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The Effects of Reinforcer Distribution During Response Elimination on Resurgence of an Instrumental ResponseSchepers, Scott Timothy 01 January 2014 (has links)
Resurgence is the relapse of an extinguished instrumental behavior that can occur when an alternative behavior that was introduced to replace it is itself extinguished. In a typical resurgence experiment, rats are trained to make a response (R1) for food reinforcers. In a second phase, responses on R1 are no longer reinforced, but a new response (R2) is introduced and responses on it are reinforced. During a third phase, reinforcement for R2 is removed and behavior on R1 often returns (or "resurges") despite remaining on extinction.
The current experiments were designed to examine the effects of the temporal distribution of reinforcers delivered during Phase 2 on later resurgence. The role of these alternative reinforcers is central to theories that have been proposed to account for resurgence. The experiments provided a special opportunity to contrast predictions made by the Shahan-Sweeney Model (Shahan & Sweeney, 2011) and a contextual account of resurgence (Winterbauer & Bouton, 2010).
Experiments 1 and 2 examined resurgence when alternative reinforcement during Phase 2 was delivered according to the same set of daily reinforcement schedules presented in different orders. That is, one group received rich reinforcement rates that were gradually thinned to leaner ones (Group Thinning) and another group received lean rates that were gradually increased to richer ones (Group Reverse Thinning). Both procedures weakened resurgence compared to that in a group that received the richest rate (a variable interval, or VI 10-s schedule that arranged for a reinforcer to be available for a response every 10s on average) during all of the Phase 2 sessions. However, the forward thinning procedure was more effective than the reverse thinning procedure at eliminating the resurgence effect.
Experiment 3 examined resurgence when alternative reinforcement was only available for R2 during every other session. The results indicated that daily alternations of a VI 10-s schedule with an extinction schedule for R2 weakened resurgence compared to groups that either received the same average rate over the entire phase (VI 17.5-s) or that received the same terminal rate (VI 10-s) in every session.
The Shahan-Sweeney model cannot account for several of the current results. Instead, the results are most consistent with a contextual account of resurgence. That is, resurgence can be conceptualized as an ABC renewal effect in which extinguished R1 behavior returns when an animal is removed from an extinction "context" provided by R2 reinforcement. Lean reinforcement rates at any time during Phase 2 allow the animal to learn to inhibit R1 under conditions that generalize to the extinction conditions that prevail during the resurgence test. The results also suggest that experience with alternating extinction sessions or lean reinforcement rates close to the final resurgence test are especially effective at eliminating the resurgence effect.
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Modélisation du conditionnement animal par représentations factorisées dans un système d'apprentissage dual : explication des différences inter-individuelles aux niveaux comportemental et neurophysiologique / Modelling animal conditioning with factored representations in dual-learning : explaining inter-individual differences at behavioural and neurophysiological levelsLesaint, Florian 26 September 2014 (has links)
Le conditionnement Pavlovien, l'acquisition de réponses vers des stimuli neutres associés à des récompenses, et le conditionnement instrumental, l'expression de comportements pour atteindre des buts, sont au cœur de nos capacités d'apprentissage. Ils sont souvent étudiés séparément malgré les preuves de leur enchevêtrement. Les modèles de conditionnement instrumental reposent sur le formalisme de l'apprentissage par renforcement (RL), alors que les modèles du conditionnement Pavlovien reposent surtout sur des architectures dédiées souvent incompatibles avec ce formalisme, compliquant l'étude de leurs interactions.Notre objectif est de trouver des concepts, qui combinés à des modèles RL puissent offrir une architecture unifiée permettant une telle étude. Nous développons un modèle qui combine un système RL classique, qui apprend une valeur par état, avec un système RL révisé, évaluant les stimuli séparément et biaisant le comportement vers ceux associés aux récompenses. Le modèle explique certaines réponses inadaptées par l'interaction néfaste des systèmes, ainsi que certaines différences inter-individuelles par une simple variation au niveau de la population de la contribution de chaque système dans le comportement global.Il explique une activité inattendue de la dopamine, vis-à-vis de l'hypothèse qu'elle encode un signal d'erreur, par son calcul sur les stimuli et non les états. Il est aussi compatible avec une hypothèse alternative que la dopamine contribue aussi à rendre certains stimuli recherchés pour eux-mêmes. Le modèle présente des propriétés prometteuses pour l'étude du conditionnement Pavlovien,du conditionnement instrumental et de leurs interactions. / Pavlovian conditioning, the acquisition of responses to neutral stimuli previously paired with rewards, and instrumental conditioning, the acquisition of goal-oriented responses, are central to our learning capacities. However, despite some evidences of entanglement, they are mainly studied separately. Reinforcement learning (RL), learning by trials and errors to reach goals, is central to models of instrumental conditioning, while models of Pavlovian conditioning rely on more dedicated and often incompatible architectures. This complicates the study of their interactions. We aim at finding concepts which combined with RL models may provide a unifying architecture to allow such a study. We develop a model that combines a classical RL system, learning values over states, with a revised RL system, learning values over individual stimuli and biasing the behaviour towards reward-related ones. It explains maladaptive behaviours in pigeons by the detrimental interaction of systems, and inter-individual differences in rats by a simple variation at the population level in the contribution of each system to the overall behaviour. It explains unexpected dopaminergic patterns with regard to the dominant hypothesis that dopamine parallels a reward prediction error signal by computing such signal over features rather than states, and makes it compatible with an alternative hypothesis that dopamine also contributes to the acquisition of incentive salience, making reward-related stimuli wanted for themselves. The present model shows promising properties for the investigation of Pavlovian conditioning, instrumental conditioning and their interactions.
