Sensorimotor and cognitive factors associated with the age-related increase of visual field dependence: a cross-sectional study

Visual Field Dependence Persists in Age-Related Central Visual Field Loss

Purpose

To examine whether the age-related increase in visual field dependence persists in older adults with central field loss (CFL).

Methods

Twenty individuals with CFL were grouped into participants with age-related binocular CFL (CFL, n = 9), age-related monocular CFL/relative scotomata (mCFL, n = 8), and CFL occurring at a young age (yCFL, n = 3). Seventeen controls were age-matched to the older CFL groups (OA) and three to the yCFL group (yOA). Participants judged the tilt direction of a rod presented at various orientations under conditions with and without a visual reference. Visual field dependence was determined as the difference in judgment bias between trials with and without the visual reference. Visual field dependence was examined between groups and relative to visual acuity and contrast sensitivity.

Results

All older groups performed similarly without the visual reference. The CFL group showed greater visual field dependence than the OA group (Mann-Whitney U test; U = 39, P = 0.045). However, there was no group difference when considering all three older groups (Kruskal-Wallis ANOVA; H(2, N = 34) = 4.31, P = 0.116). Poorer contrast sensitivity correlated with greater visual field dependence (P = 0.017; ρ = -0.43).

Conclusions

Visual field dependence persists in older adults with CFL and seems exacerbated in those with dense binocular scotomata. This could be attributed to the sensitivity of the spared peripheral retina to orientation and motion cues. The relationship with contrast sensitivity further suggests that a decline in visual function is associated with an increase in visual field dependence beyond the effects of normal aging. These observations can guide tailored care and rehabilitation in older adults with CFL.

Perceptual visual dependence for spatial orientation in patients with schizophrenia

BACKGROUND

Patients with schizophrenia are reported to have vestibular dysfunction and to weigh vestibular input to a lesser extent compared to healthy controls. Such deficits may increase visual dependence (VD) for spatial orientation at a perceptual level in these patients. The aim of this study is to compare VD levels between healthy control and patients with schizophrenia and to explore associations between VD and clinical measures in these patients. Relation of VD to antipsychotic drug treatment is also discussed.

METHOD

18 patients with schizophrenia and 19 healthy controls participated in this study. The Rod and Disc Test (RDT) was used to create an optokinetic surround around a centrally located rod. Participants aligned the rod to their subjective visual vertical (SVV) in both static and dynamic disc conditions. VD was calculated as the difference in SVV between these two conditions.

RESULTS

There was no group difference or gender difference in static or dynamic SVV as well as VD. There was no correlation between VD and any of the Positive and Negative Syndrome Scale (PANSS) scores, however VD was significantly correlated to illness duration in the patient group.

CONCLUSIONS

Schizophrenia is not associated with greater VD levels at a perceptual level, compared to controls, indicating adequate visuo-vestibular integration for judging line verticality in these patients. Patients with greater chronicity of the disease are more visually dependent than those less chronically ill, consistent with previous reports of possible vestibular dysfunction in patients with schizophrenia. This may affect their daily functioning in dynamic visual environments.

Perceptual lateralization on the Rod-and-Frame Test in young and older adults

INTRODUCTION

There is an overall left visual field/right hemisphere advantage in young adults for masked, tachistoscopically presented images on the Rod-and-Frame Test (RFT). This study explored potential age-related lateralization differences in processing of visual context on the RFT.

METHODS

The 35 young and 33 older adults aligned a rod surrounded either by no frame, a vertical, or leftward/rightward tilted frame to their perceived vertical. Algebraic errors of rod alignment were used to derive the rod-and-frame effect (RFE) and asymmetry index.

RESULTS

Young adults had frequent indirect effects, mostly to the right-tilted frame, while older adults hardly produced any. Compared with nontilted frames, young adults displayed larger alignment errors with left-tilted frames; however, older adults exhibited this same effect for both frame tilt conditions. Young adults had smaller RFE values than older adults for the right-tilted frame, with no age-related difference in RFE for the left-tilted frame or asymmetry index. The negative asymmetry index was statistically different from the true vertical only in young adults.

CONCLUSION

There is an age-related reduction in the right hemisphere processing of left-sided visual contexts on the RFT. Such findings can assist clinicians to improve interpretation of RFT findings in clinical patients.

