In this dissertation, a new method of interaction with virtual reality (VR) has been presented. The VR environment, developed in this work provides a realistic and immersive environment that is developed for studying human’s spatial cognition abilities. Different technical aspects of the implementation are described. To improve the accuracy of the experiments, a new method for comparing and analyzing trajectories has been presented. A set of human subject experiments have been conducted using the developed platform. The first experiment was based on an ordinary computer, a joystick and 40 cognitively healthy participants within the age range of 19 to 82 years. Participants were asked to perform the VR spatial cognition test by navigating in the VR environment. It was found that computer usage skills had an effect on the overall performance of the participants as well as motion sickness; such an effect was undesirable. To resolve both problems, a novel input device made from the combination of a wheelchair and a motion capture unit, called VRNChair was developed. The VRNChair allows the participant to move physically in the real world in order to navigate in the VR environment. This allows participants to have a more intuitive interaction with the VR environment. Since the participant physically experiences the motion seen in the VR, motion sickness is minimized. A test based on two age groups, 34 young (< 40 years) and 20 older (60+ years) participants was performed. The results showed no difference between using the VRNChair or the joystick for the young participants while it showed considerable improvement among the older participants. Furthermore, it was noted that participants became distracted while using the VRNChair, Hence, a head mounted display (HMD) was added to the platform. A test with 14 males showed less distraction to the participant by using the HMD. Overall, the VR environment designed in this work passed all the validation experiments successfully. It offers a novel solution to overcome induced motion sickness experienced as a side effect of VR environments. / October 2016

In this thesis I explore how older people make use of, and interact with, their physical environment in home and near-by settings to manage cognitive situations, specifically prospective memory situations. Older adults have in past research been shown to perform better on prospective memory in real-life settings than what findings in laboratory-like settings predict. An explanation for this paradox is that older adults has a more developed skill of using the environment for prospective memory than younger adults. However, research investigating this explanation has primarily been based on self-reports. I contribute to the understanding of this skill by doing two related things. First I introduce distributed cognition, a theoretical perspective that primarily has been used within professional and socio-technical environments, to the research field of prospective memory in everyday life. Second I present a cognitive ethnography conducted during two years across eight home, and near-by, environments and old-age retired persons, for which I have used theoretical concepts from distributed cognition to analyze observations. The analysis shows rich variations in how participants use common cultural cognitive tools, invent their own cognitive tools, deliberately and incidentally shape more or less functional spaces, make use of other physical features, orient themselves toward and make sense of cognitive resources. I complement both prospective memory and distributed cognition research by describing both the intelligent shaping and use of space. Furthermore, by taking a distributed cognitive perspective I show that prospective memory processes in home environments involve properties, and the management, of a multipurpose environment. Altogether this supports the understanding of distributed cognition as a perspective on all cognition. Distributed cognition is not a reflection of particular work practices, instead it is a formulation of the general features of human cognition. Prospective memory in everyday life can be understood as an ability persons have. However, in this thesis I show that prospective memory can also be understood as a process that takes place between persons, arrangements of space, and tools.

While some cognitive decline is part of the normal aging process, certain changes have been linked to physical health or lifestyle-related diseases and may be preventable. Hypertension and type 2 diabetes are two conditions that have been associated with a heightened risk of accelerated cognitive decline. In terms of protective factors, physical activity can positively impact a broad range of cognitive processes including memory, attention, and executive function and may also protect against or delay cognitive decline and dementia. The present study examined the extent to which physical activity moderates the impacts of hypertension and diabetes (and their interactions) on different cognitive functions. Data are from the Memory and Aging Project (MAP), a longitudinal study of older adults (N = 1400, mean age = 79). A series of multilevel models evaluated baseline differences and linear and quadratic change on four cognitive measures: mental status, perceptual speed, and immediate and delayed episodic memory. Higher levels of self-reported physical activity were associated with better perceptual speed at baseline, and significantly less linear decline across all four measures. Physical activity was not significantly associated with curvilinear change. Individuals with diabetes had significantly worse immediate episodic memory performance at baseline, but diabetes was largely unrelated to rate of change and initial performance on the other measures. Hypertension was associated with better initial mental status (linear and quadratic models) and delayed episodic memory (quadratic model). Contrary to expectations, most interactions between physical activity and the two health conditions were non-significant. However, physical activity appeared to moderate the relationship between comorbid diabetes and hypertension on immediate episodic memory, such that individuals with the two conditions who were more physically active experienced a reduced rate of linear and curvilinear decline compared to inactive individuals with diabetes and hypertension. The findings from this study suggest that physical activity may reduce the impact of comorbid conditions on certain cognitive functions, and that immediate episodic memory may be particularly susceptible. / Graduate

