Perception Of Verticality Research Articles

Cortical involvement of lateral trunk flexion and verticality misperception in Parkinson's disease

Abstract Lateral trunk flexion is a common form of postural abnormality in Parkinson's disease and could be associated with verticality misperception. However, the mechanisms underlying lateral trunk flexion and verticality misperception in Parkinson's disease remain unclear. In the current study, we examined whether lateral trunk flexion is associated with verticality misperception in patients with Parkinson's disease. We also identified the brain regions involved in lateral trunk flexion and altered verticality perception. In this cross-sectional study, we evaluated the verticality perception using the subjective visual vertical test in 81 patients with Parkinson's disease and 14 age-matched healthy controls. According to the 97.5th percentile upper reference limit of the body tilt angle in the healthy controls, patients with Parkinson's disease were grouped into 37 patients with lateral trunk flexion and 44 patients without lateral trunk flexion. The mean of absolute subjective visual vertical angles was compared between Parkinson's disease patients with lateral trunk flexion, those without lateral trunk flexion, and the healthy controls, and the impact of verticality misperception on lateral trunk flexion was evaluated using multivariate logistic regression models. We further performed a voxel-wise comparison of regional cerebral blood flow using N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography (height threshold of P < 0.001, uncorrected for multiple comparisons, extent threshold of 100 voxels) to identify the brain regions associated with lateral trunk flexion, and to investigate the relationship between verticality misperception and regional hypoperfusion. The mean of absolute subjective visual vertical angles was larger in Parkinson's disease patients with and without lateral trunk flexion than in healthy controls (P < 0.001 and P < 0.001). Additionally, the subjective visual vertical angle was associated with the presence of lateral trunk flexion (odds ratio 2.25, 95% confidence interval 1.51–3.36, P < 0.001). The regional cerebral blood flow in Parkinson's disease patients with lateral trunk flexion was decreased in the right inferior parietal lobule, right superior parietal lobule, right superior temporal gyrus, and right dorsal posterior cingulate cortex compared with those without lateral trunk flexion. The subjective visual vertical angle was inversely correlated with regional cerebral blood flow in these regions, except for the dorsal posterior cingulate cortex. Our study reveals that hypofunction in the right temporoparietal association cortices is involved in verticality misperception and the development of lateral trunk flexion in patients with Parkinson's disease. These results provide insights into potential therapeutic targets for addressing lateral trunk flexion.

Integrating vestibular and visual cues for verticality perception.

Verticality is the perception of what's upright relative to gravity. The vestibular system provides information about the head's orientation relative to gravity, while visual cues influence the perception of external objects' alignment with the vertical. According to Bayesian integration, the perception of verticality depends on the relative reliability of visual and vestibular cues. Ambiguities in vestibular signals are resolved through visual information, with the brain integrating these cues alongside prior knowledge of the upright orientation. While it is established that both vestibular and visual cues contribute to verticality perception, the precise mechanisms underlying this integration remain unclear. Here we investigated how the human brain combines vestibular and visual cues to perceive verticality based on their reliability. We assessed verticality perception using a signal detection theory based visual verticality detection task. Participants were shown lines that were either vertical or tilted and asked to judge their orientation. To manipulate cue reliability, we used optokinetic stimulation for visual cues, galvanic vestibular stimulation for vestibular cues, and a combined visual-vestibular condition by simultaneously delivering optokinetic and galvanic vestibular stimulation. Sham stimulations were administered to control for non-specific effects. Our findings demonstrate that reductions in the reliability of visual and vestibular cues impair sensitivity to verticality, with visual cues exerting a more pronounced influence. Importantly, no changes in response bias were observed. The observed pattern aligns with a model in which the relative contributions of visual and vestibular inputs are determined by linear weightings and their combined summation.

Age-related differences of subjective visual vertical perception in adults-a functional near-infrared spectroscopy study.

