Visual-vestibular Mismatch Research Articles

Short-term learning of the vestibulo-ocular reflex induced by a custom interactive computer game.

Retinal image slip during head rotation drives motor learning in the rotational vestibulo-ocular reflex (VOR) and forms the basis of gaze-stability exercises that treat vestibular dysfunction. Clinical exercises, however, are unengaging, cannot easily be titrated to the level of impairment, and provide neither direct feedback nor tracking of the patient's adherence, performance, and progress. To address this, we have developed a custom application for VOR training based on an interactive computer game. In this study, we tested the ability of this game to induce VOR learning in individuals with normal vestibular function, and we compared the efficacy of single-step and incremental learning protocols. Eighteen participants played the game twice on different days. All participants tolerated the game and were able to complete both sessions. The game scenario incorporated a series of brief head rotations, similar to active head impulses, that were paired with a dynamic acuity task and with a visual-vestibular mismatch (VVM) intended to increase VOR gain (single-step: 300 successful trials at ×1.5 viewing; incremental: 100 trials each of ×1.13, ×1.33, and ×1.5 viewing). Overall, VOR gain increased by 15 ± 4.7% (mean ± 95% CI, P < 0.001). Gains increased similarly for active and passive head rotations, and, contrary to our hypothesis, there was little effect of the learning strategy. This study shows that an interactive computer game provides robust VOR training and has the potential to deliver effective, engaging, and trackable gaze-stability exercises to patients with a range of vestibular dysfunctions.NEW & NOTEWORTHY This study demonstrates the feasibility and efficacy of a customized computer game to induce motor learning in the high-frequency rotational vestibulo-ocular reflex. It provides a physiological basis for the deployment of this technology to clinical vestibular rehabilitation.

Visualisation ergonomics and robotic surgery.

Stereopsis may be an advantage of robotic surgery. Perceived robotic ergonomic advantages in visualisation include better exposure, three-dimensional vision, surgeon camera control, and line of sight screen location. Other ergonomic factors relating to visualisation include stereo-acuity, vergence-accommodation mismatch, visual-perception mismatch, visual-vestibular mismatch, visuospatial ability, visual fatigue, and visual feedback to compensate for lack of haptic feedback. Visual fatigue symptoms may be related to dry eye or accommodative/binocular vision stress. Digital eye strain can be measured by questionnaires and objective tests. Management options include treatment of dry eye, correction of refractive error, and management of accommodation and vergence anomalies. Experienced robotic surgeons can use visual cues like tissue deformation and surgical tool information as surrogates for haptic feedback.

The effects of visual context on visual-vestibular mismatch revealed by electrodermal and postural response measures

BackgroundNo objective criteria exist for diagnosis and treatment of visual-vestibular mismatch (VVM).ObjectiveTo determine whether measures of electrodermal activity (EDA) and trunk acceleration will identify VVM when exposed to visual-vestibular conflict.MethodsA modified VVM questionnaire identified the presence of VVM (+ VVM) in 13 of 23 young adults (34 ± 8 years) diagnosed with vestibular migraine. Rod and frame tests and outcome measures for dizziness and mobility were administered. Participants stood on foam while viewing two immersive virtual environments. Trunk acceleration in three planes and electrodermal activity (EDA) were assessed with wearable sensors. Linear mixed effect (LME) models were used to examine magnitude and smoothness of trunk acceleration and tonic and phasic EDA. Welch’s t-test and associations between measures were assessed with a Pearson Correlation Coefficient. Effect sizes of group mean differences were calculated.ResultsGreater than 80% of all participants were visually dependent. Outcome measures were significantly poorer in the + VVM group: tonic EDA was lower (p < 0.001) and phasic EDA higher (p < 0.001). Postural accelerations varied across groups; LME models indicated a relationship between visual context, postural, and ANS responses in the + VVM group.ConclusionsLower tonic EDA with + VVM suggests canal-otolith dysfunction. The positive association between vertical acceleration, tonic EDA, and visual dependence suggests that increased vertical segmental adjustments are used to compensate. Visual context of the spatial environment emerged as an important control variable when testing or treating VVM.

Visual-vestibular mismatch correlates with headache.

