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Enduring changes in reward mechanisms after developmental exposure to cocaine: The role of the D2 receptorStansfield, Kirstie H 01 June 2007 (has links)
During adolescent brain maturation, there are likely sensitive periods where environmental conditions, including drug exposure, may influence development by modifying neuronal connections. Altering neuronal function may produce different phenotypes than expected under normal conditions that may influence subsequent responding to drugs of abuse after the brain is fully mature. Experiment one investigated the relationship between novelty preference and cocaine place preference in adolescent and adult rats. High responding adolescent rats displaying greater free choice novelty exploration (but not forced novelty locomotion) expressed decreased cocaine place conditioning compared to low responding rats. No relationship was found in adult rats. Experiment two evaluated novelty-induced behaviors in adulthood after adolescent cocaine exposure. Repeated cocaine administration produced greater stress and anxiogenic behavioral responses to novelty in adult rats. Repeated alcohol administration produced less-inhibited novelty-induced behaviors in adulthood. Experiment three and four evaluated the consequence of developmental cocaine exposure on the rewarding efficacy of cocaine in adolescence and adulthood. Additionally, the interaction of D2 receptors and the rewarding efficacy of cocaine were investigated. After developmental cocaine exposure, adolescent and adult rats demonstrate decreased rewarding efficacy to cocaine. Importantly, blockade of the D2 receptor prevents cocaine-induced neurochemical changes, potentially regulating the behavioral and neurochemical alterations that occur after repeated drug use that increases the likelihood of dependence. Together, these data implicate both short and long-term behavioral adaptations that occur after developmental cocaine exposure that may result in a predisposition to develop adulthood drug dependence.
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Individual Differences in the Dopaminergic Reward System: The Effect of Genetic Risk on Neural Reward Sensitivity and Risky ChoiceSoder, Heather E. 01 January 2015 (has links)
When making decisions, individuals evaluate several possible outcomes of their choice; however, some display heightened reward sensitivity, despite the potential for future negative consequences, which can lead one to make risky choices. Rewards are processed in the mesolimbic dopamine reward system, and this system is in part modulated by genetic polymorphisms that are associated with dopamine transmission. The current study tested if genetic polymorphisms that are associated with enhanced dopamine neurotransmission will be more neurally reward sensitive, score higher on self-reported impulsivity, and make riskier choices. In a sample of 85 participants, five genetic polymorphisms were genotyped and used to create a genetic risk score that represented dopamine transmission efficiency. Two groups (high and low efficiency) were created via median split and then compared on neural reward sensitivity (assessed by event-related potentials, specifically, the medial-frontal negativity [MFN] and the error-related negativity), impulsivity (assessed via self-report), and risky choice (measured using the Balloon Analogue Risk Task and self-report measures). Results indicated that individuals with higher levels of dopamine displayed a less negative MFN and more drinking behaviors than those with lower levels of dopamine. These results suggest that individuals with higher levels of dopamine are less sensitive to punishments, which could lead them to make riskier choices.
