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Sample records for aberrant reward prediction

  1. Aberrant reward processing in Parkinson's disease is associated with dopamine cell loss.

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    Aarts, Esther; Helmich, Rick C; Janssen, Marcel J R; Oyen, Wim J G; Bloem, Bastiaan R; Cools, Roshan

    2012-02-15

    Dopamine has been implicated in reward-related impulsivity, but the exact relationship between dopamine, reward and impulsivity in humans remains unknown. We address this question in Parkinson's disease (PD), which is characterized by severe dopamine depletion. PD is associated primarily with motor and cognitive inflexibility, but can also be accompanied by reward-related impulsivity. This paradoxical symptom of PD has often been attributed to dopaminergic overstimulation by antiparkinson medication, which is necessary to relieve the motor and cognitive inflexibility. However, factors other than medication may also contribute to aberrant impact of reward. Here we assess whether cognitive inflexibility and aberrant reward impact in PD are two sides of the same coin, namely dopamine cell loss. To measure dopamine cell loss, we employed (123)I-FP-CIT Single Photon Emission Computed Tomography (SPECT) in 32 PD patients (10 never-medicated patients and 22 patients after withdrawal of all medication for >12h) and related the values to behavior on a rewarded task-switching paradigm. Dopamine cell loss was associated not only with cognitive inflexibility (under low reward), but also with aberrant impact of reward. These effects could not be attributed to medication use. Relative to controls (n=26), aberrant reward processing in PD was particularly expressed as reduced capacity to maintain (i.e., repeat) the current task-set under high reward. Our findings demonstrate that factors intrinsically related to PD may underlie the paradoxical symptoms of inflexibility and reward-related impulsivity in PD. The present results concur with observations that low baseline dopamine states predispose to drug and other addictions.

  2. Contextual Bandit Learning with Predictable Rewards

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    Agarwal, Alekh; Kale, Satyen; Langford, John; Schapire, Robert E

    2012-01-01

    Contextual bandit learning is a reinforcement learning problem where the learner repeatedly receives a set of features (context), takes an action and receives a reward based on the action and context. We consider this problem under a realizability assumption: there exists a function in a (known) function class, always capable of predicting the expected reward, given the action and context. Under this assumption, we show three things. We present a new algorithm---Regressor Elimination--- with a regret similar to the agnostic setting (i.e. in the absence of realizability assumption). We prove a new lower bound showing no algorithm can achieve superior performance in the worst case even with the realizability assumption. However, we do show that for any set of policies (mapping contexts to actions), there is a distribution over rewards (given context) such that our new algorithm has constant regret unlike the previous approaches.

  3. Working memory load strengthens reward prediction errors.

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    Collins, Anne G E; Ciullo, Brittany; Frank, Michael J; Badre, David

    2017-03-20

    Reinforcement learning in simple instrumental tasks is usually modeled as a monolithic process in which reward prediction errors are used to update expected values of choice options. This modeling ignores the different contributions of different memory and decision-making systems thought to contribute even to simple learning. In an fMRI experiment, we asked how working memory and incremental reinforcement learning processes interact to guide human learning. Working memory load was manipulated by varying the number of stimuli to be learned across blocks. Behavioral results and computational modeling confirmed that learning was best explained as a mixture of two mechanisms: a fast, capacity-limited, and delay-sensitive working memory process together with slower reinforcement learning. Model-based analysis of fMRI data showed that striatum and lateral prefrontal cortex were sensitive to reward prediction error, as shown previously, but critically, these signals were reduced when the learning problem was within capacity of working memory. The degree of this neural interaction related to individual differences in the use of working memory to guide behavioral learning. These results indicate that the two systems do not process information independently, but rather interact during learning.SIGNIFICANCE STATEMENTReinforcement learning theory has been remarkably productive at improving our understanding of instrumental learning as well as dopaminergic and striatal network function across many mammalian species. However, this neural network is only one contributor to human learning, and other mechanisms such as prefrontal cortex working memory, also play a key role. Our results show in addition that these other players interact with the dopaminergic RL system, interfering with its key computation of reward predictions errors.