Future trends in brain aging research: Visuo-cognitive functions at stake during mobility and spatial navigation

Aging leads to a complex pattern of structural and functional changes, gradually affecting sensorimotor, perceptual, and cognitive processes. These multiscale changes can hinder older adults' interaction with their environment, progressively reducing their autonomy in performing tasks relevant to everyday life. Autonomy loss can further be aggravated by the onset and progression of neurodegenerative disorders (e.g., age-related macular degeneration at the sensory input level; and Alzheimer's disease at the cognitive level). In this context, spatial cognition offers a representative case of high-level brain function that involves multimodal sensory processing, postural control, locomotion, spatial orientation, and wayfinding capabilities. Hence, studying spatial behavior and its neural bases can help identify early markers of pathogenic age-related processes. Until now, the neural correlates of spatial cognition have mostly been studied in static conditions thereby disregarding perceptual (other than visual) and motor aspects of natural navigation. In this review, we first demonstrate how visuo-motor integration and the allocation of cognitive resources during locomotion lie at the heart of real-world spatial navigation. Second, we present how technological advances such as immersive virtual reality and mobile neuroimaging solutions can enable researchers to explore the interplay between perception and action. Finally, we argue that the future of brain aging research in spatial navigation demands a widespread shift toward the use of naturalistic, ecologically valid experimental paradigms to address the challenges of mobility and autonomy decline across the lifespan.

Visuomotor control dynamics of quiet standing under single and dual task conditions in younger and older adults

Visual input facilitates stable postural control; however, ageing alters visual gaze strategies and visual input processing times. Understanding the complex interaction between visual gaze behaviour and the effects of age may inform future interventions to improve postural control in older adults. The purpose of this study was to determine effects of age and dual task on gaze and postural sway dynamics, and the sway-gaze complexity coupling to explore the coupling between sensory input and motor output. Ten older and 10 younger adults performed single and dual task quiet standing while gaze behaviour and centre of mass motion were recorded. The complexity and stability of postural sway, saccade characteristics, visual input duration and complexity of gaze were calculated in addition to sway-gaze coupling quantified by cross-sample entropy. Dual tasking increased complexity and decreased stability of sway with increased gaze complexity and visual input duration, suggesting greater automaticity of sway with greater exploration of the visual field but with longer visual inputs to maintain postural stability in dual task conditions. In addition, older adults had lower complexity and stability of sway than younger adults indicating less automated and stable postural control. Older adults also demonstrated lower gaze complexity, longer visual input durations and greater sway-gaze coupling. These findings suggest older adults adopted a strategy to increase the capacity for visual information input, whilst exploring less of the visual field than younger adults.

The Impact of Aging on Spatial Abilities in Deaf Users of a Sign Language

Research involving the general population of people who use a spoken language to communicate has demonstrated that older adults experience cognitive and physical changes associated with aging. Notwithstanding the differences in the cognitive processes involved in sign and spoken languages, it is possible that aging can also affect cognitive processing in deaf signers. This research aims to explore the impact of aging on spatial abilities among sign language users. Results showed that younger signers were more accurate than older signers on all spatial tasks. Therefore, the age-related impact on spatial abilities found in the older hearing population can be generalized to the population of signers. Potential implications for sign language production and comprehension are discussed.

Postural Control While Walking Interferes With Spatial Learning in Older Adults Navigating in a Real Environment

Cognitive demands for postural control increase with aging and cognitive-motor interference (CMI) exists for a number of walking situations, especially with visuo-spatial cognitive tasks. Such interference also influences spatial learning abilities among older adults; however, this is rarely considered in research on aging in spatial navigation. We posited that visually and physically exploring an unknown environment may be subject to CMI for older adults. We investigated potential indicators of postural control interfering with spatial learning. Given known associations between age-related alterations in gait and brain structure, we also examined potential neuroanatomical correlates of this interference. Fourteen young and 14 older adults had to find an invisible goal in an unfamiliar, real, ecological environment. We measured walking speed, trajectory efficiency (direct route over taken route) and goal fixations (proportion of visual fixations toward the goal area). We calculated the change in walking speed between the first and last trials and adaptation indices for all three variables to quantify their modulation across learning trials. All participants were screened with a battery of visuo-cognitive tests. Eighteen of our participants (10 young, 8 older) also underwent a magnetic resonance imaging (MRI) examination. Older adults reduced their walking speed considerably on the first, compared to the last trial. The adaptation index of walking speed correlated positively with those of trajectory efficiency and goal fixations, indicating a reduction in resource sharing between walking and encoding the environment. The change in walking speed correlated negatively with gray matter volume in superior parietal and occipital regions and the precuneus. We interpret older adults’ change in walking speed as indicative of CMI, similar to dual task costs. This is supported by the correlations between the adaptation indices and between the change in walking speed and gray matter volume in brain regions that are important for navigation, given that they are involved in visual attention, sensory integration and encoding of space. These findings under ecological conditions in a natural spatial learning task question what constitutes dual tasking in older adults and they can lead future research to reconsider the actual cognitive burden of postural control in aging navigation research.

