Vestibular pathways involved in cognition

Amphibian spatial cognition, medial pallium and other supporting telencephalic structures

Vertebrate hippocampal formation is central to conversations on the comparative analysis of spatial cognition, especially in light of variation found in different vertebrate classes. Assuming the medial pallium (MP) of extant amphibians resembles the hippocampal formation (HF) of ancestral stem tetrapods, we propose that the HF of modern amniotes began with a MP characterized by a relatively undifferentiated cytoarchitecture, more direct thalamic/olfactory sensory inputs, and a more generalized role in associative learning-memory processes. As such, hippocampal evolution in amniotes, especially mammals, can be seen as progressing toward a cytoarchitecture with well-defined subdivisions, regional connectivity, and a functional specialization supporting map-like representations of space. We then summarize a growing literature on amphibian spatial cognition and its underlying brain organization. Emphasizing the MP/HF, we highlight that further research into amphibian spatial cognition would provide novel insight into the role of the HF in spatial memory processes, and their supporting neural mechanisms. A more complete reconstruction of hippocampal evolution would benefit from additional research on non-mammalian vertebrates, with amphibians being of particular interest.

Association of Vestibular Disorders and Cognitive Function: A Systematic Review

OBJECTIVES

The purpose of this study is to consolidate and condense the available evidence about the potential association between vestibular diseases and cognitive impairment.

DATA SOURCES AND METHODS

A systematic search was conducted on four English databases (PubMed, Embase, Web of Science, Cochrane Library) from the time of library construction to March 2024. The study incorporated various keywords such as "vestibular disorders," "vertigo," "dizziness," "Meniere's disease," "benign paroxysmal positional vertigo," "vestibular migraine," "vestibular neuritis," "labyrinthitis," "bilateral vestibular disease," as well as "cognitive function" and "cognitive dysfunction." A qualitative review was conducted to look for and assess pertinent studies.

RESULTS

A total of 45 publications were incorporated, encompassing prevalent vestibular disorders, mostly targeting individuals in the middle-aged and older demographic. The findings indicate that individuals with vestibular disorders experience varying levels of cognitive impairment, which is evident in different aspects, with visuospatial cognitive deficits being more prominent. Furthermore, patients with chronic vestibular syndromes are more prone to cognitive dysfunction. Lastly, the hippocampus plays a crucial role in the intricate vestibular neural network.

CONCLUSION

The findings of this comprehensive review indicate that vestibular disorders can result in impairments across various aspects of cognitive functioning, particularly in visuospatial cognition. The underlying mechanism may be associated with a decrease in the size of the hippocampus. Individuals suffering from chronic vestibular dysfunction exhibit a higher likelihood of experiencing cognitive deficits.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Altered thalamus functional connectivity in patients with acute unilateral vestibulopathy: a resting-state fMRI study

Objective

Acute unilateral vestibulopathy (AUVP) is the second leading cause of peripheral vestibular vertigo. Full recovery of AUVP is related to sufficient central vestibular compensation. It has been confirmed that the vestibular nucleus and vestibular cortex are involved in the process of vestibular compensatory in AUVP patients. However, few studies have focused on the functional compensation of thalamus in patients with AUVP. This study aimed to explore the alterations of resting-state functional connectivity (FC) focused on thalamus using functional magnetic resonance imaging (fMRI) in AUVP patients.

Methods

Data of 3D-T1 and resting-state fMRI were collected from 40 AUVP patients and 35 healthy controls (HC). Seeds-based (bilateral thalamus) FC was analyzed to investigate the changes in FC between the two groups. Furthermore, we evaluated the associations between altered thalamus FC and clinical features in AUVP patients using Pearson's partial correlation.

Results

Compared with HC, AUVP patients showed decreased FC between bilateral thalamus and left insula. We also observed decreased FC between right thalamus and left supramarginal gyrus. Additionally, we found increased FC between left thalamus and right postcentral gyrus (PCG), as well as increased FC between right thalamus and regions of bilateral PCG, right middle frontal gyrus and right middle occipital gyrus in AUVP patients. Furthermore, the FC between left thalamus and left insula was negatively correlated with values of canal paresis in patients with AUVP (p = 0.010, r = -0.434).

Conclusion

Our results provided first evidence for the decreased thalamo-vestibular cortex pathway, as well as increased thalamo-somatosensory and thalamo-visual cortex pathway in AUVP patients. These findings help us better understand the underlying mechanisms of central dynamic compensatory following an acute unilateral peripheral vestibular damage.

Impact of repetitive home-based galvanic vestibular stimulation on cognitive skills in healthy older adults

The human vestibular system is adversely affected by the aging process. Recent evidence indicates that vestibular information and cognitive functions are related, suggesting that age-related vestibular loss may contribute to cognitive impairment. In this study, we aimed to investigate the effects of repetitive, home-based galvanic vestibular stimulation (GVS) on cognitive functions in healthy older adults. Twenty-one participants (age = 64.66 ± 2.97 years, 12 females) were randomly allocated to either a home-based GVS or an active control group. The GVS intervention lasted 20 min per session, five times a week, for two weeks (10 sessions). Cognitive functions were assessed before and after the intervention using the Stroop Test, Trail Making Test A&B, and Dual-Task (digit recall and paper-pencil tracking test). Our findings revealed a significant group-by-time interaction effect for the tracking accuracy (F(1,18) = 7.713, p = 0.012, η p2 = 0.30), with only the home-based GVS group showing significant improvement (t = -2.544, p = 0.029). The proposed home-based GVS protocol offers a promising non-pharmacological avenue for enhancing visuospatial ability in healthy older adults. Further research is needed to investigate the effects of different GVS protocols on various cognitive functions, particularly in older individuals with different health conditions.

Vestibular-evoked myogenic potential abnormalities in Parkinson's disease with freezing of gait

BACKGROUND

Vestibular dysfunction is closely associated with the pathophysiology of Parkinson's disease (PD) accompanied by freezing of gait (FOG); however, evidence supporting this clinical association is lacking. Vestibular-evoked myogenic potentials (VEMPs) have been widely acknowledged as a crucial electrophysiological parameter in the clinical evaluation of vestibular function.

OBJECTIVE

The present study investigated the possible correlation of FOG occurrence with VEMP observations in patients diagnosed with PD.

METHODS

Altogether, 95 idiopathic PD patients were recruited into the present cross-sectional study. All patients underwent motor and non-motor assessments using serial scales. In addition, the electrophysiological vestibular evaluation was conducted, which included cervical (cVEMP) and ocular VEMP (oVEMP) assessments. Furthermore, the correlations of bilateral c/oVEMP absence with clinical phenotypes, especially FOG, among the PD patients were analyzed.

RESULTS

Among the 95 patients with PD, 44 (46.3%) had bilateral oVEMP absence and 23 (24.2%) had bilateral cVEMP absence, respectively. The proportions of patients with bilateral oVEMP absence (77.8% vs 30.9%, p = 0.004) and bilateral cVEMP absence (44.4% vs 19.5%, p = 0.035) were higher in the patient group exhibiting FOG than in the group without FOG. Following the adjustment of confounding variables, bilateral oVEMP absence (OR = 8.544, p = 0.007), rather than bilateral cVEMP absence, was shown to independently predict FOG occurrence in patients with PD.

CONCLUSION

The close correlation between bilateral oVEMP absence and FOG in PD patients sheds new light on the possible role of central vestibular/upper brainstem dysfunction in FOG development in patients with PD.

The Current Status and Trends of Research Related to Vestibular Disorders, Vertigo, and Cognitive Impairment in the Elderly Population: A Bibliometric Analysis

Background: The vestibular system not only supports reflex function at the brainstem level, but is also associated with higher levels of cognitive function. Vertigo due to vestibular disorders may lead to or be associated with cognitive dysfunction. Patients with deficits of both vestibular as well as cognitive function may be at particularly high risk for events like falls or certain diseases, such as Alzheimer's. Objective: To analyze the current state of research and trends in the global research literature regarding the correlation between vestibular disorders, vertigo, and cognitive impairment. Methods: We utilized Bibliometrix package to search databases including PubMed, Web of Science, etc for search terms. Results: Databases were searched up to December 15, 2022, and a total of 2222 publications were retrieved. Ultimately, 53 studies were included. A total of 261 authors published in 38 journals and conferences with an overall increasing annual growth rate of 6.94%. The most-published journal was Frontiers in Neurology. The most-published country was the United States, followed by Italy and Brazil. The most-published institution was Johns Hopkins University with a total of 13 articles. On performing trend analysis, we found that the most frequent focus of research in this field include the testing of vestibular perception, activation of the brain-related cortex, and the influence of stimulus-triggered vestibular snail reflex on visual space. The potential focal points are the risk of falling and the ability to extract spatial memory information, and the focus of research in recent decades has revolved around balance, falling, and Alzheimer's disease. Conclusions: Vestibular impairment in older adults affects cognitive function, particularly immediate memory, visuospatial cognition, and attention, with spatial cognition being the most significantly affected. In the future, virtual reality-based vestibular rehabilitation techniques and caloric stimulation could be potential interventions for the treatment of cognitive impairment.