The perception of Subjective Visual Vertical (SVV) is crucial for postural orientation and significantly reflects an individual's postural control ability, relying on vestibular, visual, and somatic sensory inputs to assess the Earth's gravity line. The neural mechanisms and aging effects on SVV perception, however, remain unclear. This study seeks to examine aging-related changes in SVV perception and uncover its neurological underpinnings through functional near-infrared spectroscopy (fNIRS). In a comparative study of 19 young and 19 older adults, the standardized SVV task executed in Eprime 3.0 software evaluated participants' SVV orientation and uncertainty. Cortical responses were monitored via fNIRS during the task, with block averaging analysis employed to delineate the associated hemodynamic responses. The study further correlated these neuroimaging findings with behavioral measures. Young individuals exhibit superior accuracy and stability in perceiving the subjective visual vertical (SVV) direction. Neuroimaging data, adjusted for multiple comparisons using the false discovery rate, reveal activation of the right supramarginal gyrus (SMG) and the left dorsolateral superior frontal gyrus (SFGdor) in both age groups during SVV tasks. However, older participants show additional activation in regions such as the bilateral postcentral gyrus (PoCG) and the right middle frontal gyrus (MFG). Lateralization studies indicate that young participants predominantly exhibit right lateralization in sensory and dorsolateral prefrontal cortices, with left lateralization in the motor cortex. In contrast, elderly participants demonstrate bilateral dominance across sensory, dorsolateral prefrontal, and motor cortices. Correlational analyses link modified SVV metrics to the activation levels of various brain regions, with negative correlations observed in both age groups, and a unique positive correlation with the left inferior frontal gyrus of the triangular part (IFGtriang) in young participants. Young individuals outperform the older individuals in SVV performance due to age-related differences in brain functional patterns during the execution of vertical perception judgment. Both age groups activate the right SMG and left SFGdor, but the older individuals additionally activate regions such as bilateral PoCG and right MFG. While young people exhibit right-brain dominance, the older people rely on bilateral cognitive resources, indicating bilateral dominance. Except for the left IFGtriang in the young, higher activation in brain regions correlates with better SVV performance.

Age-related changes in the vestibulothalamic pathway: Association with balance ability and subjective visual vertical of vestibular function.

The thalamus regulates various sensory information to each related brain area. The vestibular nucleus transmits information of motor control to the thalamus regulating coordination function. The vestibulothalamic tract (VTT) is a neural pathway between the vestibular nucleus and thalamus that processes vestibular information for postural balance and spatial perception. Therefore, this study analyzed ipsilateral VTT to compare the neural pathway and the differences in vestibular and balance functions according to aging. Eleven elderly and 12 young healthy adults were recruited. This study measured subjective visual vertical (SVV) for vestibular function and body sway during one-leg standing. The ipsilateral VTT were reconstructed to investigate changes of neural pathway between two groups using diffusion tensor imaging. Track volume of left and right VTTs was significantly more in the young healthy adults. In eyes-open (EO) condition during one-leg standing, the body sway demonstrated significant differences between two groups. In the eyes-closed (EC) condition, the degree of hip sway was decreased in the young healthy adults. In the EO condition, the body sway except for antero-posterior direction was significantly correlated with VTT. Meanwhile, in the EC condition, hip sway and all values of body sway were negatively correlated with VTT. In addition, the VTT revealed a negative correlation with SVV. The tract volume of VTT and static balance decreased according to aging. The changes of VTT also affected verticality perception and static balance. Therefore, the study could be helpful in providing the data for patients with thalamus or vestibular injury.

Verbalization of the spatial model of the world in modern Russian and English women’s prose (based on the works of A. Matveeva and E. Gilbert)

The article analyzes the explication of the spatial model of the world in modern women’s fictional discourse. The focus of attention is on the ways of constructing space and their linguistic representation in the works of A. Matveeva and E. Gilbert, modern women authors of Russian and English literature. A comparative analysis of the two pieces of discourse helps to reveal the individual characteristics of the female authors, as well as the national characteristics of the two linguistic worldviews. The research is aimed at identifying the influence of gender identity on the formation of a spatial model of the world. The novelty of this work lies in the fact that for the first time it has examined the peculiarities of space perception by modern female authors. As a result of the research, we determined the parameters of space perception by the female authors. The analyzed material showed that the main features of A. Matveeva and E. Gilbert’s space are “length”, “volume”, “livability”, “openness”, “evenness” and “spaciousness”. The article highlights the following parameters in the spatial model of the analyzed authors’ world: features of the objects’ location; binary signs of space characteristics; correlation of the category “ours-theirs”; horizontal and vertical perception of space; temporal significance of space. The spatial model of A. Matveeva is built in the form of a straight line; among binary oppositions, “top-bottom” and “in front-behind” prevail; the key spatial loci are apartment, temple, camino and albergo; the discourse describes the space that surrounds her, where she is in the center. In her fictional discourse, the key binary opposition is “heaven-earth”. To achieve the goal, we used the following methods: descriptive, comparative, contextual and a stylistic analysis.