  4. Trait Anticipatory Pleasure Predicts Effort Expenditure for Reward.

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    Joachim T Geaney

    Full Text Available Research in motivation and emotion has been increasingly influenced by the perspective that processes underpinning the motivated approach of rewarding goals are distinct from those underpinning enjoyment during reward consummation. This distinction recently inspired the construction of the Temporal Experience of Pleasure Scale (TEPS, a self-report measure that distinguishes trait anticipatory pleasure (pre-reward feelings of desire from consummatory pleasure (feelings of enjoyment and gratification upon reward attainment. In a university community sample (N = 97, we examined the TEPS subscales as predictors of (1 the willingness to expend effort for monetary rewards, and (2 affective responses to a pleasant mood induction procedure. Results showed that both anticipatory pleasure and a well-known trait measure of reward motivation predicted effort-expenditure for rewards when the probability of being rewarded was relatively low. Against expectations, consummatory pleasure was unrelated to induced pleasant affect. Taken together, our findings provide support for the validity of the TEPS anticipatory pleasure scale, but not the consummatory pleasure scale.

  5. Dopamine neurons share common response function for reward prediction error.

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    Eshel, Neir; Tian, Ju; Bukwich, Michael; Uchida, Naoshige

    2016-03-01

    Dopamine neurons are thought to signal reward prediction error, or the difference between actual and predicted reward. How dopamine neurons jointly encode this information, however, remains unclear. One possibility is that different neurons specialize in different aspects of prediction error; another is that each neuron calculates prediction error in the same way. We recorded from optogenetically identified dopamine neurons in the lateral ventral tegmental area (VTA) while mice performed classical conditioning tasks. Our tasks allowed us to determine the full prediction error functions of dopamine neurons and compare them to each other. We found marked homogeneity among individual dopamine neurons: their responses to both unexpected and expected rewards followed the same function, just scaled up or down. As a result, we were able to describe both individual and population responses using just two parameters. Such uniformity ensures robust information coding, allowing each dopamine neuron to contribute fully to the prediction error signal.

  6. Aberrant Reward Center Response to Partner Reputation During a Social Exchange Game in Generalized Social Phobia

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    Sripada, Chandra; Angstadt, Michael; Liberzon, Israel; McCabe, Kevin; Phan, K. Luan

    2014-01-01

    Objective Generalized social anxiety disorder (GSAD) is characterized by excessive fear of public scrutiny and reticence in social engagement. Previous studies have probed the neural basis of GSAD often using static, non-interactive stimuli (e.g., face photographs) and have identified dysfunction in fear circuitry. We sought to investigate brain-based dysfunction in GSAD during more real-world, dynamic social interactions, focusing on the role of reward-related regions that are implicated in social decision-making. Methods Thirty-six healthy individuals (HC) and 36 individuals with GSAD underwent fMRI scanning while participating in a behavioral economic game (‘Trust Game’) involving iterative exchanges with fictive partners who acquire differential reputations for reciprocity. We investigated brain responses to reciprocation of trust in one’s social partner, and how these brain responses are modulated by partner reputation for repayment. Results In both HC and GSAD, receipt of reciprocity robustly engaged ventral striatum, a region implicated in reward. In HC, striatal responses to reciprocity were specific to partners who have consistently returned the investment (‘cooperative partners’), and were absent for partners who lack a cooperative reputation. In GSAD, modulation of striatal responses by partner reputation was absent. Social anxiety severity predicted diminished responses to cooperative partners. Conclusion These results suggest abnormalities in GSAD in reward-related striatal mechanisms that may be important for the initiation, valuation, and maintenance of cooperative social relationships. Moreover, this study demonstrates that dynamic, interactive task paradigms derived from economics can help illuminate novel mechanisms of pathology in psychiatric illnesses in which social dysfunction is a cardinal feature. PMID:23576237

  7. Inferring reward prediction errors in patients with schizophrenia: a dynamic reward task for reinforcement learning.

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    Li, Chia-Tzu; Lai, Wen-Sung; Liu, Chih-Min; Hsu, Yung-Fong

    2014-01-01

    Abnormalities in the dopamine system have long been implicated in explanations of reinforcement learning and psychosis. The updated reward prediction error (RPE)-a discrepancy between the predicted and actual rewards-is thought to be encoded by dopaminergic neurons. Dysregulation of dopamine systems could alter the appraisal of stimuli and eventually lead to schizophrenia. Accordingly, the measurement of RPE provides a potential behavioral index for the evaluation of brain dopamine activity and psychotic symptoms. Here, we assess two features potentially crucial to the RPE process, namely belief formation and belief perseveration, via a probability learning task and reinforcement-learning modeling. Forty-five patients with schizophrenia [26 high-psychosis and 19 low-psychosis, based on their p1 and p3 scores in the positive-symptom subscales of the Positive and Negative Syndrome Scale (PANSS)] and 24 controls were tested in a feedback-based dynamic reward task for their RPE-related decision making. While task scores across the three groups were similar, matching law analysis revealed that the reward sensitivities of both psychosis groups were lower than that of controls. Trial-by-trial data were further fit with a reinforcement learning model using the Bayesian estimation approach. Model fitting results indicated that both psychosis groups tend to update their reward values more rapidly than controls. Moreover, among the three groups, high-psychosis patients had the lowest degree of choice perseveration. Lumping patients' data together, we also found that patients' perseveration appears to be negatively correlated (p = 0.09, trending toward significance) with their PANSS p1 + p3 scores. Our method provides an alternative for investigating reward-related learning and decision making in basic and clinical settings.