A Clinical Framework for Video Head Impulse Testing and Vestibular Evoked Myogenic Potential Assessments in Primary School-Aged Children

OBJECTIVES

This study aimed to offer normative data and age trends of an age-appropriate vestibular test protocol in a large group (n = 140) of school-aged children (6 to 13 years old) as well as to provide a practical and clinical framework for accurate performance and interpretation of vestibular test results in this specific age group.

DESIGN

The typically developing participants (mean age of 9.51 ± 2.04 years) were recruited to provide a representative group of 20 children for each of the seven age groups that were composed of children aged from 6 to 13 years in 1-year intervals. Each age group consisted of 10 boys and 10 girls. The protocol comprises the video head impulse test, and cervical and ocular vestibular evoked myogenic potential assessments to provide a child-friendly, noninvasive, short, and portable test battery, which is equally applicable in the hospital and office-practice, and which provides information on the integrity of all five parts of the peripheral vestibular system.

RESULTS

The study demonstrates that all included tests and methods, with an overall test duration of 25 min 12 sec ± 5 min 10 sec, were feasible to perform in primary school-aged children, taking into account some practical adaptations. Concerning the video head impulse test, no clinically relevant sex and age effects were noted. However, t tests revealed significant differences for the mean gain of the horizontal (right > left; t[139] = 14.563; p < 0.001) and posterior semicircular canals (left > right; t[139] = -4.823; p < 0.001) between both sides. For the cVEMP assessment, no laterality differences were observed for any of the parameters, but a significantly shorter N1 latencies in the youngest age categories (<8 years), compared with the oldest groups were observed [F(6,118) = 8.336; p < 0.001; partial ƞ² = 0.298]. For all oVEMP parameters, no laterality, sex, or age differences were seen. On the basis of the presented normative data, cutoff criteria were proposed with accompanying clinical recommendations to perform vestibular function testing in this target population.

CONCLUSIONS

This is the first study in a large group of school-aged children offering normative data and age trends of an age-appropriate vestibular test protocol that evaluates the integrity of all parts of the peripheral vestibular organ. The reported normative values and clinical cutoff values will enable appropriate and age-specific interpretation of clinical and scientific results. Moreover, in combination with extensive history taking, and additional vestibular testing (e.g., rotatory chair test, caloric testing) when needed, the results of this study may support clinicians in the diagnosis of side-specific and location-specific vestibular deficits, which is required for accurate counseling and referral for further follow-up and/or intervention.

Non-invasive neuromodulation of cerebello-hippocampal volume-behavior relationships

The study here explores the link between transcranial direct current stimulation (tDCS) and brain-behavior relationships. We propose that tDCS may indirectly influence the complex relationships between brain volume and behavior. We focused on the dynamics between the hippocampus (HPC) and cerebellum (CB) in cognitive processes, a relationship with significant implications for understanding memory and motor skills. Seventy-four young adults (mean age: 22±0.42 years, mean education: 14.7±0.25 years) were randomly assigned to receive either anodal, cathodal, or sham stimulation. Following stimulation, participants completed computerized tasks assessing working memory and sequence learning in a magnetic resonance imaging (MRI) environment. We investigated the statistical interaction between CB and HPC volumes. Our findings showed that individuals with larger cerebellar volumes had shorter reaction times (RT) on a high-load working memory task in the sham stimulation group. In contrast, the anodal stimulation group exhibited faster RTs during the low-load working memory condition. These RT differences were associated with the cortical volumetric interaction between CB-HPC. Literature suggests that anodal stimulation down-regulates the CB and here, those with larger volumes perform more quickly, suggesting the potential need for additional cognitive resources to compensate for cerebellar downregulation. This new insight suggests that tDCS can aid in revealing structure-function relationships, due to greater performance variability, especially in young adults. It may also reveal new targets of interest in the study of aging or in diseases where there is also greater behavioral variability.

Vestibular dysfunction leads to cognitive impairments: State of knowledge in the field and clinical perspectives (Review)

The vestibular system may have a critical role in the integration of sensory information and the maintenance of cognitive function. A dysfunction in the vestibular system has a significant impact on quality of life. Recent research has provided evidence of a connection between vestibular information and cognitive functions, such as spatial memory, navigation and attention. Although the exact mechanisms linking the vestibular system to cognition remain elusive, researchers have identified various pathways. Vestibular dysfunction may lead to the degeneration of cortical vestibular network regions and adversely affect synaptic plasticity and neurogenesis in the hippocampus, ultimately contributing to neuronal atrophy and cell death, resulting in memory and visuospatial deficits. Furthermore, the extent of cognitive impairment varies depending on the specific type of vestibular disease. In the present study, the current literature was reviewed, potential causal relationships between vestibular dysfunction and cognitive performance were discussed and directions for future research were proposed.

Neonatal GABAergic transmission primes vestibular gating of output for adult spatial navigation

GABAergic interneurons are poised with the capacity to shape circuit output via inhibitory gating. How early in the development of medial vestibular nucleus (MVN) are GABAergic neurons recruited for feedforward shaping of outputs to higher centers for spatial navigation? The role of early GABAergic transmission in assembling vestibular circuits for spatial navigation was explored by neonatal perturbation. Immunohistochemistry and confocal imaging were utilized to reveal the expression of parvalbumin (PV)-expressing MVN neurons and their perineuronal nets. Whole-cell patch-clamp recording, coupled with optogenetics, was conducted in vitro to examine the synaptic function of MVN circuitry. Chemogenetic targeting strategy was also employed in vivo to manipulate neuronal activity during navigational tests. We found in rats a neonatal critical period before postnatal day (P) 8 in which competitive antagonization of GABAergic transmission in the MVN retarded maturation of inhibitory neurotransmission, as evidenced by deranged developmental trajectory for excitation/inhibition ratio and an extended period of critical period-like plasticity in GABAergic transmission. Despite increased number of PV-expressing GABAergic interneurons in the MVN, optogenetic-coupled patch-clamp recording indicated null-recruitment of these neurons in tuning outputs along the ascending vestibular pathway. Such perturbation not only offset output dynamics of ascending MVN output neurons, but was further accompanied by impaired vestibular-dependent navigation in adulthood. The same perturbations were however non-consequential when applied after P8. Results highlight neonatal GABAergic transmission as key to establishing feedforward output dynamics to higher brain centers for spatial cognition and navigation.

Vestibular contribution to spatial orientation and navigation

PURPOSE OF REVIEW

The vestibular system provides three-dimensional idiothetic cues for updating of one's position in space during head and body movement. Ascending vestibular signals reach entorhinal and hippocampal networks via head-direction pathways, where they converge with multisensory information to tune the place and grid cell code.

RECENT FINDINGS

Animal models have provided insight to neurobiological consequences of vestibular lesions for cerebral networks controlling spatial cognition. Multimodal cerebral imaging combined with behavioural testing of spatial orientation and navigation performance as well as strategy in the last years helped to decipher vestibular-cognitive interactions also in humans.

SUMMARY

This review will update the current knowledge on the anatomical and cellular basis of vestibular contributions to spatial orientation and navigation from a translational perspective (animal and human studies), delineate the behavioural and functional consequences of different vestibular pathologies on these cognitive domains, and will lastly speculate on a potential role of vestibular dysfunction for cognitive aging and impeding cognitive impairment in analogy to the well known effects of hearing loss.

Cognition in vestibular disorders: state of the field, challenges, and priorities for the future

Vestibular disorders are prevalent and debilitating conditions of the inner ear and brain which affect balance, coordination, and the integration of multisensory inputs. A growing body of research has linked vestibular disorders to cognitive problems, most notably attention, visuospatial perception, spatial memory, and executive function. However, the mechanistic bases of these cognitive sequelae remain poorly defined, and there is a gap between our theoretical understanding of vestibular cognitive dysfunction, and how best to identify and manage this within clinical practice. This article takes stock of these shortcomings and provides recommendations and priorities for healthcare professionals who assess and treat vestibular disorders, and for researchers developing cognitive models and rehabilitation interventions. We highlight the importance of multidisciplinary collaboration for developing and evaluating clinically relevant theoretical models of vestibular cognition, to advance research and treatment.