Perceiving jittering self-motion in a field of lollipops from ages 4 to 95

An internal model of self-motion provides a fundamental basis for action in our daily lives, yet little is known about its development. The ability to control self-motion develops in youth and often deteriorates with advanced age. Self-motion generates relative motion between the viewer and the environment. Thus, the smoothness of the visual motion created will vary as control improves. Here, we study the influence of the smoothness of visually simulated self-motion on an observer's ability to judge how far they have travelled over a wide range of ages. Previous studies were typically highly controlled and concentrated on university students. But are such populations representative of the general public? And are there developmental and sex effects? Here, estimates of distance travelled (visual odometry) during visually induced self-motion were obtained from 466 participants drawn from visitors to a public science museum. Participants were presented with visual motion that simulated forward linear self-motion through a field of lollipops using a head-mounted virtual reality display. They judged the distance of their simulated motion by indicating when they had reached the position of a previously presented target. The simulated visual motion was presented with or without horizontal or vertical sinusoidal jitter. Participants' responses indicated that they felt they travelled further in the presence of vertical jitter. The effectiveness of the display increased with age over all jitter conditions. The estimated time for participants to feel that they had started to move also increased slightly with age. There were no differences between the sexes. These results suggest that age should be taken into account when generating motion in a virtual reality environment. Citizen science studies like this can provide a unique and valuable insight into perceptual processes in a truly representative sample of people.

Young and Older Adults Differ in Integration of Sensory Cues for Vertical Perception

Introduction

The subjective visual vertical (SVV) measures the perception of a person's spatial orientation relative to gravity. Weighted central integration of vestibular, visual, and proprioceptive inputs is essential for SVV perception. Without any visual references and minimal proprioceptive contribution, the static SVV reflects balance of the otolith organs. Normal aging is associated with bilateral and progressive decline in otolith organ function, but age-dependent effects on SVV are inconclusive. Studies on sensory reweighting for visual vertical and multisensory integration strategies reveal age-dependent differences, but most studies have included elderly participants in comparison to younger adults. The aim of this study was to compare young adults with older adults, an age group younger than the elderly.

Methods

Thirty-three young and 28 older adults (50–65 years old) adjusted a tilted line accurately to their perceived vertical. The rod's final position from true vertical was recorded as tilt error in degrees. For otolithic balance, visual vertical was recorded in the dark without any visual references. The rod and frame task (RFT) with tilted disorienting visual frames was used for creating visuovestibular conflict. We adopted Nyborg's analysis method to derive the rod and frame effect (RFE) and trial-to-trial variability measures. Rod alignment times were also analyzed.

Results

There was no age difference in signed tilts of SVV without visual reference. There was an age effect on RFE and on overall trial-to-trial variability of rod tilt, with older adults displaying larger frame effects and greater variability in rod tilts. Alignment times were longer in the tilted-frame conditions for both groups and in the older adults compared to their younger counterparts. The association between tilt accuracy and tilt precision was significant for older adults only during visuovestibular conflict, revealing an increase in RFE with an increase in tilt variability. Correlation of σ_SVV, which represents vestibular input precision, with RFE yielded exactly the same contribution of σ_SVV to the variance in RFE for both age groups.

Conclusions

Older adults have balanced otolithic input in an upright position. Increased reliance on visual cues may begin at ages younger than what is considered elderly. Increased alignment times for older adults may create a broader time window for integration of relevant and irrelevant sensory information, thus enhancing their multisensory integration. In parallel with the elderly, older adults may differ from young adults in their integration of sensory cues for visual vertical perception.

Persistent postural perceptual dizziness is on a spectrum in the general population

Objective

To examine the idea that symptoms of persistent postural perceptual dizziness (PPPD) are more common than previously assumed and lie on a spectrum in the general population, thus challenging current theories that PPPD is only a consequence of a vestibular insult.

Methods

We collected 2 common clinical questionnaires of PPPD (Visual Vertigo Analogue Scale [VVAS] and Situational Characteristics Questionnaire [SCQ]) in 4 cohorts: community research volunteers (n = 1941 for VVAS, n = 1,474 for SCQ); paid online participants (n = 190 for VVAS, n = 125 for SCQ); students (n = 204, VVAS only); and patients diagnosed with PPPD (n = 25).

