form and in 30 cases in the apogeotropic form. Out of these, five transformed into the geotropic form during the first examination; in 5 patients we observed geotropic nystagmus at the follow-up visit; the last 20 never showed geotropic nystagmus before resolution. Conclusion: We hypothesize that in the geotropic form the debris is free floating in the posterior arm of the LSC (canalolithiasis). In the apogeotropic form the debris can be free floating in the anterior arm or attached to the cupula of the ampulla; if we observe transformation from the apogeotropic into the geotropic form this suggested a canalolithiasis, otherwise we have assumed a cupulolithiasis.
Anatomical observations of the caudal vestibulo-sympathetic pathway
Authors: Holstein Gay R. , Martinelli Giorgio P. , Friedrich Victor L.
Published: December 2019

The vestibular system senses the movement and position of the head in space and uses this information to stabilize vision, control posture, perceive head orientation and self-motion in three-dimensional space, and modulate autonomic and limbic activity in response to locomotion and changes in posture. Most vestibular signals are not consciously perceived and are usually appreciated through effector pathways classically described as the vestibulo-ocular, vestibulo-spinal, vestibulo-collic and vestibulo-autonomic reflexes. The present study reviews some of the recent data concerning the connectivity and chemical anatomy of vestibular projections to autonomic sites that are important in the sympathetic control of blood pressure.
Vestibular signal processing by separate sets of neuronal filters
Authors: Beraneck Mathieu , Straka Hans
Published: December 2019

Second-order vestibular neurons (2°VN) are the central element for the transformation of body motion-related sensory signals into extraocular motor commands for retinal image stabilization during locomotion. The wide range of motion dynamics necessitates sensory signal transformation in parallel, frequency-tuned channels. Accordingly, in various vertebrates, 2°VN have been shown to form differently tuned functional subgroups. In frog, these neurons subdivide into two separate populations with distinctly different intrinsic membrane properties, discharge dynamics and synaptic response characteristics. Frog tonic 2°VN exhibit low-pass filter characteristics and membrane properties that cause amplification of synaptic inputs, whereas phasic 2°VN form band-pass filters that allow frequency-dependent shunting of repetitive inputs. The differential, yet complementary membrane properties render tonic 2°VN particularly suitable for synaptic integration and phasic 2°VN for differentiation and event detection. Differential insertion of the two cell types into local circuits reinforces the functional consequences of the intrinsic membrane properties, respectively. As a consequence, the synergy of cellular and network properties creates sets of neuronal elements with particular filter characteristics that form flexible, frequency-tuned components for optimal transformation of all dynamic aspects of body motion-related multisensory signals.
Visual vertigo analogue scale: An assessment questionnaire for visual vertigo
Authors: Dannenbaum Elizabeth , Chilingaryan Gevorg , Fung Joyce
Published: December 2019

A common symptom for people with vestibulopathy is dizziness induced by dynamic visual input, known as visual vertigo (VV). The goal of this study is to present a novel method to assess VV, using a nine-item analog scale. The subjects rated the intensity of their dizziness on each item of the Visual Vertigo Analogue Scale (VVAS), which represented a daily situation typically inducing VV. The questionnaire was completed by participants with vestibulopathy (n = 102) and by subjects receiving out-patient orthopaedic physiotherapy (n = 102). The dizziness handicap inventory (DHI) was also completed by the vestibulopathic group. The Cronbach's Alpha index indicated the VVAS is internally consistent and reliable (Cronbach's Alpha = 0.94). The study also found that the VVAS severity scores from vestibular and a non-vestibular population were significantly different (Wilcoxon-Mann Whitney test p < 0.0001). Spearman correlation analysis conducted between DHI and VVAS scores for the clients with vestibulopathy showed positive moderate correlations between the VVAS score and the total DHI score (r = 0.67, p < 0.0001). This study showed that the VVAS scale may be useful in providing a quantitative evaluation scale of visual vertigo.
Visual analog scale to assess vertigo and dizziness after repositioning maneuvers for benign paroxysmal positional vertigo
Authors: Toupet Michet , Ferrary Evelyne , Grayeli Alexis Bozorg
Published: December 2019

