Visuo-vestibular contributions to anxiety and fear

Modality-specific effects of threat on self-motion perception

BACKGROUND

Threat and individual differences in threat-processing bias perception of stimuli in the environment. Yet, their effect on perception of one's own (body-based) self-motion in space is unknown. Here, we tested the effects of threat on self-motion perception using a multisensory motion simulator with concurrent threatening or neutral auditory stimuli.

RESULTS

Strikingly, threat had opposite effects on vestibular and visual self-motion perception, leading to overestimation of vestibular, but underestimation of visual self-motions. Trait anxiety tended to be associated with an enhanced effect of threat on estimates of self-motion for both modalities.

CONCLUSIONS

Enhanced vestibular perception under threat might stem from shared neural substrates with emotional processing, whereas diminished visual self-motion perception may indicate that a threatening stimulus diverts attention away from optic flow integration. Thus, threat induces modality-specific biases in everyday experiences of self-motion.

Post-stroke dizziness, depression and anxiety

OBJECTIVE

Vestibular and psychiatric disorders are very closely related. Previous research shows that the discomfort and dysfunction caused by dizziness in patients can affect psychological processes, leading to anxiety and depression, and the irritation of anxiety and depression can aggravate the discomfort of dizziness. But the causal relationship between dizziness in the recovery period of stroke and Post-stroke depression (PSD) / Post-stroke anxiety (PSA) is not clear. Identifying the causal relationship between them can enable us to conduct more targeted treatments.

METHODS

We review the epidemiology and relationship of dizziness, anxiety, and depression, along with the related neuroanatomical basis. We also review the pathophysiology of dizziness after stroke, vestibular function of patients experiencing dizziness, and the causes and mechanisms of PSD and PSA. We attempt to explore the possible relationship between post-stroke dizziness and PSD and PSA.

CONCLUSION

The treatment approach for post-stroke dizziness depends on its underlying cause. If the dizziness is a result of PSD and PSA, addressing these psychological factors may alleviate the dizziness. This can be achieved through targeted treatments for PSD and PSA, such as psychotherapy, antidepressants, or anxiolytics, which could indirectly improve dizziness symptoms. Conversely, if PSA and PSD are secondary to vestibular dysfunction caused by stroke, a thorough vestibular function assessment is crucial. Identifying the extent of vestibular impairment allows for tailored interventions. These could include vestibular rehabilitation therapy and medication aimed at vestibular restoration. By improving vestibular function, secondary symptoms like anxiety and depression may also be mitigated.

Spatial anxiety contributes to the dizziness-related handicap of adults with peripheral vestibular disease

In subjects with peripheral vestibular disease and controls, we assessed: 1. The relationship between spatial anxiety and perceived stress, and 2. The combined contribution of spatial anxiety, spatial perspective-taking, and individual cofactors to dizziness-related handicap. 309 adults participated in the study (153 with and 156 without peripheral vestibular disease), including patients with bilateral vestibular deficiency, unilateral deficiency (evolution <3 or ≥3 months), Meniere's disease, and Benign Paroxysmal Positional Vertigo. Assessments included: general health, personal habits, spatial anxiety (3-domains), perceived stress, spatial perspective-taking, dizziness-related handicap (3-domains), unsteadiness, sleep quality, motion sickness susceptibility, trait anxiety/depression, state anxiety, depersonalization/derealization. After bivariate analyses, analysis of covariance was performed (p ≤ 0.05). Spatial anxiety was related to unsteadiness and perceived stress, with an inverse relationship with trait anxiety (ANCoVA, adjusted R2 = 0.27-0.30, F = 17.945-20.086, p < 0.00001). Variability on perspective-taking was related to vestibular disease, trait and state anxiety, motion sickness susceptibility, and age (ANCoVA, adjusted R2 = 0.18, F = 5.834, p < 0.00001). All domains of spatial anxiety contributed to the Physical domain of dizziness-related handicap, while the Navigation domain contributed to the Functional domain of handicap. Handicap variability was also related to unsteadiness, spatial perspective-taking, quality of sleep, and trait anxiety/depression (ANCoVA, adjusted R2 = 0.66, F = 39.07, p < 0.00001). Spatial anxiety is related to perceived stress in adults both with and without vestibular disease, subjects with trait anxiety rated lower on spatial anxiety. State anxiety and acute stress could be helpful for recovery after peripheral vestibular lesion. Spatial anxiety and perspective-taking contribute to the Physical and Functional domains of dizziness-related handicap, possibly because it discourages behavior beneficial to adaptation.

The Cerebellum's Role in Affective Disorders: The Onset of Its Social Dimension

Major Depressive Disorder (MDD) and Bipolar Disorder (BD) are the most frequent mental disorders whose indeterminate etiopathogenesis spurs to explore new aetiologic scenarios. In light of the neuropsychiatric symptoms characterizing Cerebellar Cognitive Affective Syndrome (CCAS), the objective of this narrative review is to analyze the involvement of the cerebellum (Cbm) in the onset of these conditions. It aims at detecting the repercussions of the Cbm activities on mood disorders based on its functional subdivision in vestibulocerebellum (vCbm), pontocerebellum (pCbm) and spinocerebellum (sCbm). Despite the Cbm having been, for decades, associated with somato-motor functions, the described intercellular pathways, without forgiving the molecular impairment and the alteration in the volumetric relationships, make the Cbm a new important therapeutic target for MDD and BD. Given that numerous studies have showed its activation during mnestic activities and socio-emotional events, this review highlights in the Cbm, in which the altered external space perception (vCbm) is strictly linked to the cognitive-limbic Cbm (pCbm and sCbm), a crucial role in the MDD and BD pathogenesis. Finally, by the analysis of the cerebellar activity, this study aims at underlying not only the Cbm involvement in affective disorders, but also its role in social relationship building.