Cortical Areas Involved in Subjective Visual Vertical Perception: A Systematic Review

Background and Aim: The information related to brain oscillation, head rotation and head orientation relative to gravity is obtained from the vestibular system. An important reference for upright posture and navigation is gravity-based vertical perception. Many studies have been conducted for the determination of cortical areas involved in Subjective Visual Vertical (SVV) perception in healthy people or patients with brain injuries. Their results have indicated an extensive and bilateral cortical area involved in SVV perception. The purpose of this review study is to investigate these cortical areas and their functional role. Recent Findings: Neuroimaging studies in patients with brain injuries showed that multiple cortical areas have a role in SVV perception. These areas mainly include the occipital cortex, frontal cortex, posterior temporoparietal, temporo-occipital, parieto-occipital, superior temporal gyrus, inferior parietal lobe in temporoparietal junction, posterior insula, cuneus, lingual gyrus, precuneus, ventral dentate nucleus, cerebellum, and brainstem. Conclusion: The cortical areas involved in SVV perception are a part of the vestibular system, which is distributed bilaterally. These areas have a multi-sensory processing task and play a role in processing of cognitive and motor sensory information.Keywords: Subjective visual verticality; vertical perception; cortex; vestibular network

A head-mounted Tilted Reality Device for the treatment of pusher syndrome: a usability study in healthy young and older adults

Pusher syndrome is a disorder of postural control after stroke. Patients show a mismatch in their perception of (almost preserved) visual and (pathologically tilted) postural verticality. In order to reduce this mismatch, we developed a novel head-mounted Tilted Reality Device (TRD). It presents patients visual footage of their actual surroundings but tilted to one side rather than upright. We investigated its usability and possible limitations in its use for the treatment of pusher patients in two samples of healthy participants with an average age of 26.4 years and 63.9 years respectively. Individuals from both age groups showed similar levels of tolerance to prolonged exposure to the tilted visual environment for an average of 40.4 min while walking around in the hospital. The TRD was found to be comfortable and not frustrating whilst wearing, but somewhat challenging in terms of technical handling, particularly for older participants. At the end of the maximally tolerated exposure time participants of both groups experienced some feelings of discomfort, like dizziness or increased stomach awareness, which disappeared rapidly after terminating TRD exposure. Our TRD appears to be a practical device especially for an older population, like pusher patients. While users must be aware of the possibility of side effects, these should be balanced against the benefits of future use for rehabilitation purposes.

Several components of postural control are affected by benign paroxysmal positional vertigo but improve after particle-repositioning maneuvers: A systematic review and meta-analysis

Objective Benign Paroxysmal Positional Vertigo is a vestibular disorder causing vertigo and imbalance. This systematic review and meta-analysis aims to explore the impact of benign paroxysmal positioning vertigo and repositioning maneuvers on postural control. Data Sources In September 2024, PubMed, Web of Science, Scopus and reference lists of included studies were systematically searched. Articles comparing measures of postural control between patients and controls, and/or pre- and posttreatment were considered relevant. Methods Study selection, data extraction and identification of risk of bias were done by two researchers. If possible, meta-analysis was performed with Review Manager version 5.4.1 and standardized mean differences were calculated with a random-effects model. Results Twenty-one of the 37 included studies were useful for meta-analyses. Meta-analyses revealed that benign paroxysmal positional vertigo negatively affects perception of verticality (p < .001; SMD = 0.73; 95% CI = [0.39;1.08]) and sensory orientation (p < .001; SMD = −1.66; 95% CI = [−2.08, −1.23]). The perception of verticality (p < .001; SMD = 0.99; 95% CI = [0.76;1.21]) and sensory orientation (p < .001; SMD = −0.77; 95% CI = [−1.11, −0.44]) improved after treatment with repositioning maneuvers. Results of systematic review indicate stability in gait was impaired, vertigo but improve after repositioning maneuvers. Limits of stability were impaired in older patients, but did not improved after repositioning maneuvers. Conclusion Benign paroxysmal positioning vertigo affects several underlying components of postural control. Repositioning maneuvers can significantly improve the related postural control impairments. This may partly explain the increased odds of falling in these patients, and the positive treatment effect of repositioning maneuvers on falls and fear of falling.