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Belöningssystem som styrmedel för kvalitetsmål : En studie om den svenska telekombranschen / Reward systems as a tool for strategic aim on quality goals : A study of the Swedish telecommunication industryAl Dwek, Josef, Åberg, Alexander January 2015 (has links)
Telekombranschen står inför flera utmaningar, fokuset för den här studien handlar om utmaningen med kvalitetsmål. För den här studien blev det naturligt att undersöka problematiken genom att studera de anställda inom branschen. Den här studien utforskar vad som motiverar de anställda att arbeta kvalitativt med de tjänster som erbjuds kunderna, studien fokuserar på fem olika ledare i fem olika organisationer och anställda med olika säljandebefattningar. Studien undersöker belöningssystem och hur dessa är tänkta att motivera medarbetare att nå sina målbilder men även om organisationerna tenderar att lyfta fram vissa mål framför andra. I studien används både semistrukturerade intervjuer samt ett kvantitativt enkätutskick för att samla in data. Studien baseras på etablerade teorier inom marknadsföring, management samt psykologi. Det empiriska datamaterialet analyserades med stöd från teorierna vilket gav slutsatsen att belöningssystemen i branschen tyder på att vara missriktade i den utsträckning att det kan ha en påverkan på medarbetarnas motivation och deras driv för att arbeta för en hög kvalitet. / The telecommunication industry stands before many challenges, the focus in this essay is based on the quality goal challenges. In this study the natural way to explore this challenge is to investigate the employees working with sales in the industry. This essay explores what motivates the employees to work for high quality in the services they provide to the customers. The study focus on the relationship between the leaders and the employees of the industry. This study explore the reward systems and how the systems intend to motivate the employees to reach their goals and if there is any differences in how the goals that tend to be of greater importance to the organizations. In this study both semi-structured interviews as well as a quantitative survey is used to complement each other in order to collect data. The essay is based on different established theories in management, marketing and behaviorist studies. The analysis compared the empirical data with our theories which gave us the conclusion that reward systems in this industry may be misdirected in the case of motivating and rewarding employees to work for quality goals.
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Crowdfunding Social EntrepreneurshipStapylton-Smith, Charles January 2015 (has links)
In crowdfunding, funders often have very little or no information about the social entrepreneur and the venture. This asymmetric information hinders funding in that potential funders only make a pledge if they can trust the entrepreneur and the seriousness of the project. Thus entrepreneurs have to signal information to potential funders. In the case of conventional ventures, this means showing that the company is committed to the financial returns or the quality of the product, for instance. However, in the case of social enterprises, entrepreneurs can signal their commitment to a social or an environmental challenge. The information that entrepreneurs want to convey to potential funders depends very much on the type of crowdfunding. The type of crowdfunding determines whether the entrepreneur is pitching to potential investors, lenders or potential consumers and general supporters of the project. While investors tend to be more concerned with the financial returns, the quality of the product or service tends to be the variable that matters most to the potential consumer. This thesis examines the crowdfunding campaigns of social ventures in order to understand how to crowdfund social enterprises. It identifies the signals with which, social entrepreneurs try to attract funding through different types of crowdfunding, mainly reward-based. It finds that reward-based crowdfunding offers a good basis for social entrepreneurs to attract funding by advertising and signaling their commitment to social or environmental issues. This is all the more true when the social enterprise seeking to be crowdfunded only aims to be financially autonomous and thus cannot offer attractive financial returns to potential investors.
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Inhibitory Control and Reward Processes in Children and Adolescents with Traumatic Brain Injury and Secondary Attention-deficit/Hyperactivity DisorderSinopoli, Katia Joanne 23 February 2011 (has links)
Children with traumatic brain injury (TBI) often experience difficulties with inhibitory control (IC), manifest in both neurocognitive function (poor performance on the stop signal task, SST) and behavior (emergence of de novo attention-deficit/hyperactivity disorder, or secondary ADHD, S-ADHD). IC allows for the regulation of thought and action, and interacts with reward to modify behaviour adaptively as environments change. Children with developmental or primary ADHD (P-ADHD) exhibit poor IC and abnormalities when responding to rewards, yet the extent to which S-ADHD is similar to and different from P-ADHD in terms of these behaviours is not well-characterized. The cancellation and restraint versions of the SST were used to examine the effects of rewards on 2 distinct forms of IC in children and adolescents divided into 4 groups (control, TBI, S-ADHD, and P-ADHD). The SST requires participants to respond to a “go signal” and inhibit their responses when encountering a “stop signal”. Rewards improved performance similarly across groups, ages, and cancellation and restraint IC tasks. Adolescents exhibited better IC and faster and less variable response execution relative to children. Significant IC deficits were found in both tasks in the P-ADHD group, with participants with S-ADHD exhibiting intermediate cancellation performance relative to the other groups. Participants with TBI without S-ADHD were not impaired on either task. The relationship between neurocognitive and behavioral IC was examined by comparing multi-informant ratings of IC across groups, and examining the relationship between ratings and IC performance on the SST. Participants in the control and TBI groups were rated within the typical range, and exhibited fewer problems than either of the ADHD groups, who differed from each other (the P-ADHD group was rated as more inattentive than the S-ADHD group). Moderate to high concordance was found between parent and teacher reports, each of which was poorly concordant with self-reports. The P-ADHD and S-ADHD groups were unaware of their own deficits. Poorer IC predicted parent and teacher classification of participants into ADHD subtypes, although IC did not predict rating concordance. Despite similar clinical presentations, S-ADHD and P-ADHD differ in the phenotypic expression of behaviour and manifestation of IC across contexts.