Effect of Late-Stage Meniere's Disease and Vestibular Functional Impairment on Hippocampal Atrophy

OBJECTIVE

We investigated correlations among clinical features, degree of inner ear endolymphatic hydrops (EH), and hippocampal volume (HV) in different stages of Meniere's disease (MD).

METHODS

From February 2021 to April 2022, clinical data were collected from 99 patients (39 males, 60 females, mean age: 50.4 ± 10.0 [range: 26-69] years) with unilateral MD admitted to the Department of Vertigo Disease of Shandong ENT Hospital. The left and right ears were affected in 64 and 35 patients, respectively. There were 50 and 49 cases in early (Stages 1, 2) and late stages (Stages 3, 4), respectively. Fifty healthy participants were included as controls. Audiovestibular function test results, EH grading using gadolinium-enhanced magnetic resonance imaging (MRI), and HV determined on MRI were analyzed for patients at different stages of MD.

RESULTS

Between-group comparisons of early and late MD revealed significant differences in the disease course, vestibular function (VF), degree of EH, and HV. There were no significant between-group differences based on age, sex, affected side, subjective degree of dizziness, hospital anxiety, or depression. Mean HV in patients with early-stage MD was correlated with the canal paresis value of the caloric test and pure tone hearing threshold, HV in late-stage patients was correlated with vestibular EH.

CONCLUSION

Patients with late-stage MD exhibited severe auditory and VF impairments, increased EH, and atrophy of the HV. More advanced disease was associated with greater vestibular damage and degree of EH.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:410-418, 2024.

Functional Dizziness as a Spatial Cognitive Dysfunction

(1) Background: Persistent postural-perceptual dizziness (PPPD) is a common chronic dizziness disorder with an unclear pathophysiology. It is hypothesized that PPPD may involve disrupted spatial cognition processes as a core feature. (2) Methods: A cohort of 19 PPPD patients underwent psycho-cognitive testing, including assessments for anxiety, depression, memory, attention, planning, and executive functions, with an emphasis on spatial navigation via a virtual Morris water maze. These patients were compared with 12 healthy controls and 20 individuals with other vestibular disorders but without PPPD. Vestibular function was evaluated using video head impulse testing and vestibular evoked myogenic potentials, while brain magnetic resonance imaging was used to exclude confounding pathology. (3) Results: PPPD patients demonstrated unique impairments in allocentric spatial navigation (as evidenced by the virtual Morris water maze) and in other high-demand visuospatial cognitive tasks that involve executive functions and planning, such as the Towers of London and Trail Making B tests. A factor analysis highlighted spatial navigation and advanced visuospatial functions as being central to PPPD, with a strong correlation to symptom severity. (4) Conclusions: PPPD may broadly impair higher cognitive functions, especially in spatial cognition. We discuss a disruption in the creation of enriched cognitive spatial maps as a possible pathophysiology for PPPD.

Appropriate Vestibular Stimulation in Children and Adolescents-A Prerequisite for Normal Cognitive, Motor Development and Bodily Homeostasis-A Review

The structural development of the vestibular part of the inner ear is completed by birth but its central connections continue to develop until adolescence. Their development is dependent on vestibular stimulation-vestibular experience. Studies have shown that vestibular function, modulated by experience and epigenetic factors, is not solely an instrument for body position regulation, navigation, and stabilization of the head and images but also influences cognition, emotion, the autonomous nervous system and hormones. To emphasize the importance of appropriate vestibular stimulation, we present a literature review of its effect on bodily homeostasis, cognition and emotion.

Effects of stochastic vestibular stimulation on cognitive performance in children with ADHD

Previous work has shown that exposure to auditory white noise (WN) can improve cognitive performance in children with ADHD, but it is unknown whether this improvement generalizes to other sensory modalities. To address this knowledge gap, we tested the effect of Stochastic Vestibular Stimulation (SVS) on cognitive performance and reaction time (RT) variability in two groups: children with ADHD and typically developing children (TDC). Children with ADHD (N=42) and TDC (N=28) performed three cognitive tasks (Spanboard, Word Recall and N-back tasks) at two different occasions, with and without exposure to SVS, in a double blinded design. The results showed no main effects of SVS on neither performance nor RT variability for children in any of the groups, and no interactions between SVS and group. Based on these results we conclude that, using our stimulation protocol, the positive effects of WN exposure on cognition in children with ADHD do not generalize to Stochastic Vestibular Stimulation.

Combinatorial genetic strategies for dissecting cell lineages, cell types, and gene function in the mouse brain

Research in neuroscience has greatly benefited from the development of genetic approaches that enable lineage tracing, cell type targeting, and conditional gene regulation. Recent advances in combinatorial strategies, which integrate multiple cellular features, have significantly enhanced the spatiotemporal precision and flexibility of these manipulations. In this minireview, we introduce the concept and design of these strategies and provide a few examples of their application in genetic fate mapping, cell type targeting, and reversible conditional gene regulation. These advancements have facilitated in-depth investigation into the developmental principles underlying the assembly of brain circuits, granting experimental access to highly specific cell lineages and subtypes, as well as offering valuable new tools for modeling and studying neurological diseases. Additionally, we discuss future directions aimed at expanding and improving the existing genetic toolkit for a better understanding of the development, structure, and function of healthy and diseased brains.

The bidirectional relationship between the cerebellum and seizure networks: a double-edged sword

Epilepsy is highly prevalent and notoriously pharmacoresistant. New therapeutic interventions are urgently needed, both for preventing the seizures themselves as well as negative outcomes and comorbidities associated with chronic epilepsy. While the cerebellum is not traditionally associated with epilepsy or seizures, research over the past decade has outlined the cerebellum as a brain region that is uniquely suited for both therapeutic needs. This review discusses our current understanding of the cerebellum as a key node within seizure networks, capable of both attenuating seizures in several animal models, and conversely, prone to altered structure and function in chronic epilepsy. Critical next steps are to advance therapeutic modulation of the cerebellum more towards translation, and to provide a more comprehensive characterization of how the cerebellum is impacted by chronic epilepsy, in order to subvert negative outcomes.

Mechanisms and Impact of Aminoglycoside-Induced Vestibular Deficits

PURPOSE

Acquired vestibulotoxicity from hospital-prescribed medications such as aminoglycoside antibiotics affects as many as 40,000 people each year in North America. However, there are no current federally approved drugs to prevent or treat the debilitating and permanent loss of vestibular function caused by bactericidal aminoglycoside antibiotics. This review will cover our current understanding of the impact of, and mechanisms underlying, aminoglycoside-induced vestibulotoxicity and highlight the gaps in our knowledge that remain.

CONCLUSIONS

Aminoglycoside-induced vestibular deficits have long-term impacts on patients across the lifespan. Additionally, the prevalence of aminoglycoside-induced vestibulotoxicity appears to be greater than cochleotoxicity. Thus, monitoring for vestibulotoxicity should be independent of auditory monitoring and encompass patients of all ages from young children to older adults before, during, and after aminoglycoside therapy.

Impact and experiences of vestibular disorders and psychological distress: Qualitative findings from patients, family members and healthcare professionals

INTRODUCTION

People with vestibular disorders frequently experience reduced quality of life and challenges with activities of daily living. Anxiety, depression and cognitive problems often co-present with vestibular disorders and can aggravate symptoms and prolong clinical recovery. We aimed to gain in-depth insights into the impact of vestibular disorders and the contribution of psychological factors by exploring multistakeholder perspectives.

METHODS

Semistructured interviews were conducted between October 2021 and March 2022 with 47 participants in the United Kingdom including: 20 patients (age M = 50.45 ± 13.75; 15 females), nine family members (age M = 61.0 ± 14.10; four females), and 18 healthcare professionals. Data were analysed using framework analysis.

RESULTS

Vestibular disorders impact diverse aspects of patients' lives including work, household chores, socialising, and relationships with family and friends. Being unable to engage in valued activities or fulfil social roles contributes to feelings of grief and frustration, affecting identity, confidence, and autonomy. Anxiety and low mood contribute to negative thought processes, avoidance, and social withdrawal, which can impede clinical recovery through reduced activity levels, and end engagement with treatment. Coping strategies were thought to help empower patients to self-manage their symptoms and regain a sense of control, but these require oversight from healthcare providers.

