Psychological and psychophysical aspects of spatial orientation.

These studies were undertaken to investigate the psychological and psychophysical factors that mediate spatial orientation/disorientation in both healthy and patient populations. PERCEPTION OF ANGULAR VELOCITY: Using a new method of examining perception of rotation this study found a similarity between the sensation and ocular responses following velocity step stimuli. Both decayed exponentially with a time constant of circa 15 seconds following rotation in yaw; circa 7 seconds following rotation in roll. Both the ocular and sensation responses were significantly reduced following repeated vestibular and optokinetic stimulation. The test was conducted with patients suffering from congenital nystagmus, ophthalmoplegia or cerebellar lesions, all of whom had markedly reduced post-rotational sensation responses of approximately 7 to 9 seconds. ADAPTATION TO OSCILLOPSIA: Labyrinthine defective subjects were found to prefer less self- motion when viewing a moving video-image than either ophthalmoplegia subjects or normal controls. The results suggest that adaptation to oscillopsia may be related to an active approach to recovery (i.e. high external locus of control) and also to increased tolerance to retinal slip. This serves to illustrate the coactive role of psychological and psychophysical mechanisms in adaptation to vestibular disorders. INVESTIGATION OF PSYCHOLOGICAL AND PSYCHOSOCIAL FACTORS: This questionnaire- based study aimed to examine adjustment to illness in patients with balance disorders and with congenital nystagmus. The study identified a greater use of emotion-focused coping strategies than problem-focused strategies. It highlighted the prevaience of anxiety and depression among these patients and pointed towards several psychosocial variables (locus of control, self-esteem and social support) that play a significant role in the coping behaviour of these patients. MENSTRUATION, MIGRAINE AND MOTION SICKNESS: The relationship between hormonal cycles and migraine and motion sickness is poorly understood. The study demonstrated that motion sickness and headache occurred independently although exposure to rough seas could be a specific migraine trigger in certain individuals who did not otherwise suffer attacks. Female subjects were more prone to motion sickness around the period of menstruation and less so around ovulation

Vestibular System: Anatomy, Physiology, and Clinical Evaluation

Аbstract Studies on vestibular system have brought new experimental studies, clinical examinations, and the development of effective treatment for a number of diseases of this system. In particular, vestibular paroxysmal positional disorders of peripheral and central origin have been studied. The main criteria for differential diagnosis of these disorders have been determined. Vestibular dysfunction in canalolithiasis and cupololithiasis has been investigated clinically and histologically. Effective therapeutic and prophylactic positional maneuvers of three types have been introduced into clinical practice. They were developed taking into account the anatomical and physiological features of the vestibular system. Currently only 20% of vestibular reactions, in particular, using electronystagmography test (ENG), are estimated in the horizontal plane. Videonystagmography (VNG) gives the possibility of video recording of nystagmus in the directions of semicircular channels (vertical, diagonal, horizontal). The vestibular evoked myogenic potential test (VEMP) is being widely used in clinical practice. Magnetic coils and scanning laser ophthalmoscopes are gaining increasing significance in examining patients. A brief information on vestibular disorders after the Chornobyl nuclear power plant accident is also given