  8. Stimulus-dependent adjustment of reward prediction error in the midbrain.

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    Hiromasa Takemura

    Full Text Available Previous reports have described that neural activities in midbrain dopamine areas are sensitive to unexpected reward delivery and omission. These activities are correlated with reward prediction error in reinforcement learning models, the difference between predicted reward values and the obtained reward outcome. These findings suggest that the reward prediction error signal in the brain updates reward prediction through stimulus-reward experiences. It remains unknown, however, how sensory processing of reward-predicting stimuli contributes to the computation of reward prediction error. To elucidate this issue, we examined the relation between stimulus discriminability of the reward-predicting stimuli and the reward prediction error signal in the brain using functional magnetic resonance imaging (fMRI. Before main experiments, subjects learned an association between the orientation of a perceptually salient (high-contrast Gabor patch and a juice reward. The subjects were then presented with lower-contrast Gabor patch stimuli to predict a reward. We calculated the correlation between fMRI signals and reward prediction error in two reinforcement learning models: a model including the modulation of reward prediction by stimulus discriminability and a model excluding this modulation. Results showed that fMRI signals in the midbrain are more highly correlated with reward prediction error in the model that includes stimulus discriminability than in the model that excludes stimulus discriminability. No regions showed higher correlation with the model that excludes stimulus discriminability. Moreover, results show that the difference in correlation between the two models was significant from the first session of the experiment, suggesting that the reward computation in the midbrain was modulated based on stimulus discriminability before learning a new contingency between perceptually ambiguous stimuli and a reward. These results suggest that the human

  9. Inferring reward prediction errors in patients with schizophrenia: a dynamic reward task for reinforcement learning

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    Chia-Tzu eLi

    2014-11-01

    Full Text Available Abnormalities in the dopamine system have long been implicated in explanations of reinforcement learning and psychosis. The updated reward prediction error (RPE—a discrepancy between the predicted and actual rewards—is thought to be encoded by dopaminergic neurons. Dysregulation of dopamine systems could alter the appraisal of stimuli and eventually lead to schizophrenia. Accordingly, the measurement of RPE provides a potential behavioral index for the evaluation of brain dopamine activity and psychotic symptoms. Here, we assess two features potentially crucial to the RPE process, namely belief formation and belief perseveration, via a probability learning task and reinforcement-learning modeling. Forty-five patients with schizophrenia (26 high-psychosis and 19 low-psychosis, based on their p1 and p3 scores in the positive-symptom subscales of the Positive and Negative Syndrome Scale (PANSS and 24 controls were tested in a feedback-based dynamic reward task for their RPE-related decision making. While task scores across the three groups were similar, matching law analysis revealed that the reward sensitivities of both psychosis groups were lower than that of controls. Trial-by-trial data were further fit with a reinforcement learning model using the Bayesian estimation approach. Model fitting results indicated that both psychosis groups tend to update their reward values more rapidly than controls. Moreover, among the three groups, high-psychosis patients had the lowest degree of choice perseveration. Lumping patients’ data together, we also found that patients’ perseveration appears to be negatively correlated (p = .09, trending towards significance with their PANSS p1+p3 scores. Our method provides an alternative for investigating reward-related learning and decision making in basic and clinical settings.

  10. Curiosity and reward: Valence predicts choice and information prediction errors enhance learning.

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    Marvin, Caroline B; Shohamy, Daphna

    2016-03-01

    Curiosity drives many of our daily pursuits and interactions; yet, we know surprisingly little about how it works. Here, we harness an idea implied in many conceptualizations of curiosity: that information has value in and of itself. Reframing curiosity as the motivation to obtain reward-where the reward is information-allows one to leverage major advances in theoretical and computational mechanisms of reward-motivated learning. We provide new evidence supporting 2 predictions that emerge from this framework. First, we find an asymmetric effect of positive versus negative information, with positive information enhancing both curiosity and long-term memory for information. Second, we find that it is not the absolute value of information that drives learning but, rather, the gap between the reward expected and reward received, an "information prediction error." These results support the idea that information functions as a reward, much like money or food, guiding choices and driving learning in systematic ways.