In the field of robotics, there has recently been tremendous progress in the development of autonomous robots that offer various services to their users. Most of the systems developed so far, however, are restricted to indoor scenarios, non-urban outdoor environments, or road usage with cars. There is a serious lack of capabilities of mobile robots to navigate safely in highly populated outdoor environments. This ability, however, is a key competence for a series of robotic applications. We consider the task of developing a spatially motivated dialogue system that can operate on a robotic platform, where the purpose of such a robot is to aid pedestrians in urban environments to provide information about surrounding objects and services, and guide users to desired destinations. In this thesis, we make a number of contributions to the fields of spatial language interpretation/generation and discourse modelling. This includes the development of a dialogue framework called HURDLE which builds on the strengths of existing systems, accompanied by a specific implementation for spatially oriented dialogue including disambiguating amongst objects and locations in the environment, and a natural language parser which combines an extension of Synchronous Context Free Grammars with a Part-of-Speech tagger. Our research also presents a number of probabilistic models for spatial prepositions such as `in front of' and `between' that make significant advances in effectively utilising geometric environment data, encompassing visibility considerations and being reusable for both indoor and outdoor environments. We also present a number of algorithms in which these models can be utilised, most significantly a novel and highly effective algorithm that can generate natural language descriptions of objects that disambiguates on their location. All these components, while modular, operate in tandem and interact with a variety of external components (such as path planning) on the robot platform.

The present study was conducted to clarify and expand knowledge of cognitive functioning in chronic schizophrenia patients (N=21) as compared to a bipolar group (N=20) and a normal group (N=20).

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This thesis provides a conceptual and empirical analysis of implicit concept formation. A review of concept formation studies highlights the need for improving existing methodology in establish- ing the claim for implicit concept formation. Eight experiments are reported that address this aim. A review of theoretical issues highlights the need for computational modelling to elucidate the nature of implicit learning. Two chapters address the feasibility of different exemplar and Connectionist models in accounting for how subjects perform on tasks typically employed in the implicit learn- ing literature. The first five experiments use a concept formation task that involves classifying "computer people" as belonging to a particular town or income category. A number of manipulations are made of the underlying rule to be learned and of the cover task given subjects. In all cases, the knowledge underlying classification performance can be elicited both by free recall and by forced choice tasks. The final three experiments employ Reber's (e.g., 1989) grammar learning paradigm. More rigorous methods for eliciting the knowledge underlying classification performance are employed than have been used previously by Reber. The knowledge underlying clas- sification performance is not elicited by free recall, but is elicited by a forced-choice measure. The robustness of the learning in this paradigm is investigated by using a secondary task methodol- ogy. Concurrent random number generation interferes with all knowledge measures. A number of parameter-free Connectionist and exemplar models of artificial grammar learning are tested against the experimental data. The importance of different assumptions regarding the coding of features and the learning rule used is investigated by determin- ing the performance of the model with and without each assumption. Only one class of Connectionist model passes all the tests. Fur- ther, this class of model can simulate subject performance in a different task domain. The relevance of these empirical and theoretical results for understanding implicit learning is discussed, and suggestions are made for future research.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