Dizziness affects 20-30%of the general population. A subgroup of dizzy patients with chronic migraine suffers vertigo implying that the migraine has a vestibular component. Vestibular migraine remains a diagnosis of exclusion based on history. A link between headaches and dizziness suggests that these individuals would demonstrate dizziness and instability in complex, dynamic visual environments as a result of an inability to correctly process conflicting visual and vestibular signals. A convenience sample of 74 patients (22 men and 52 women; average age 56.2 years) who presented with complaints of dizziness participated. Effects of Visual-Vestibular Mismatch (VVM) were measured using a modified VVM questionnaire. Visual dependence was measured as the error to subjective visual vertical using a computerized Rod and Frame test. Forty-two participants (56.8%) tested positive for VVM. Of these, 68.9%were patients with concomitant complaints of headaches. Visual dependence was present in 41.5%of all patients but showed no significant correlation with headache. 22.2%of patients had visual dependence and complained of headaches. These results demonstrate that sensory reweighting occurs in patients experiencing dizziness and headache, supports the role of vestibular involvement in this disorder, and provides future direction for novel interventions.

Integrating visual-vestibular mismatch and posture instability in Virtual Reality: A cyber-sickness study

Integrating visual-vestibular mismatch and posture instability in Virtual Reality: A cyber-sickness study

Histochemical Characterization of the Vestibular Y-Group in Monkey

The Y-group plays an important role in the generation of upward smooth pursuit eye movements and contributes to the adaptive properties of the vertical vestibulo-ocular reflex. Malfunction of this circuitry may cause eye movement disorders, such as downbeat nystagmus. To characterize the neuron populations in the Y-group, we performed immunostainings for cellular proteins related to firing characteristics and transmitters (calretinin, GABA-related proteins and ion channels) in brainstem sections of macaque monkeys that had received tracer injections into the oculomotor nucleus. Two histochemically different populations of premotor neurons were identified: The calretinin-positive population represents the excitatory projection to contralateral upgaze motoneurons, whereas the GABAergic population represents the inhibitory projection to ipsilateral downgaze motoneurons. Both populations receive a strong supply by GABAergic nerve endings most likely originating from floccular Purkinje cells. All premotor neurons express nonphosphorylated neurofilaments and are ensheathed by strong perineuronal nets. In addition, they contain the voltage-gated potassium channels Kv1.1 and Kv3.1b which suggests biophysical similarities to high-activity premotor neurons of vestibular and oculomotor systems. The premotor neurons of Y-group form a homogenous population with histochemical characteristics compatible with fast-firing projection neurons that can also undergo plasticity and contribute to motor learning as found for the adaptation of the vestibulo-ocular reflex in response to visual-vestibular mismatch stimulation. The histochemical characterization of premotor neurons in the Y-group allows the identification of the homologue cell groups in human, including their transmitter inputs and will serve as basis for correlated anatomical-neuropathological studies of clinical cases with downbeat nystagmus.

Motion Sickness Manifestations and Prevention

Motion sickness is an ancient problem associated with transportation (ships and other vehicles), which is affecting humans since ages. Motion sickness is characteristically occurring during abnormal movements induced by the motion and when there is a conflict between various senses such as visual, vestibular and motor system. Depending on the type of motion, various kinds of sicknesses, such as air sickness, car sickness, train sickness, seasickness, etc. may occur. A very less per cent of individuals are highly susceptible to motion sickness and very less per cent of individuals are highly insusceptible for motion sickness. However, most of the population comes in between. The primary symptoms of motion sickness include nausea, vomiting, wanes, and cold sweating. Varieties of drugs are available to reduce susceptibility to motion sickness. However, nausea, pallor, sweating, headache, dizziness, malaise, increased salivation, apathy, drowsiness, belching, hyperventilation and stomach awareness are the other symptoms of motion sickness. Anti-cholinergics and anti-histamines are the most effective motion sickness prophylactics with apparent side effects such as dry mouth, drowsiness, and depression. There are theories and mechanisms which include intra-vestibular (Canal-Otolith) mismatch theory, sensory conflict theory, visual-vestibular mismatch theory, the poison theory, the postural instability theory, and the movement program theory. Benzodiazepines, anticholinergics, anti-histamines and monoamine antagonists have commonly used treatment regimes. The traditional way of tackling the problem is the consumption of ginger, peppermint, lemon, fennel, marjoram, rosemary, basil. This review summarizes prediction and evaluation, behavioural strategies to prevent or minimize symptoms of motion sickness and available countermeasures of motion sickness.