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Belöningssystem : Har den nya ersättningspolicyn efter finanskrisen påverkat motivationen hos de anställda på Skandinaviska Enskilda Bankens distrikt Stockholm Norr?Stenvall, Sofia, Langöe, Sara January 2013 (has links)
Syfte: Syftet med denna uppsats är att utifrån Finansinspektionens nya regelverk om belöningssystem som infördes 2010 se om det har bidragit till en förändring i motivationen hos medarbetarna på Skandinaviska Enskilda Bankens distrikt Stockholm Norr. Metod: Datainsamlingen görs i form av en kvantitativ enkätundersökning med ett utskick till samtliga medarbetare på de utvalda bankkontoren inom distrikt Stockholm Norr på Skandinaviska Enskilda Banken. Teori: De teorier som används i studien är Abraham Maslows behovspyramid, David L Stums performance pyramid och Vrooms förväntningsteori. Slutsats: Motivationen hos medarbetarna på bankkontoren inom distrikt Stockholm Norr har inte förändrats trots en minskning i förmåner genom den nya ersättningspolicyn.
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Electrophysiological indices of feedback processingChristie, Gregory J, University of Lethbridge. Faculty of Arts and Science January 2010 (has links)
All sentient organisms use contextual information to assess the amount of reward associated
with a particular behavior. Human beings have arguably evolved the most sophisticated of these
mechanisms and are capable of integrating information over a long duration of time to
accurately assess the expected outcome of a chosen action. This thesis used
electroencephalography (EEG) to measure how the human brain processes rewarding and
punishing feedback in a gambling-type game with variable risk and reward. Experiment 1
determined that phase-locked (evoked) and non-phase-locked (induced) electroencephalographic
activity share only partially overlapping generators in human mediofrontal cortex. Experiment 2
determined that the magnitude of certain evoked EEG components during reward processing
tracked subsequent changes in bets placed in the next round. These results extend the body of
literature by assessing the overlap between induced and evoked EEG components and the role
of evoked activity in affecting future decision making. / xii, 76 leaves : ill. (chiefly col.) ; 29 cm
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Factors affecting amphetamine-induced 50 kHz ultrasonic vocalizations in adult ratsChehayeb, Diala. January 2007 (has links)
Adult rats produce two main types of ultrasonic vocalizations (USVs), occurring at 22 and 50 kHz USVs. These calls are associated with aversive and rewarding stimuli, respectively. The neural mechanism of amphetamine-induced calling was examined in lesion and antagonist studies. We also tested whether amphetamine-induced 50 kHz USVs could predict individual differences in intravenous self-administration or conditioned place preference behavior. Further experiments examined whether 50 kHz USVs could be evoked by amphetamine-conditioned sensory stimuli and by rewarding electrical brain stimulation. Overall, our experimental findings: (1) identify certain experimental conditions that increase amphetamine-induced 50 kHz calling, (2) provide evidence that these calls may be dependent on mesolimbic dopaminergic transmission, (3) relate individual differences in 50 kHz vocalizing to other behavioural measures of drug reward, and (4) show that in some situations, 50 kHz calls reflect anticipation of expected rewards.