De nombreuses études menées chez l’homme ont montré que l’obésité est associée à un état inflammatoire chronique caractérisé par une augmentation de la sécrétion de nombreuses molécules dont la leptine et des cytokines inflammatoires comme le TNF-a et l’IL-6 (Clement et al., 2004). Des données récentes suggèrent que cette inflammation périphérique pourrait également présenter une composante au niveau cérébral se caractérisant notamment par une augmentation de l’expression de différentes cytokines inflammatoires (IL-6, TNF-a, IL-1ß…) et de l’activation de leurs voies de signalisation intracellulaire (augmentation de l’activité c-Jun-N-terminal kinase et de NFkB)(De Souza et al., 2005). De plus, l’intensité de la situation inflammatoire semble être liée au degré d’obésité. Ainsi, il est possible de distinguer différentes situations d’obésité : une obésité modérée qui ne s’accompagne pas forcément de pathologies comorbides et une obésité morbide associée à différents types de complications comme des maladies cardio-vasculaires, de l’hypertension artérielle ou un diabète de type 2. L’obésité s’accompagne également d’une forte prévalence de troubles de l’humeur (anxiété, dépression) et de la cognition. Notre laboratoire a été un des pionniers dans l’étude de l’expression et de l’action des cytokines au niveau central et de leurs conséquences, tant comportementales que neurobiologiques. Cette relation entre système de l'immunité innée et cerveau a particulièrement été étudiée dans le cadre du comportement de maladie regroupant un ensemble de symptômes non spécifiques (fièvre, activations neuroendocriniennes, anorexie, anhédonie, repli sur soi, perte d’intérêt pour l’environnement…) observés chez les individus malades et pouvant être reproduits chez l’animal en réponse à l’injection d’un inducteur de cytokines tel que le lipopolysaccharide (LPS)(Dantzer, 2001). Dans le cas d’une exposition prolongée ou non régulée de l’activation du réseau de cytokines, le comportement de maladie peut laisser place à de véritables troubles de l’humeur et de la cognition associés à une chute des taux circulants de tryptophane, un acide aminé essentiel servant de précurseur et de facteur limitant à la synthèse de sérotonine. Il a été montré que l'indoléamine 2,3-dioxygénase (IDO), une enzyme dégradant le tryptophane en réponse aux cytokines (Lestage et al., 2002; Moreau et al., 2005) est impliquée dans l’induction des symptômes de type dépressif observés notamment suite à production soutenue de cytokines et que cette action serait dépendante du catabolisme du tryptophane via la voie de la kynurenine (O'Connor et al., 2008). L’activation de l’IDO en situation inflammatoire aboutit à la production de dérivés neurotoxiques (3-OH-kynurénine, acide quinolinique) se comportant comme des agonistes des récepteurs glutamatergiques de type NMDA (Taylor and Feng, 1991), au dépend de la production de sérotonine. Ainsi, l’activation de l’IDO par les cytokines pourrait jouer un rôle dans l’apparition de troubles cognitifs associés aux états inflammatoires via l’altération de la neurotransmission sérotoninergique et/ou glutamatergique. Ces mêmes mécanismes pourraient également sous-tendre le développement des troubles de l’humeur et de la cognition couramment observés chez les personnes obèses. L’ensemble des études réalisées dans ce travail de thèse a donc eu pour objectif général de déterminer chez la souris si l’inflammation chronique à bas bruit qui est associée à un état d’obésité entraînait le développement de troubles de l’humeur et de la cognition [...]. / Severe obesity is associated with a low grade inflammation characterized by an increased release of inflammatory markers like cytokines and leptin. It has been suggested that some of these mediators of inflammation could also be found in the brain, as manifested by the increased hypothalamic expression of inflammatory cytokines (IL-6, TNF-a, IL-1) and the activation of their intracellular pathways. Moreover, the intensity of the inflammation state seems to increase with the degree of obesity. Morbid obesity, which is accompanied by different comorbid pathologies like cardiovascular disease, hypertension, type 2 diabetes and a high prevalence of mood (anxiety, depression) and cognitive disorders, is clearly associated with peripheral inflammation. Such an association is less clear in the case of a moderate obesity which is not systematically associated with comorbid pathologies. It is clearly established that during an infection brain actions of cytokines that are released as a result of the innate immune system activation induce development of sickness behaviour. In the case of a prolonged and/or unregulated activation of the cytokine network, sickness behaviour that includes non-specific symptoms such as behavioral alterations, fever and neuroendocrine activation can lead to the development of mood and cognitive disorders. Moreover, such a development is associated with a drastic drop of circulating levels of tryptophan, the essential amino acid acting as limiting factor of the serotonin synthesis. It has been proposed that these alterations could be at least partially explained by cytokine-induced peripheral and/or central activation of the indoleamine 2,3-dioxygenase (IDO), a tryptophan-catabolizing enzyme that is potently induced in monocytes, macrophages and brain microglia by cytokines. IDO activation can result in the lowering of the bioavailability of tryptophan for 5-HT synthesis and the increase of neurotoxic derivates (3-OH-kynurenine, quinolinic acid). Both consequences of cytokine-induced IDO activation may play a role in the development of the cognitive and mood disorders associated with obesity. The present study aimed therefore at studying in mice the relationship between inflammation and development of mood and cognitive disorders associated with obesity. This study was performed in two different but complementary experimental conditions reproducing 1) a moderate obesity devoid of marked pathological complications (a model of diet induced obesity) and 2) a morbid obesity associated with comorbid pathologies like type 2 diabetes (db/db mice). Our results showed that: 1) The degree of obesity is correlated with the intensity of the alterations affecting innate immune system activation. 2) Obesity exacerbates the innate immune system activation as manifested by the increase of peripheral and central cytokine production, and related neurochemical, neuroendocrine and behavioral alterations. 3) The inflammation-related alterations induced by obesity are associated with impairment of cognitive abilities and emotional reactivity, as well as development of anxiety-like symptoms, although differences in their respective time-course of appearance seem to exist. Taken together, these findings showed the key role of the inflammation associated with obesity in its related mood and cognitive disorders. This work provides therefore a first important step towards the identification of new pharmacological and/or nutritional strategies aimed at ameliorating life quality of obese subjects and preventing development of related comorbidities.