Balance Rehabilitation with Peripheral Visual Stimulation in Patients with Panic Disorder and Agoraphobia: An Open-Pilot Intervention Study

Given the involvement of balance system abnormalities in the pathophysiology of panic disorder and agoraphobia (PD-AG), we evaluated initial evidence for feasibility, acceptability, and potential clinical usefulness of 10 sessions of balance rehabilitation with peripheral visual stimulation (BR-PVS) in an open-pilot 5-week intervention study including six outpatients with PD-AG who presented residual agoraphobia after selective serotonin reuptake inhibitor (SSRI) treatment and cognitive-behavioral therapy, dizziness in daily life, and peripheral visual hypersensitivity measured by posturography. Before and after BR-PVS, patients underwent posturography, otovestibular examination (no patients presented peripheral vestibular abnormalities), and panic-agoraphobic symptom and dizziness evaluation with psychometric tools. After BR-PVS, four patients achieved postural control normalization measured by posturography, and one patient exhibited a favorable trend of improvement. Overall, panic-agoraphobic symptoms and dizziness decreased, even though to a lesser extent in one patient who had not completed the rehabilitation sessions. The study presented reasonable levels of feasibility and acceptability. These findings suggest that balance evaluation should be considered in patients with PD-AGO presenting residual agoraphobia and that BR-PVS might be an adjunctive therapeutic option worth being tested in larger randomized controlled studies.

An ethologically based view into human fear

The quality of the defensive response to a threat depends on the elements that trigger the fear response. The current classification system of phobias does not account for this. Here, we analyze the fear-eliciting elements and discern the different types of fears that originate from them. We propose Pain, Disgust, Vasovagal response, Visual-vestibular and postural interactions, Movement and Speed, Distance and Size, Low and mid-level visual features, Smell, and Territory and social status. We subdivide phobias according to the fear-eliciting elements most frequently triggered by them and their impact on behavior. We discuss the implications of a clinical conceptualization of phobias in humans by reconsidering the current nosology. This conceptualization will facilitate finding etiological factors in defensive behavior expression, fine-tuning exposure techniques, and challenging preconceived notions of preparedness. This approach to phobias leads to surprising discoveries and shows how specific responses bear little relation to the interpretation we might later give to them. Dividing fears into their potentially fear-eliciting elements can also help in applying the research principles formulated by the Research Domain Criteria initiative.

The role of self-reported fear and disgust in the activation of behavioral harm avoidance related to medical settings

INTRODUCTION

Although adaptive defense mechanisms are useful in helping us avoid getting injured, they are also triggered by medical interventions and procedures, when avoidance is harmful. A body of previous results showed that both fear and disgust play a pivotal role in medical avoidance. However, the underlying mechanisms are not fully understood. Thus, the aim of the current study was to examine the effects of experience, perceived control, and pain on medical avoidance with disgust and fear as mediating factors from an evolutionary perspective.

METHODS

We assessed participants' knowledge of and experience with medical procedures, former negative medical experiences, and health-related information; their life history strategy variation; pain-related fear and anxiety of medical procedures; perceived control over emotional reactions and extreme threats; disgust sensitivity; blood-injury-injection phobia and medical treatment avoidance.

RESULTS

We found that more knowledge, experience, and a slower life strategy were linked to a greater level of perceived control and attenuated emotional reactions. Further, better ability to control affective and stress reactions to negative experiences was linked to reduced disgust and fear of pain, and thus might mitigate the level of perceived threat, and diminish fear and disgust reactions.

DISCUSSION

More knowledge and experiences, better perceived control together with reduced disgust and fear of pain can decrease the probability of avoiding medical situations. Implications to treatment are discussed. Results support the importance of targeting these contextual factors in prevention to increase the likelihood of people attending regular screenings or seeking medical care when needed.

The Role of the Cerebellar and Vestibular Networks in Anxiety Disorders and Depression: the Internal Model Hypothesis

Clinical data and animal studies confirmed that the cerebellum and the vestibular system are involved in emotions. Nowadays, no real consensus has really emerged to explain the clinical symptoms in humans and behavioral deficits in the animal models. We envisage here that the cerebellum and the vestibular system play complementary roles in emotional reactivity. The cerebellum integrates a large variety of exteroceptive and proprioceptive information necessary to elaborate and to update the internal model: in emotion, as in motor processes, it helps our body and self to adapt to the environment, and to anticipate any changes in such environment in order to produce a time-adapted response. The vestibular system provides relevant environmental stimuli (i.e., gravity, self-position, and movement) and is involved in self-perception. Consequently, cerebellar or vestibular disorders could generate « internal fake news» (due to lack or false sensory information and/or integration) that could, in turn, generate potential internal model deficiencies. In this case, the alterations provoke false anticipation of motor command and external sensory feedback, associated with unsuited behaviors. As a result, the individual becomes progressively unable to cope with the environmental solicitation. We postulate that chronically unsuited, and potentially inefficient, behavioral and visceral responses to environmental solicitations lead to stressful situations. Furthermore, this inability to adapt to the context of the situation generates chronic anxiety which could precede depressive states.

The Walls Are Closing In: Postural Responses to a Virtual Reality Claustrophobic Simulation

Background: Changes in the visual environment and thereby, the spatial orientation, can induce postural instability leading to falls. Virtual reality (VR) has been used to expose individuals to virtual environments (VE) that increase postural threats. Claustrophobia is an anxiety disorder categorized under situational phobias and can induce such postural threats in a VE. Purpose: The purpose of the study was to investigate if VR-generated claustrophobic simulation has any impact on postural threats that might lead to postural instability. Methods: Thirty healthy men and women (age: 20.7 ± 1.2 years; height: 166.5 ± 7.3 cm; mass: 71.7 ± 16.2 kg) were tested for postural stability while standing on a force platform, upon exposure to five different testing trials, including a normal stance (NoVR), in stationary VE (VR), and three consecutive, randomly initiated, unexpected claustrophobia trials (VR CP1, VR CP2, VR CP3). The claustrophobia trials involved all four walls closing in towards the center of the room. Center of pressure (COP)-derived postural sway variables were analyzed with a one-way repeated measures analysis of variance at an alpha level of 0.05. Results: Significant main effect differences existed in all but one dependent COP-derived postural sway variables, at p < 0.05. Post-hoc pairwise comparisons with a Bonferroni correction revealed that, predominantly, postural sway excursions were significantly lower in claustrophobia trials compared to NoVR and VR, but only accomplished with significantly increased sway velocity. Conclusion: The VR CP trials induced lower postural sway magnitude, but with increased velocity, suggesting a bracing and co-contraction strategy when exposed to virtual claustrophobic postural threats. Additionally, postural sway decreased with subsequent claustrophobia trials, suggesting potential motor learning effects. Findings from the study offer insights to postural control behavior under virtual claustrophobic simulations and can aid in VR exposure therapy for claustrophobia.