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Reinforcement learning for qualitative group behaviours applied to non-player computer game charactersBradley, Jay January 2010 (has links)
This thesis investigates how to train the increasingly large cast of characters in modern commercial computer games. Modern computer games can contain hundreds or sometimes thousands of non-player characters that each should act coherently in complex dynamic worlds, and engage appropriately with other non-player characters and human players. Too often, it is obvious that computer controlled characters are brainless zombies portraying the same repetitive hand-coded behaviour. Commercial computer games would seem a natural domain for reinforcement learning and, as the trend for selling games based on better graphics is peaking with the saturation of game shelves with excellent graphics, it seems that better artificial intelligence is the next big thing. The main contribution of this thesis is a novel style of utility function, group utility functions, for reinforcement learning that could provide automated behaviour specification for large numbers of computer game characters. Group utility functions allow arbitrary functions of the characters’ performance to represent relationships between characters and groups of characters. These qualitative relationships are learned alongside the main quantitative goal of the characters. Group utility functions can be considered a multi-agent extension of the existing programming by reward method and, an extension of the team utility function to be more generic by replacing the sum function with potentially any other function. Hierarchical group utility functions, which are group utility functions arranged in a tree structure, allow character group relationships to be learned. For illustration, the empirical work shown uses the negative standard deviation function to create balanced (or equal performance) behaviours. This balanced behaviour can be learned between characters, groups and also, between groups and single characters. Empirical experiments show that a balancing group utility function can be used to engender an equal performance between characters, groups, and groups and single characters. It is shown that it is possible to trade some amount of quantitatively measured performance for some qualitative behaviour using group utility functions. Further experiments show how the results degrade as expected when the number of characters and groups is increased. Further experimentation shows that using function approximation to approximate the learners’ value functions is one possible way to overcome the issues of scale. All the experiments are undertaken in a commercially available computer game engine. In summary, this thesis contributes a novel type of utility function potentially suitable for training many computer game characters and, empirical work on reinforcement learning used in a modern computer game engine.
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The Rewarding Nature of Anger Rumination in Borderline Personality Disorder: An fMRI InvestigationPeters, Jessica R. 01 January 2015 (has links)
Anger rumination, or persistently dwelling on feelings of anger, is associated with borderline personality disorder (BPD) and related features, such as aggressive behavior and cognitive distortions. To develop more effective treatments, it is crucial to understand why individuals with BPD engage in anger rumination despite its negative outcomes. The activation of energy associated with anger, as well as feelings of justification and validation, may be experienced in the short-term as rewarding. This may prevent individuals with BPD from attempting to reduce their rumination.
Functional magnetic resonance imaging (fMRI) and behavioral methods were utilized to examine this theory in a sample of women diagnosed with BPD (n=13) and healthy controls (n=15). In an initial session, all participants were an administered a diagnostic interview for BPD, as well a series of self-report measures. In a second session, all participants completed an essay-writing task prior to the fMRI scan. All participants were provided with identical, highly critical feedback about their essays from a supposed essay evaluator. In response to this interpersonal provocation, participants with BPD demonstrated higher activation in brain regions associated with self-conscious reactivity to errors (insula, ventrolateral prefrontal cortex). Subsequent directed provocation-focused thought, compared to neutral-focused thought, produced greater activation in regions previously associated with anger rumination (dorsomedial prefrontal cortex, lateral orbitofrontal cortex) across groups. As hypothesized, anger rumination, relative to neutral-focused thought, produced greater activation in brain regions associated with reward and pleasure (nucleus accumbens) for the BPD group only. No significant differences were observed for self-focused thought. Following the directed rumination task, participants completed a competitive reaction time task that provides an opportunity for participants to act aggressively, supposedly against their essay evaluator. The BPD group demonstrated significantly higher levels of aggressive behavior; however, no significant group differences emerged in neural functioning during the task. These findings suggest that anger rumination may be positively reinforcing for individuals with BPD, which has implications for treatment approaches.
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