• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 10
  • 5
  • 4
  • 3
  • 3
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 83
  • 83
  • 28
  • 15
  • 12
  • 11
  • 11
  • 10
  • 10
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Bayesian cognitive modeling of the balancing between goal-directed and habitual behavior

Schwöbel, Sarah 05 November 2020 (has links)
This thesis proposes a novel way to describe habit learning and the resulting balancing of goal-directed and habitual behavior using cognitive computational modeling. This approach builds on experimental evidence that habits may be understood as context-dependent automated sequences of behavior embedded in a hierarchical model. These assumptions were implemented in a Bayesian model, where goal-directed action sequences are encoded using a Markov decision process, and habits are interpreted to arise from a Bayesian prior over such sequences. Simulations show that this modeling approach yields key properties of habit learning, such as increased habit strength with increased training duration. This novel mechanistic description may lead to an improved understanding of habit learning mechanisms and individual learning trajectories, which may have implications for mental disorders which are believed to be accompanied by a maladapted balance between goal-directed an habitual control. / Diese Arbeit stellt eine neue mechanistische Beschreibung von Gewohnheitslernen und der daraus resultierenden Balance zwischen zielgerichtetem und habituellem Verhalten vor, die auf einem mathematischen kognitiven Modell aufbaut. Der Ansatz beruht auf experimenteller Evidenz, dass Gewohnheiten als kontext-abhängige, automatisierte Verhaltenssequenzen verstanden werden können, die in ein hierarchisches Modell eingebettet sind. Diese Annahmen werden mathematisch in einem Bayes'schen Modell umgesetzt, in dem zielgerichtetes Handeln als ein Markov'scher Entscheidungsprozess implementiert ist und Gewohnheiten aus einer Bayes'schen a-priori Wahrscheinlichkeit von Verhaltenssequenzen entstehen. Simulationen zeigen, dass dieser Ansatz wichtige Eigenschaften von Gewohnheitslernen reproduzieren kann, wie beispielsweise dass längere Trainingsdauern zu stärkeren Gewohnheiten führen. Diese neue mechanistische Beschreibung kann zu einem besseren Verständis individueller Lerntrajektorien und der Mechanismen beitragen, die dem Gewohnheitslernen zugrundeliegen. Dies könnte auch Auswirkungen auf das Verständnis psychischer Erkrankungen haben, bei denen davon ausgegangen wird, dass sie von einer maladaptiven Balance zwischen zielgerichtetem und habituellem Verhalten begleitet werden.
62

Prospective Control: Effect of Exploratory-task-generated-motion on Adaptation in Real and Virtual Environments

Littman, Eric Marshall 25 March 2009 (has links)
No description available.
63

A Neuro-dynamical model of Synergistic Motor Control

Byadarhaly, Kiran January 2013 (has links)
No description available.
64

Reference frames for planning reach movement in the parietal and premotor cortices

Taghizadeh, Bahareh 17 February 2015 (has links)
No description available.
65

Les comportements orientés vers un but : implication de l'hippocampe et du cortex préfrontal chez le rat