Vertical perception following stroke: a survey of rehabilitation therapists’ opinions on the impact of vertical perception deficits on rehabilitation and recovery

Background/Aims Following stroke, people can present with spatial perceptual deficits, which are associated with vertical perception deficits and are known to negatively influence the outcome of rehabilitation. It is not known how vertical perception deficits influence rehabilitation therapists’ assessment and treatment choices. A survey of mainly UK-based physiotherapists and occupational therapists was undertaken to explore views and current practice in relation to vertical perception following stroke. Specifically, the survey investigated rehabilitation therapists’ views on terminology, assessment and treatment, impact on functional outcome and clinical decision making. Methods An online survey was completed by a convenience sample of 70 rehabilitation therapists (52 physiotherapists and 18 occupational therapists). Results Vertical perception deficits were commonly encountered by respondents and were diagnosed mainly through observation. Respondents were confident in their ability to assess and treat vertical perception deficits. Vertical perception deficits were understood to be associated with pushing behaviour, neglect, weight-bearing asymmetry and decreased balance. Respondents understood it was related to severe, right-sided strokes with sensory and proprioceptive loss, but were inconsistent in their awareness of the specific brain regions involved in vertical perception deficits, specifically in posterior circulation strokes. Respondents reported that stroke survivors with vertical perception deficits require longer periods of rehabilitation, and overall have a worse functional outcome than those without. A variety of treatment options were used to address vertical perception deficits. Conclusions Further research should investigate the treatment and assessment used by rehabilitation therapists in relation to vertical perception deficits following stroke. Implications for practice Vertical perception deficits are commonly encountered in stroke rehabilitation. Rehabilitation therapists identify this mainly through observation. There are currently no methods to quantify vertical perception deficits in the clinical environment. Individuals living with vertical perception deficit may require longer periods of rehabilitation. At present, there are no evidence-based interventions to address vertical perception deficits in people who have had a stroke.

Test-Retest Reliability of Dynamic Subjective Visual Vertical and Visual Dependency in Older Adults Using Virtual Reality Methods.

The perception of verticality is formed through the integration of multisensory gravitational information, including somatosensory, visual, and vestibular inputs. Older adults exhibit visual dependency (VD) as they rely more on visual information to compensate for reduced somatosensory and vertical perception. Increased VD is associated with falls, and the dynamic subjective visual vertical (SVV) is used to assess VD. However, the measurement reliability of dynamic SVV and VD using virtual reality (VR), which has garnered considerable attention in recent years, remains unclear. Therefore, our purpose in this study was to assess the test-retest reliability of dynamic SVVs and VDs using a VR method. We evaluated static and dynamic SVV of 40 older adults using a smartphone-based VR system (SVR-SVV). Dynamic SVV consisted of numerous spheres on the background rotating clockwise (CW-SVV) or counterclockwise (CCW-SVV). Each SVV measurement consisted of one set of 10 trials. VD was calculated as the mean value of dynamic SVV minus the mean values of static SVV. A re-test was conducted after one week. Reliability was analyzed using Bland-Altman plots and intraclass correlation coefficients (ICC 2, k) for each SVV measure. We observed no systematic bias in any of the SVV values, which were 0.1° (SD = 2.8°), 13.3° (SD = 8.3°), -12.8° (SD = 6.9°), and 15.7° (SD = 8.1°) for static SVV, CW-SVV, CCW-SVV, and VD, respectively. Test-retest reliability was good for static SVV (ICC = .817, p < .001), CW-SVV (ICC = .896, p < .001) and excellent for CCW-SVV (ICC = .914, p < .001), VD (ICC = .937, p < .001). The dynamic SVV and VD measurements using SVR-SVV demonstrated good test-retest reliability. Moreover, the SVR-SVV is more portable than conventional methods, making it highly useful in clinical practice.