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Dopamine et contrôle de l’action : implication et maturation de la voie mésocorticale chez le rat / Dopamine and action control : involvement and maturation of the mesocortical pathway in the RatNaneix, Fabien 09 December 2011 (has links)
La prise de décision est une capacité cognitive essentielle à l’adaptation de l’individu aux changements de son environnement, et résulte de l’intégration de processus émotionnels, motivationnels et exécutifs. Le contrôle de l’action nécessite notamment l’intégration de la représentation du but de l’action et les relations causales entre une action et ses conséquences. Ces processus sont dépendants de plusieurs circuits préfronto-striataux et des données récentes indiquent que le système dopaminergique serait un élément central de leur modulation. Par ailleurs, ces circuits pourraient également se développer tardivement au moment de l’adolescence. Mon travail de thèse s’est donc employé à déterminer, d’une part, l’implication de la voie dopaminergique mésocorticale dans le contrôle de l’action, et d’autre part, le développement de ce système et de ces processus cognitifs au moment de l’adolescence.En utilisant des procédures d’apprentissage instrumental permettant de dégrader la contingence instrumentale ou de dévaluer la récompense, nous avons mis en évidence que la perturbation du système dopaminergique au sein du cortex préfrontal médian altère la capacité des animaux à s’adapter à des changements des relations action-récompense, mais non à des changements de la valeur de celle-ci. Par la suite, nous avons montré que les processus de contrôle de l’action lors de changements des relations causales action-conséquence apparaissaient tardivement au cours de l’adolescence, en relation avec le développement de la voie dopaminergique mésocorticale. De plus, l’altération du système dopaminergique lors de l’adolescence modifie également le développement des processus de contrôle des réponses instrumentales. / Decision making is an essential cognitive ability which allows a correct adaptation to an ever changing environment. This function results from the integration of emotional, motivational and executive processes. In particular, action control requires the encoding of both action goal value and action-outcome causal relationships. Previous studies have established that these processes are dependent on activity within segregated prefronto-striatal circuits whom activity might be tightly modulated by dopamine. In addition, the neurobehavioral maturation of these processes is not well understood but may occur during adolescence. Therefore, the aim of this work was to determinate the role of the mesocortical dopamine pathway in action control and the maturation of these neurobiological and cognitive processes during adolescence.Using instrumental conditioning tasks, allowing us to manipulate selectively the action-outcome contingency or the value of the outcome, we have demonstrated that alteration of the mesocortical dopamine pathway disrupts animals’ adaptation to changes in action-outcome relationships but not to changes in the outcome value. Interestingly, we provided evidence for the emergence of these cognitive abilities during adolescence in association with the delayed maturation of the mesocortical dopamine pathway. Finally, the alteration of the dopamine system maturation during adolescence also disrupts the development of action control processes.