Stabilometric Biofeedback Training in Cognitive and Affective Function Improvement. Contribution of the Russian Scientific School. Part II

This review is the second part of the critical analysis of recent papers of Russian and other authors devoted to the study of the stabilometric parameters in postural control biofeedback training and rehabilitation, associated with psychological functions. The review presents the studies of postural control features in chronic pain syndrome, chronic fatigue syndrome, Parkinson’s disease, multiple sclerosis, and depression. The leading role of Russian researchers in the development and application of stabilometric biofeedback in the training of optimal functioning, rehabilitation, and correction of neurological disorders is noted. The paradigm of stabilometric biofeedback training of the cognitive and affective functions is offered.

Fear inoculation among snake experts

BACKGROUND

Fear acquisition of certain stimuli, such as snakes, is thought to be rapid, resistant to extinction, and easily transferable onto other similar objects. It has been hypothesized that due to increased survival chances, preparedness to instantly acquire fear towards evolutionary threats has been hardwired into neural pathways of the primate brain. Here, we compare participants' fear of snakes according to experience; from those who often deal with snakes and even suffer snakebites to those unfamiliar with snakes.

METHODS

The Snake Questionnaire-12 (SNAQ-12) and Specific Phobia Questionnaire (SPQ) were administered to three groups of participants with a different level of experience with snakes and snakebites: 1) snake experts, 2) firefighters, and 3) college students.

RESULTS

This study shows that individuals more experienced with snakes demonstrate lower fear. Moreover, participants who have suffered a snakebite (either venomous or not) score lower on fear of snakes (SNAQ-12), but not of all other potentially phobic stimuli (SPQ).

CONCLUSIONS

Our results suggest that a harmless benign exposure might immunize people to highly biologically prepared fears of evolutionary threats, such as snakes.

Anxiety and Motion Sickness Susceptibility May Influence the Ability to Update Orientation in the Horizontal Plane of Healthy Subjects

Few studies have evaluated the influence of idiosyncrasies that may influence the judgment of space-time orientation after passive motion. We designed a study to assess the influence of anxiety/depression (which may distort time perception), motion sickness susceptibility (which has been related to vestibular function, disorientation, and to the velocity storage mechanism), and personal habits on the ability to update orientation, after passive rotations in the horizontal plane. Eighty-one healthy adults (22–64 years old) accepted to participate. After they completed an in-house general health/habits questionnaire, the short Motion Sickness Susceptibility Questionnaire, the Hospital Anxiety and Depression Scale (HADS), the Pittsburgh Sleep Quality Index, and the short International Physical Activity Questionnaire, they were exposed to 10 manually driven whole-body rotations (45°, 90°, or 135°), in a square room, with distinctive features on the walls, while seated in the normal upright position, unrestrained, with noise-attenuating headphones and blindfolded. After each rotation, they were asked to report which wall or corner they were facing. To calculate the error of estimation of orientation, the perceived rotation was subtracted from the actual rotation. Multivariate analysis showed that the estimation error of the first rotation was strongly related to the results of the orientation test. The magnitude and the frequency of estimation errors of orientation were independently related to HADS anxiety sub-score and to adult motion sickness susceptibility, with no influence of age, but a contribution from the interaction of the use of spectacles, the quality of sleep and sex. The results suggest that idiosyncrasies may contribute to the space-time estimation of passive self-motion, with influence from emotional traits, adult motion sickness susceptibility, experience, and possibly sleep quality.

Motion Sickness Lessons from the Southern Ocean

BACKGROUND: The objectives were to assess the prevalence, severity, and medication taken, and to look for predictive factors in order to better identify characteristics of passengers at risk of motion sickness during transport from Hobart in Tasmania to the French polar stations in Antarctica. METHODS: There were 239 passengers who were surveyed over 4 yr with 4 round trips per year using the Motion Sickness Susceptibility Questionnaire (MSSQ), Simulator Sickness Questionnaire (SSQ), state-trait anxiety test (STAI-Trait and STAI-State), and general parameters (age, gender, number of trips, jet-lag, direction of the trip), medication, calculation of the distance of each passengers cabin to the center of gravity (CoG). RESULTS: While the passengers had a low intrinsic sensitivity to motion sickness (MSSQ), 94 reported at least one SSQ symptom of motion sickness, and 38 vomited. Five associated factors were discovered: greater initial sensitivity (MSSQ), anticipation of being ill, younger age, higher level of anxiety at midtrip, and greater distance from the CoG. Of the passengers, there were 54 who took anti-motion sickness medication at different times of the trip, however, these passengers experienced more nausea. This could be due to self-selection since they were more sensitive to motion sickness. CONCLUSION: We identified three predictive factors of motion sickness (greater intrinsic susceptibility, younger age, and greater cabin distance from the CoG). For preventive purposes, two associated factors of MS (anticipation of being ill, MSSQ score) were determined to classify three groups of risk of MS to improve passenger care during the trip. Besnard S, Bois J, Hitier M, Vogt J, Laforet P, Golding JF. Motion sickness lessons from the Southern Ocean. Aerosp Med Hum Perform. 2021; 92(9):720727.