Saint Blanquat, Paul de 20 December 2011 (has links)
Les comportements orientés vers un but sont complexes et font appel à un grand nombre de processus cérébraux. Le cortex préfrontal médian (mPFC) apparaît comme une structure clef dans la réalisation de ces comportements de par son rôle dans la planification. De plus, il existe au sein du mPFC des cellules signalant les lieux à forte valeur motivationnelle. L’activité de ces neurones pourrait être essentielle à la mise en place d’un comportement spatial dirigé vers un but. S’orienter vers un but nécessite aussi la construction d’une représentation stable de l’environnement, qui repose sur l’activité de l’hippocampe (HPC). Néanmoins, peu de travaux ont analysé le rôle respectif de ces deux structures, et leurs interactions, lors de l’acquisition et de la consolidation d’une stratégie comportementale orientée vers un but. L’objectif des recherches réalisées au cours de ma thèse est donc d’étudier l’implication de l’hippocampe et du cortex préfrontal médian du rat dans ce processus. Notre première étude a montré l’existence d’un codage prospectif au sein des neurones du mPFC durant la réalisation d’une tâche de mémoire de travail.L’activité des neurones signale à la fois, la séquence temporelle comportementale, et l’anticipation de la récompense, et jouerait ainsi un rôle dans les fonctions exécutives. Dans la deuxième étude, nous nous sommes intéressés aux structures cérébrales impliquées dans la mise à jour de la valence du but ainsi que dans sa rétention à long terme. Nos résultats ont montré que l’inactivation de l’hippocampe intermédiaire provoque des déficits dans le traitement à court terme d’un changement de valence. En revanche, l’inactivation du mPFC empêche le stockage à long terme de ce changement. L’activité de ces deux structures serait donc essentielle pour effectuer une mise à jour en temps réel de la valence d’un but et pour sa consolidation en mémoire à long terme. Leur interaction permettrait d’adapter rapidement et de façon durable la stratégie comportementale de l’animal face aux changements de l’environnement. / Goal-directed behaviors are complex and involve a variety of cognitive processes. Medial prefrontal cortex (mPFC) plays a key role in behavioral planning. More over, cells in the rat mPFC show specific firing modulations at location with a high motivational value. Such neuronal activity could be essential for the setting up installation of a goal-directed behavior. Further more, navigating to a spatial goal requires the building of a stable presentation of the environment which is hippocampus-dependent. So far however, only few studies have addressed the respective role of these two structures, and their interaction, during the acquisition and the consolidation of a goal directed-behavior. The work conducted during my PhD thesis aimed at studying the role of hippocampus and prefrontal cortex in this process. In a first study,we showed the existence of a prospective coding by mPFC neurons when the rat performs a working memory task. Neuronal activity signals both, the temporal sequence of the behavior, and the prediction of reward. These neurons would play a role inexecutive functions. In a second study, we focused on cerebral structures involved in the updating of the value of a goal as well as in its long-term retention. Our results showed that the inactivation of the intermediate hippocampus causes deficit in the short-term processing of a change in the goal value. On the other hand, the inactivation of the mPFC prevents long-term consolidation of this change. Integrity of this two structures would therefore be essential to perform an on-line updating of the goal value and for its long-term consolidation. Their interaction would be necessary to rapidly adapt, and in a lasting manner, the behavioral strategy of the animal when it faces an environmental change.
66

Neuronal mechanisms of the adaptation of conditional visuomotor behavior / Neuronale Mechanismen für die Adaptation von konditionellem visuomotorischem Verhalten

Westendorff, Stephanie 28 October 2010 (has links)
No description available.
67

Prospective control effect of exploratory-task-generated-motion on adaptation in real and virtual environments /

Littman, Eric Marshall. January 2009 (has links)
Thesis (M.A.)--Miami University, Dept. of Psychology, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 43-47).
68

Hemodynamika v časné fázi kritických stavů a perioperační medicíně / Hemodynamics in the early stages of the critical illness and in the perioperative setting

Beneš, Jan January 2012 (has links)
Beneš J.: HEMODYNAMIKA V ČASNÉ FÁZI KRITICKÝCH STAVŮ A PERIOPERAČNÍ MEDICÍNĚ - Využití méně invazivních monitorovacích prostředků k cílené hemodynamické péči ABSTRACT Hemodynamic instability occurs very often in critically ill patients and during the perioperative period. Insufficiency in the preload, contractility and afterload contribute in major part to this phenomenon. Hemodynamic monitoring allows clinicians to recognize and to intervene early the underlying cause. Due to new technologies development in recent years it is possible to provide continuous monitoring of hemodynamic parameters with diminished invasivity. Hemodynamic optimization and goal directed therapy show treatment benefit in some groups of critically ill patients and mainly during the perioperative period. Aim of hemodynamic optimizations is to attain the best obtainable hemodynamic conditions with use of fluid loading and inotropic support. In many studies in recent years goal-directed therapy was associated with morbidity and mortality reduction. According to the results of our clinical research hemodynamic optimization using stroke volume variation and minimally invasive device based on the pressure wave analysis is feasible and show the same results as other works with more invasive devices. Key words Hemodynamic monitoring,...
69

Social causality in motion : Visual bias and categorization of social interactions during the observation of chasing in infancy