  11. Rewards.

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    Gunderman, Richard B; Kamer, Aaron P

    2011-05-01

    For much of the 20th century, psychologists and economists operated on the assumption that work is devoid of intrinsic rewards, and the only way to get people to work harder is through the use of rewards and punishments. This so-called carrot-and-stick model of workplace motivation, when applied to medical practice, emphasizes the use of financial incentives and disincentives to manipulate behavior. More recently, however, it has become apparent that, particularly when applied to certain kinds of work, such approaches can be ineffective or even frankly counterproductive. Instead of focusing on extrinsic rewards such as compensation, organizations and their leaders need to devote more attention to the intrinsic rewards of work itself. This article reviews this new understanding of rewards and traces out its practical implications for radiology today.

  12. Morphological elucidation of basal ganglia circuits contributing reward prediction

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    Fumino eFujiyama

    2015-02-01

    Full Text Available Electrophysiological studies in monkeys have shown that dopaminergic neurons respond to the reward prediction error. In addition, striatal neurons alter their responsiveness to cortical or thalamic inputs in response to the dopamine signal, via the mechanism of dopamine-regulated synaptic plasticity. These findings have led to the hypothesis that the striatum exhibits synaptic plasticity under the influence of the reward prediction error and conduct reinforcement learning throughout the basal ganglia circuits.The reinforcement learning model is useful; however, the mechanism by which such a process emerges in the basal ganglia needs to be anatomically explained. The actor–critic model has been previously proposed and extended by the existence of role sharing within the striatum, focusing on the striosome/matrix compartments. However, this hypothesis has been difficult to confirm morphologically, partly because of the complex structure of the striosome/matrix compartments. Here, we review recent morphological studies that elucidate the input/output organization of the striatal compartments.

  13. Mindfulness meditation modulates reward prediction errors in the striatum in a passive conditioning task

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    Ulrich eKirk

    2015-02-01

    Full Text Available Reinforcement learning models have demonstrated that phasic activity of dopamine neurons during reward expectation encodes information about the predictability of rewards and cues that predict reward. Evidence indicates that mindfulness-based approaches reduce reward anticipation signal in the striatum to negative and positive incentives suggesting the hypothesis that such training influence basic reward processing. Using a passive conditioning task and fMRI in a group of experienced mindfulness meditators and age-matched controls, we tested the hypothesis that mindfulness meditation influence reward and reward prediction error signals. We found diminished positive and negative prediction error-related blood-oxygen level-dependent (BOLD responses in the putamen in meditators compared with controls. In the meditators, this decrease in striatal BOLD responses to reward prediction was paralleled by increased activity in posterior insula, a primary interoceptive region. Critically, responses in the putamen during early trials of the conditioning procedure (run 1 were elevated in both meditators and controls. These results provide evidence that experienced mindfulness meditators show attenuated reward prediction signals to valenced stimuli, which may be related to interoceptive processes encoded in the posterior insula.

  14. The Dopamine Prediction Error: Contributions to Associative Models of Reward Learning

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    Nasser, Helen M.; Calu, Donna J.; Schoenbaum, Geoffrey; Sharpe, Melissa J.

    2017-01-01

    Phasic activity of midbrain dopamine neurons is currently thought to encapsulate the prediction-error signal described in Sutton and Barto’s (1981) model-free reinforcement learning algorithm. This phasic signal is thought to contain information about the quantitative value of reward, which transfers to the reward-predictive cue after learning. This is argued to endow the reward-predictive cue with the value inherent in the reward, motivating behavior toward cues signaling the presence of reward. Yet theoretical and empirical research has implicated prediction-error signaling in learning that extends far beyond a transfer of quantitative value to a reward-predictive cue. Here, we review the research which demonstrates the complexity of how dopaminergic prediction errors facilitate learning. After briefly discussing the literature demonstrating that phasic dopaminergic signals can act in the manner described by Sutton and Barto (1981), we consider how these signals may also influence attentional processing across multiple attentional systems in distinct brain circuits. Then, we discuss how prediction errors encode and promote the development of context-specific associations between cues and rewards. Finally, we consider recent evidence that shows dopaminergic activity contains information about causal relationships between cues and rewards that reflect information garnered from rich associative models of the world that can be adapted in the absence of direct experience. In discussing this research we hope to support the expansion of how dopaminergic prediction errors are thought to contribute to the learning process beyond the traditional concept of transferring quantitative value. PMID:28275359

  15. A simple solution for model comparison in bold imaging: the special case of reward prediction error and reward outcomes.