Results

We found that around 9%, 4%, and 11%, respectively, of the 3 nonclinical cohorts scored above the 25th percentile patient score on 1 PPPD measure (VVAS) and 49% and 54% scored above the 25th percentile patient score on the other measure (SCQ). Scores correlated negatively with age (counter to expectation). As expected, scores correlated with migraine in 2 populations, but this only explained a small part of the variance, suggesting that migraine is not the major factor underlying the spectrum of PPPD symptoms in the general population.

Conclusion

We found high levels of PPPD symptoms in nonclinical populations, suggesting that PPPD is a spectrum that preexists in the population, rather than only being a consequence of vestibular insult. Atypical visuo-vestibular processing predisposes some individuals to visually induced dizziness, which is then exacerbated should vestibular insult (or more generalized insult) occur.

Use of Commercial Virtual Reality Technology to Assess Verticality Perception in Static and Dynamic Visual Backgrounds

OBJECTIVES

The Subjective Visual Vertical (SVV) test and the closely related Rod and Disk Test (RDT) are measures of perceived verticality measured in static and dynamic visual backgrounds. However, the equipment used for these tests is variable across clinics and is often too expensive or too primitive to be appropriate for widespread use. Commercial virtual reality technology, which is now widely available, may provide a more suitable alternative for collecting these measures in clinical populations. This study was designed to investigate verticality perception in symptomatic patients using a modified RDT paradigm administered through a head-mounted display (HMD).

DESIGN

A group of adult patients referred by a physician for vestibular testing based on the presence of dizziness symptoms and a group of healthy adults without dizziness symptoms were included. We investigated degree of visual dependence in both groups by measuring SVV as a function of kinematic changes to the visual background.

RESULTS

When a dynamic background was introduced into the HMD to simulate the RDT, significantly greater shifts in SVV were found for the patient population than for the control population. In patients referred for vestibular testing, the SVV measured with the HMD was significantly correlated with traditional measures of SVV collected in a rotary chair when accounting for head tilt.

CONCLUSIONS

This study provides initial proof of concept evidence that reliable SVV measures in static and dynamic visual backgrounds can be obtained using a low-cost commercial HMD system. This initial evidence also suggests that this tool can distinguish individuals with dizziness symptomatology based on SVV performance in dynamic visual backgrounds.

Effects of Aging on Postural Responses to Visual Perturbations During Fast Pointing

People can quickly adjust their goal-directed hand movements to an unexpected visual perturbation (a target jump or background motion). Does this ability decrease with age? We examined how aging affects both the timing and vigor of fast manual and postural adjustments to visual perturbations. Young and older adults stood in front of a horizontal screen. They were instructed to tap on targets presented on the screen as quickly and accurately as possible by moving their hand in the sagittal direction. In some trials, the target or the background moved laterally when the hand started to move. The young and older adults tapped equally accurately, but older adults’ movement times were about 160 ms longer. The manual responses were similar for the young and older adults, but the older adults took about 15 ms longer to respond to both kinds of visual perturbations. The manual responses were also less vigorous for the older adults. In contrast to the young adults, the older adults responded more strongly to the motion of the background than to the target jump, probably because the elderly rely more on visual information for their posture. Thus, aging delays responses to visual perturbations, while at the same time making people rely more on the visual surrounding to adjust goal-directed movements.

Visual dependence and spatial orientation in benign paroxysmal positional vertigo

People with benign paroxysmal positional vertigo (BPPV) probably have otoconial particles displaced from the utricle into the posterior semicircular canal. This unilateral change in the inertial load distributions of the labyrinth may result in visual dependence and may affect balance control. The goal of this study was to explore the interaction between visual dependence and balance control. We compared 23 healthy controls to 17 people with unilateral BPPV on the Clinical Test of Sensory Interaction and Balance on compliant foam with feet together, the Rod-and-Frame Test and a Mental Rotation Test. In controls, but not BPPV subjects, subjects with poor balance scores had significantly greater visual dependence, indicating that reliance on visual cues can affect balance control. BPPV and control subjects did not differ on the mental rotation task overall but BPPV reaction time was greater at greater orietantions, suggesting that this cognitive function was affected by BPPV. The side of impairment was strongly related to the side of perceived bias in the Earth vertical determined by BPPV subjects, indicating the relationship between the effect of asymmetric otolith unloading with simultaneous canal loading on spatial orientation perception.

