Exploring the relationship between spatial cognitive ability and movement ecology

Spatial cognitive ability is hypothesised to be a key determinant of animal movement patterns. However, empirical demonstrations linking intra-individual variations in spatial cognitive ability with movement ecology are rare. I reared ~200 simultaneously hatched pheasant chicks per year over three years in standardised conditions without parents, controlling for the confounding effects of experience, maternal influences and age. I tested the chicks on spatial cognitive tasks from three weeks old to obtain measures of inherent, early-life spatial cognitive ability. Each year, I released birds when 10 weeks old into an open-topped enclosure in woodland. Birds dispersed from this enclosure after about one-month. Importantly, all birds were released into the same, novel area simultaneously, thus their experiences and opportunities were standardised. I remotely tracked pheasant movement through either RFID antenna placed under 43 supplementary feeders situated throughout our field site (2016) or by using a novel reverse-GPS tracking system (2017-2018). Spatial cognitive ability, determined through binary spatial discrimination (2016) or a Barnes maze (2017), was related to the diversity of foraging sites an individual used (Chapter 2: 2016). Those with better spatial cognitive ability used a more diverse range of artificial feeders than poor performing counterparts, perhaps to retain a buffer of alternative foraging sites where resource profitability was known. I found no relationship between the timing of daily foraging onset between birds of differing cognitive ability (Chapter 3; 2016), which I had hypothesised to be a consequence of birds developing efficient routes between refuges and feeders. After establishing a reverse GPS system on our field site (Chapter 4: 2017), I collected more detailed information about pheasant movement and found that birds with higher accuracy scores on the cognition tasks initially moved between foraging and resting sites more slowly than inaccurate birds in novel environments, perhaps to gather more detailed information. Accurate birds increased their speed over one month to match the same speed as inaccurate birds. All birds increased the straightness of their routes at a similar rate. Lastly, I found intraspecific differences in the orientation strategy that birds used to solve a dual strategy maze task (Chapter 5: 2018). These differences predicted habitat use after release: birds that utilised landmarks (allocentric strategies) showed less aversion to urban habitats (farm buildings/yards) than egocentric/mixed strategy birds, which is potentially due to the presence of large, stable landmarks within these habitats. In this thesis, I provide several empirical links between spatial cognitive ability and movement ecology across a range of ecological contexts. I suggest that very specific cognitive processes may govern particular movement behaviours and that there is not one overarching general spatial ability.European Commissio

Modelling individual heterogeneity in behaviour for wildlife management and conservation.

When modelling the population dynamics of wild animals we traditionally assume individual variation in behaviour is of only minor relevance to population dynamics. However, just like humans, animals exhibit consistent variation in behaviour among individuals (“personality”) and most wild populations are behaviourally heterogeneous. In this thesis, we defend the argument that individual heterogeneity in animal behaviour should not be treated only as a source of “noise” in models. Instead, significant behavioural differences between members of the same species can have important consequences for population-level processes and ecological interactions. We ask to what extent individual heterogeneity affects pest eradication, what modelling strategies can be used and what kind of empirical data allow us to quantify these effects. Using the example of invasive mammal pest species in New Zealand, we first perform a meta-analysis to summarise some key characteristics of these species’ trappability and space use, across a range of population densities, habitats and types of surveillance device. We then used numerical simulations to show that individual heterogeneity and the possible transmission of personalities from parent to offspring can have significant effects on the eradication of these species. Finally, we analyse empirical data from field trials to explore the different behavioural profiles observable in North Island brown kiwi, a bird species at the core of New Zealand’s wildlife conservation efforts. The significance of this study is that it adds to our theoretical understanding of animal personalities by introducing a focus on their implications on wildlife management, and informs on what factors to consider when designing field experiments aimed at quantifying animal personalities