Asymmetry and rehabilitation of the subjective visual vertical in unilateral vestibular hypofunction patients.

Patients with acute unilateral peripheral vestibular hypofunction (AUVP) show postural, ocular motor, and perceptive signs on the diseased side. The subjective visual vertical (SVV) test measures the perceived bias in earth-vertical orientation with a laser line in darkness. This study was aimed at (1) examining whether SVV bias could depend on preset line orientation and angles, and (2) investigating whether vestibular rehabilitation (VR) can improve SVV normalization. To our knowledge, SVV symmetry/asymmetry and impact of VR on SVV normalization have never been documented in the literature. We investigated the SVV bias in a retrospective study (Study 1: n = 42 AUVP patients) comparing the data recorded for line orientation to the ipsilateral and contralateral sides at preset angles of 15° and 30°. We investigated the effects of VR on SVV normalization in a prospective study (Study 2: n = 20 AUPV patients) in which patients were tilted in the roll plane using a support tilted to the hypofunction side with the same amplitude as the SVV bias. This VR protocol was performed twice a week for 4 weeks. Supplementary data on body weight distribution and medio-lateral position of the center of foot pressure (CoP) were obtained using posturography recordings. Study 1 showed asymmetrical values of the SVV bias. On average, the SVV errors were significantly higher for ipsilateral compared to contralateral line orientation (6.98° ± 3.7° vs. 4.95° ± 3.6°; p < 0.0001), and for 30° compared to 15° preset angle (6.76° ± 4.2° vs. 5.66° ± 3.3°; p < 0.0001). Study 2 showed a fast SVV normalization with VR. Non-pathological SVV bias (below ±2°) was found after only 3 to 5 VR sessions while pathological SVV values were still observed at the same time after symptoms onset in patients without VR (1.25° ± 1.46° vs. 4.32° ± 2.81°, respectively; p < 0.0001). A close temporal correlation was observed in the time course of body weight distribution, mediolateral CoP position, and SVV bias over time, suggesting beneficial effects of the VR protocol at both the perceptive and postural levels. We recommend routine assessment of the ipsilateral and contralateral SVV bias separately for a better evaluation of otolith organs imbalance that can trigger chronic instability and dizziness. The SVV bias and the postural impairment caused by the imbalanced otolith inputs after unilateral vestibular loss can be rapidly normalized by tilting the patients in the roll plane, an additional means in the physiotherapist's toolbox. The protocol likely reweights the visual and somatosensory cues involved in the perception of verticality.

Human senses and sensors from Aristotle to the present.

This historical review on the semantic evolution of human senses and sensors revealed that Aristotle's list of the five senses sight, hearing, touch, taste, and smell is still in use among non-scientific lay persons. It is no surprise that his classification in the work "De Anima" (On the Soul) from 350 BC confuses the sensor "touch" with the now more comprehensively defined somatosensory system and that senses are missing such as the later discovered vestibular system and the musculotendinous proprioception of the position of parts of the body in space. However, it is surprising that in the three most influential ancient cultures, Egypt, Greece, and China-which shaped the history of civilization-the concept prevailed that the heart rather than the brain processes perception, cognition, and emotions. This "cardiocentric view" can be traced back to the "Doctrine of Aristotle," the "Book of the Dead" in ancient Egypt, and the traditional Chinese medicine of correspondence documented in the book "Huang di Neijing." In Greek antiquity the philosophers Empedocles, Democritus and Aristotle were proponents of the allocation of the spirit and the soul to the heart connected to the body via the blood vessels. Opponents were the pre-Socratic mathematician Pythagoras, the philosopher Plato, and especially the Greek physician Hippocrates who regarded the brain as the most powerful organ in humans in his work "De Morbo Sacro." The Greek physician Galen of Pergamon further elaborated on the concept of the brain ("cephalocentric hypothesis") connected to the body by a network of nerves. The fundamental concepts for understanding functions and disorders of the vestibular system, the perception of self-motion, verticality and balance control were laid by a remarkable group of 19th century scientists including Purkynӗ, Mach, Breuer, Helmholtz, and Crum-Brown. It was also in the 19th century that Bell described a new sense of a reciprocal sensorimotor loop between the brain and the muscles which he called "muscular sense," later termed "kinaesthesia" by Bastian and defined in 1906 as "proprioception" by Sherrington as "the perception of joint and body movements as well as position of the body or body segments, in space." Both, the vestibular system and proprioception could be acknowledged as senses six or seven. However, we hesitate to recommend "pain"-which is variously assigned to the somatosensory system or extero-, intero-, visceroception-as a separate sensory system. Pain sensors are often not specific but have multisensory functions. Because of this inconsistent, partly contradictory classification even by experts in the current literature on senses and sensors we consider it justified to recommend a comprehensive reorganization of classification features according to the present state of knowledge with an expansion of the number of senses. Such a project has also to include the frequent task-dependent multisensory interactions for perceptual and sensorimotor achievements, and higher functions or disorders of the visual and vestibular systems as soon as cognition or emotions come into play. This requires a cooperation of sensory physiologists, neuroscientists and experienced physicians involved in the management of patients with sensory and multisensory disorders.

