A Calibrated Olfactory Display for High Fidelity Virtual Environments

Olfactory displays provide a means to reproduce olfactory stimuli for use in virtual environments. Many of the designs produced by researchers, strive to provide stimuli quickly to users and focus on improving usability and portability, yet concentrate less on providing high levels of accuracy to improve the fidelity of odour delivery. This paper provides the guidance to build a reproducible and low cost olfactory display which is able to provide odours to users in a virtual environment at accurate concentration levels that are typical in everyday interactions; this includes ranges of concentration below parts per million and into parts per billion. This paper investigates build concerns of the olfactometer and its proper calibration in order to ensure concentration accuracy of the device. An analysis is provided on the recovery rates of a specific compound after excitation. This analysis provides insight into how this result can be generalisable to the recovery rates of any volatile organic compound, given knowledge of the specific vapour pressure of the compound

Programmable Immersive Peripheral Environmental System (PIPES): A Prototype Control System for Environmental Feedback Devices

This paper describes an environmental feedback device (EFD) control system aimed at simplifying the VR development cycle. Programmable Immersive Peripheral Environmental System (PIPES) affords VR developers a custom approach to programming and controlling EFD behaviors while relaxing the required knowledge and expertise of electronic systems. PIPES has been implemented for the Unity engine and features EFD control using the Arduino integrated development environment. PIPES was installed and tested on two VR systems, a large format CAVE system and an Oculus Rift HMD system. A photocell based end-to-end latency experiment was conducted to measure latency within the system. This work extends previously unpublished prototypes of a similar design. Development and experiments described in this paper are part of the VR community goal to understand and apply environment effects to VEs that ultimately add to usersâ perceived presence

The development of a simple projection-based, portable olfactory display device

Olfactory displays are digital devices designed to provide the controlled release of odours to users. In this paper, we report on the design and development of a simple vortex-based olfactory display for a single user. By employing a vortex approach, we are able to minimize the amount of required odour, whilst still producing a good user experience. The olfactory display designed here is based on a steel tube with 3D-printed apertures and solenoid valve operation. A number of different design parameters (such as aperture size) were investigated, and the best combination was combined into a functional olfactory display. User testing was undertaken with four volunteers who were presented with four different odours, at two concentrations. It was found that the time to identify an odour was not strongly related to concentration. However, the intensity of the odour was correlated. We also found that there was a wide variance in human panel results when considering the length of time for a subject to identify an odour to its perceived intensity. This is likely linked to the subject group receiving no odour training before the experiments. However, we were able to produce a working olfactory display, based on a scent project method, which could be applicable to a range of application scenarios

Relationships between behavioral and physiological performance under elevated CO₂ in marine fishes