Innovative vestibular testing

Dizziness and vertigo are common complaints in the general population, affecting yearly 15-20% of adults and 5-25% of children of school age and having considerable impact on everyday life. As the assessment of peripheral vestibular deficits is challenging, it is crucial to dispose of techniques to provide clinicians support for the correct diagnosis. The aim of this dissertation is therefore to apply in the clinical context cutting-edge diagnostic tools for the easy, quick and reliable assessment of peripheral vestibular impairments and the related functionality. Traditional techniques for the evaluation of semicircular canals, such as the caloric test, the rotational test or the search-coil Head Impulse Test, present several disadvantages, being unpleasant, expensive, time-consuming, not always available at the bedside or appropriate for any group of patients. Additionally, testing the vestibular system at low frequencies, such as in the caloric test, does not cover the physiologically relevant range. The video Head Impulse Test (vHIT) represents an alternative to indirectly evaluate semicircular canals’ function, stimulating the vestibulo-ocular reflex (VOR) with high-frequency head rotations and measuring the resulting eye and head movements. The first study reported in this dissertation extends the potentiality of the vHIT, assessing its feasibility in a group of healthy children and validating its use as a simple and well-tolerated bedside test for the vestibular screening of the pediatric population. The quantitative outcomes of the vHIT, however, do not always reflect functionality, i.e., how efficient is the VOR in stabilizing the visual scene during head perturbations. This represents the starting point for the development of tests whose aim is to assess the subjective perception of this ability. Among the most recently introduced techniques, the Head Impulse Testing Device (HITD) quantifies, without recording eye movements, patient’s reading abilities while performing high-frequency passive head rotations during equally challenging visual stimuli. The second section introduces and validates a new diagnostic tool, the Head Impulse Testing Device-Functional Testing (HITD-FT), which combines the HITD with eye movements recording. The HITD-FT is tested on healthy participants, whose vestibular functionality is transiently impaired by opioid administration. The work assesses the combined effect of VOR and re-fixation saccades on gaze stabilization during high-frequency passive head rotations. Moreover, it describes the role of covert re-fixation saccades on image stabilization and in enhancing overall dynamic vision. The HIDT-FT is furthermore exploited within the context of this dissertation to monitor the overall dynamic visual performance of vestibular patients during rehabilitation. The same experimental set-up, with healthy subjects undergoing opioid administration, is lately also exploited to explore the causes underlying post-operative nausea and vomiting, whose mechanism is still not completely understood. Preliminary studies suggest that opioids, acting on semicircular canals, generate a mismatch between the altered canals’ inputs and other non-consistently altered sensory inputs, triggering nausea and vomiting. The here reported study investigates whether the mismatch between semicircular canals’ inputs and other vestibular sensory inputs, or the mismatch between vestibular and visual inputs, are clinically relevant. A better understanding of this mechanism, i.e. that intra-vestibular mismatches have a particular importance, can help reducing the unpleasant side effects and improve pain management with opioids.Schwindelsyndrome sind häufig. Sie betreffen jährlich 15-20% der Erwachsenen und 5- 25% der Schulkinder und haben erhebliche Auswirkungen auf den Alltag. Die Beurteilung peripherer vestibulärer Defizite ist eine Herausforderung. Daher ist es entscheidend, Meth- oden zur Verfügung zu haben um Mediziner bei der Diagnosestellung zu unterstützen. Ziel dieser Doktorarbeit ist es, innovative Diagnose-Tools zur einfachen, schnellen und zuverlässigen Beurteilung der Funktion des vestibulären Systems in die Klinik zu übertragen. Traditionelle Methoden zur Evaluation der Bogengänge wie Kalorik, Drehstuhltest oder der Search-Coil-Kopfimpulstest haben mehrere Nachteile: sie sind unangenehm, teuer, zeitaufwändig, nicht am Krankenbett verfügbar oder eignen sich nicht für jede Patientengruppe. Die Untersuchung des vestibulären Systems im Niederfrequenzbereich wie bei der Kalorik deckt zudem nicht den physiologisch relevanten Bereich ab. Der videobasierte Kopfimpuls-Test (vHIT) ist dafür eine Alternative. Durch Stimulation des vestibulo- okulären Reflexes (VOR) mit Hochfrequenz-Kopfdrehungen und Messung von Auge- und Kopfbewegung wird dabei indirekt die Funktion der Bogengänge untersucht. Die erste Studie dieser Doktorarbeit erweitert die Anwendung des vHITs; seine Durchführbarkeit wird bei gesunden Kindern geprüft. Er stellt sich als einfacher und gut verträglicher „Bed- side Test“ für das vestibuläre Screening bei Kindern heraus. Die quantitativen vHIT Ergebnisse alleine spiegeln nicht immer wider, wie gut das Se- hen während Kopfbewegung stabil gehalten wird. Dies war Ausgangspunkt für die Entwicklung von Tests zur subjektiven Wahrnehmung dieser Funktion. Eine neue Methode auf diesem Gebiet, der Head Impulse Testing Device (HITD), untersucht - ohne Mes- sung der Augenbewegungen - die Lesefähigkeit anspruchsvoller visueller Stimuli während passiven Hochfrequenz-Kopfimpulsen. Im zweiten Teil der Doktorarbeit wird ein innovatives Diagnose-Tool – Head Impulse Testing Device – Functional Testing (HIDT-FT)– eingeführt und validiert. Der Test kombiniert HIDT mit Augenbewegungsmessung. Der HITD-FT wird an gesunden Probanden geprüft, deren vestibuläre Funktion mit Opi- oiden vorübergehend beeinträchtig ist. Die Studie untersucht den kombinierten Effekt von VOR und Re-Fixationsakkaden auf die Blickstabilisierung während passiver Hochfrequenz- Kopfimpulsen. Außerdem wird die Rolle sogenannter verdeckter (covert) Re-Fixationsakkaden bei der Bildstabilisierung und beim dynamischen Sehen geprüft. Der HITD-FT wird im Rahmen der Doktorarbeit zudem erfolgreich zur Dokumentation des dynamischen Sehens bei der Rehabilitation vestibulärer Patienten eingesetzt. Zum Schluss wird ein ähnlicher Versuchsaufbau mit Gabe von Opioiden bei Gesunden benutzt, um der Ursache von postoperativer Übelkeit und Erbrechen näher zu kommen, deren Mechanismus bisher nicht gut verstanden ist. Vorarbeiten legen nahe, dass Opiate eine Wirkung auf die Bogengänge haben und dass so eine Inkongruenz zwischen geänderten Bogengangs-Eingängen und nicht konsistenten geänderten anderen sensorische In- puts entsteht, die zu Übelkeit und Erbrechen führt. Die hier vorgelegte Arbeit untersucht, ob die Inkongruenz zwischen Bogengangsinformation und anderen vestibulären Sensoren oder die zwischen vestibulärem und visuellem Eingang klinisch relevant ist. Das Verständnis, dass intra-vestibuläre Inkongruenzen vor allem von Bedeutung sind, kann helfen diese unangenehmen Nebenwirkungen zu reduzieren und die Schmerzbehandlung mit Opiate zu verbessern