Influence of scene aspect ratio and depth cues on verticality perception bias.

Perceiving verticality is crucial for accurate spatial orientation. Previous research has revealed that tilted scenes can bias verticality perception. Verticality perception bias can be represented as the sum of multiple periodic functions that play a role in the perception of visual orientation, where the specific factors affecting each periodicity remain uncertain. This study investigated the influence of the width and depth of an indoor scene on each periodic component of the bias. The participants were presented with an indoor scene showing a rectangular checkerboard room (Experiment 1), a rectangular aperture on the wall (Experiment 2), or a rectangular dotted room (Experiment 3), with various aspect ratios. The stimuli were presented with roll orientations ranging from 90° clockwise to 90° counterclockwise. The participants were asked to report their subjective visual vertical (SVV) perceptions. The contributions of 45°, 90°, and 180° periodicities to the SVV error were assessed by the weighted vector sum model. In Experiment 1, the periodic components of the SVV error increased with the aspect ratio. In Experiments 2 and 3, only the 90° component increased with the aspect ratio. These findings suggest that extended transverse surfaces may modulate the periodic components of verticality perception.

Asymmetry of the Subjective Visual Vertical in Patients With Unilateral Peripheral Vestibular Deficit.

Perception of verticality is clinically assessed using the subjective visual vertical (SVV), a test of the otolith system that consists of aligning a bar on the gravitational vertical in darkness. Patients with acute unilateral vestibulopathy (AUVP) show a systematic SVV bias toward the affected side, whichever the side of line orientation. Whether SVV estimates are symmetrical has not been investigated. This study included 10 patients with AUVP (vestibular neuritis) and 10 with BPPV (posterior semicircular canal). SVV measurements were made at two preset angles of line orientation (15° and 30°) toward the ipsilateral and contralateral sides, relative to the affected side. The results showed asymmetrical SVV estimates in the AUVP group, with significantly greater SVV errors for ipsilateral than contralateral line orientation, as well as for the preset angle of 30° compared to 15°. SVV estimates were significantly lower in patients with BPPV who also exhibited SVV asymmetry. SVV estimates remained unchanged just after the maneuver and were normalized some days later or after supplementary maneuvers. SVV asymmetry should be routinely considered in the clinic. We recommend individually assessing ipsilateral and contralateral SVV and using at least two preset angles. This allows for a better assessment and diagnosis of otolith organ imbalance that can trigger chronic instability and dizziness. The contribution of neck afferents related to head position in space seems to be the main source of SVV asymmetry.

Clinical Assessment of Subjective Visual and Haptic Vertical Norms in Healthy Adults.