Relationships Between Accuracy in Predicting Direction of Gravitational Vertical and Academic Performance and Physical Fitness in Schoolchildren

Enhanced levels of cardio-respiratory fitness (CRF) and physical activity (PA) are both positively associated with health and academic outcomes, but less is known about the spatial processing and perceptual components of PA. Perception of vertical (PV) is a spatial orientation ability that is important for PA, and is usually measured as relative accuracy in aligning an object to gravitational vertical against a tilted background. However, evidence is inconclusive regarding the relationship of PV to educational outcomes – most importantly, numeracy. Students were recruited from primary schools in the Australian Capital Territory. A group of 341 (females n = 162, mean age 11.3 years) children performed all the tests required for this study. A computerised rod and frame test of PV employing a small (20°) visual angle was administered, and socio-economic status (SES), national education test results (NAPLAN, 2010), and CRF and PA data were collected. Correlation and hierarchical regression analysis were used to examine the inter-relationships between PV and CRF, PA, SES and NAPLAN results. The two extreme quartile score groups from the measures of PV, PA and CRF were examined in relation to NAPLAN scores. PV scores arising from testing with a small visual angle and SES were found to be significantly associated with overall academic scores, and with the Numeracy, Reading, and Writing components of academic performance. Female gender was significantly associated with Writing score, and male with Numeracy score. Being less influenced by the background tilted frame, and therefore having visual field independence (FI), was associated with significantly higher academic scores, with the largest effect in Numeracy scores (effect size, d = 0.82) and also associated with higher CRF and PA levels. FI was positively associated with all the academic modules examined, and most strongly with Numeracy test results, suggesting that FI provides an indicator of STEM ability. These findings suggest that further longitudinal research into strategies designed to enhance visual FI deserve consideration, with a focus on specialized PA programs for pre-pubescent children. It is possible that small visual angle spatial tasks during PA may stimulate neural networks involved in numerical cognition.

Relationship of visual dependence to age, balance, attention, and vertigo

[Purpose] The aim of this study was to investigate the relationship of increased visual dependence to age, balance, attention, and vertigo. [Subjects and Methods] Twelve younger, 12 visually independent (VI) older and 12 visually dependent (VD) older adults were assessed for levels of visual dependence using Subjective Visual Vertical (SVV) tilt values, balance ability using the Clinical Test of Sensory Integration for Balance (CTSIB), and attentional requirements through the dual-task paradigm and experience of vertigo by completing the Situational Vertigo Questionnaire (SVQ). [Results] VD older adults had higher SVV tilt values, greater postural sway in a scenario where visual and proprioceptive inputs were simultaneously altered, similar dual-task cost and lower SVQ scores compared with younger and VI older adults. No difference was observed between the latter two. [Conclusion] Visual dependence may not necessarily increase with age but affect balance in a sensory condition involving visual-proprioceptive conflict. There is a non-significant trend for elevated visual dependence with increased attentional demands. Greater visual dependence is not accompanied by more frequent symptoms of vertigo in visually complex environments.

Regularity of Center of Pressure Trajectories in Expert Gymnasts during Bipedal Closed-Eyes Quiet Standing

We compared postural control of expert gymnasts (G) to that of non-gymnasts (NG) during bipedal closed-eyes quiet standing using conventional and nonlinear dynamical measures of center of foot pressure (COP) trajectories. Earlier findings based on COP classical variables showed that gymnasts exhibited a better control of postural balance but only in demanding stances. We examined whether the effect of expertise in Gymnastic can be uncovered in less demanding stances, from the analysis of the dynamic patterns of COP trajectories. Three dependent variables were computed to describe the subject's postural behavior: the variability of COP displacements (A_CoP), the variability of the COP velocities (V_CoP) and the sample entropy of COP (SEn_CoP) to quantify COP regularity (i.e., predictability). Conventional analysis of COP trajectories showed that NG and G exhibited similar amount and control of postural sway, as indicated by similar A_CoP and V_CoP values observed in NG and G, respectively. These results suggest that the specialized balance training received by G may not transfer to less challenging balance conditions such as the bipedal eyes-closed stance condition used in the present experiment. Interestingly, nonlinear dynamical analysis of COP trajectories regarding COP regularity showed that G exhibited more irregular COP fluctuations relative to NG, as indicated by the higher SEn_CoP values observed for the G than for the NG. The present results showed that a finer-grained analysis of the dynamic patterns of the COP displacements is required to uncover an effect of gymnastic expertise on postural control in nondemanding postural stance. The present findings shed light on the surplus value in the nonlinear dynamical analysis of COP trajectories to gain further insight into the mechanisms involved in the control of bipedal posture.