Modulatory effects of magnetic vestibular stimulation on resting-state networks can be explained by subject-specific orientation of inner-ear anatomy in the MR static magnetic field

Strong static magnetic fields, as used in magnetic resonance imaging (MRI), stimulate the vestibular inner ear leading to a state of imbalance within the vestibular system that causes nystagmus. This magnetic vestibular stimulation (MVS) also modulates fluctuations of resting-state functional MRI (RS-fMRI) networks. MVS can be explained by a Lorentz force model, indicating that MVS is the result of the interaction of the static magnetic field strength and direction (called \textquotedblB0 magnetic field\textquotedbl in MRI) with the inner ear's continuous endolymphatic ionic current. However, the high variability between subjects receiving MVS (measured as nystagmus slow-phase velocity and RS-fMRI amplitude modulations) despite matching head position, remains to be explained. Furthermore, within the imaging community, an \textquotedbleasy-to-acquire-and-use\textquotedbl proxy accounting for modulatory MVS effects in RS-fMRI fluctuations is needed. The present study uses MRI data of 60 healthy volunteers to examine the relationship between RS-fMRI fluctuations and the individual orientation of inner-ear anatomy within the static magnetic field of the MRI. The individual inner-ear anatomy and orientation were assessed via high-resolution anatomical CISS images and related to fluctuations of RS-fMRI networks previously associated with MVS. More specifically, we used a subject-specific proxy for MVS (pMVS) that corresponds to the orientation of the individual inner-ear anatomy within the static magnetic field direction (also called \textquotedblz-direction\textquotedbl in MR imaging). We found that pMVS explained a considerable fraction of the total variance in RS-fMRI fluctuations (for instance, from 11% in the right cerebellum up to 36% in the cerebellar vermis). In addition to pMVS, we examined the angle of Reid's plane, as determined from anatomical imaging as an alternative and found that this angle (with the same sinus transformation as for pMVS) explained considerably less variance, e.g., from 2 to 16%. In our opinion, an excess variability due to MVS should generally be addressed in fMRI research analogous to nuisance regression for movement, pulsation, and respiration effects. We suggest using the pMVS parameter to deal with modulations of RS-fMRI fluctuations due to MVS. MVS-induced variance can easily be accounted by using high-resolution anatomical imaging of the inner ear and including the proposed pMVS parameter in fMRI group-level analysis