Survey of motion sickness susceptibility in children and adolescents aged 3months to 18years.

We conducted two representative, cross-sectional, population-based surveys on the susceptibility to motion sickness (MSS) in childhood: One was targeted at parents with children aged 6months to 18years (7569 households approached) and the other at parents with children aged 3months to 5years (12,720 households approached). In both surveys 3285 parents provided information on 5041 children. The main findings in the first survey were: 369 children (9.2%) were susceptible to motion sickness with a slight female preponderance, and in the second study 16 (1.2%) were susceptible; first occurrence of motion sickness (MS) below the age of 1year was exceptionally rare (n = 2); if MS occurred after the age of 1year it was more severe in the younger children, most pronounced between the age of 6 and 9years; the frequency of MSS was highest in the range between the age of 4 and 13years; in postpubertal children and adolescents MSS frequency declined. The course of MSS frequency from infancy to adolescence is an inverse U-shaped curve. It is characterised by three phases which may be related to the visual-vestibular mismatch theory, the major pathophysiological cause of MS. Phase one is a high resistance in the first year of life. In this phase infants may be less subject to visual-vestibular mismatch, because they do not yet use visual cues for self-motion perception. Phase two is a prepubertal peak. This is possibly due to an oversensitivity to a visual-vestibular mismatch, which reflects sensorimotor maturation. Phase three is a postpubertal decline. This can be explained by habituation through repetitive motion stimulation during various kinds of vehicle transportations.

Motion sickness in children and adolescents: pathogenesis, symptoms, profylaxis and treatment (literature review)

There are presented data concerning terminology, pathogenesis, semiology, (complaints, signs), prevention and management of symptom complex of motion sickness and kinetosis. These issues are depicted in the framework of the review of special literature. There is accentuated the importance and possibilities of the solution of this problem in pediatric practice. There are described data related to the development of neuroautonomic symptom complex during road trip and the use of visual informational technologies. The concepts of the "state after the motion sickness" is reported. There are considered mechanisms and examples of sensory conflict during rocking (as well canal-otolith as visual-vestibular mismatch). There are described mechanisms of the action of antinaupathic drugs. There are drilled down issues of the pharmacological prevention and treatment with the use of dimenhydrinate in the combination therapy of motion sickness.

Towards dynamic modeling of visual-vestibular conflict detection.

Visual-vestibular mismatch is a common occurrence, with causes ranging from vehicular travel, to vestibular dysfunction, to virtual reality displays. Behavioral and physiological consequences of this mismatch include adaptation of reflexive eye movements, oscillopsia, vertigo, and nausea. Despite this significance, we still do not have a good understanding of how the nervous system evaluates visual-vestibular conflict. Here we review research that quantifies perceptual sensitivity to visual-vestibular conflict and factors that mediate this sensitivity, such as noise on visual and vestibular sensory estimates. We emphasize that dynamic modeling methods are necessary to investigate how the nervous system monitors conflict between time-varying visual and vestibular signals, and we present a simple example of a drift-diffusion model for visual-vestibular conflict detection. The model makes predictions for detection of conflict arising from changes in both visual gain and latency. We conclude with discussion of topics for future research.

Arabic version of situational characteristic questionnaire for diagnosis of visual vertigo syndrome

Objectives: To develop and validate an Arabic version of the situational characteristic questionnaire (SCQ), which is the gold standard and easy method in diagnosing visual vertigo syndrome (VV).Methods: The adapted SCQ was translated according to the cross-cultural adaptation guidelines that included: original author permission, forward and backward translation, Expert committee review, pretesting and final version of the Arabic SCQ. The questionnaire was completed by 100 normal controls (control group) and 100 patients with VV symptoms (VV group). Validity and reliability of the questionnaire were examined. Reliability included internal consistency and test–retest reliability. Validity was examined by evaluating the content and construct validity. Receiver operating characteristic curve was used to determine the possible cut-off values.Results: Indicated good reliability of the Arabic SCQ (Cronbach’s Alpha = 0.84 for control group, and = 0.79 for VV group). Test–retest correlation was done on a subgroup of 46 control subjects and 50 VV patients after 1 week. Repeatability of the questionnaire was high for the total Arabic SCQ score using Spearman’s correlation (r = 0.99 and 0.97 for the control and VV groups, respectively). For construct validity, Spearman’s correlation analysis showed significant positive correlations between the Arabic SCQ total score and the modified Arabic visual vestibular mismatch score (r = 0.64, p < .001*). The Arabic SCQ total scores of VV patients were significantly different from normal controls (p < .001* using the Mann-Whitney test).Conclusion: The Arabic version of the SCQ is a valid and reliable tool for diagnosing VV and for the assessment of severity of symptoms in the Egyptian and Arabic populations. The most sensitive cut-off point of the Arabic SCQ for diagnosing VV was (1.15).