The Neuropsychology of Dizziness and Related Disorders

There is a reciprocal relationship between vestibular and neuropsychological disorders. People with vertigo and dizziness are at higher risk of various psychiatric disorders, particularly anxiety, depression, and panic disorder. On the other hand, people with mood disorders are at higher risk of experiencing vertigo and dizziness. Vestibular information plays a crucial role in cognitive processes, especially visuo-spatial abilities. Consequently, vestibular disorders (both peripheral and central) often result in visuo-spatial deficits. In addition, lesions of the cortical and subcortical components of the vestibular system result in disorders of higher vestibular function, such as hemispatial neglect, pusher syndrome, and topographagnosia.

Clinical predictors of cybersickness in virtual reality (VR) among highly stressed people

The use of virtual reality (VR) in the treatment of psychiatric disorders is increasing, and cybersickness has emerged as an important obstacle to overcome. However, the clinical factors affecting cybersickness are still not well understood. In this study, we investigated clinical predictors and adaptation effect of cybersickness during VR application in highly stressed people. Eighty-three healthy adult participants with high stress level were recruited. At baseline, we conducted psychiatric, ophthalmologic, and otologic evaluations and extracted physiological parameters. We divided the participants into two groups according to the order of exposure to VR videos with different degrees of shaking and repetitively administered the Simulator Sickness Questionnaire (SSQ) and the Fast Motion sickness Scale (FMS). There was no significant difference in changes in the SSQ or the FMS between groups. The 40–59 years age group showed a greater increase in FMS compared to the 19–39 years age group. Smoking was negatively associated with cybersickness, and a high Positive Affect and Negative Affect Schedule score was positively associated with cybersickness. In conclusion, changing the intensity of shaking in VR did not affect cybersickness. While smoking was a protective factor, more expression of affect was a risk factor for cybersickness.

Effects of acquired vestibular pathology on the organization of mouse exploratory behavior

Rodent open field behavior is highly organized and occurs spontaneously in novel environments. This organization is disrupted in mice with vestibular pathology, suggesting vestibular signals provide important contributions to this behavior. A caveat to this interpretation is that previous studies have investigated open field behavior in adult mice with congenital vestibular dysfunction, and the observed deficits may have resulted from developmental changes instead of the lack of vestibular signals. To determine which aspects of open field behavior depend specifically on vestibular signals, mouse movement organization was examined under dark and light conditions at two time points, 1 and 2 months, after bilateral chemical labyrinthectomy. Our results show that acquired vestibular damage selectively disrupted the organization of open field behavior. Access to visual environmental cues attenuated, but did not eliminate, these significant group differences. Improvement in movement organization from the first to the second testing session was limited to progression path circuity. These observations provide evidence for the role of the vestibular system in maintaining spatial orientation and establishes a foundation to investigate neuroplasticity in brain systems that process self-movement information.

Representation of Fear of Heights by Basolateral Amygdala Neurons

Fear of heights is evolutionarily important for survival, yet it is unclear how and which brain regions process such height threats. Given the importance of the basolateral amygdala (BLA) in mediating both learned and innate fear, we investigated how BLA neurons may respond to high-place exposure in freely behaving male mice. We found that a discrete set of BLA neurons exhibited robust firing increases when the mouse was either exploring or placed on a high place, accompanied by increased heart rate and freezing. Importantly, these high-place fear neurons were only activated under height threats, but not looming, acoustic startle, predatory odor, or mild anxiogenic conditions. Furthermore, after a fear-conditioning procedure, these high-place fear neurons developed conditioned responses to the context, but not the cue, indicating a convergence in processing of dangerous/risky contextual information. Our results provide insights into the neuronal representation of the fear of heights and may have implications for the treatment of excessive fear disorders.SIGNIFICANCE STATEMENT Fear can be innate or learned, as innate fear does not require any associative learning or experiences. Previous research mainly focused on studying the neural mechanism of learned fear, often using an associative conditioning procedure such as pairing a tone with a footshock. Only recently scientists started to investigate the neural circuits of innate fear, including the fear of predator odors and looming visual threats; however, how the brain processes the innate fear of heights is unclear. Here we provide direct evidence that the basolateral amygdala (BLA) is involved in representing the fear of heights. A subpopulation of BLA neurons exhibits a selective response to height and contextual threats, but not to other fear-related sensory or anxiogenic stimuli.

'Excess anxiety' and 'less anxiety': both depend on vestibular function

PURPOSE OF REVIEW

To present evidence of a functional interrelation between the vestibular and the anxiety systems based on a complex reciprocally organized network. The review focuses on the differential effects of various vestibular disorders, on psychiatric comorbidity, and on anxiety related to vertigo.

RECENT FINDINGS

Episodic vertigo syndromes such as vestibular migraine, vestibular paroxysmia, and Menière's disease are associated with a significant increase of psychiatric comorbidity, in particular anxiety/phobic disorders and depression. Chronic unilateral and bilateral vestibulopathy (BVP) do not exhibit a higher than normal psychiatric comorbidity. Anxiety related to the vertigo symptoms is also increased in episodic structural vestibular disorders but not in patients with chronic unilateral or bilateral loss of vestibular function. The lack of vertigo-related anxiety in BVP is a novel finding. Several studies have revealed special features related to anxiety in patients suffering from BVP: despite objectively impaired postural balance with frequent falls, they usually do not complain about fear of falling; they do not report an increased susceptibility to fear of heights; they do not have an increased psychiatric comorbidity; and they do not report increased anxiety related to the perceived vertigo. Subtle or moderate vestibular stimulation (by galvanic currents or use of a swing) may have beneficial effects on stress or mood state in healthy adults, and promote sleep in humans and rodents. The intimate structural and functional linkage of the vestibular and anxiety systems includes numerous nuclei, provincial and connector hubs, the thalamocortical network, and the cerebellum with many neural transmitter systems.

