Comparative visual cognition in jumping spiders

Thesis by publication.Includes bibliographical references.1. Introduction -- 2. Electric shock for aversion training of jumping spiders: towards an arachnid model of avoidance learning -- 3. Factors influencing place avoidance learning and memory in a jumping spider -- 4. Jumping spiders ignore predictive visual information in an active avoidance conditioning task -- 5. A virtual reality paradigm for the study of visually mediated behaviour and cognition in spiders -- 6. Visual working memory in jumping spiders: an expectancy violation paradigm in virtual reality -- 7. General discussion -- Appendices.Uncertainty is a common feature of the natural world. Associative learning, which enables animals to form predictive relationships between contingent events, reduces uncertainty and equips animals to respond adaptively. Associative learning is widespread across the animal kingdom, and has been particularly well characterized in a few key invertebrate model taxa. Invertebrates exhibit a broad repertoire of associative learning abilities, have significant molecular overlap with vertebrate systems, and are considerably more amenable to analyses at cellular and behavioural levels. Jumping spiders (Salticidae) - and arachnids as a whole - have been underrepresented in the comparative cognition literature but possess many traits that make them suitable and interesting models. The principle aim of this thesis was to begin to bridge the gap between spiders and traditional invertebrate model taxa. To do so, I developed methods that permitted rigorous and repeatable analysis of cognitive processes, and assessed how salticids integrate different sources of information during learning and meVmory. My research focuses on an Australian salticid, Servaea incana, but the methods and principles developed here should be relevant to other cursorial arachnids or invertebrates in which vision is well developed. I develop a novel method to produce electric shock platforms that is precise, easy to use, and highly repeatable, and isolate the changes in mobility and behaviour that are dependent on shock. Additionally, to overcome the constraints of commonly used playback methods, I develop an immersive, closed-loop virtual reality system tailored for studies of salticid cognition. Using passive and active avoidance conditioning assays coupled with the aversive electric shock stimulus, and a change detection paradigm in virtual reality, I characterize the critical determinants of learning and memory in salticids. These experiments reveal that the ecological relevance, or ‘salience’ of available visual cues, together with hunger level and the temporal nature of the training protocol, play a significant role in determining performance. At the same time, when spiders are provided with a number of cues predicting an aversive event, they learn an operant escape response while ignoring reliable visual information. These results are very surprising given the extent to which vision is known to mediate behaviour and decision making in jumping spiders.Mode of access: World wide web1 online resource (x, 141 pages) illustration

Place avoidance learning and memory in a jumping spider

Using a conditioned passive place avoidance paradigm, we investigated the relative importance of three experimental parameters on learning and memory in a salticid, Servaea incana. Spiders encountered an aversive electric shock stimulus paired with one side of a two-sided arena. Our three parameters were the ecological relevance of the visual stimulus, the time interval between trials and the time interval before test. We paired electric shock with either a black or white visual stimulus, as prior studies in our laboratory have demonstrated that S. incana prefer dark ‘safe’ regions to light ones. We additionally evaluated the influence of two temporal features (time interval between trials and time interval before test) on learning and memory. Spiders exposed to the shock stimulus learned to associate shock with the visual background cue, but the extent to which they did so was dependent on which visual stimulus was present and the time interval between trials. Spiders trained with a long interval between trials (24 h) maintained performance throughout training, whereas spiders trained with a short interval (10 min) maintained performance only when the safe side was black. When the safe side was white, performance worsened steadily over time. There was no difference between spiders tested after a short (10 min) or long (24 h) interval before test. These results suggest that the ecological relevance of the stimuli used and the duration of the interval between trials can influence learning and memory in jumping spiders.10 page(s

A Virtual reality paradigm for the study of visually mediated behaviour and cognition in spiders

Jumping spiders (Salticidae) are well known for their unique, high-acuity visual system and complex, visually mediated behaviour. To overcome the limitations of video playback and other open loop systems that are currently available for the study of visually mediated behaviour in jumping spiders, we developed a closed-loop, virtual reality (VR) system in which a spider on a spherical treadmill walks through a projected 3D world that updates in real time in response to its movements. To investigate VR as an experimental technique for spiders as well as validate it as a proxy of the real world, we conducted two experiments to assess whether individual behavioural tendencies and learning transferred from real to virtual environments. In the first experiment, we examined transference of individual behaviour tendencies (spontaneous locomotion and dark/light preference) between real and VR environments, and found that individual differences were conserved. In the second experiment, we investigated transference of beacon-learning tasks between real and VR environments. We found that spiders that had learned a beacon-nest site association in the real world tended to expresses similar associations in the virtual world. Virtual reality offers great promise as a new tool to explore the cognitive processes underlying vision-mediated learning, memory and navigation in jumping spiders.9 page(s

Electric shock for aversion training of jumping spiders : towards an arachnid model of avoidance learning

Electric shock is used widely as an aversive stimulus in conditioning experiments, yet little attention has been given to its physiological effects and their consequences for bioassays. In the present study, we provide a detailed characterization of how electric shock affects the mobility and behaviour of Servaea incana, a jumping spider. We begin with four mobility assays and then narrow our focus to a single effective assay with which we assess performance and behaviour. Based on our findings, we suggest a voltage range that may be employed as an aversive stimulus while minimizing decrements in physical performance and other aspects of behaviour. Additionally, we outline a novel method for constructing electric shock platforms that overcome some of the constraints of traditional methods while being highly effective and easily modifiable to suit the study animal and experimental context. Finally, as a demonstration of the viability of our aversive stimulus in a passive avoidance conditioning task, we successfully train spiders to associate a dark compartment with electric shock. Future research using electric shock as an aversive stimulus with terrestrial invertebrates such as spiders and insects may benefit from the flexible and reliable methods outlined in the present study.6 page(s

A systematic review and narrative synthesis of interventions for uncomplicated obesity : weight loss, well-being and impact on eating disorders

Objective: Most weight loss research focuses on weight as the primary outcome, often to the exclusion of other physiological or psychological measures. This study aims to provide a holistic evaluation of the effects from weight loss interventions for individuals with obesity by examining the physiological, psychological and eating disorders outcomes from these interventions. Methods: Databases Medline, PsycInfo and Cochrane Library (2011-2016) were searched for randomised controlled trials and systematic reviews of obesity treatments (dietary, exercise, behavioural, psychological, pharmacological or surgical). Data extracted included study features, risk of bias, study outcomes, and an assessment of treatment impacts on physical, psychological or eating disorder outcomes. Results: From 3628 novel records, 134 studies met all inclusion criteria and were evaluated in this review. Lifestyle interventions had the strongest evidence base as a first-line approach, with escalation to pharmacotherapy and bariatric surgery in more severe or complicated cases. Quality of life was the most common psychological outcome measure, and improved in all cases where it was assessed, across all intervention types. Behavioural, psychological and lifestyle interventions for weight loss led to improvements in cognitive restraint, control over eating and binge eating, while bariatric surgery led to improvements in eating behaviour and body image that were not sustained over the long-term. Discussion: Numerous treatment strategies have been trialled to assist people to lose weight and many of these are effective over the short-term. Quality of life, and to a lesser degree depression, anxiety and psychosocial function, often improve alongside weight loss. Weight loss is also associated with improvements in eating disorder psychopathology and related measures, although overall, eating disorder outcomes are rarely assessed. Further research and between-sector collaboration is required to address the significant overlap in risk factors, diagnoses and treatment outcomes between obesity and eating disorders