Introduction: The aim of this study was to evaluate the value of Visual Analog Scale (VAS) in evaluating vertigo and dizziness in patients with benign paroxysmal positional vertigo (BPPV). Materials and methods: 226 adult patients suffering from a BPPV and undergoing repositioning maneuvers were included in this prospective study. Vertigo (V) and dizziness (D) were separately evaluated from day 0 to 5 by VAS. V and D scores decreased both exponentially but with different constants. D scores were not correlated to V suggesting the independency of the ratings. D was related to the dizziness intensity level expressed at interrogation. Both D and V scores were related to patients' global satisfaction. Conclusion: VAS allows differentiating vertigo from dizziness and provides coherent results with other clinical indicators.
Pre-flight sensorimotor adaptation protocols for suborbital flight1
Authors: Shelhamer Mark , Beaton Kara
Published: December 2019

Commercial suborbital flights, which include 3–5 minutes of 0 g between hyper-g launch and landing phases, will present suborbital passengers with a challenging sensorimotor experience. Based on the results of neurovestibular research in parabolic and orbital flight, and the anticipated wide range of fitness and experience levels of suborbital passengers, neurovestibular disturbances are likely to be problematic in this environment. Pre-flight adaptation protocols might alleviate some of these issues. Therefore, we describe a set of sensorimotor tests to evaluate passengers before suborbital flight, including assessment of the angular vestibulo-ocular reflex (VOR), ocular skew and disconjugate torsion, subjective visual vertical, and roll vection. Performance on these tests can be examined for correlations with in-flight experience, such as motion sickness, disorientation, and visual disturbances, based on questionnaires and cabin video recordings. Through an understanding of sensorimotor adaptation to parabolic and orbital flight, obtained from many previous studies, we can then suggest appropriate pre-flight adaptation procedures.
The science of migraine
Authors: Burstein Rami , Jakubowski Moshe , Rauch Steven D.
Published: December 2019

The cardinal symptom of migraine is headache pain. In this paper we review the neurobiology of this pain as it is currently understood. In recent years, we discovered that the network of neurons that sense pain signals from the dura changes rapidly during the course of a single migraine attack and that the treatment of an attack is a moving target. We found that if the pain is not stopped within 10–20 minutes after it starts, the first set of neurons in the network, those located in the trigeminal ganglion, undergo molecular changes that make them hypersensitive to the changing pressure inside the head, which explains why migraine headache throbs and is worsened by bending over and sneezing. We found that if the pain is not stopped within 60–120 minutes, the second group of neurons in the network, those located in the spinal trigeminal nucleus, undergoes molecular changes that convert them from being dependent on sensory signals they receive from the dura by the first set of neurons, into an independent state in which they themselves become the pain generator of the headache. When this happens, patients notice that brushing their hair, taking a shower, touching their periorbital skin, shaving, wearing earrings, etc become painful, a condition called cutaneous allodynia. Based on this scenario, we showed recently that the success rate of rendering migraine patients pain-free increased dramatically if medication was given before the establishment of cutaneous allodynia and central sensitization. The molecular shift from activity-dependent to activity-independent central sensitization together with our recent conclusion that triptans have the ability to disrupt communications between peripheral and central trigeminovascular neurons (rather than inhibiting directly peripheral or central neurons) explain their clinical effects. Both our clinical and pre-clinical findings of the last five years point to possible short- and long-term advantages in using an early-treatment approach in the treatment of acute migraine attacks.
Responses evoked by a vestibular implant providing chronic stimulation1
Authors: Thompson Lara A. , Haburcakova Csilla , Gong Wangsong , Lee Daniel J. , Wall Conrad , Merfeld Daniel M. , Lewis Richard F.
Published: December 2019