Out-of-body experience in vestibular disorders – A prospective study of 210 patients with dizziness

Out-of-body experiences (OBEs) are states during which people experience their centre of awareness as located outside of their physical body, along with the sensation of seeing the environment from an elevated viewpoint. OBE is encountered in epilepsy, migraine and depersonalization, and it is not an uncommon experience in the general population. Current neuroscientific models of bodily self-consciousness consider that OBE are related to a failure to integrate visual, somatosensory and vestibular signals. These models have highlighted the importance of visual-vestibular mismatch in OBE. Case reports from older clinical literature suggest that vestibular disorders may precipitate OBE, but we were lacking population-based evidence that OBE is related to vestibular disorders. The present observational, prospective study describes otoneurological, neuropsychological and phenomenological correlates of OBE in the largest sample of patients with dizziness to date (n = 210) compared to a group of age- and gender-matched controls with no history of dizziness (n = 210). We show a significantly higher occurrence of OBE in patients with dizziness (14%) than in healthy participants (5%). Most of the patients experienced OBE only after they started having dizziness for the first time. OBE in patients with dizziness were mainly related to peripheral vestibular disorders. We also identify depersonalization-derealization, depression and anxiety as the main predictors of OBE in patients with dizziness, as well as a contribution of migraine. Depersonalization-derealization was the only significant predictor of OBE in healthy controls. Altogether, our data indicate that OBE in patients with dizziness may arise from a combination of perceptual incoherence evoked by the vestibular dysfunction with psychological factors (depersonalization-derealization, depression and anxiety) and neurological factors (migraine).

Adaptation of the vertical vestibulo-ocular reflex in cats during low-frequency vertical rotation

ObjectiveWe examined plastic changes in the vestibulo-ocular reflex (VOR) during low-frequency vertical head rotation, a condition under which otolith inputs from the vestibular system are essential for VOR generation. MethodsFor adaptive conditioning of the vertical VOR, 0.02Hz sinusoidal pitch rotation for one hour about the earth’s horizontal axis was synchronized with out-of-phase vertical visual stimulation from a random dot pattern. ResultsA vertical VOR was well evoked when the upright animal rotated around the earth-horizontal axis (EHA) at low frequency due to the changing gravity stimulus and dynamic stimulation of the otoliths. After adaptive conditioning, the amplitude of the vertical VOR increased by an average of 32.1%. ConclusionOur observations showing plasticity in the otolithic contribution to the VOR may provide a new strategy for visual-vestibular mismatch training in patients with otolithic disorders. This low-frequency vertical head rotation protocol also provides a model for investigating the mechanisms underlying the adaptation of VORs mediated by otolith activation.

The Effect of Optokinetic Stimulation on Perceptual and Postural Symptoms in Visual Vestibular Mismatch Patients.

BackgroundVestibular patients occasionally report aggravation or triggering of their symptoms by visual stimuli, which is called visual vestibular mismatch (VVM). These patients therefore experience discomfort, disorientation, dizziness and postural unsteadiness.ObjectiveFirstly, we aimed to get a better insight in the underlying mechanism of VVM by examining perceptual and postural symptoms. Secondly, we wanted to investigate whether roll-motion is a necessary trait to evoke these symptoms or whether a complex but stationary visual pattern equally provokes them.MethodsNine VVM patients and healthy matched control group were examined by exposing both groups to a stationary stimulus as well as an optokinetic stimulus rotating around the naso-occipital axis for a prolonged period of time. Subjective visual vertical (SVV) measurements, posturography and relevant questionnaires were assessed.ResultsNo significant differences between both groups were found for SVV measurements. Patients always swayed more and reported more symptoms than healthy controls. Prolonged exposure to roll-motion caused in patients and controls an increase in postural sway and symptoms. However, only VVM patients reported significantly more symptoms after prolonged exposure to the optokinetic stimulus compared to scores after exposure to a stationary stimulus.ConclusionsVVM patients differ from healthy controls in postural and subjective symptoms and motion is a crucial factor in provoking these symptoms. A possible explanation could be a central visual-vestibular integration deficit, which has implications for diagnostics and clinical rehabilitation purposes. Future research should focus on the underlying central mechanism of VVM and the effectiveness of optokinetic stimulation in resolving it.