Accurate verticality perception is essential for daily life activities, such as correctly estimating object orientation in space. This study established normative data for the subjective visual vertical (SVV) and subjective haptic vertical (SHV) using the portable and self-constructable modified Bucket test and Rotating-Column test. Additionally, the contribution of age, sex, and starting position of the line/ column on SVV and SHV accuracy were evaluated. This study, part of the PRECISE project (ClinicalTrials.gov ID NCT05978596), was conducted following the STROBE guidelines. Healthy adults without visual/neurological/vestibular disorders were recruited. Subjective visual vertical and SHV accuracy were described in terms of constant errors (i.e., mean deviation from 0° [true vertical] respecting its direction), unsigned errors (i.e., mean deviation from 0° irrespective of direction), and variability (i.e., intra-individual standard deviation). Sixty participants were evaluated (mean age: 41.14 [SD = 16.74] years). Subjective visual vertical constant errors between -2.82° and 2.90°, unsigned errors up to 2.15°, and variability up to 1.61° are considered normal. Subjective haptic vertical constant errors ranged from -6.94° to 8.18°, unsigned errors up to 6.66° and variability up to 4.25°. Higher ages led to higher SVV unsigned errors and variability. SHV variability was higher in females compared to males. Certain starting positions led to higher SVV and SHV constants and SVV unsigned errors. Normative data are provided for affordable, self-constructable, and portable SVV and SHV tools. These norms are consistent with more sophisticated equipment and can be used to distinguish between normal and abnormal values.

Morphological and Position Factors of Vertical Surface Light Source Affecting Discomfort Glare Perception

Distinguished from conventional lighting, the LED vertical surface light source (VSLS) is directly exposed to human view, and the effects of which form it takes on visual perception are non-negligible. In the current discomfort glare evaluation system, the solid angle and the position index, which represent the relative relation between the glaring light source and human visual field, are not completely applicable for large-area VSLS, and hence are awaiting supplementation and modification. In this study, a physical experimental setup was established to conduct an evaluation experiment on discomfort glare, employing an LED display and white translucent frosted film to simulate vertical surface light sources (VSLS). The experiments were arranged with 21 VSLS shapes (comprising 3 areas and 7 length-to-width ratios) and 11 mounting positions. Subjective ratings and four eye-movement data parameters—namely, the change rate of pupil diameter (CRPD), mean saccadic amplitude (SA), blinking frequency (BF), and saccadic speed (SS)—were collected from 24 participants under each working condition using the Boyce Evaluation Scale and eye tracking techniques. The main results of this study are the following: (a) CRPD is the most appropriate eye-movement index for characterizing VSLS glare perception; (b) The area of the VSLS is the primary shape element influencing discomfort glare. Furthermore, with the same surface area, the lateral view angle (LaVA) and the longitudinal view angle (LoVA) perceived by the human eye also impact glare perception; (c) A functional equation between the VSLS area, LaVA, and LoVA to the borderline luminance between comfort and discomfort (BCD luminance) is fitted; (d) Based on the eccentric angle and the azimuthal angle, a modified position index P’ is proposed to represent the relative position of the VSLS in the visual field, and the ratio function of BCD luminance of the VSLS at non-central positions and the central position is fitted.

Visual vertigo and motion sickness is different between persistent postural-perceptual dizziness and vestibular migraine

IntroductionPersistent postural-perceptual dizziness (PPPD) and vestibular migraine (VM) share symptoms of visual vertigo and motion sickness that can be confusing for clinicians to distinguish. We compare the severity of these symptoms and dynamic subjective visual vertical (dSVV) in these two common vestibular conditions. MethodTwenty-nine patients with PPPD, 37 with VM, and 29 controls were surveyed for subjective symptoms using the visual vertigo analogue scale (VVAS) and motion sickness susceptibility questionnaire during childhood (MSA) and the past 10 years (MSB). dSVV is a measure of visual dependence measures perception of verticality against a rotating background (5 deg./s). ResultsVVAS revealed contextual differences for dizziness between those with PPPD and VM. Ratings of visual vertigo were most severe in PPPD, less in VM, and mild in controls (VVAS PPPD 27.1, VM 11.2, control 4.6, p < 0.001). MSA was more severe in VM than in PPPD or control (12.8 vs 7.6 vs 8.5, p = 0.01). MSB was more severe in VM than controls (MSB score 12.9 VS 8.1 p = 0.009) but was not different than PPPD (MSB score 10.0, p = 0.10). dSVV alignment was similar among the three groups (p = 0.83). Both VM and PPPD groups had greater simulator sickness than controls after completing the dSVV. ConclusionsPatients with PPPD report more visual vertigo than those with VM, but a history of motion sickness as a child is more common in VM. Additionally, the environmental context that induces visual vertigo is different between PPPD and VM.