Social Preference in Juvenile Zebrafish

Social behaviours are essential for the survival and reproduction of many species, including our own. A fundamental feature of all social behaviour is social preference, which is an individual’s propensity to interact with members of their species (termed conspecifics). In an average population, various social preference behaviours are readily observed, ranging from uninterested (not engaging with conspecifics) to very social (engaging with conspecifics). Individuals expressing these behaviours are typically labelled as having an asocial or prosocial, respectively. Little is known about how the underlying social circuitry gives rise to such distinct social behaviours in the population. It is well established that adverse social experiences can impact social behaviour, including isolation during early development. Undesired social isolation (loneliness) alters behavioural patterns, neuroanatomy (e.g., brain volume) and neurochemistry in ways that resemble developmental neuropsychiatric disorders, including autism and schizophrenia. However, few studies have investigated the impact of early life isolation on social circuitry, and how this results in dysfunctional social behaviour commonly associated with these and other disorders. In this thesis, juvenile zebrafish was used to model social preference behaviour, as it is an excellent translational model for human developmental and behavioural disorders. Population-level analysis revealed that several features of social preference behaviour could be summarised via Visual Preference Index (VPI) scores representing sociality. Using multiple behavioural parameters, comprehensive investigations of asocial and prosocial fish identified via VPIs revealed distinct responses towards conspecifics between the two phenotypes. These initial results served as a baseline for facilitating the identification of atypical social behaviour following periods of social isolation. The impact of isolation on social preference was assessed by applying either the full isolation over the initial three weeks of development or partial isolation, 48 hours or 24 hours, before testing. Following periods of social isolation, juvenile zebrafish displayed anxiety-like behaviours. Furthermore, full and partial isolation of 48 hours, but not 24 hours, altered responses to conspecifics. To assess the impact of social isolation on the social circuitry, the brain activities of fish were analysed and compared between different rearing conditions using high-resolution two-photon imaging. Whole-brain functional maps of isolated social phenotypes were distinct from those in the average population. Isolation-induced activity changes were found mainly in brain regions linked to social behaviour, social cue processing, and anxiety/stress (e.g., the caudal hypothalamus and preoptic area). Since some of these affected regions are modulated by serotonin, the reversibility of the adverse effects of social isolation on preference behaviour was investigated by using pharmacological manipulation of the monoaminergic system. The administration of an anxiolytic the drug buspirone demonstrated that altered social preference behaviour in isolated fish could be rescued by acutely reducing serotonin levels. By investigating social preference at the behavioural and functional level in wild-type juvenile zebrafish, this work contributes to our understanding of how the social brain circuity produces diverse social preferences. Furthermore, it provides important information on how early-life environmental adversity gives rise to atypical social behaviour and the neurotransmitters modulating the circuit, offering new opportunities for effective intervention

Learning-induced plasticity in vascular properties in the human brain

The brain is a plastic organ, able to undergo structural and functional changes following changing physiological contingencies, such as diseases and exercise training. However, the nature of the biological changes that underlie plasticity in the adult human brain is not fully understood. In light of this lack of knowledge of the biological mechanism behind brain plasticity, non-invasive imaging can be used to track plasticity changes in the living human brain. Quantitative and physiologically-specific magnetic resonance imaging (MRI) techniques are an ideal tool to study these mechanisms. Plasticity is believed to involve a variety of physiological mechanisms. Some of these mechanisms are neuronal in nature, such as synaptogenesis and changes in neuronal morphology, but changes in non-neuronal tissue components are also thought to contribute, including angiogenesis. The latter may result in increased cerebral blood flow (CBF). CBF estimation can be obtained using arterial spin labeling (ASL). In this technique, water protons in blood are magnetically labelled and this labelling is used to measure the amount of blood that perfuses brain regions. The detection of blood perfusion changes during and following learning intervention would be indicative of a contribution of vascular plasticity to learning-induced changes. In this project, we will use ASL to measure plasticity-induced changes in CBF in motor areas during and following five days of motor task learning