SUMMARY

The different involvement of emotional processes and anxiety - to the extent of 'excess anxiety' or 'less anxiety' - in structural vestibular disorders may be due to the specific dysfunction and whether the system activity is excited or diminished. Both psychiatric comorbidity and vertigo-related anxiety are maximal with excitation and minimal with loss of peripheral vestibular function.

Acrophobia Quantified by EEG Based on CNN Incorporating Granger Causality

The aim of this study is to quantify acrophobia and provide safety advices for high-altitude workers. Considering that acrophobia is a fuzzy quantity that cannot be accurately evaluated by conventional detection methods, we propose a comprehensive solution to quantify acrophobia. Specifically, this study simulates a virtual reality environment called High-altitude Plank Walking Challenge, which provides a safe and controlled experimental environment for subjects. Besides, a method named Granger Causality Convolutional Neural Network (GCCNN) combining convolutional neural network and Granger causality functional brain network is proposed to analyze the subjects' noninvasive scalp EEG signals. Here, the GCCNN method is used to distinguish the subjects with severe acrophobia, moderate acrophobia, and no acrophobia in a three-class classification task or no acrophobia and acrophobia in a two-class classification task. Compared with the mainstream methods, the GCCNN method achieves better classification performance, with an accuracy of 98.74% for the two-class classification task (no acrophobia versus acrophobia) and of 98.47% for the three-class classification task (no acrophobia versus moderate acrophobia versus severe acrophobia). Consequently, our proposed GCCNN method can provide more accurate quantitative results than the comparative methods, making it to be more competitive in further practical applications.

Impact of respiratory protective devices on respiration: Implications for panic vulnerability during the COVID-19 pandemic

BACKGROUND

The wearing of respiratory protective devices (RPDs) correctly and continually in situations where people are at risk of respiratory infections is crucial for infection prevention. Certain people are poorly compliant with RPDs due to RPD-related annoyance, including respiratory discomfort. We hypothesized that individuals vulnerable to panic attacks are included in this group. No published studies on this topic are available. The evidence for our hypothesis was reviewed in this study as a starting point for future research.

METHODS

We selected a set of experimental studies that measured the respiratory physiological burden in RPD wearers through objective and validated methods. We conducted a bibliographic search of publications in the PubMed database (January 2000-May 2020) to identify representative studies that may be of interest for panic respiratory pathophysiology.

RESULTS

Five studies were included. Wearing RPDs exerted significant respiratory effects, including increased breathing resistance, CO₂ rebreathing due to CO₂ accumulation in the RPD cavity, and decreased inhaled O₂ concentration. We discussed the implications of these effects on the respiratory pathophysiology of panic.

LIMITATIONS

Most studies had a small sample size, with a preponderance of young participants. Different methodologies were used across the studies. Furthermore, differences in physical responses between wearing RPDs in experimental settings or daily life cannot be excluded.

CONCLUSIONS

This research supports the idea that panic-prone individuals may be at higher risk of respiratory discomfort when wearing RPDs, thereby reducing their tolerance for these devices. Strategies to decrease discomfort should be identified to overcome the risk of poor compliance.

Chloroquine kills hair cells in zebrafish lateral line and murine cochlear cultures: Implications for ototoxicity

Hearing and balance deficits have been reported during and following treatment with the antimalarial drug chloroquine. However, experimental work examining the direct actions of chloroquine on mechanoreceptive hair cells in common experimental models is lacking. This study examines the effects of chloroquine on hair cells using two common experimental models: the zebrafish lateral line and neonatal mouse cochlear cultures. Zebrafish larvae were exposed to varying concentrations of chloroquine phosphate or hydroxychloroquine for 1 h or 24 h, and hair cells assessed by antibody staining. A significant, dose-dependent reduction in the number of surviving hair cells was seen across conditions for both exposure periods. Hydroxychloroquine showed similar toxicity. In mouse cochlear cultures, chloroquine damage was specific to outer hair cells in tissue from the cochlear basal turn, consistent with susceptibility to other ototoxic agents. These findings suggest a need for future studies employing hearing and balance monitoring during exposure to chloroquine and related compounds, particularly with interest in these compounds as therapeutics against viral infections including coronavirus.

Anxiety spectrum disorders are common in patients with orthostatic tremor

Background

Orthostatic Tremor (OT) is a rare movement disorder characterized by a sensation of unsteadiness while standing and associated with high frequency tremors. Patients with OT commonly report a fear of falling and significant limitations in everyday activities. The prevalence of psychiatric comorbidities in OT patients has not been well-studied.

Methods

Subjects were evaluated by trained psychiatry researchers using the Mini International Neuropsychiatric Interview (M.I.N.I.). The M.I.N.I is a validated screening tool for psychiatric disorders. A standardized history covering previous psychiatric symptoms and illnesses was also obtained.

Results

29 OT subjects were evaluated. The mean age was 67.7 years with female preponderance (89.3%). The average disease symptom duration was 18.2 years. 58.6% of the subjects had seen a mental health professional during the course of their OT illness. 24.1% of the subjects had a past history of depression, and 10.3% reported a family history of any psychiatric condition. 37.9% of the subjects screened positive for agoraphobia. Two of 29 subjects (6.9%) were classified as having a current major depressive episode and one subject (3.4%) was at risk for suicide.

Conclusions

Psychiatric comorbidities are highly prevalent in OT patients, especially anxiety-spectrum disorders. Further studies are needed to understand if psychiatric disorders appear as a secondary response to the patient's symptoms, or are a primary non-motor manifestation of OT.