Evaluation of Subjective Visual Vertical and Cervical Neuromotor Control in Young Nomophobians: A Cross Sectional Study.

Misperceptions of subjective visual vertical are associated with poor balance, increasing the risk of falls and accidents. The aim of the present study was to evaluate the effect of nomophobia on verticality perception using subjective visual vertical (S.V.V.) test and cervical neuromotor control of the deep neck flexors (DNF) in adults aged 18-29 years old. This cross-sectional study employed convenience sampling and was conducted at a tertiary health institute over an eight-month period.After obtaining the written informed consent, 102 participants were asked to fill the Nomophobia Questionnaire (NMP-Q) and based on the responses participants were stratified into mild (n1 = 34), moderate(n2 = 34), and severe(n3 = 34) nomophobian group. Each nomophobian group underwent testing for verticality perception by using the SVV test and cervical neuromotor control. 102 healthy age and gender matched controls were recruited and underwent testing for verticality perception by using the SVV test and cervical neuromotor control. The mean age of the study participants was 22 ± 3.15 years with 35(33.98%) males and 67(65.04%) females. There was a statistically significant difference between the median scores across the three nomophobian groups with S.V.V. (p = 0.005), activation score (p = 0.012), and endurance score (p = 0.000) of the deep neck flexors in the severe nomophobia group. This study demonstrated that SVV and cervical neuromotor control was predominantly affected in the severe nomophobian group.

Vestibular dysfunction and its association with cognitive impairment and dementia.

The vestibular system plays an important role in maintaining balance and posture. It also contributes to vertical perception, body awareness and spatial navigation. In addition to its sensory function, the vestibular system has direct connections to key areas responsible for higher cognitive functions, such as the prefrontal cortex, insula and hippocampus. Several studies have reported that vestibular dysfunction, in particular bilateral vestibulopathy, is associated with an increased risk of cognitive impairment and the development of dementias such as Alzheimer's disease. However, it is still controversial whether there is a causal relationship between vestibular damage and cognitive dysfunction. In this mini-review, we will explore the relationship between the vestibular system, cognitive dysfunction and dementia, hypotheses about the hypothesis and causes that may explain this phenomenon and also some potential confounders that may also lead to cognitive impairment. We will also review multimodal neuroimaging approaches that have investigated structural and functional effects on the cortico-vestibular network and finally, describe some approaches to the management of patients with vestibular damage who have shown some cognitive impairment.

Gravity-Dependent Modulation of Downbeat Nystagmus and Subjective Visual Vertical in the Roll Plane

Downbeat nystagmus (DBN) is the most common form of acquired central vestibular nystagmus. Gravity perception in patients with DBN has previously been investigated by means of subjective visual straight ahead (SVA) and subjective visual vertical (SVV) in the pitch and roll planes only during whole-body tilts. To our knowledge, the effect of head tilt in the roll plane on the SVV and on DBN has not yet been systematically studied in patients. In this study, we investigated static and dynamic graviceptive function in the roll-plane in patients with DBN (patients) and healthy-controls (controls) by assessment of the Subjective Visual Vertical (SVV) and the modulation of slow-phase-velocity (SPV) of DBN. SPV of DBN and SVV were tested at different head-on trunk-tilt positions in the roll-plane (0°,30° clockwise (cw) and 30° counterclockwise (ccw)) in 26 patients suffering from DBN and 13 controls. In patients, SPV of DBN did not show significant modulations at different head-tilt angles in the roll-plane. SVV ratings did not differ significantly between DBN patients vs. controls, however patients with DBN exhibited a higher variability in mean SVV estimates than controls. Our results show that the DBN does not exhibit any modulation in the roll-plane, in contrast to the pitch-plane. Furthermore, patients with DBN show a higher uncertainty in the perception of verticality in the roll-plane in form of a higher variability of responses.