Engineering evolutionary control for real-world robotic systems

Evolutionary Robotics (ER) is the field of study concerned with the application of evolutionary computation to the design of robotic systems. Two main issues have prevented ER from being applied to real-world tasks, namely scaling to complex tasks and the transfer of control to real-robot systems. Finding solutions to complex tasks is challenging for evolutionary approaches due to the bootstrap problem and deception. When the task goal is too difficult, the evolutionary process will drift in regions of the search space with equally low levels of performance and therefore fail to bootstrap. Furthermore, the search space tends to get rugged (deceptive) as task complexity increases, which can lead to premature convergence. Another prominent issue in ER is the reality gap. Behavioral control is typically evolved in simulation and then only transferred to the real robotic hardware when a good solution has been found. Since simulation is an abstraction of the real world, the accuracy of the robot model and its interactions with the environment is limited. As a result, control evolved in a simulator tends to display a lower performance in reality than in simulation. In this thesis, we present a hierarchical control synthesis approach that enables the use of ER techniques for complex tasks in real robotic hardware by mitigating the bootstrap problem, deception, and the reality gap. We recursively decompose a task into sub-tasks, and synthesize control for each sub-task. The individual behaviors are then composed hierarchically. The possibility of incrementally transferring control as the controller is composed allows transferability issues to be addressed locally in the controller hierarchy. Our approach features hybridity, allowing different control synthesis techniques to be combined. We demonstrate our approach in a series of tasks that go beyond the complexity of tasks where ER has been successfully applied. We further show that hierarchical control can be applied in single-robot systems and in multirobot systems. Given our long-term goal of enabling the application of ER techniques to real-world tasks, we systematically validate our approach in real robotic hardware. For one of the demonstrations in this thesis, we have designed and built a swarm robotic platform, and we show the first successful transfer of evolved and hierarchical control to a swarm of robots outside of controlled laboratory conditions.A Robótica Evolutiva (RE) é a área de investigação que estuda a aplicação de computação evolutiva na conceção de sistemas robóticos. Dois principais desafios têm impedido a aplicação da RE em tarefas do mundo real: a dificuldade em solucionar tarefas complexas e a transferência de controladores evoluídos para sistemas robóticos reais. Encontrar soluções para tarefas complexas é desafiante para as técnicas evolutivas devido ao bootstrap problem e à deception. Quando o objetivo é demasiado difícil, o processo evolutivo tende a permanecer em regiões do espaço de procura com níveis de desempenho igualmente baixos, e consequentemente não consegue inicializar. Por outro lado, o espaço de procura tende a enrugar à medida que a complexidade da tarefa aumenta, o que pode resultar numa convergência prematura. Outro desafio na RE é a reality gap. O controlo robótico é tipicamente evoluído em simulação, e só é transferido para o sistema robótico real quando uma boa solução tiver sido encontrada. Como a simulação é uma abstração da realidade, a precisão do modelo do robô e das suas interações com o ambiente é limitada, podendo resultar em controladores com um menor desempenho no mundo real. Nesta tese, apresentamos uma abordagem de síntese de controlo hierárquica que permite o uso de técnicas de RE em tarefas complexas com hardware robótico real, mitigando o bootstrap problem, a deception e a reality gap. Decompomos recursivamente uma tarefa em sub-tarefas, e sintetizamos controlo para cada subtarefa. Os comportamentos individuais são então compostos hierarquicamente. A possibilidade de transferir o controlo incrementalmente à medida que o controlador é composto permite que problemas de transferibilidade possam ser endereçados localmente na hierarquia do controlador. A nossa abordagem permite o uso de diferentes técnicas de síntese de controlo, resultando em controladores híbridos. Demonstramos a nossa abordagem em várias tarefas que vão para além da complexidade das tarefas onde a RE foi aplicada. Também mostramos que o controlo hierárquico pode ser aplicado em sistemas de um robô ou sistemas multirobô. Dado o nosso objetivo de longo prazo de permitir o uso de técnicas de RE em tarefas no mundo real, concebemos e desenvolvemos uma plataforma de robótica de enxame, e mostramos a primeira transferência de controlo evoluído e hierárquico para um exame de robôs fora de condições controladas de laboratório.This work has been supported by the Portuguese Foundation for Science and Technology (Fundação para a Ciência e Tecnologia) under the grants SFRH/BD/76438/2011, EXPL/EEI-AUT/0329/2013, and by Instituto de Telecomunicações under the grant UID/EEA/50008/2013

Methodological approaches for sound training in underepresented learners: a case study with american toads (anaxyrus americanus)

efforts to better understand the minds of animals have been flourishing, with methodological breakthroughs and a remarkable increase in the number of publications dealing with a wide variety of non-model species. The growing interest in species that are distantly related to humans in the field of comparative physiology and cognition was confirmed with the general reviewed performed in this dissertation. Yet, the progress is unbalanced among the ectothermic vertebrates (fish, reptiles, and amphibians), with almost no research on amphibians. Many animals remain unstudied, even though they may possess unique and powerful adaptations to respond to environmental stimuli that can be useful for learning and cognition research. Inspired by the efforts to increase species representation in studies of learning and cognition, this dissertation also explored two methods of spatial learning to train American toads to respond to tone burst cues in order to find the reward. As frogs and toads have been able to acquire maze task associated to visual cues and mating calls, I predicted that a protocol based on these previously successful methods could be reliable in testing toads to associate and discriminate tone bursts of different frequencies (HZ). None of the methods were effective in demonstrate learning abilities in American toads, but the results pointed to important challenges to calibrate methods for future studies. Aspects to consider such as sex effects on side bias and can be used to reflect behavioral plasticity as a metric for the process of learning, such as time latency (longer it takes a toad to succeed, the more likely they will be successful) and the behavior displayed during the task as an indication of behavioral flexibility for decision making. Besides these aspects of the procedure, there are physiological and evolutionary aspects that might make toads unable to interact with non-mating sounds. These aspects and the level of hearing constraints that can affect learning assessment in toads are critical to answer broad questions on anuran auditory role beyond mating purposes