Biologically Inspired Monocular Vision Based Navigation and Mapping in GPS-Denied Environments

This paper presents an in-depth theoretical study of bio-vision inspired feature extraction and depth perception method integrated with vision-based simultaneous localization and mapping (SLAM). We incorporate the key functions of developed visual cortex in several advanced species, including humans, for depth perception and pattern recognition. Our navigation strategy assumes GPS-denied manmade environment consisting of orthogonal walls, corridors and doors. By exploiting the architectural features of the indoors, we introduce a method for gathering useful landmarks from a monocular camera for SLAM use, with absolute range information without using active ranging sensors. Experimental results show that the system is only limited by the capabilities of the camera and the availability of good corners. The proposed methods are experimentally validated by our self-contained MAV inside a conventional building

Vestibular paroxysmia: clinical characteristics and long-term course

In 2016, the Bárány Society defined new diagnostic criteria for the neurovascular compression syndrome of the eighth nerve, called “vestibular paroxysmia” (VP), differentiating between definite (dVP) and probable (pVP) forms. The aim of this study was (1) to describe clinical symptoms and laboratory findings in a well-diagnosed large patient cohort according to those criteria, and (2) to evaluate the long-term course over years in dVP. We identified 146 patients (73 dVP, 73 pVP) from our tertiary dizziness center registry. Data of structured history-taking, clinical neurological, neuro-ophthalmological/-otological examinations as well as MRI imaging were extracted for analyses. Overall, attack frequency ranged between 5 and 30 attacks per day; spinning vertigo was the most frequent type. In two-thirds of patients, attacks occurred spontaneously; in one-quarter, they were triggered by head movements. The majority (approximately 70%) reported no accompanying symptoms; in those with symptoms, mild unilateral cochlear symptoms prevailed. One-third of patients initially showed hyperventilation-induced nystagmus without specific direction, and a deviation of the subjective visual vertical between 3° and 6°. Complete loss of peripheral vestibular function was never evident. dVP and pVP significantly differed concerning the vertigo type, e.g., spinning vertigo was more frequent in dVP. Fortunately, three-quarters of dVP patients remained attack-free during follow-up (mean 4.8 years, standardized questionnaire), more than half of them even without any medication. Patients with ongoing attacks showed significantly higher attack frequency at baseline, but reported persistent frequency reduction. Overall, the long-term prognosis of VP appears favorable, not necessarily requiring ongoing treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00415-022-11151-6

Functional requirements for the man-vehicle systems research facility

The NASA Ames Research Center proposed a man-vehicle systems research facility to support flight simulation studies which are needed for identifying and correcting the sources of human error associated with current and future air carrier operations. The organization of research facility is reviewed and functional requirements and related priorities for the facility are recommended based on a review of potentially critical operational scenarios. Requirements are included for the experimenter's simulation control and data acquisition functions, as well as for the visual field, motion, sound, computation, crew station, and intercommunications subsystems. The related issues of functional fidelity and level of simulation are addressed, and specific criteria for quantitative assessment of various aspects of fidelity are offered. Recommendations for facility integration, checkout, and staffing are included