Vestibular neurons with direct projections to the solitary nucleus in the rat

Anterograde and retrograde tract tracing were combined with neurotransmitter and modulator immunolabeling to identify the chemical anatomy of vestibular nuclear neurons with direct projections to the solitary nucleus in rats. Direct, sparsely branched but highly varicose axonal projections from neurons in the caudal vestibular nuclei to the solitary nucleus were observed. The vestibular neurons giving rise to these projections were predominantly located in ipsilateral medial vestibular nucleus. The cell bodies were intensely glutamate immunofluorescent, and their axonal processes contained vesicular glutamate transporter 2, supporting the interpretation that the cells utilize glutamate for neurotransmission. The glutamate-immunofluorescent, retrogradely filled vestibular cells also contained the neuromodulator imidazoleacetic acid ribotide, which is an endogenous CNS ligand that participates in blood pressure regulation. The vestibulo-solitary neurons were encapsulated by axo-somatic GABAergic terminals, suggesting that they are under tight inhibitory control. The results establish a chemoanatomical basis for transient vestibular activation of the output pathways from the caudal and intermediate regions of the solitary nucleus. In this way, changes in static head position and movement of the head in space may directly influence heart rate, blood pressure, respiration, as well as gastrointestinal motility. This would provide one anatomical explanation for the synchronous heart rate and blood pressure responses observed after peripheral vestibular activation, as well as disorders ranging from neurogenic orthostatic hypotension, postural orthostatic tachycardia syndrome, and vasovagal syncope to the nausea and vomiting associated with motion sickness.NEW & NOTEWORTHY Vestibular neurons with direct projections to the solitary nucleus utilize glutamate for neurotransmission, modulated by imidazoleacetic acid ribotide. This is the first direct demonstration of the chemical neuroanatomy of the vestibulo-solitary pathway.

Toward a personalized therapy for panic disorder: preliminary considerations from a work in progress

Although several treatment options for panic disorder (PD) are available, the best intervention for each individual patient remains uncertain and the use of a more personalized therapeutic approach in PD is required. In clinical practice, clinicians combine general scientific information and personal experience in the decision-making process to choose a tailored treatment for each patient. In this sense, clinicians already use a somehow personalized medicine strategy. However, the influence of their interpretative personal models may lead to bias related to personal convictions, not sufficiently grounded on scientific evidence. Hence, an effort to give some advice based on the science of personalized medicine could have positive effects on clinicians' decisions. Based on a narrative review of meta-analyses, systematic reviews, and experimental studies, we proposed a first-step attempt of evidence-based personalized therapy for PD. We focused on some phenomenological profiles, encompassing symptoms during/outside panic attacks, related patterns of physiological functions, and some aspects of physical health, which might be worth considering when developing treatment plans for patients with PD. We considered respiratory, cardiac, vestibular, and derealization/depersonalization profiles, with related implications for treatment. Given the extensiveness of the topic, we considered only medications and some somatic interventions. Our proposal should be considered neither exhaustive nor conclusive, as it is meant as a very preliminary step toward a future, robust evidence-based personalized therapy for PD. Clearly much more work is needed to achieve this goal, and recent technological advances, such as wearable devices, big data platforms, and the application of machine learning techniques, may help obtain reliable findings. We believe that combining the efforts of different research groups in this work in progress can lead to largely shared conclusions in the near future.

Acute findings in an acquired neurosensory dysfunction

Background

In the Autumn of 2016, diplomatic personnel residing in Havana began to present with symptoms of dizziness, ear pain, and tinnitus that emerged after perception of high frequency noise and/or a pressure sensation. Understanding the acute symptoms of this disorder is important for better defining the disorder and developing optimal diagnostic, preventive, and treatment algorithms.

Objectives

To define the presenting symptoms in a cohort of patients in the acute time period after perceiving a noise/pressure exposure in Havana.

Design/Settings/Participants

Review of 25 symptomatic individuals who reported a localized sensation of noise/pressure and 10 asymptomatic individuals (roommates of those affected) who did not experience the sound/pressure.

Results

Immediately after the exposure, the majority of individuals reported intense ear pain in one or both ears and experienced tinnitus. All of the individuals noticed unsteadiness and features of cognitive impairment. On presentation to our center, dizziness (92%) and cognitive complaints (56%) were the most common symptoms. Formal testing revealed that 100% of individuals had an otolithic abnormality and evidence of cognitive dysfunction.

Conclusion and Relevance

This study focuses on the acute presentation of a phenomenon in which symptoms emerge after perception of a localized noise/pressure and in which the acute symptomology includes the universal nature of vestibular injuries and select cognitive deficits. The findings presented in this acute group of patients begin to provide a better picture of the initial injury pattern seen after this exposure and may allow for more accurate diagnosis of this disorder in future cases.

Level of Evidence

Retrospective review

Integrating Hypnosis with Other Therapies for Treating Specific Phobias: A Case Series

There is a high prevalence of anxiety disorders including specific phobias and panic disorder in the United States and Europe. A variety of therapeutic modalities including pharmacotherapy, cognitive behavioral therapy, systematic desensitization, hypnosis, in vivo exposure, and virtual reality exposure therapy have been applied. No one modality has been entirely successful. There has been only a limited attempt to combine psychological therapies in the treatment of specific phobias and panic disorder and what has been done has been primarily with systematic desensitization or cognitive behavioral therapy along with hypnotherapy. I present two cases of multiple specific phobias that were successfully treated with hypnotherapy combined with virtual reality exposure therapy or in vivo exposure therapy. The rationale for this integrative therapy and the neurobiological constructs are considered.

Is panic disorder a disorder of physical fitness? A heuristic proposal

Currently, panic disorder (PD) is considered a mental disorder based on the assumptions that panic attacks (PAs) are “false alarms” that arise from abnormally sensitive defense systems in the central nervous system and that PD is treated with therapies specifically acting on anxiety or fear mechanisms. This article aims to propose an alternative perspective based on the results of some experimental studies. Our heuristic proposal suggests not only that PD may be a mental disorder but also that patients with PD have real abnormal body functioning, mainly involving cardiorespiratory and balance systems, leading to a decline in global physical fitness. PAs, as well as physical symptoms or discomfort in some environmental situations, may be “real alarms” signaling that the adaptability resources of an organism are insufficient to respond appropriately to some internal or external changes, thus representing the transient conscious awareness of an imbalance in body functioning. The antipanic properties of several modern treatments for PD may include their beneficial effects on body functions. Although anxiety or fear mechanisms are evidently involved in PD, we hypothesize that a reduction of physical fitness is the “primum movens” of PD, while anxiety or fear is induced and sustained by repeated signals of impaired body functioning. We propose considering panic in a broader perspective that offers a central role to the body and to contemplate the possible role of somatic treatments in PD.