Over the past decade there has been a concerted effort to determine how ocean acidification will affect a range of fitness-related traits in marine fishes, with studies often finding negative impacts on either behavioral or physiological performance. Until recently, most studies have focused on the mean responses of the sampled populations to ocean acidification. However, there is a growing recognition of the value in examining individual variation in responses. This can highlight individuals that are best suited to survival in future conditions. Identifying these individuals, however, can be challenging, because performance is not always consistent across all traits. Indeed, correlations can exist between traits that could either help or hinder survival at the individual level, and even affect the ability of marine fishes to adapt to ocean acidification. For instance, if two traits are negatively correlated with respect to the fitness landscape, then selection on one trait will diminish the other, slowing the rate of adaptation, and vice versa. Thus, identifying correlations among key traits is a crucial step towards understanding the potential of marine species to adapt to future climatic conditions. This thesis seeks to identify such correlations by examining the relationship between behavioral and physiological performance in marine fishes and determining how environmental conditions and parental effects might alter this relationship. Theory predicts that environmental stressors can alter relationships between behavioral and physiological traits, either revealing or masking significant relationships. While both ocean acidification and warming have been found to affect behavioral and physiological performance in marine fishes, they can often interact in complex, non-additive ways, making it difficult to predict their combined impacts on marine fishes. Therefore, in Chapter 2 I explored the relationship between behavioral and physiological performance in a juvenile reef fish, Acanthochromis polyacanthus, reared in a full crossed design of current-day control and predicted future ocean CO₂ and temperature levels. Behaviorally, elevated CO₂, but not elevated temperature, disrupted the fish’s response to an alarm odor. Physiologically, aerobic scope was diminished under elevated temperature, but not elevated CO₂. A significant negative correlation was observed between these behavioral and physiological traits in the combined elevated CO₂ and temperature treatment. These results suggest that correlations between behavior and physiology may only be evident when fish are exposed to multiple stressors. Importantly, the negative correlation between these traits could slow the rate of adaptation to climate change. Chapter 2 revealed a negative correlation between behavioral and physiological performance in a coral reef fish, but this relationship might not hold for other fishes. It has been hypothesized that different sensitivities of marine fishes to elevated CO₂ may derive from their life styles and the variation in seawater pCO₂ they naturally experience. For example, pelagic fishes could be more susceptible to elevated CO₂ than coral reef fishes due to the relatively stable CO₂ conditions they experience in the open ocean. Therefore, in Chapter 3 I tested the relationship between behavioral and physiological performance in a large pelagic fish, the yellowtail kingfish Seriola lalandi, in a full crossed experimental design of current-day control and predicted future CO₂ and temperature levels. In contrast to the juvenile reef fish, larval kingfish exhibited no behavioral changes in elevated CO₂ conditions. They did, however, exhibit increased resting oxygen uptake (ṀO₂Rest) at elevated CO₂, and also at higher temperature. Correlations between behavioral and physiological performance were observed, which were inversely related based on the temperature treatment; ṀO₂Rest and boldness were negatively correlated at ambient temperature, but positively correlated at elevated temperature. These results show that higher water temperature can alter the relationship between behavioral and physiological performance, potentially altering the direction and pace of adaptation. Most ocean acidification experiments to date have employed elevated CO₂ treatments that are stable through time. Yet shallow-water habitats such as coral reefs can experience substantial diel cycles in CO₂, and the magnitude of these cycles is predicted to increase as the buffering capacity of the oceans decreases. Diel CO₂ cycles have been shown to reduce the negative effects of elevated CO₂ on behavioral traits in marine fishes, but their effect on physiological traits remains unknown. Nor is it known if diel CO₂ cycles will interact with elevated temperature, or how they might affect relationships between behavioral and physiological performance. In Chapter 4, I compared physiological performance of juvenile A. polyacanthus under stable elevated CO₂ (1000 μatm) to a diel-cycling elevated CO₂ treatment (1000 ± 500 μatm) at both current-day control and elevated (+2 °C) temperatures. The ṀO₂Rest of fish reared at stable elevated CO₂ was higher than that of fish reared in control conditions. By contrast, ṀO₂Rest of fish in the diel-cycling elevated CO₂ treatment was comparable to controls, suggesting that diel CO₂ cycles mitigated the negative effect of elevated CO₂. This mitigating effect was not observed at elevated temperature. In the stable elevated CO₂ and temperature treatment, a positive correlation was observed between ṀO₂Rest and routine activity. However, as A. polyacanthus will likely be subjected to fluctuating, rather than stable, elevated CO₂ in the future, this correlation will not likely influence selection or adaptation. Furthermore, because these fish live in shallow environments exposed to warming, they may not benefit from the mitigating effects of diel CO₂ cycles. These findings highlight the importance of considering the habitats that fishes experience when designing experimental treatments to test the effects of elevated CO₂. Parental effects can modify the performance of offspring in elevated CO₂, yet it is unknown if they also alter the relationship between behavioral and physiological performance in marine fishes. In Chapter 5, I exposed adult pairs of A. polyacanthus to either current-day control or elevated CO₂ conditions. I split their offspring equally between control and elevated CO₂ conditions and measured their behavioral and physiological performance (response to an alarm odor for behavior, and aerobic scope for physiology). Offspring exposed to elevated CO₂ displayed an impaired response to alarm odors, regardless of their parental treatment. However, maximal oxygen uptake rates (ṀO₂Max) were higher in offspring with CO₂-exposed parents, regardless of offspring treatment, and ṀO₂Rest and aerobic scope showed significant differences between some treatments. These results demonstrate that parental effects can ameliorate some negative effects of ocean acidification, but not others. There were no correlations observed between behavioral and physiological performance. This result, along with Chapters 2 and 4, suggests that relationships between traits may only arise when fish are exposed to both warmer and more acidic conditions. This research is among the first to examine the relationship between behavioral and physiological performance of marine fishes in a climate change context. The results demonstrate that correlations between behavioral and physiological performance do exist, but can shift depending on complex interactions between stressors, traits, and parental effects. Importantly, significant correlations between behavior and physiology were only observed under elevated CO₂ and temperature conditions, which supports the hypothesis that tradeoffs between behavior and physiology can be strengthened under environmental stress. These relationships are important because they have the potential to alter the direction and pace of future adaptation to climate change. Future studies could investigate the causal mechanisms for these relationships and extend this research beyond marine fishes to examine changes to adaptation rates in short-lived organisms. This research underscores the importance of looking beyond the mean to understand individual variation and relationships between different types of performance in order to predict the effects of climate change on marine ecosystems