CONCLUSIONS

Daily activity limitations, social participation restrictions, and psychological distress can interact to impact quality of life, sense of self, and clinical recovery amongst people with vestibular disorders. Information and resources could aid societal awareness of the impact of vestibular disorders and help patients and families feel understood. An individualised and comprehensive approach that concurrently addresses mental, physical, social, and occupational needs is likely to be beneficial.

PATIENT OR PUBLIC CONTRIBUTION

Two group meetings were held at the beginning and end of the study with a patient and public involvement network formed of people with vestibular disorders and family members. These individuals commented on the study aims, interview schedule, participant recruitment practices, and interpretation of the themes identified. Two core patient members were involved at all stages of the research. These individuals contributed to the formulation of the interview schedule, development and application of the coding scheme, development and interpretation of themes, and preparation of the final manuscript.

Relationships between sensory integration and the core symptoms of attention-deficit/hyperactivity disorder: the mediating effect of executive function

Attention-deficit/hyperactivity disorder (ADHD) is often accompanied by executive function deficits and functional alterations in sensory integration. The present study aimed to investigate the relationship between ADHD core symptoms, executive function, and sensory integration in children with ADHD. A total of 228 children with ADHD were recruited for our study. The Sensory Organization Test (SOT) and Child Sensory Integration Scale (CSIS) evaluated the sensory integration ability from lab-based and scaled-based perspectives, respectively. Three core components of executive functions (inhibition, working memory, and set-shifting) were assessed using both lab-based tests and the relevant factors from the behavior rating inventory of executive function (BRIEF). Partial correlation analysis was performed to explore the correlation of sensory integration with EF and ADHD core symptoms. Based on the observed significant correlation, bootstrap analyses were further conducted to explore the potential mediating effect of EF on the relationship between sensory integration and ADHD core symptoms. ADHD symptoms and EF were significantly correlated with CSIS scores; no factors were significantly correlated with SOT performance. In detail, the vestibular-balance score was negatively correlated with both inattention and hyperactivity/impulsivity symptoms, while the hyper-sensory and proprioception scores were negatively correlated with only inattention symptoms. For the scaled-based EF, vestibular-balance was negatively correlated with inhibition and working memory, and the hyper-sensory score was negatively correlated with shift factor. No correlation was found for the lab-based EF tests. The subsequent mediation analysis found that inhibition partially mediated the relationship between vestibular balance and hyperactivity/impulsivity symptoms. Working memory completely mediated the relationship between vestibular-balance, hyper-sensory, proprioception, and inattention symptoms. These results were well validated in an independent sample. Our present findings demonstrated that the functional alteration in basic sensory integration might be associated with impairments of executive functions and then lead to the behavioral expression of ADHD. The present findings might provide a new perspective to understand the occurrence of ADHD symptoms and potential precise intervention methods.

Superior semicircular canal dehiscence and subsequent closure induces reversible impaired decision-making

Background

Vestibular loss and dysfunction has been associated with cognitive deficits, decreased spatial navigation, spatial memory, visuospatial ability, attention, executive function, and processing speed among others. Superior semicircular canal dehiscence (SSCD) is a vestibular-cochlear disorder in humans in which a pathological third mobile window of the otic capsule creates changes to the flow of sound pressure energy through the perilymph/endolymph. The primary symptoms include sound-induced dizziness/vertigo, inner ear conductive hearing loss, autophony, headaches, and visual problems; however, individuals also experience measurable deficits in basic decision-making, short-term memory, concentration, spatial cognition, and depression. These suggest central mechanisms of impairment are associated with vestibular disorders; therefore, we directly tested this hypothesis using both an auditory and visual decision-making task of varying difficulty levels in our model of SSCD.

Methods

Adult Mongolian gerbils (n = 33) were trained on one of four versions of a Go-NoGo stimulus presentation rate discrimination task that included standard ("easy") or more difficult ("hard") auditory and visual stimuli. After 10 days of training, preoperative ABR and c+VEMP testing was followed by a surgical fenestration of the left superior semicircular canal. Animals with persistent circling or head tilt were excluded to minimize effects from acute vestibular injury. Testing recommenced at postoperative day 5 and continued through postoperative day 15 at which point final ABR and c+VEMP testing was carried out.

Results

Behavioral data (d-primes) were compared between preoperative performance (training day 8-10) and postoperative days 6-8 and 13-15. Behavioral performance was measured during the peak of SSCD induced ABR and c + VEMP impairment and the return towards baseline as the dehiscence began to resurface by osteoneogenesis. There were significant differences in behavioral performance (d-prime) and its behavioral components (Hits, Misses, False Alarms, and Correct Rejections). These changes were highly correlated with persistent deficits in c + VEMPs at the end of training (postoperative day 15). The controls demonstrated additional learning post procedure that was absent in the SSCD group.

Conclusion

These results suggest that aberrant asymmetric vestibular output results in decision-making impairments in these discrimination tasks and could be associated with the other cognitive impairments resulting from vestibular dysfunction.

Vestibular perceptual testing from lab to clinic: a review

Not all dizziness presents as vertigo, suggesting other perceptual symptoms for individuals with vestibular disease. These non-specific perceptual complaints of dizziness have led to a recent resurgence in literature examining vestibular perceptual testing with the aim to enhance clinical diagnostics and therapeutics. Recent evidence supports incorporating rehabilitation methods to retrain vestibular perception. This review describes the current field of vestibular perceptual testing from scientific laboratory techniques that may not be clinic friendly to some low-tech options that may be more clinic friendly. Limitations are highlighted suggesting directions for additional research.

Visuospatial cognition in acute unilateral peripheral vestibulopathy

Background

This study aims to investigate the presence of spatial cognitive impairments in patients with acute unilateral peripheral vestibulopathy (vestibular neuritis, AUPV) during both the acute phase and the recovery phase.

Methods

A total of 72 AUPV patients (37 with right-sided AUPV and 35 with left-sided AUPV; aged 34-80 years, median 60.5; 39 males, 54.2%) and 35 healthy controls (HCs; aged 43-75 years, median 59; 20 males, 57.1%) participated in the study. Patients underwent comprehensive neurotological assessments, including video-oculography, video head impulse and caloric tests, ocular and cervical vestibular-evoked myogenic potentials, and pure-tone audiometry. Additionally, the Visual Object and Space Perception (VOSP) battery was used to evaluate visuospatial perception, while the Block design test and Corsi block-tapping test assessed visuospatial memory within the first 2 days (acute phase) and 4 weeks after symptom onset (recovery phase).

Results

Although AUPV patients were able to successfully perform visuospatial perception tasks within normal parameters, they demonstrated statistically worse performance on the visuospatial memory tests compared to HCs during the acute phase. When comparing right versus left AUPV groups, significant decreased scores in visuospatial perception and memory were observed in the right AUPV group relative to the left AUPV group. In the recovery phase, patients showed substantial improvements even in these previously diminished visuospatial cognitive performances.

Conclusion

AUPV patients showed different spatial cognition responses, like spatial memory, depending on the affected ear, improving with vestibular compensation over time. We advocate both objective and subjective visuospatial assessments and the development of tests to detect potential cognitive deficits after unilateral vestibular impairments.

Identification of Follow-Up Markers for Rehabilitation Management in Patients with Vestibular Schwannoma

This study delves into the absence of prognostic or predictive markers to guide rehabilitation in patients afflicted with vestibular schwannomas. The objective is to analyze the reweighting of subjective and instrumental indicators following surgery, at 7 days and 1 month postoperatively. This retrospective cohort encompasses 32 patients who underwent unilateral vestibular schwannoma surgery at the Marseille University Hospital between 2014 and 2019. Variations in 54 indicators and their adherence to available norms are calculated. After 1 month, one-third of patients do not regain the norm for all indicators. However, the rates of variation unveil specific responses linked to a preoperative error signal, stemming from years of tumor adaptation. This adaptation is reflected in a postoperative visual or proprioceptive preference for certain patients. Further studies are needed to clarify error signals according to lesion types. The approach based on variations in normative indicators appears relevant for post-surgical monitoring and physiotherapy.

A cross-sectional study on the neurocognitive outcomes in vestibular impaired school-aged children: are they at higher risk for cognitive deficits?