Somatosensory induced adaptation in the human otolith-ocular reflex

The vestibulo-ocular reflex (VOR) generates smooth eye movements that compensate for head movements to ensure gaze stabilization during head rotation. The VOR is under adaptive control and corrects VOR performance when visual-vestibular mismatch arises during head movement. During normal visual-vestibular interaction, cooperation between the VOR and vision results in stabilization of the retinal image. Adaptive VOR recalibration occurs when visual-vestibular mismatch arises through the manipulation of visual feedback during head movement. In consideration of how important VOR is in stabilizing gaze, it could be predicted that when VOR is lost, patients would be severely disabled by retinal image movement due to head movement. The vestibular center uses substitutes such as visual and somatosensory information to compensate for lost vestibular signals. In the present study, to investigate the contribution of somatosensory signals to VOR, especially the otolith-ocular reflex (OOR), we examined the plasticity of the OOR using vestibular-somatosensory interaction and the effect of the adaptive plasticity of the OOR by somatosensory stimulation using alternative pressure stimulation on the outer side of the bilateral upper arms for 20 seconds. To study the influence of somatosensory input on the otolith-ocular reflex, we used sinusoidal off-vertical axis rotation at a tilt angle of 30 degrees. Subjects were rotated with their eyes open in complete darkness at frequencies of 0.32 Hz with a maximum angular velocity of 60 o/s. Results showed a significant gain decrement in EVAR after somatosensory adaptive stimulation, whereas gain change was not significantly different in OVAR. We suggest that somatosensory input had an additive effect on the otolith-ocular reflex in this study. This result could be applied to vestibular rehabilitation using somatosensory input.

Impact of Vertigo and Spatial Disorientation on Concurrent Cognitive Tasks

Disorientation may draw attention from other activities and its impact on cognition may cause pilot error and problems of concentration in dizzy patients. Tasks used to study the impact of disorientation include number processing, intelligence scales and Brookes matrices (reproduction of 2xD patterns of numbers vs. nonsensical sentences), and Stroop tasks to probe selective effects on spatial versus verbally-loaded tasks. This variety of tasks has been used to evaluate cognitive performance in numerous scenarios, including visual-vestibular mismatch, vection, spinning, coriolis, balancing, and flight maneuvers. A meta-analysis provides an overview of how spatial disorientation may affect cognition: Substantial individual differences in managing disorientation are to be expected; errors on cognitive tasks occur during the first few experiences of a disorienting situation and subjects rapidly learn to "quarantine" this "novelty effect"; familiarity with and practice on a test gives protection against disorientation; task performance continues to suffer if the protagonist is unaware of disorientation; with disorientation that demands external resolution (e.g., interpretation of instruments) the subject must learn to switch priority to the cognitive task; there is a moderate preferential impact of disorientation on spatial tasks; anxiety of real situations probably exacerbates the impact of disorientation.