User-centered Virtual Environment Assessment And Design For Cognitive Rehabilitation Applications

Virtual environment (VE) design for cognitive rehabilitation necessitates a new methodology to ensure the validity of the resulting rehabilitation assessment. We propose that benchmarking the VE system technology utilizing a user-centered approach should precede the VE construction. Further, user performance baselines should be measured throughout testing as a control for adaptive effects that may confound the metrics chosen to evaluate the rehabilitation treatment. To support these claims we present data obtained from two modules of a user-centered head-mounted display (HMD) assessment battery, specifically resolution visual acuity and stereoacuity. Resolution visual acuity and stereoacuity assessments provide information about the image quality achieved by an HMD based upon its unique system parameters. When applying a user-centered approach, we were able to quantify limitations in the VE system components (e.g., low microdisplay resolution) and separately point to user characteristics (e.g., changes in dark focus) that may introduce error in the evaluation of VE based rehabilitation protocols. Based on these results, we provide guidelines for calibrating and benchmarking HMDs. In addition, we discuss potential extensions of the assessment to address higher level usability issues. We intend to test the proposed framework within the Human Experience Modeler (HEM), a testbed created at the University of Central Florida to evaluate technologies that may enhance cognitive rehabilitation effectiveness. Preliminary results of a feasibility pilot study conducted with a memory impaired participant showed that the HEM provides the control and repeatability needed to conduct such technology comparisons. Further, the HEM affords the opportunity to integrate new brain imaging technologies (i.e., functional Near Infrared Imaging) to evaluate brain plasticity associated with VE based cognitive rehabilitation