This study aimed to assess if children with a vestibular impairment (VI) are more prone to have neurocognitive deficits compared to typically developing (TD) peers, taking into account important confounding factors with hearing loss being the most important. The neurocognitive performance of fifteen VI children (6-13 years old) was compared to that of an age-, handedness- and sex-weighted group of TD peers (n = 60). Secondly, their performance was also compared to matched groups of TD and hearing impaired (HI) children to evaluate the involvement of HI. The protocol comprises cognitive tests assessing response inhibition, emotion recognition, visuospatial memory, selective and sustained attention, visual memory and visual-motor integration.Based on the results, the VI group had significantly reduced scores on 'social cognition' (p = 0.018), 'executive functions' (p < 0.01), and 'perceptual-motor functioning' (p = 0.020) compared to their TD and HI peers. For the categories 'complex attention' and 'learning and memory' no differences could be observed. Analogous to the findings of previous literature, the symptoms of a VI are often not limited to the primary functions of the system, but also comprise an impact on emotional and cognitive performance. Therefore, more holistic rehabilitation approaches should be encouraged, with a screening and attention for cognitive, emotional and behavioral dysfunctions in the vestibular population. Since this is one of the first studies to investigate the involvement of a VI in a child's cognitive development, these findings support the need for studies further characterizing the impact of a VI, the underlying pathophysiology and the effect of different rehabilitation procedures.

Associations between cognition, anxiety, depression, and residual dizziness in elderly people with BPPV

Objective

To investigate the associations between cognition, anxiety, depression, and residual dizziness after successful repositioning maneuvers in the elderly with benign paroxysmal positional vertigo (BPPV).

Methods

We enrolled 40 elderly patients with BPPV in our outpatient department. We used the Dizziness Handicap Inventory (DHI), Visual Analog Scale (VAS), Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder Questionnaire-7 (GAD-7) to assess the degree of dizziness, anxiety, and depression of participants before repositioning therapy, respectively. At the 1-week follow-up after BPPV treatment, each participant will be reassessed and divided into a group with residual dizziness (RD) and a group without residual dizziness (NRD) based on the follow-up DHI score. The Mini-Mental State Examination (MMSE) evaluated the cognitive function of the participants.

Results

The age, gender, duration of BPPV, and involved semicircular canals in the two groups did not show a significant difference. The RD group scored significantly higher on the DHI (p = 0.006), GAD-7 (p < 0.001), and PHQ-9 (p = 0.002) before the repositioning treatment than the NRD group. The two groups had no significant difference in MMSE score (p = 0.381). Anxiety and depression scores before repositioning treatment significantly and positively correlated with follow-up DHI scores (r = 0.678 and 0.522, respectively), but the MMSE score did not significantly relate to it. The univariate linear regression showed that the DHI (p < 0.001), GAD-7 (p < 0.001), and PHQ-9 (p = 0.002) scores before treatment could predict residual dizziness. The multivariate linear regression showed that GAD-7 before treatment was the only significant predictor of residual dizziness (p < 0.001).

Conclusion

The level of dizziness, anxiety, and depression before treatment can predict residual dizziness after successful repositioning maneuvers in the elderly with BPPV. Anxiety may be the strongest predictor of residual dizziness after successful repositioning treatment in elderly BPPV patients.

Subtle alterations of vestibulomotor functioning in conductive hearing loss

Introduction

Conductive hearing loss (CHL) attenuates the ability to transmit air conducted sounds to the ear. In humans, severe hearing loss is often accompanied by alterations to other neural systems, such as the vestibular system; however, the inter-relations are not well understood. The overall goal of this study was to assess vestibular-related functioning proxies in a rat CHL model.

Methods

Male Sprague-Dawley rats (N=134, 250g, 2months old) were used in a CHL model which produced a >20dB threshold shift induced by tympanic membrane puncture. Auditory brainstem response (ABRs) recordings were used to determine threshold depth at different times before and after CHL. ABR threshold depths were assessed both manually and by an automated ABR machine learning algorithm. Vestibular-related functioning proxy assessment was performed using the rotarod, balance beam, elevator vertical motion (EVM) and Ferris-wheel rotation (FWR) assays.

Results

The Pre-CHL (control) threshold depth was 27.92dB±11.58dB compared to the Post-CHL threshold depth of 50.69dB±13.98dB (mean±SD) across the frequencies tested. The automated ABR machine learning algorithm determined the following threshold depths: Pre-CHL=24.3dB, Post-CHL same day=56dB, Post-CHL 7 days=41.16dB, and Post-CHL 1 month=32.5dB across the frequencies assessed (1, 2, 4, 8, 16, and 32kHz). Rotarod assessment of motor function was not significantly different between pre and post-CHL (~1week) rats for time duration (sec) or speed (RPM), albeit the former had a small effect size difference. Balance beam time to transverse was significantly longer for post-CHL rats, likely indicating a change in motor coordination. Further, failure to cross was only noted for CHL rats. The defection count was significantly reduced for CHL rats compared to control rats following FWR, but not EVM. The total distance traveled during open-field examination after EVM was significantly different between control and CHL rats, but not for FWR. The EVM is associated with linear acceleration (acting in the vertical plane: up-down) stimulating the saccule, while the FWR is associated with angular acceleration (centrifugal rotation about a circular axis) stimulating both otolith organs and semicircular canals; therefore, the difference in results could reflect the specific vestibular-organ functional role.

Discussion

Less movement (EVM) and increase time to transverse (balance beam) may be associated with anxiety and alterations to defecation patterns (FWR) may result from autonomic disturbances due to the impact of hearing loss. In this regard, vestibulomotor deficits resulting in changes in balance and motion could be attributed to comodulation of auditory and vestibular functioning. Future studies should manipulate vestibular functioning directly in rats with CHL.

P300 Event-Related Potential Predicts Cognitive Dysfunction in Patients with Vestibular Disorders

OBJECTIVE

Our aim was to determine the correlation between cognitive impairment and P300 event-related potential (ERP) in older adults with vertigo and imbalance, which further provides a reference for clinical diagnosis and patients' rehabilitation.

METHODS

A total of 79 older adult patients with vertigo and imbalance in our outpatient department from January 2022 to December 2022 were selected and divided into the mild group (n = 20), moderate group (n = 39), and severe group (n = 20) according to the Dizziness Handicap Inventory (DHI). The auditory P300 component of event-related potentials (ERPs), Generalized Anxiety Disorder Questionnaire-7 (GAD-7), Patient Health Questionnaire-9 (PHQ-9), and Mini-Mental State Examination (MMSE) were used to evaluate depression, anxiety, and cognitive function in these patients, respectively.

RESULTS

The P300 latencies of the different severity groups were 292 ± 10 ms, 301 ± 8 ms, and 328 ± 5 ms, respectively, and the differences were statistically significant (p = 0.010). The P300 amplitudes of the different severity groups were 14.4 ± 2.6 μV, 3.9 ± 0.8 μV, and 5.1 ± 1.4 μV, respectively, and the differences were also statistically significant (p = 0.004). There was no statistically significant difference in the DHI evaluation or VAS visual simulation scoring between the two groups (p = 0.625, and 0.878, respectively). Compared with the short-course group, the long-course group showed prolonged P300 latency and decreased amplitude, higher scores in PHQ-9 and GAD-7, and lower scores in MMSE, and all the differences were statistically significant (p = 0.013, 0.021, 0.006, 0.004, and 0.018, respectively).

CONCLUSION

Older patients with more severe symptoms of vertigo and imbalance are at higher risk of developing abnormal cognitive function. The P300 can be used as an objective neurophysiological test for the assessment of cognitive function relevant to elderly patients with vertigo and imbalance.

Interpreting the meaning of changes in hippocampal volume associated with vestibular loss

Many studies have documented cognitive deficits, especially spatial cognitive deficits, in patients with some form of vestibular loss. Almost 20 years ago, hippocampal (HPC) atrophy was reported to be correlated with spatial memory deficits in such patients and the idea has gradually emerged that HPC atrophy may be causally responsible for the cognitive deficits. However, the results of studies of HPC volume following vestibular loss have not always been consistent, and a number of studies have reported no evidence of HPC atrophy. This paper argues that HPC atrophy, if it does occur following vestibular loss, may not be directly, causally responsible for the cognitive deficits, and that it is more likely that rapid functional changes in the HPC are responsible, due to the interruption of the transmission of vestibular information to the HPC. The argument presented here rests on 3 tranches of evidence: (1) Cognitive deficits have been observed in humans even in the absence of HPC atrophy; (2) HPC atrophy has not been reported in animal studies following vestibular loss, despite cognitive deficits; and (3) Animal studies have shown that the interruption of the transmission of vestibular information to the HPC has immediate consequences for HPC place cells, far too quickly to be explained by HPC atrophy. It is possible that HPC atrophy, when it does occur, is related to the longer-term consquences of living with vestibular loss, which are likely to increase circulating cortisol.