Management of Treatment-Resistant Panic Disorder

PURPOSE OF REVIEW

Purpose of Review Management of treatment-resistant (TR) panic disorder (PD) is an unresolved issue. In this paper, we provide a brief summary of previous findings, an updated (2015-2017) systematic review of pharmacological/non-pharmacological studies, and our personal perspective on this topic.

RECENT FINDINGS

Recent Findings We found a very limited number of recent findings. Quetiapine extended-release augmentation has not been found to be beneficial, in comparison to placebo, in non-responders to previously recommended pharmacotherapy. In non-responders to cognitive behavioral therapy (CBT), switching to paroxetine/citalopram has been found to be more effective than continuing CBT. Acceptance and commitment therapy (ACT) has shown some improvement in patients' resistance to previous psychological/pharmacological interventions compared with a waiting-list condition.

SUMMARY

Summary Previous and recent findings regarding the treatment of TR PD suffer from several methodological limitations. Available studies provide insufficient evidence to support the use of medications alternative to the recommended medications; the efficacy of ACT needs confirmation with more rigorous methodology. Prolonged pharmacotherapy may produce significant improvement in patients with unsatisfactory response to short-term pharmacotherapy, while switching to pharmacotherapy may help non-responders to CBT. We discuss our personal perspective on the definition of "treatment resistance" as it relates to PD and provide personalized intervention strategies to increase favorable clinical outcomes based on our clinical expertise and review of experimental studies on the pathophysiology of PD.

Psychological Support for Young Adults with Down Syndrome: Dohsa-Hou Program for Maladaptive Behaviors and Internalizing Problems

Psychological and psychiatric dysfunction is a major problem in a substantial proportion of young adults with Down syndrome. Some patients develop psychiatric issues, such as depressive, obsessive-compulsive, or psychotic-like disorders, in their late adolescence or young adulthood. Furthermore, these individuals may experience moderate to severe emotional and psychological distress. Development of a psychosocial treatment to address these issues is needed in addition to psychotropic medication. The current study reports two cases of young adults with Down syndrome, who presented psychiatric symptoms and marked disruption in their daily lives. These individuals participated in a Dohsa-hou treatment program. Following treatment, adaptive levels, maladaptive behaviors, and internalizing problems were evaluated by the Vineland Adaptive Behavior Scales-II. Participants showed improvement in maladaptive behaviors and internalizing problems; however, improvement in these areas may be influenced by baseline severity of the problems. This case report suggests that Dohsa-hou could be an effective therapeutic approach for maladaptive and internalizing problems in adults with Down syndrome.

Neuroticism modulates brain visuo-vestibular and anxiety systems during a virtual rollercoaster task

Different lines of research suggest that anxiety‐related personality traits may influence the visual and vestibular control of balance, although the brain mechanisms underlying this effect remain unclear. To our knowledge, this is the first functional magnetic resonance imaging (fMRI) study that investigates how individual differences in neuroticism and introversion, two key personality traits linked to anxiety, modulate brain regional responses and functional connectivity patterns during a fMRI task simulating self‐motion. Twenty‐four healthy individuals with variable levels of neuroticism and introversion underwent fMRI while performing a virtual reality rollercoaster task that included two main types of trials: (1) trials simulating downward or upward self‐motion (vertical motion), and (2) trials simulating self‐motion in horizontal planes (horizontal motion). Regional brain activity and functional connectivity patterns when comparing vertical versus horizontal motion trials were correlated with personality traits of the Five Factor Model (i.e., neuroticism, extraversion‐introversion, openness, agreeableness, and conscientiousness). When comparing vertical to horizontal motion trials, we found a positive correlation between neuroticism scores and regional activity in the left parieto‐insular vestibular cortex (PIVC). For the same contrast, increased functional connectivity between the left PIVC and right amygdala was also detected as a function of higher neuroticism scores. Together, these findings provide new evidence that individual differences in personality traits linked to anxiety are significantly associated with changes in the activity and functional connectivity patterns within visuo‐vestibular and anxiety‐related systems during simulated vertical self‐motion. Hum Brain Mapp 38:715–726, 2017. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Evidence for a Role of Orexin/Hypocretin System in Vestibular Lesion-Induced Locomotor Abnormalities in Rats

Vestibular damage can induce locomotor abnormalities in both animals and humans. Rodents with bilateral vestibular loss showed vestibular deficits syndrome such as circling, opisthotonus as well as locomotor and exploratory hyperactivity. Previous studies have investigated the changes in the dopamine system after vestibular loss, but the results are inconsistent and inconclusive. Numerous evidences indicate that the orexin system is implicated in central motor control. We hypothesized that orexin may be potentially involved in vestibular loss-induced motor disorders. In this study, we examined the effects of arsanilate- or 3,3′-iminodipropionitrile (IDPN)-induced vestibular lesion (AVL or IVL) on the orexin-A (OXA) labeling in rat hypothalamus using immunohistochemistry. The vestibular lesion-induced locomotor abnormalities were recorded and verified using a histamine H4 receptor antagonist JNJ7777120 (20 mg/kg, i.p.). The effects of the orexin receptor type 1 antagonist SB334867 (16 μg, i.c.v.) on these behavior responses were also investigated. At 72 h post-AVL and IVL, animals exhibited vestibular deficit syndrome and locomotor hyperactivity in the home cages. These responses were significantly alleviated by JNJ7777120 which also eliminated AVL-induced increases in exploratory behavior in an open field. The numbers of OXA-labeled neurons in the hypothalamus were significantly increased in the AVL animals at 72 h post-AVL and in the IVL animals at 24, 48, and 72 h post-IVL. SB334867 significantly attenuated the vestibular deficit syndrome and locomotor hyperactivity at 72 h post-AVL and IVL. It also decreased exploratory behavior in the AVL animals. These results suggested that the alteration of OXA expression might contribute to locomotor abnormalities after acute vestibular lesion. The orexin receptors might be the potential therapeutic targets for vestibular disorders.