Apprentissage visuel en réalité virtuelle chez Apis mellifera

Dotées d'un cerveau de moins d'un millimètre cube et contenant environ 950 000 neurones, les abeilles présentent un riche répertoire comportemental, parmi lesquels l'apprentissage appétitif et la mémoire jouent un rôle fondamental dans le contexte des activités de recherche de nourriture. Outre les formes élémentaires d'apprentissage, où les abeilles apprennent une association spécifique entre des événements de leur environnement, les abeilles maîtrisent également différentes formes d'apprentissage non-élémentaire, à la fois dans le domaine visuel et olfactif, y compris la catégorisation, l'apprentissage contextuel et l'abstraction de règles. Ces caractéristiques en font un modèle idéal pour l'étude de l'apprentissage visuel et pour explorer les mécanismes neuronaux qui sous-tendent leurs capacités d'apprentissage. Afin d'accéder au cerveau d'une abeille lors d'une tâche d'apprentissage visuel, l'insecte doit être immobilisé. Par conséquent, des systèmes de réalité virtuelle (VR) ont été développés pour permettre aux abeilles d'agir dans un monde virtuel, tout en restant stationnaires dans le monde réel. Au cours de mon doctorat, j'ai développé un logiciel de réalité virtuelle 3D flexible et open source pour étudier l'apprentissage visuel, et je l'ai utilisé pour améliorer les protocoles de conditionnement existants en VR et pour étudier le mécanisme neuronal de l'apprentissage visuel. En étudiant l'influence du flux optique sur l'apprentissage associatif des couleurs, j'ai découvert que l'augmentation des signaux de mouvement de l'arrière-plan nuisait aux performances des abeilles. Ce qui m'a amené à identifier des problèmes pouvant affecter la prise de décision dans les paysages virtuels, qui nécessitent un contrôle spécifique par les expérimentateurs. Au moyen de la VR, j'ai induit l'apprentissage visuel chez des abeilles et quantifié l'expression immédiate des gènes précoces (IEG) dans des zones spécifiques de leur cerveau pour détecter les régions impliquées dans l'apprentissage visuel. En particulier, je me suis concentré sur kakusei, Hr38 et Egr1, trois IEG liés à la recherche de nourriture et à l'orientation des abeilles et qui peuvent donc également être pertinents pour la formation d'association visuelle appétitive. Cette analyse suggère que les corps pédonculés sont impliqués dans l'apprentissage associatif des couleurs. Enfin, j'ai exploré la possibilité d'utiliser la VR sur d'autres modèles d'insectes et effectué un conditionnement différentiel sur des bourdons. Cette étude a montré que non seulement les bourdons sont capables de résoudre cette tâche cognitive aussi bien que les abeilles, mais aussi qu'ils interagissent davantage avec la réalité virtuelle, ce qui entraîne un ratio plus faible d'individus rejetés de l'expérience par manque de mouvement. Ces résultats indiquent que les protocoles VR que j'ai établis au cours de cette thèse peuvent être appliqués à d'autres insectes, et que le bourdon est un bon candidat pour l'étude de l'apprentissage visuel en VR.Equipped with a brain smaller than one cubic millimeter and containing ~950,000 neurons, honeybees display a rich behavioral repertoire, among which appetitive learning and memory play a fundamental role in the context of foraging activities. Besides elemental forms of learning, where bees learn specific association between environmental features, bees also master different forms of non-elemental learning, including categorization, contextual learning and rule abstraction. These characteristics make them an ideal model for the study of visual learning and its underlying neural mechanisms. In order to access the working brain of a bee during visual learning the insect needs to be immobilized. To do so, virtual reality (VR) setups have been developed to allow bees to behave within a virtual world, while remaining stationary within the real world. During my PhD, I developed a flexible and open source 3D VR software to study visual learning, and used it to improve existing conditioning protocols and to investigate the neural mechanism of visual learning. By developing a true 3D environment, we opened the possibility to add frontal background cues, which were also subjected to 3D updating based on the bee movements. We thus studied if and how the presence of such motion cues affected visual discrimination in our VR landscape. Our results showed that the presence of frontal background motion cues impaired the bees' performance. Whenever these cues were suppressed, color discrimination learning became possible. Our results point towards deficits in attentional processes underlying color discrimination whenever motion cues from the background were frontally available in our VR setup. VR allows to present insects with a tightly controlled visual experience during visual learning. We took advantage of this feature to perform ex-vivo analysis of immediate early gene (IEG) expression in specific brain area, comparing learner and non-learner bees. Using both 3D VR and a lore restrictive 2D version of the same task we tackled two questions, first what are the brain region involved in visual learning? And second, is the pattern of activation of the brain dependent on the modality of learning? Learner bees that solved the task in 3D showed an increased activity of the Mushroom Bodies (MB), which is coherent with the role of the MB in sensory integration and learning. Surprisingly we also found a completely different pattern of IEGs expression in the bees that solved the task in 2D conditions. We observed a neural signature that spanned the optic lobes and MB calyces and was characterized by IEG downregulation, consistent with an inhibitory trace. The study of visual learning's neural mechanisms requires invasive approach to access the brain of the insects, which induces stress in the animals and can thus impair behaviors in itself. To potentially mitigate this effect, bumble bees Bombus terrestris could constitute a good alternative to Apis mellifera as bumble bees are more robust. That's why in the last part of this work we explored the performances of bumblebees in a differential learning task in VR and compared them to those of honey bees. We found that, not only bumble bees are able to solve the task as well as honey bees, but they also engage more with the virtual environment, leading to a lower ratio of discarded individuals. We also found no correlation between the size of bumble bees and their learning performances. This is surprising as larger bumble bees, that assume the role of foragers in the colony, have been shown to be better at learning visual tasks in the literature