Elucidating the role of muscarinic acetylcholine receptor (mAChR) signaling in efferent mediated responses of vestibular afferents in mammals

The peripheral vestibular system detects head position and movement through activation of vestibular hair cells (HCs) in vestibular end organs. HCs transmit this information to the CNS by way of primary vestibular afferent neurons. The CNS, in turn, modulates HCs and afferents via the efferent vestibular system (EVS) through activation of cholinergic signaling mechanisms. In mice, we previously demonstrated that activation of muscarinic acetylcholine receptors (mAChRs), during EVS stimulation, gives rise to a slow excitation that takes seconds to peak and tens of seconds to decay back to baseline. This slow excitation is mimicked by muscarine and ablated by the non-selective mAChR blockers scopolamine, atropine, and glycopyrrolate. While five distinct mAChRs (M1-M5) exist, the subtype(s) driving EVS-mediated slow excitation remain unidentified and details on how these mAChRs alter vestibular function is not well understood. The objective of this study is to characterize which mAChR subtypes drive the EVS-mediated slow excitation, and how their activation impacts vestibular physiology and behavior. In C57Bl/6J mice, M3mAChR antagonists were more potent at blocking slow excitation than M1mAChR antagonists, while M2/M4 blockers were ineffective. While unchanged in M2/M4mAChR double KO mice, EVS-mediated slow excitation in M3 mAChR-KO animals were reduced or absent in irregular afferents but appeared unchanged in regular afferents. In agreement, vestibular sensory-evoked potentials (VsEP), known to be predominantly generated from irregular afferents, were significantly less enhanced by mAChR activation in M3mAChR-KO mice compared to controls. Finally, M3mAChR-KO mice display distinct behavioral phenotypes in open field activity, and thermal profiles, and balance beam and forced swim test. M3mAChRs mediate efferent-mediated slow excitation in irregular afferents, while M1mAChRs may drive the same process in regular afferents.

Association of Bilateral Vestibulopathy With and Without Hearing Loss With Cognitive-Motor Interference

Importance

The past years, evidence suggested that the primary symptoms traditionally associated with bilateral vestibulopathy (BV) do not represent the full picture of this patient population. Recent literature also demonstrated cognitive impairment. However, although multitasking and dual-tasking are widely present in everyday activities, most of these studies assessed cognitive function only in single-task conditions.

Objective

To uncover the association of BV with and without hearing loss with cognitive and motor performance and cognitive-motor interference.

Design, Setting, and Participants

This prospective case-control study assessed persons with an isolated BV and persons with BV and a concomitant hearing loss compared with a healthy control group. Data were analyzed in December 2022. The study was conducted at Ghent University (Ghent, Belgium). Data collection took place between March 26, 2021, and November 29, 2022.

Main Outcomes and Measures

All participants completed the 2BALANCE dual-task protocol, comprising a static and a dynamic motor task that was combined with 5 visual cognitive tasks. These cognitive tasks assessed mental rotation, visuospatial memory, working memory, response inhibition (executive function), and processing speed. All cognitive tasks were performed in a single-task condition (while seated) and in a dual-task condition (combined with a static and a dynamic motor task). The static task comprised balancing on a force platform with foam pad, and the dynamic task comprised walking at a self-selected speed on the GAITRite Walkway. Both motor tasks were performed in the single-task and dual-task condition.

Results

Nineteen persons with BV and hearing loss (mean [SD] age, 56.70 [10.12] years; 10 women [52.6%]), 22 persons with an isolated BV (mean [SD] age, 53.66 [13.35] years; 7 women [31.8%]), and 28 healthy control participants were included (mean [SD] age, 53.73 [12.77] years; 12 women [42.9%]). Both patient groups had mental rotation and working memory impairment in a single-task condition and slower processing speed when walking (ie, during the dynamic dual-task condition). Additionally, the patient group with hearing loss had impaired visuospatial memory and executive function deficits in single-task and dual-task conditions, while this could only be elicited when performing a motor task in persons with isolated BV (ie, when dual-tasking).

Conclusion and Relevance

The findings of this case-control study suggest an association between vestibular function and cognitive and motor performance, even greater in persons with a concomitant hearing loss than in persons with an isolated BV.

The interplay between cognition, functional and dual-task gait in persons with a vestibular disorder versus healthy controls

Close links exist between vestibular function and cognition. Dual-task (DT) tests may have ecological validity to assess the impact of daily life cognitive-motor demands in people with vestibular dysfunction (PwVD), functional gait and falls risk. The present paper aimed at building predictive models for functional gait under DT conditions, while clarifying the impact of vestibular dysfunction, individual characteristics, varying task types and motor-cognitive demands. Case-controlled observational study with 39 PwVD and 62 healthy participants. The Functional Gait Assessment (FGA), with and without an additional motor, numeracy, or literacy task, was completed. Multiple linear regression was used to fit models to predict FGA under single and DT performance. Dual task cost (DTC, %) was calculated to assess DT interference on FGA performance using the equation: 100*(single task score-dual task score)/single-task score. Following Bonferroni corrections for multiple comparisons (corrected alpha level of 0.003), PwVD had poorer performance than controls for all FGA conditions (p < 0.001), motor (- 3.94%; p = 0.002) and numeracy (- 22.77%; p = 0.001) DTCs and spatial working memory (p = 0.002). The literacy DTC was marginally significant (- 19.39% p = 0.005). FGA single and DT motor, numeracy, and literacy models explained 76%, 76%, 66% and 67% of the variance respectively for PwVD. Sustained attention, visual memory and sex contributed to all models; short-term visual recognition memory, balance confidence, and migraine contributed to some models. Cognitive performance is impaired in PwVD. Motor, numeracy and literacy tasks impair functional gait performance. Cognitive assessment and FGA with a numeracy or literacy cognitive component should be included within assessment protocols and considered in the provision of targeted interventions for PwVD.

Daily artificial gravity is associated with greater neural efficiency during sensorimotor adaptation

Altered vestibular signaling and body unloading in microgravity results in sensory reweighting and adaptation. Microgravity effects are well-replicated in head-down tilt bed rest (HDBR). Artificial gravity (AG) is a potential countermeasure to mitigate the effects of microgravity on human physiology and performance. We examined the effectiveness of daily AG for mitigating brain and/or behavioral changes in 60 days of HDBR. One group received AG for 30 minutes daily (AG; n = 16) and a control group spent the same time in HDBR but received no AG (CTRL; n = 8). All participants performed a sensorimotor adaptation task five times during fMRI scanning: twice prior to HDBR, twice during HDBR, and once following HDBR. The AG group showed similar behavioral adaptation effects compared with the CTRLs. We identified decreased brain activation in the AG group from pre to late HDBR in the cerebellum for the task baseline portion and in the thalamus, calcarine, cuneus, premotor cortices, and superior frontal gyrus in the AG group during the early adaptation phase. The two groups also exhibited differential brain-behavior correlations. Together, these results suggest that AG may result in a reduced recruitment of brain activity for basic motor processes and sensorimotor adaptation. These effects may stem from the somatosensory and vestibular stimulation that occur with AG.

The cerebellum's understated role and influences in the epilepsies

Approximately 1 in 26 people will develop epilepsy in their lifetime, but current treatment options leave as many as half of all epilepsy patients with uncontrolled seizures. In addition to the burden of the seizures themselves, chronic epilepsy can be associated with cognitive deficits, structural changes, and devastating negative outcomes such as sudden unexpected death in epilepsy (SUDEP). Thus, major challenges in epilepsy research surround the need to both develop new therapeutic targets for intervention as well as shed light on the mechanisms by which chronic epilepsy can lead to comorbidities and negative outcomes. Despite not being traditionally associated with epilepsy or seizures, the cerebellum has emerged as not only a brain region that can serve as an important target for seizure control, but one that may also be profoundly impacted by chronic epilepsy. Here, we discuss targeting the cerebellum for potential therapeutic intervention and discuss pathway insights gained from recent optogenetic studies. We then review observations of cerebellar alterations during seizures and in chronic epilepsy, as well as the potential for the cerebellum to be a seizure focus. Cerebellar alterations in epilepsy may be critical to patient outcomes, highlighting the need for a more comprehensive understanding and appreciation of the cerebellum in the epilepsies.