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    Erdeniz, Burak; Rohe, Tim; Done, John; Seidler, Rachael D

    2013-01-01

    Conventional neuroimaging techniques provide information about condition-related changes of the BOLD (blood-oxygen-level dependent) signal, indicating only where and when the underlying cognitive processes occur. Recently, with the help of a new approach called "model-based" functional neuroimaging (fMRI), researchers are able to visualize changes in the internal variables of a time varying learning process, such as the reward prediction error or the predicted reward value of a conditional stimulus. However, despite being extremely beneficial to the imaging community in understanding the neural correlates of decision variables, a model-based approach to brain imaging data is also methodologically challenging due to the multicollinearity problem in statistical analysis. There are multiple sources of multicollinearity in functional neuroimaging including investigations of closely related variables and/or experimental designs that do not account for this. The source of multicollinearity discussed in this paper occurs due to correlation between different subjective variables that are calculated very close in time. Here, we review methodological approaches to analyzing such data by discussing the special case of separating the reward prediction error signal from reward outcomes.

  16. Lateral habenula neurons signal errors in the prediction of reward information.

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    Bromberg-Martin, Ethan S; Hikosaka, Okihide

    2011-08-21

    Humans and animals have the ability to predict future events, which they cultivate by continuously searching their environment for sources of predictive information. However, little is known about the neural systems that motivate this behavior. We hypothesized that information-seeking is assigned value by the same circuits that support reward-seeking, such that neural signals encoding reward prediction errors (RPEs) include analogous information prediction errors (IPEs). To test this, we recorded from neurons in the lateral habenula, a nucleus that encodes RPEs, while monkeys chose between cues that provided different chances to view information about upcoming rewards. We found that a subpopulation of lateral habenula neurons transmitted signals resembling IPEs, responding when reward information was unexpectedly cued, delivered or denied. These signals evaluated information sources reliably, even when the monkey's decisions did not. These neurons could provide a common instructive signal for reward-seeking and information-seeking behavior.

  17. Trial-by-Trial Modulation of Associative Memory Formation by Reward Prediction Error and Reward Anticipation as Revealed by a Biologically Plausible Computational Model.

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    Aberg, Kristoffer C; Müller, Julia; Schwartz, Sophie

    2017-01-01

    Anticipation and delivery of rewards improves memory formation, but little effort has been made to disentangle their respective contributions to memory enhancement. Moreover, it has been suggested that the effects of reward on memory are mediated by dopaminergic influences on hippocampal plasticity. Yet, evidence linking memory improvements to actual reward computations reflected in the activity of the dopaminergic system, i.e., prediction errors and expected values, is scarce and inconclusive. For example, different previous studies reported that the magnitude of prediction errors during a reinforcement learning task was a positive, negative, or non-significant predictor of successfully encoding simultaneously presented images. Individual sensitivities to reward and punishment have been found to influence the activation of the dopaminergic reward system and could therefore help explain these seemingly discrepant results. Here, we used a novel associative memory task combined with computational modeling and showed independent effects of reward-delivery and reward-anticipation on memory. Strikingly, the computational approach revealed positive influences from both reward delivery, as mediated by prediction error magnitude, and reward anticipation, as mediated by magnitude of expected value, even in the absence of behavioral effects when analyzed using standard methods, i.e., by collapsing memory performance across trials within conditions. We additionally measured trait estimates of reward and punishment sensitivity and found that individuals with increased reward (vs. punishment) sensitivity had better memory for associations encoded during positive (vs. negative) prediction errors when tested after 20 min, but a negative trend when tested after 24 h. In conclusion, modeling trial-by-trial fluctuations in the magnitude of reward, as we did here for prediction errors and expected value computations, provides a comprehensive and biologically plausible description of

  18. Trial-by-Trial Modulation of Associative Memory Formation by Reward Prediction Error and Reward Anticipation as Revealed by a Biologically Plausible Computational Model

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    Aberg, Kristoffer C.; Müller, Julia; Schwartz, Sophie