Galazka, Martyna A. January 2017 (has links)
Since the seminal work of Fritz Heider and Marienne Simmel (1944) the study of animacy perception, or the perception and attribution of life from the motion of simple geometrical shapes has intrigued researchers. The intrigue for psychologists and vision scientists then and today centered on the stark disconnect between the simplicity of the visual input and the universal richness of the resulting percept. Infant research in this domain has become critical in examining the ontological processes behind the formation of animated percepts. To date, little is known about how infants process these kinds of stimuli. While numerous habituation studies have shown sensitivity to animate motion in general, none to date has examined whether infants actually perceive animate displays as social interactions. The overarching goal of the present thesis is to answer this question and further augment knowledge about the mechanisms behind the formation of animated percepts in infancy. I, along with my collaborators, do so in three ways, in three separate studies. First, we examined visual attention during online observation of randomly moving geometrical shapes in adults and infants (Study I, using eye tracking). Second, we examine distribution of visual attention in infancy during online observation of non-contact causal interactions, focusing on the most ubiquitous, fitness relevant of interactions – chasing (Study II, using eye tracking). Third, we answer the question whether infants perceive social content in chasing displays by measuring the neural correlates in response to chasing (Study III, using EEG). The collective contribution of the present work is also three fold. First, it demonstrates that starting at the end of the first year of life, human visual system is sensitive to cues that efficiently predict an interaction. Second, at 5-months infants begins allocating attention differently across agents within interactions. Finally, attention to specific objects is not due to low-level saliency but the social nature of the interaction. Subsequently, I present the case that perception of social agents is fast, direct, and reflects the workings of a specialized learning mechanisms whose function is the detection of heat-seeking animates in motion.
70

Neuroscience of decision making : from goal-directed actions to habits / Neuroscience de la prise de décision : des actions dirigées vers un but aux habitudes

Topalidou, Meropi 10 October 2016 (has links)
Les processus de type “action-conséquence” (orienté vers un but) et stimulus-réponse sont deux composants importants du comportement. Le premier évalue le bénéfice d’une action pour choisir la meilleure parmi celles disponibles (sélection d’action) alors que le deuxième est responsable du comportement automatique, suscitant une réponse dès qu’un stimulus connu est présent. De telles habitudes sont généralement associées (et surtout opposées) aux actions orientées vers un but qui nécessitent un processus délibératif pour évaluer la meilleure option à prendre pour atteindre un objectif donné. En utilisant un modèle computationnel, nous avons étudié l’hypothèse classique de la formation et de l’expression des habitudes au niveau des ganglions de la base et nous avons formulé une nouvelle hypothèse quant aux rôles respectifs des ganglions de la base et du cortex. Inspiré par les travaux théoriques et expérimentaux de Leblois et al. (2006) et Guthrie et al. (2013), nous avons conçu un modèle computationnel des ganglions de la base, du thalamus et du cortex qui utilise des boucles distinctes (moteur, cognitif et associatif) ce qui nous a permis de poser l’hypothèse selon laquelle les ganglions de la base ne sont nécessaires que pour l’acquisition d’habitudes alors que l’expression de telles habitudes peut être faite par le cortex seul. En outre, ce modèle a permis de prédire l’existence d’un apprentissage latent dans les ganglions de la base lorsque leurs sorties (GPi) sont inhibées. En utilisant une tâche de bandit manchot à 2 choix, cette hypothèse a été expérimentalement testée et confirmée chez le singe; suggérant au final de rejeter l’idée classique selon laquelle l’automatisme est un trait subcortical. / Action-outcome and stimulus-response processes are two important components of behavior. The former evaluates the benefit of an action in order to choose the best action among those available (action selection) while the latter is responsible for automatic behavior, eliciting a response as soon as a known stimulus is present. Such habits are generally associated (and mostly opposed) to goal-directed actions that require a deliberative process to evaluate the best option to take in order to reach a given goal. Using a computational model, we investigated the classic hypothesis of habits formation and expression in the basal ganglia and proposed a new hypothesis concerning the respective role for both the basal ganglia and the cortex. Inspired by previous theoretical and experimental works (Leblois et al., 2006; Guthrie et al., 2013), we designed a computational model of the basal ganglia-thalamus-cortex that uses segregated loops (motor, cognitive and associative) and makes the hypothesis that basal ganglia are only necessary for the acquisition of habits while the expression of such habits can be mediated through the cortex. Furthermore, this model predicts the existence of covert learning within the basal ganglia ganglia when their output is inhibited. Using a two-armed bandit task, this hypothesis has been experimentally tested and confirmed in monkey. Finally, this works suggest to revise the classical idea that automatism is a subcortical feature.

Page generated in 0.0551 seconds