Vestibular prosthesis: from basic research to clinics

Balance disorders are highly prevalent worldwide, causing substantial disability with high personal and socioeconomic impact. The prognosis in many of these patients is poor, and rehabilitation programs provide little help in many cases. This medical problem can be addressed using microelectronics by combining the highly successful cochlear implant experience to produce a vestibular prosthesis, using the technical advances in micro gyroscopes and micro accelerometers, which are the electronic equivalents of the semicircular canals (SCC) and the otolithic organs. Reaching this technological milestone fostered the possibility of using these electronic devices to substitute the vestibular function, mainly for visual stability and posture, in case of damage to the vestibular endorgans. The development of implantable and non-implantable devices showed diverse outcomes when considering the integrity of the vestibular pathways, the device parameters (current intensity, impedance, and waveform), and the targeted physiological function (balance and gaze). In this review, we will examine the development and testing of various prototypes of the vestibular implant (VI). The insight raised by examining the state-of-the-art vestibular prosthesis will facilitate the development of new device-development strategies and discuss the feasibility of complex combinations of implantable devices for disorders that directly affect balance and motor performance.

Analysis of cognitive function and its related factors after treatment in Meniere’s disease

A growing body of research recently suggested the association between vestibular dysfunction and cognitive impairment. Meniere’s disease (MD), a common clinical vestibular disorder, is usually accompanied by hearing loss and emotional stress, both of which may mediate the relationship between vestibule dysfunction and cognition. It is currently unknown whether the cognitive decline in MD patients could improve through treatment and how it relates to multiple clinical characteristics, particularly the severity of vertigo. Therefore, in the present study, the MD patients were followed up for 3, 6, and 12 months after treatment, and the cognitive functions, vertigo symptoms, and related physical, functional, and emotional effects of the patients were assessed using the Montreal Cognitive Assessment (MoCA) and Dizziness Handicap Inventory (DHI), aiming to explore the change in cognition before and after therapy and the correlation with various clinical features. It was found that cognitive decline in MD patients compared to healthy controls before therapy. Importantly, this cognitive impairment could improve after effective therapy, which was related to the severity of vertigo, especially in functional and physical impacts. Our results support the view that vestibular dysfunction is a potentially modifiable risk factor for cognitive decline.

Vestibulo-spatial navigation: pathways and sense of direction

Aims of the present article are: 1) assessing vestibular contribution to spatial navigation, 2) exploring how age, global positioning systems (GPS) use, and vestibular navigation contribute to subjective sense of direction (SOD), 3) evaluating vestibular navigation in patients with lesions of the vestibular-cerebellum (patients with downbeat nystagmus, DBN) that could inform on the signals carried by vestibulo-cerebellar-cortical pathways. We applied two navigation tasks on a rotating chair in the dark: return-to-start (RTS), where subjects drive the chair back to the origin after discrete angular displacement stimuli (path reversal), and complete-the-circle (CTC) where subjects drive the chair on, all the way round to origin (path completion). We examined 24 normal controls (20-83 yr), five patients with DBN (62-77 yr) and, as proof of principle, two patients with early dementia (84 and 76 yr). We found a relationship between SOD, assessed by Santa Barbara Sense of Direction Scale, and subject's age (positive), GPS use (negative), and CTC-vestibular-navigation-task (positive). Age-related decline in vestibular navigation was observed with the RTS task but not with the complex CTC task. Vestibular navigation was normal in patients with vestibulo-cerebellar dysfunction but abnormal, particularly CTC, in the demented patients. We conclude that vestibular navigation skills contribute to the build-up of our SOD. Unexpectedly, perceived SOD in the elderly is not inferior, possibly explained by increased GPS use by the young. Preserved vestibular navigation in cerebellar patients suggests that ascending vestibular-cerebellar projections carry velocity (not position) signals. The abnormalities in the cognitively impaired patients suggest that their vestibulo-spatial navigation is disrupted.NEW & NOTEWORTHY Our subjective sense-of-direction is influenced by how good we are at spatial navigation using vestibular cues. Global positioning systems (GPS) may inhibit sense of direction. Increased use of GPS by the young may explain why the elderly's sense of direction is not worse than the young's. Patients with vestibulo-cerebellar dysfunction (downbeat nystagmus syndrome) display normal vestibular navigation, suggesting that ascending vestibulo-cerebellar-cortical pathways carry velocity rather than position signals. Pilot data indicate that dementia disrupts vestibular navigation.

Relationship between hippocampal subfields volume and balance function in healthy older adults

BACKGROUND

The volume of the hippocampus and its subfields is known to be affected by aging, disease, and physical training. In regard to training, the differential effects of aerobic exercise and dance training on the subfield volume suggest that balance function may be involved. However, the relationship between balance function and the volume of the hippocampus and its subfields remains unclear.

METHODS

Subjects were 30 cognitively intact individuals. They underwent balance tests, cognitive tests and structural MRI scans. The balance index measured was the index of postural stability (IPS) under a visual block condition and/or a proprioception block condition. MR images acquired using a 3-tesla system and three-dimensional T1-weighted images were segmented in the hippocampal subfield with Freesurfer 6.0.0. The relationship between the IPS and hippocampal volume was evaluated.

RESULTS

A positive correlation was observed only between the IPS closed eyes/soft surface condition and whole hippocampal volume ratio. In the subfields, positive correlations were found between the IPS and molecular layer of the hippocampus, granule cell layer of the dentate gyrus (GC-ML-DG), and cornu ammonis areas (CA)3 and CA4. These correlations were stronger under the closed eyes/soft surface condition than under the other conditions.

CONCLUSIONS

A correlation between balance function and the volume of the hippocampus and subfields was found in healthy elderly subjects. The balance function may be involved in the volume of the whole hippocampus and specific subfields. The IPS closed eyes/soft surface condition is considered to reflect vestibular function. Thus, IPS may be useful in evaluations of the relationship between the vestibular system function via the hippocampus and balance.

Timely insertion of AMPA receptor in developing vestibular circuits is required for manifestation of righting reflexes and effective navigation

Vestibular information processed first by the brainstem vestibular nucleus (VN), and further by cerebellum and thalamus, underlies diverse brain function. These include the righting reflexes and spatial cognitive behaviour. While the cerebellar and thalamic circuits that decode vestibular information are known, the importance of VN neurons and the temporal requirements for their maturation that allow developmental consolidation of the aforementioned circuits remains unclear. We show that timely unsilencing of glutamatergic circuits in the VN by NMDA receptor-mediated insertion of AMPAR receptor type 1 (GluA1) subunits is critical for maturation of VN and successful consolidation of higher circuits that process vestibular information. Delayed unsilencing of NMDA receptor-only synapses of neonatal VN neurons permanently decreased their functional connectivity with inferior olive circuits. This was accompanied by delayed pruning of the inferior olive inputs to Purkinje cells and permanent reduction in their plasticity. These derangements led to deficits in associated vestibular righting reflexes and motor co-ordination during voluntary movement. Vestibular-dependent recruitment of thalamic neurons was similarly reduced, resulting in permanently decreased efficiency of spatial navigation. The findings thus show that well-choreographed maturation of the nascent vestibular circuitry is prerequisite for functional integration of vestibular signals into ascending pathways for diverse vestibular-related behaviours.

Time perception in astronauts on board the International Space Station

We perceive the environment through an elaborate mental representation based on a constant integration of sensory inputs, knowledge, and expectations. Previous studies of astronauts on board the International Space Station have shown that the mental representation of space, such as the perception of object size, distance, and depth, is altered in orbit. Because the mental representations of space and time have some overlap in neural networks, we hypothesized that perception of time would also be affected by spaceflight. Ten astronauts were tested before, during, and after a 6-8-month spaceflight. Temporal tasks included judging when one minute had passed and how long it had been since the start of the workday, lunch, docking of a vehicle, and a spacewalk. Compared to pre-flight estimates, there is a relative overestimation for the 1-min interval during the flight and a relative underestimation of intervals of hours in duration. However, the astronauts quite accurately estimated the number of days since vehicle dockings and spacewalks. Prolonged isolation in confined areas, stress related to workload, and high-performance expectations are potential factors contributing to altered time perception of daily events. However, reduced vestibular stimulations and slower motions in weightlessness, as well as constant references to their timeline and work schedule could also account for the change in the estimation of time by the astronauts in space.