The provision of key text reading lists relies on students to select one they will utilise in undertaking a course. In anatomy and physiology an array of texts exist providing lecturers with the task of deciding the most suitable for inclusion within this list, the final choice for a student to undertake. Little evidence was found to identify the decision-making a student undertook in selecting a text. Based on disparate theoretical concepts an initial development of a conceptual process framework followed to provide a basis from which to identify influences which impacted on the student decision-making process. Using a mixed methods design a survey of students (N=964) undertaking anatomy and physiology courses was conducted whose results, following analysis provided the focus for in depth interviews. These included students (n=15), lecturers (n=3) authors (n=5) and publishers (n=2). Thematic analysis of the transcripts identified four overarching themes these being the Perception of the Textbook, Choice of the Textbook, Mismatch of Perceived Needs and Place of the Textbook. The results suggested two main influences which impacted on the student when choosing a text, those of existing prior knowledge and recommendation. Without prior knowledge, comprehension and cognition of the text was difficult. Recommendation by a lecturer or reading list, a strong influence, saw students selecting a recommended text without considering their own needs leading to an inability to use this. Without knowledge and recommendation students utilised aesthetic preference and heuristics in selecting a text, with many selecting additional texts to assist in using recommended texts. The results led to the development of the conceptual process framework indicating choice was a complex process for the student. Selecting a text is complex and affected by numerous influences. The study highlights a process through which a student traverses as they undertake the selection of their text. The study conclusions have led to the development of the Process Framework for Text Selection providing a novel and coherent linking of established theoretical concepts.