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L’amygdale et la réponse aux stimuli associés aux récompenses : rôle des récepteurs glutamatergiques métabotropes du groupe IIGarceau, Caroline 08 1900 (has links)
Les stimuli conditionnés (CS) guident les animaux vers des récompenses essentielles à leur
survie, telle que la quête de nourriture et d'eau. Ils peuvent également promouvoir la poursuite
excessive de récompense, comme dans l’addiction. La transmission glutamatergique dans
l’amygdale basolatérale (BLA) régule les effets des CS. Cependant, le rôle des récepteurs
glutamatergiques métabotropes du groupe II (mGlu2/3) de la BLA est inconnu. Les mGlu2/3 sont
principalement localisés au niveau extrasynaptique sur les terminaisons neuronales. L’activation
de ces récepteurs diminue la libération synaptique de glutamate. Ainsi, nous avons émis
l’hypothèse que l'activation des mGlu2/3 dans la BLA diminue la capacité des CS à potentialiser la
recherche de récompense via la réduction de la libération de glutamate. La méthode de transfert
Pavlovien-à-instrumental (PIT) a été utilisée pour tester cette hypothèse. Nous avons d'abord
confirmé un effet PIT chez des rats mâles. Les rats ont initialement appris à appuyer sur un levier
pour obtenir de l’eau comme récompense. Ils ont ensuite appris qu'un stimulus auditif (CS+) prédit
la livraison non-contingente d'eau, tandis qu’un stimulus auditif différent (CS-) ne signale aucune
récompense. Le jour du test PIT, les rats ont pu appuyer sur le levier sous extinction (eau omise)
et nous avons évalué l’influence des CS+ et CS- sur ce comportement. Les rats ont appuyé
davantage sur le levier pendant le CS+ comparé au CS-, indiquant que le CS+ incite les rats à
rechercher la récompense. Chez un nouveau groupe de rats mâles, les mêmes méthodes ont été
appliquées avec un agoniste des mGlu2/3, le LY379268 (0, 3 ou 6 μg/hémisphère) injecté dans la
BLA avant le test PIT. Le LY379268 a diminué la capacité du CS+ à inciter l’appui sur le levier.
Dans une dernière étude, nous avons examiné l’influence d’une administration systémique de
LY379268 (0, 0.3 ou 1 mg/kg, sous-cutanée) sur l’effet PIT chez un groupe de rats mâles et
femelles. Les effets motivationnels du CS+ sur la recherche de récompense étaient similaires
entre les rats mâles et femelles. De plus, l’injection systémique de LY379268 a diminué ces effets
chez les deux sexes. Ces résultats indiquent que les mGlu2/3 régulent les propriétés
motivationnelles des CS chez les deux sexes. / Conditioned stimuli (CS) guide animals towards rewards needed for survival, such as food and
water. In parallel, they can also promote maladaptive reward seeking, as in addiction. Glutamate
signaling within the basolateral amygdala (BLA) modulates the effects of cues. However, the role
of metabotropic group II glutamate (mGlu2/3) receptors in the BLA is unknown. mGlu2/3 are
localized predominantly extrasynaptically on presynaptic terminals. The activation of these
receptors suppresses synaptic glutamate release. Thus, we hypothesized that activating BLA
mGlu2/3 receptors would attenuate cue-triggered increases in incentive motivation for reward, via
reduced glutamate release. The Pavlovian-to-Instrumental transfer (PIT) method was used to test
this hypothesis. We first confirmed a PIT effect in a cohort of male rats. Rats initially learned to
press a lever to obtain a water reward. Then, they learned that one auditory cue predicts noncontingent
delivery of water (CS+), while a second different auditory cue does not (CS-). On PIT
test day, the rats could lever press under extinction (water deliveries omitted), and we assessed
changes in lever pressing in response to CS+ and CS-. The rats pressed more on the lever during
CS+ versus CS-, indicating cue-triggered potentiation of incentive motivation. In a separate cohort
of male rats, the methods were repeated with the mGlu2/3 agonist LY379268 (0, 3 or 6
μg/hemisphere) infused into the BLA prior to PIT testing. LY379268 abolished CS+ potentiated
pressing on the water-associated lever. In a last study, we examined the influence of systemic
administration of LY379268 (0, 0.3 or 1 mg/kg, subcutaneous) on PIT, in a cohort of female and
male rats. We found that cue-triggered increases in incentive motivation was similar across sexes,
and that systemic injection of LY379268 decreased this effect in both sexes. These results
indicate that mGlu2/3 receptors mediate the motivational effects of cues in both sexes.
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Consumer Identity / Consumer IdentityYoung, Melissa Marie January 2009 (has links)
The purpose of this thesis is to prove that despite consumers' impression that they are alone in deciding their consumption decision they are wrong. Consumers are manipulated on various levels by marketers. It is the marketer who decides what consumer identities should be created. Consumers are persuaded by marketers on different levels beginning with consumers' needs. Marketers begin by appealing to consumer drives, motivations and emotions to persuade their consumers to purchase their brand. On a more in-depth level marketers manipulate consumers by using a variety of human behaviour learning strategies to sway consumers' purchasing decisions. In addition, marketers use various environmental and social-environmental influences to control their consumers. Lastly, a practical example illustrating the multinational corporation Nike is used, to prove that marketers are aware of these different methods and use them to manipulate consumers. In the end of this paper it is very obvious that consumers are easily persuade by marketers. A consumer is only the puppet while the marketer is the puppet string master.
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