Research progress on vestibular dysfunction and visual-spatial cognition in patients with Alzheimer's disease

Alzheimer's disease (AD) or vestibular dysfunction may impair visual-spatial cognitive function. Recent studies have shown that vestibular dysfunction is increasingly common in patients with AD, and patients with AD with vestibular impairment show more visual-spatial cognitive impairment. By exploring the relationship and interaction mechanism among the vestibular system, visual-spatial cognitive ability, and AD, this study aims to provide new insights for the screening, diagnosis, and rehabilitation intervention of patients with AD. In contrast, routine vestibular function tests are particularly important for understanding the vestibular function of patients with AD. The efficacy of vestibular function test as a tool for the early screening of patients with AD must also be further studied. Through the visual-spatial cognitive ability test, the "spatial impairment" subtype of patients with AD, which may be significant in caring for patients with AD to prevent loss and falls, can also be determined. Additionally, the visual-spatial cognitive ability test has great benefits in preventing and alleviating cognitive decline of patients with AD.

The little brain and the seahorse: Cerebellar-hippocampal interactions

There is a growing appreciation for the cerebellum beyond its role in motor function and accumulating evidence that the cerebellum and hippocampus interact across a range of brain states and behaviors. Acute and chronic manipulations, simultaneous recordings, and imaging studies together indicate coordinated coactivation and a bidirectional functional connectivity relevant for various physiological functions, including spatiotemporal processing. This bidirectional functional connectivity is likely supported by multiple circuit paths. It is also important in temporal lobe epilepsy: the cerebellum is impacted by seizures and epilepsy, and modulation of cerebellar circuitry can be an effective strategy to inhibit hippocampal seizures. This review highlights some of the recent key hippobellum literature.

Spatial orientation, postural control and the vestibular system in healthy elderly and Alzheimer's dementia

Background

While extensive research has been advancing our understanding of the spatial and postural decline in healthy elderly (HE) and Alzheimer's disease (AD), much less is known about how the vestibular system contributes to the spatial and postural processing in these two populations. This is especially relevant during turning movements in the dark, such as while walking in our garden or at home at night, where the vestibular signal becomes central. As the prevention of falls and disorientation are of serious concern for the medical service, more vestibular-driven knowledge is necessary to decrease the burden for HE and AD patients with vestibular disabilities.

Overview of the article

The review briefly presents the current "non-vestibular based" knowledge (i.e. knowledge based on research that does not mention the "vestibular system" as a contributor or does not investigate its effects) about spatial navigation and postural control during normal healthy ageing and AD pathology. Then, it concentrates on the critical sense of the vestibular system and explores the current expertise about the aspects of spatial orientation and postural control from a vestibular system point of view. The norm is set by first looking at how healthy elderly change with age with respect to their vestibular-guided navigation and balance, followed by the AD patients and the difficulties they experience in maintaining their balance or during navigation.

Conclusion

Vestibular spatial and vestibular postural deficits present a considerable disadvantage and are felt not only on a physical but also on a psychological level by all those affected. Still, there is a clear need for more (central) vestibular-driven spatial and postural knowledge in healthy and pathological ageing, which can better facilitate our understanding of the aetiology of these dysfunctions. A possible change can start with the more frequent implementation of the "vestibular system examination/rehabilitation/therapy" in the clinic, which can then lead to an improvement of future prognostication and disease outcome for the patients.

Impact of cognitive capacity on physical performance in chronic obstructive pulmonary disease patients: A scoping review

Background: Chronic obstructive pulmonary disease (COPD) is often accompanied by impaired cognitive and physical function. However, the role of cognitive function on motor control and purposeful movement is not well studied. The aim of the review was to determine the impact of cognition on physical performance in COPD. Methods: Scoping review methods were performed including searches of the databases: MEDLINE, EMBASE, Cochrane Systematic Reviews, Cochrane (CENTRAL), APA PsycINFO, and CINAHL. Two reviewers independently assessed articles for inclusion, data abstraction, and quality assessment. Results: Of 11,252 identified articles, 44 met the inclusion criteria. The review included 5743 individuals with COPD (68% male) with the forced expiratory volume in one second range of 24-69% predicted. Cognitive scores correlated with strength, balance, and hand dexterity, while 6-min walk distance (n = 9) was usually similar among COPD patients with and without cognitive impairment. In 2 reports, regression analyses showed that delayed recall and the trail making test were associated with balance and handgrip strength, respectively. Dual task studies (n = 5) reported impaired balance or gait in COPD patients compared to healthy adults. Cognitive or physical Interventions (n = 20) showed variable improvements in cognition and exercise capacity. Conclusions: Cognition in COPD appears to be more related to balance, hand, and dual task function, than exercise capacity.

Vestibular cognition assessment system: Tablet-based computerized visuospatial abilities test battery

Introduction

The vestibular system is anatomically connected to extensive regions of the cerebral cortex, hippocampus, and amygdala. However, studies focusing on the impact of vestibular impairment on visuospatial cognition ability are limited. This study aimed to develop a mobile tablet-based vestibular cognitive assessment system (VCAS), enhance the dynamic and three-dimensional (3D) nature of the test conditions, and comprehensively evaluate the visuospatial cognitive ability of patients with vestibular dysfunction.

Materials and methods

First, the VCAS assessment dimensions (spatial memory, spatial navigation, and mental rotation) and test content (weeding, maze, card rotation, and 3D driving tests) were determined based on expert interviews. Second, VCAS was developed based on Unity3D, using the C# language and ILruntime hot update framework development technology, combined with the A* algorithm, prime tree algorithm, and dynamic route rendering. Further, the online test was built using relevant game business logic. Finally, healthy controls (HC) and 78 patients with vertigo (VP) were recruited for the VCAS test. The validity of VCAS was verified using the test results of random controls.

Results

In the weeding test, the HC group had a significantly longer span and faster velocity backward than did the VP group. In the 12 × 12 maze, statistically significant differences in step and time were observed between the two groups, with VP taking longer time and more steps. In the mental rotation task, no significant difference was observed between the two groups. Similarly, no significant difference was found in the performance of the two groups on maps 2, 3, and 4 in the 3D driving task.

Discussion

Thus, impaired visuospatial cognition in patients with vestibular dysfunction is primarily related to spatial memory and navigation. VCAS is a clinically applicable visuospatial cognitive ability test for VP.

[Bilateral peripheral vestibulopathy]

Bilateral vestibulopathy is a relatively widespread and at the same time rarely diagnosed cause of chronic postural instability. Numerous toxic factors, dysmetabolic, autoimmune and neurodegenerative processes can lead to this condition. The main clinical manifestations of bilateral vestibulopathy are balance disorders and visual disturbances (oscillopsia), which can significantly increase the risks of falls in such patients. In addition, cognitive and affective disorders, which also reduce the quality of life in patients with bilateral vestibulopathy, have been described and actively studied in recent years. The diagnosis of bilateral vestibulopathy is based on the results of a clinical neurovestibular study, including a dynamic visual acuity test and a Halmagyi test. A video head impulse test, a bithermal caloric test and a sinusoidal rotation test are used as instrumental methods confirming the dysfunction of the peripheral vestibular system. However, they are still not widespread in neurological practice. Treatment of bilateral vestibulopathy is reduced to vestibular rehabilitation. Encouraging results have been obtained in a number of studies using galvanic vestibular stimulation and the use of vestibular implants. In addition, cognitive rehabilitation methods are currently being developed, which presumably can also improve compensation for bilateral vestibular loss.

Effects of Gaze Stabilization Exercises on Gait, Plantar Pressure, and Balance Function in Post-Stroke Patients: A Randomized Controlled Trial

This study aims to explore the effects of gaze stabilization exercises (GSEs) on gait, plantar pressure, and balance function in post-stroke patients (≤6 months). Forty post-stroke patients were randomly divided into an experimental group (n = 20) and a control group (n = 20). The experimental group performed GSEs combined with physical therapy, while the control group only performed physical therapy, once a day, 5 days a week, for 4 weeks. The Berg Balance Scale (BBS) was used to test the balance function and the risk of falling, which was the primary outcome. The Timed Up and Go test (TUGT) evaluated the walking ability and the fall risk. The envelope ellipse area and the plantar pressure proportion of the affected side were used to measure the patient’s supporting capacity and stability in static standing. The anterior−posterior center of pressure displacement velocity was used to test the weight-shifting capacity. Compared to the control group, the swing phase of the affected side, swing phase’s absolute symmetric index, envelope ellipse area when eyes closed, and TUGT of the experimental group had significantly decreased after GSEs (p < 0.05); the BBS scores, TUGT, the anterior−posterior COP displacement velocity, and the plantar pressure proportion of the affected side had significantly increased after 4 weeks of training (p < 0.05). In conclusion, GSEs combined with physical therapy can improve the gait and balance function of people following stroke. Furthermore, it can enhance the weight-shifting and one-leg standing capacity of the affected side, thus reducing the risk of falling.