What is nausea? A historical analysis of changing views

The connotation of "nausea" has changed across several millennia. The medical term 'nausea' is derived from the classical Greek terms ναυτια and ναυσια, which designated the signs and symptoms of seasickness. In classical texts, nausea referred to a wide range of perceptions and actions, including lethargy and disengagement, headache (migraine), and anorexia, with an awareness that vomiting was imminent only when the condition was severe. However, some recent articles have limited the definition to the sensations that immediately precede emesis. Defining nausea is complicated by the fact that it has many triggers, and can build-up slowly or rapidly, such that the prodromal signs and symptoms can vary. In particular, disengagement responses referred to as the "sopite syndrome" are typically present only when emetic stimuli are moderately provocative, and do not quickly culminate in vomiting or withdrawing from the triggering event. This review considers how the definition of "nausea" has evolved over time, and summarizes the physiological changes that occur prior to vomiting that may be indicative of nausea. Also described are differences in the perception of nausea, as well as the accompanying physiological responses, that occur with varying stimuli. This information is synthesized to provide an operational definition of nausea.

Neurotransmitters in the vestibular system

Neuronal networks that are linked to the peripheral vestibular system contribute to gravitoinertial sensation, balance control, eye movement control, and autonomic function. Ascending connections to the limbic system and cerebral cortex are also important for motion perception and threat recognition, and play a role in comorbid balance and anxiety disorders. The vestibular system also shows remarkable plasticity, termed vestibular compensation. Activity in these networks is regulated by an interaction between: (1) intrinsic neurotransmitters of the inner ear, vestibular nerve, and vestibular nuclei; (2) neurotransmitters associated with thalamocortical and limbic pathways that receive projections originating in the vestibular nuclei; and (3) locus coeruleus and raphe (serotonergic and nonserotonergic) projections that influence the latter components. Because the ascending vestibular interoceptive and thalamocortical pathways include networks that influence a broad range of stress responses (endocrine and autonomic), memory consolidation, and cognitive functions, common transmitter substrates provide a basis for understanding features of acute and chronic vestibular disorders.

Human upright posture control models based on multisensory inputs; in fast and slow dynamics

Posture control to maintain an upright stance is one of the most important and basic requirements in the daily life of humans. The sensory inputs involved in posture control include visual and vestibular inputs, as well as proprioceptive and tactile somatosensory inputs. These multisensory inputs are integrated to represent the body state (body schema); this is then utilized in the brain to generate the motion. Changes in the multisensory inputs result in postural alterations (fast dynamics), as well as long-term alterations in multisensory integration and posture control itself (slow dynamics). In this review, we discuss the fast and slow dynamics, with a focus on multisensory integration including an introduction of our study to investigate "internal force control" with multisensory integration-evoked posture alteration. We found that the study of the slow dynamics is lagging compared to that of fast dynamics, such that our understanding of long-term alterations is insufficient to reveal the underlying mechanisms and to propose suitable models. Additional studies investigating slow dynamics are required to expand our knowledge of this area, which would support the physical training and rehabilitation of elderly and impaired persons.

A multi-pathway hypothesis for human visual fear signaling

A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the "low road" and "high road," which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested.

Differential Gene Expression Profile in the Rat Caudal Vestibular Nucleus is Associated with Individual Differences in Motion Sickness Susceptibility

OBJECTIVE

To identify differentially expressed genes associated with motion sickness (MS) susceptibility in the rat caudal vestibular nucleus.

METHODS

We identified MS susceptible (MSS) and insusceptible (inMSS) rats by quantifying rotation-induced MS symptoms: defecation and spontaneous locomotion activity. Microarray analysis was used to screen differentially expressed genes in the caudal vestibular nucleus (CVN) after rotation. Plasma stress hormones were identified by radioimmunoassay. Candidate genes were selected by bioinformatics analysis and the microarray results were verified by real-time quantitative-PCR (RT-qPCR) methods. By using Elvax implantation, receptor antagonists or recombinant adenovirus targeting the candidate genes were applied to the CVN to evaluate their contribution to MS susceptibility variability. Validity of gene expression manipulation was verified by RT-qPCR and western blot analysis.

RESULTS

A total of 304 transcripts were differentially expressed in the MSS group compared with the inMSS group. RT-qPCR analysis verified the expression pattern of candidate genes, including nicotinic cholinergic receptor (nAchR) α3 subunit, 5-hydroxytryptamine receptor 4 (5-HT4R), tachykinin neurokinin-1 (NK1R), γ-aminobutyric acid A receptor (GABAAR) α6 subunit, olfactory receptor 81 (Olr81) and homology 2 domain-containing transforming protein 1 (Shc1). In MSS animals, the nAchR antagonist mecamylamine significantly alleviated rotation-induced MS symptoms and the plasma β-endorphin response. The NK1R antagonist CP99994 and Olr81 knock-down were effective for the defecation response, while the 5-HT4R antagonist RS39604 and Shc1 over-expression showed no therapeutic effect. In inMSS animals, rotation-induced changes in spontaneous locomotion activity and the plasma β-endorphin level occurred in the presence of the GABAAR antagonist gabazine.

CONCLUSION

Our findings suggested that the variability of the CVN gene expression profile after motion stimulation might be a putative molecular basis for individual differences in MS susceptibility and provide information for the development of new therapeutic strategies for MSS individuals.