Patients with bilateral vestibular loss experience dehabilitating visual, perceptual, and postural difficulties, and an implantable vestibular prosthesis that could improve these symptoms would be of great benefit to these patients. In previous work, we have shown that a one-dimensional, unilateral canal prosthesis can improve the vestibulooccular reflex (VOR) in canal-plugged squirrel monkeys. In addition to the VOR, the potential effects of a vestibular prosthesis on more complex, highly integrative behaviors, such as the perception of head orientation and posture have remained unclear. We tested a one-dimensional, unilateral prosthesis in a rhesus monkey with bilateral vestibular loss and found that chronic electrical stimulation partially restored the compensatory VOR and also that percepts of head orientation relative to gravity were improved. However, the one-dimensional prosthetic stimulation had no clear effect on postural stability during quiet stance, but sway evoked by head-turns was modestly reduced. These results suggest that not only can the implementation of a vestibular prosthesis provide partial restitution of VOR but may also improve perception and posture in the presence of bilateral vestibular hypofunction (BVH). In this review, we provide an overview of our previous and current work directed towards the eventual clinical implementation of an implantable vestibular prosthesis.
Subjective visual vertical perception in patients with vestibular neuritis and sudden sensorineural hearing loss
Authors: Ogawa Yasuo , Otsuka Koji , Shimizu Shigetaka , Inagaki Taro , Kondo Takahito , Suzuki Mamoru
Published: December 2019

Objective: To determine the subjective visual vertical (SVV) perception in patients with vestibular neuritis (VN) and sudden sensorineural hearing loss (SSHL) using the SVV test and other neuro-otological examinations, namely, the vestibular evoked myogenic potential (VEMP) and caloric tests, and to clarify which vestibular nerve function is associated with an SVV shift. Patients and methods: We performed the SVV test in 36 VN patients and 80 SSHL patients. Thereafter, we investigated directional changes in the SVV in the VN and SSHL patients, and compared the results of the SVV test with those of the VEMP and caloric tests. Results: Abnormal SVV (> 2° was found at a rate of 69.4% in the VN patients and 26.3% in the SSHL patients. In all except 1 VN patient, the SVV tilted to the lesion side. The rate of abnormal SVV was significantly higher in patients with complete canal paresis (CP) than in patients with partial CP. There was no significant relationship between the rates of abnormal SVV and VEMP. In the SSHL patients, neither the SVV nor the VEMP affected the hearing outcome and patients with abnormal VEMP tended to show abnormal SVV. Conclusion: VN patients showed a higher rate of abnormal SVV than SSHL patients. From the results, it is speculated that the superior vestibular nerve function mainly affects the SVV tilt, although the inferior vestibular nerve function may also have an effect.
Influence of head orientation and viewpoint oscillation on linear vection1
Authors: Guterman Pearl S. , Allison Robert S. , Palmisano Stephen , Zacher James E.
Published: December 2019

Sensory conflict theories predict that adding simulated viewpoint oscillation to self-motion displays should generate significant and sustained visual-vestibular conflict and reduce the likelihood of illusory self-motion (vection). However, research shows that viewpoint oscillation enhances vection in upright observers. This study examined whether the oscillation advantage for vection depends on head orientation with respect to gravity. Displays that simulated forward/backward self-motion with/without horizontal and vertical viewpoint oscillation were presented to observers in upright (seated and standing) and lying (supine, prone, and left side down) body postures. Viewpoint oscillation was found to enhance vection for all of the body postures tested. Vection also tended to be stronger in upright postures than in lying postures. Changing the orientation of the head with respect to gravity was expected to alter the degree/saliency of the sensory conflict, which may explain the overall posture-based differences in vection strength. However, this does not explain why the oscillation advantage for vection persisted for all postures. Thus, the current postural and oscillation based vection findings appear to be better explained by ecology: Upright postures and oscillating flow (that are the norm during self-motion) improved vection, whereas lying postures and smooth optic flows (which are less common) impaired vection.