Analysis of Embodied and Situated Systems from an Antireductionist Perspective

The analysis of embodied and situated agents form a dynamical system perspective is often limited to a geometrical and qualitative description. However, a quantitative analysis is necessary to achieve a deep understanding of cognitive facts. The field of embodied cognition is multifaceted, and the first part of this thesis is devoted to exploring the diverse meanings proposed in the existing literature. This is a preliminary fundamental step as the creation of synthetic models requires well-founded theoretical and foundational boundaries for operationalising the concept of embodied and situated cognition in a concrete neuro-robotic model. By accepting the dynamical system view the agent is conceived as highly integrated and strictly coupled with the surrounding environment. Therefore the antireductionist framework is followed during the analysis of such systems, using chaos theory to unveil global properties and information theory to describe the complex network of interactions among the heterogeneous sub-components. In the experimental section, several evolutionary robotics experiments are discussed. This class of adaptive systems is consistent with the proposed definition of embodied and situated cognition. In fact, such neuro-robotics platforms autonomously develop a solution to a problem exploiting the continuous sensorimotor interaction with the environment. The first experiment is a stress test for chaos theory, a mathematical framework that studies erratic behaviour in low-dimensional and deterministic dynamical systems. The recorded dataset consists of the robots’ position in the environment during the execution of the task. Subsequently, the time series is projected onto a multidimensional phase space in order to study the underlying dynamic using chaotic numerical descriptors. Finally, such measures are correlated and confronted with the robots’ behavioural strategy and the performance in novel and unpredictable environments. The second experiment explores the possible applications of information-theoretic measures for the analysis of embodied and situated systems. Data is recorded from perceptual and motor neurons while robots are executing a wall-following task and pairwise estimations of the mutual information and the transfer entropy are calculated in order to create an exhaustive map of the nonlinear interactions among variables. Results show that the set of information-theoretic employed in this study unveils characteristics of the agent-environemnt interaction and the functional neural structure. This work aims at testing the explanatory power and impotence of nonlinear time series analysis applied to observables recorded from neuro-robotics embodied and situated systems

The persistence of memory

Distributing learning in time has the remarkable ability to enhance memory in a wide range of species and behavioral paradigms, a phenomenon termed the spacing effect. An extensive body of scientific work provides insight into the molecular and cellular processes that underlie the spacing effect. However, it is unclear how trial spacing alters the activity of the neuronal populations that store a specific memory. With my work presented in this doctoral dissertation, I explored the relationship between trial spacing, memory strength, and the pattern of in vivo neuronal activity. To achieve this aim, I executed two initial studies to address two outstanding methodological concerns. In the first study, I describe two nutritional restriction methods that balance mouse well-being and behavioral performance on an operant conditioning task. Nutritional restriction can be achieved by either food or fluid restriction and is typically necessary to ensure task engagement in mice. However, these procedures can have detrimental effects on mouse welfare if not executed diligently. I monitored the the effect of food or water restriction on mouse welfare as well as performance on a head-fixed two-choice visual discrimination task. In this study, both restriction regimen resulted in similar maximum learning performance while mouse discomfort was typically sub-threshold, providing a blueprint to the wider neuroscientific community to carry out similar experiments. In the second study, I compare a novel in vivo microscopy technique with the current golden standard for in vivo imaging of individual neurons, which is two-photon microscopy. Imaging using a miniaturized epifluorescence microscope is an efficient and effective approach to image hundreds of neurons while a mouse is engaged in a freely moving behavioral task, but does not achieve the same lateral and axial resolution as two-photon imaging. I performed in vivo calcium imaging of mouse primary visual cortex neurons expressing genetically encoded calcium indicators using both microscopy techniques while mice were presented with drifting gratings. I demonstrated that the response properties and tuning features of mouse visual cortex neurons to gratings of different orientations were quantitatively comparable in spite of qualitative differences between the two imaging methods. In the third and main study, I explore whether trial spacing affects memory strength and in vivo activity of a population of individual neocortical neurons. I addressed this question by examining two non-mutually exclusive hypotheses. Trial spacing could enhance the selective strengthening of the connections between neurons that store a preexisting memory. This would stabilize this neuronal ensemble, which would allow for more precise ensemble reactivation and thereby more effective memory retrieval. Alternatively, trial spacing could affect the recruitment of additional neurons that store new information from subsequent trials. This would increase the size of the neuronal ensemble, which would make the stored memory more resilient to destabilization. To explore these hypotheses, I trained mice on an everyday memory task, a delayed matching-to-place task that instilled episodic-like memories. Trial spacing promoted memory retrieval, yet surprisingly impaired memory encoding. Simultaneously, I measured neuronal activity using a miniaturized microscope in the dorsomedial prefrontal cortex, a neocortical structure that stored these memories as evidenced by the amnesic effect of chemogenetic inhibition of the dorsomedial prefrontal cortex during training. Trial spacing promoted reactivation of the neuronal ensemble but did not affect the size of the neuronal ensemble, thereby providing the first direct observation of the effect of trial spacing on the activity of neurons in the intact mammalian brain. In summary, the work presented in this doctoral dissertation used modern neuroscientific methods to study whether altered neuronal ensemble characteristics underlie the spacing effect, a phenomenon that was first described over a century ago