体性感覚入力が半規管‐眼反射に及ぼす影響

The vestibulo-ocular reflex (VOR) generates smooth eye movements that are compensatory for head movements to ensure gaze stabilization during head rotations. The VOR is under adaptive control that corrects VOR performance when visual-vestibular mismatch arises during head movement. During normal visual-vestibular interaction, cooperation between the VOR and vision results in stabilization of the retinal image. Adaptive VOR recalibration occurs when a visual-vestibular mismatch arises through the manipulation of visual feedback during head movement or by lesion-induced modification of vestibular input. Considering how important VOR is in stabilizing gaze, one could predict that when VOR is lost, patients would be severely disabled by retinal image movement due to head movement. To compensate for vestibular deficits, the vestibular system uses other substitutes such as visual and somatosensory information for the lost vestibular signals. To investigate the contribution of somatosensory signal to the VOR, especially the semicircular-ocular reflex (ScOR), we examined the plasticity of the ScOR using vestibular-somatosensory interaction and the effect of the adaptive plasticity of the ScOR by somatosensory stimulation. We demonstrated a reasonably consistent effect on adaptation of ScOR gain using a somatosensory stimulation paradigm. Our data suggest that the ScOR and somatosensory signals share common neural pathways in such a way that a change in the synaptic efficacy of one pathway is accompanied by a change in the other. The role of a neural storage system that receives input from both the semicircular canals and the somatosensory system to maintain a spatial orientation is discussed.

半規管―眼反射と耳石―眼反射の機能連関

Vestibulo-ocular reflex (VOR) generates smooth eye movements that are compensatory for head movements to ensure gaze stabilization during head rotations. VOR consists of the semicircular-ocular reflex (ScOR) and the otolith-ocular reflex (OOR). The ScOR induces eye movements that compensate for rotations of the head, whereas the OOR produces eye movements that compensate for linear head movements, so that visual images remain relatively steady on the retina.During normal visual-vestibular interaction, cooperation between the VOR and vision result in stabilization of the retinal image. Adaptive VOR recalibration occurs whether visual-vestibular mismatch arises through the manipulation of visual feedback during head movement or by lesion-induced modification of vestibular input. Current models of the VOR contain separate gain elements for the ScOR and the OOR.In this article, we describe our experiments to investigate the plasticity of the ScOR and OOR using OVAR and a linear sled to clarify visual-vestibular interaction. We also further addressed the relationship between adaptive change in the ScOR and the OOR.

Modeling Gravity-Dependent Plasticity of the Angular Vestibuloocular Reflex With a Physiologically Based Neural Network

A neural network model was developed to explain the gravity-dependent properties of gain adaptation of the angular vestibuloocular reflex (aVOR). Gain changes are maximal at the head orientation where the gain is adapted and decrease as the head is tilted away from that position and can be described by the sum of gravity-independent and gravity-dependent components. The adaptation process was modeled by modifying the weights and bias values of a three-dimensional physiologically based neural network of canal-otolith-convergent neurons that drive the aVOR. Model parameters were trained using experimental vertical aVOR gain values. The learning rule aimed to reduce the error between eye velocities obtained from experimental gain values and model output in the position of adaptation. Although the model was trained only at specific head positions, the model predicted the experimental data at all head positions in three dimensions. Altering the relative learning rates of the weights and bias improved the model-data fits. Model predictions in three dimensions compared favorably with those of a double-sinusoid function, which is a fit that minimized the mean square error at every head position and served as the standard by which we compared the model predictions. The model supports the hypothesis that gravity-dependent adaptation of the aVOR is realized in three dimensions by a direct otolith input to canal-otolith neurons, whose canal sensitivities are adapted by the visual-vestibular mismatch. The adaptation is tuned by how the weights from otolith input to the canal-otolith-convergent neurons are adapted for a given head orientation.

Oculomotor Plasticity During Vestibular Compensation Does Not Depend on Cerebellar LTD

Vestibular paradigms are widely used for investigating mechanisms underlying cerebellar motor learning. These include adaptation of the vestibuloocular reflex (VOR) after visual-vestibular mismatch training and vestibular compensation after unilateral damage to the vestibular apparatus. To date, various studies have shown that VOR adaptation may be supported by long-term depression (LTD) at the parallel fiber to Purkinje cell synapse. Yet it is unknown to what extent vestibular compensation may depend on this cellular process. Here we investigated adaptive gain changes in the VOR and optokinetic reflex during vestibular compensation in transgenic mice in which LTD is specifically blocked in Purkinje cells via expression of a peptide inhibitor of protein kinase C (L7-PKCi mutants). The results demonstrate that neither the strength nor the time course of vestibular compensation are affected by the absence of LTD. In contrast, analysis of vestibular compensation in spontaneous mutants that lack a functional olivo-cerebellar circuit (lurchers) shows that this form of motor learning is severely impaired. We conclude that oculomotor plasticity during vestibular compensation depends critically on intact cerebellar circuitry but not on the occurrence of cerebellar LTD.