Survey of the Current Status of Vestibular Practices in the United States

The purpose of this capstone research project was to gain a better understanding of audiologists’ practices and procedures related to vestibular assessment. Secondarily, it was of interest to determine what training and education is received by audiologists who perform vestibular testing. This study was developed to determine if variability exists, and if there are factors such as years of experience, work setting, education, geographical location that may relate to any variabilities found. Participants surveyed were active members of the American Academy of Audiology (AAA) as contact information was obtained from the electronic member directory on the AAA website. Using Qualtrics, a survey was created and distributed via email to 825 potential participants. Of those, 144 responses were collected (17.5% response rate). The survey data was organized into six sections: General/Demographics, Training, Screening, Assessment, Rehabilitation, and Vestibular Testing in Children. Descriptive analyses revealed large variability in vestibular practices among audiologists. Specifically, responses to questions regarding assessment protocols and rehabilitation methods were quite variable with respect to vascular screening prior to testing, order of testing, re-calibration during testing, and modifications to the physical maneuvers for vestibular rehabilitation. In the absence of universal guidelines and standards, students, educators, and professionals may utilize these survey results as an informative tool regarding current practices in vestibular audiology

An Investigation to Advance the Technology Readiness Level of the Centaur Derived On-orbit Propellant Storage and Transfer System

This research was carried out in collaboration with the United Launch Alliance (ULA), to advance an innovative Centaur-based on-orbit propellant storage and transfer system that takes advantage of rotational settling to simplify Fluid Management (FM), specifically enabling settled fluid transfer between two tanks and settled pressure control. This research consists of two specific objectives: (1) technique and process validation and (2) computational model development. In order to raise the Technology Readiness Level (TRL) of this technology, the corresponding FM techniques and processes must be validated in a series of experimental tests, including: laboratory/ground testing, microgravity flight testing, suborbital flight testing, and orbital testing. Researchers from Embry-Riddle Aeronautical University (ERAU) have joined with the Massachusetts Institute of Technology (MIT) Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) team to develop a prototype FM system for operations aboard the International Space Station (ISS). Testing of the integrated system in a representative environment will raise the FM system to TRL 6. The tests will demonstrate the FM system and provide unique data pertaining to the vehicle\u27s rotational dynamics while undergoing fluid transfer operations. These data sets provide insight into the behavior and physical tendencies of the on-orbit refueling system. Furthermore, they provide a baseline for comparison against the data produced by various computational models; thus verifying the accuracy of the models output and validating the modeling approach. Once these preliminary models have been validated, the parameters defined by them will provide the basis of development for accurate simulations of full scale, on-orbit systems. The completion of this project and the models being developed will accelerate the commercialization of on-orbit propellant storage and transfer technologies as well as all in-space technologies that utilize or will utilize similar FM techniques and processes

Utricular and visual aspects of inner ear disorders

The research described in this thesis is about investigation of the two less well understood mechanisms of balance system, namely utricular function and interactions of visual and vestibular system. Utricules are part of otolith apparatus and sense linear acceleration including gravity and lateral head tilts. Recent advances in rotational technology allow robust methods of assessment of unilateral utricular function using centrifugation techniques. Unilateral centrifugation generates substantial linear acceleration and the utricular response can be measured via tilt perception using subjective visual vertical (chapter 2). Utricular function was studied in common vestibular disorders seen in clinics, like chronic vestibular neuritis, benign positional paroxysmal vertigo, unilateral Ménière’s disease, migraine and bilateral vestibular hypofunction. Bilateral vestibular hypofunction produced significantly low utricular gain (chapter 3). A detailed study of the utricular function of larger group of unilateral Ménière’s disease showed significantly greater utricular asymmetry and lower utricular gain than normal controls. Interestingly, hearing loss was a predictor of utricular asymmetry (chapter 4). There was poor correlation between subjective measures and audiovestibular function. The chronic course of Ménière’s disease is well known with slow decline over years and absence of correlation between symptoms and function may point to ‘burn out’ as long term phenomenon (chapter 5). An investigation into visual dependence and vertigo was performed to understand the effect of visual dependence on tilt perception in chronic vertigo. Individuals with vestibular symptoms can have increased visual dependency and migraineurs can have a non-adaptable increase in visual dependency (chapter 6). In summary, we found that the unilateral centrifugation is a safe and well tolerated technique and provides additional, potentially useful information about utricular function. In future, the study of utricular function during acute phases of vertigo will further help overall understanding of otolith pathophysiology and mechanisms used for compensation.Open Acces