    2017-01-01

    Anticipation and delivery of rewards improves memory formation, but little effort has been made to disentangle their respective contributions to memory enhancement. Moreover, it has been suggested that the effects of reward on memory are mediated by dopaminergic influences on hippocampal plasticity. Yet, evidence linking memory improvements to actual reward computations reflected in the activity of the dopaminergic system, i.e., prediction errors and expected values, is scarce and inconclusive. For example, different previous studies reported that the magnitude of prediction errors during a reinforcement learning task was a positive, negative, or non-significant predictor of successfully encoding simultaneously presented images. Individual sensitivities to reward and punishment have been found to influence the activation of the dopaminergic reward system and could therefore help explain these seemingly discrepant results. Here, we used a novel associative memory task combined with computational modeling and showed independent effects of reward-delivery and reward-anticipation on memory. Strikingly, the computational approach revealed positive influences from both reward delivery, as mediated by prediction error magnitude, and reward anticipation, as mediated by magnitude of expected value, even in the absence of behavioral effects when analyzed using standard methods, i.e., by collapsing memory performance across trials within conditions. We additionally measured trait estimates of reward and punishment sensitivity and found that individuals with increased reward (vs. punishment) sensitivity had better memory for associations encoded during positive (vs. negative) prediction errors when tested after 20 min, but a negative trend when tested after 24 h. In conclusion, modeling trial-by-trial fluctuations in the magnitude of reward, as we did here for prediction errors and expected value computations, provides a comprehensive and biologically plausible description of

  19. The Attraction Effect Modulates Reward Prediction Errors and Intertemporal Choices.

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    Gluth, Sebastian; Hotaling, Jared M; Rieskamp, Jörg

    2017-01-11

    Classical economic theory contends that the utility of a choice option should be independent of other options. This view is challenged by the attraction effect, in which the relative preference between two options is altered by the addition of a third, asymmetrically dominated option. Here, we leveraged the attraction effect in the context of intertemporal choices to test whether both decisions and reward prediction errors (RPE) in the absence of choice violate the independence of irrelevant alternatives principle. We first demonstrate that intertemporal decision making is prone to the attraction effect in humans. In an independent group of participants, we then investigated how this affects the neural and behavioral valuation of outcomes using a novel intertemporal lottery task and fMRI. Participants' behavioral responses (i.e., satisfaction ratings) were modulated systematically by the attraction effect and this modulation was correlated across participants with the respective change of the RPE signal in the nucleus accumbens. Furthermore, we show that, because exponential and hyperbolic discounting models are unable to account for the attraction effect, recently proposed sequential sampling models might be more appropriate to describe intertemporal choices. Our findings demonstrate for the first time that the attraction effect modulates subjective valuation even in the absence of choice. The findings also challenge the prospect of using neuroscientific methods to measure utility in a context-free manner and have important implications for theories of reinforcement learning and delay discounting.

  20. Reward prediction-related increases and decreases in tonic neuronal activity of the pedunculopontine tegmental nucleus

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    Ken-Ichi eOkada

    2013-05-01

    Full Text Available The neuromodulators serotonin, acetylcholine, and dopamine have been proposed to play important roles in the execution of movement, control of several forms of attentional behavior, and reinforcement learning. While the response pattern of midbrain dopaminergic neurons and its specific role in reinforcement learning have been revealed, the roles of the other neuromodulators remain elusive. Reportedly, neurons in the dorsal raphe nucleus, one major source of serotonin, continually track the state of expectation of future rewards by showing a correlated response to the start of a behavioral task, reward cue presentation, and reward delivery. Here, we show that neurons in the pedunculopontine tegmental nucleus (PPTN, one major source of acetylcholine, showed similar encoding of the expectation of future rewards by a systematic increase or decrease in tonic activity. We recorded and analyzed PPTN neuronal activity in monkeys during a reward conditioned visually guided saccade task. The firing patterns of many PPTN neurons were tonically increased or decreased throughout the task period. The tonic activity pattern of neurons was correlated with their encoding of the predicted reward value; neurons exhibiting an increase or decrease in tonic activity showed higher or lower activity in the large reward-predicted trials, respectively. Tonic activity and reward-related modulation ended around the time of reward delivery. Additionally, some tonic changes in activity started prior to the appearance of the initial stimulus, and were related to the anticipatory fixational behavior. A partially overlapping population of neurons showed both the initial anticipatory response and subsequent predicted reward value-dependent activity modulation by their systematic increase or decrease of tonic activity. These bi-directional reward- and anticipatory behavior-related modulation patterns are suitable for the presumed role of the PPTN in reward processing and

  1. Cognitive strategies regulate fictive, but not reward prediction error signals in a sequential investment task.

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    Gu, Xiaosi; Kirk, Ulrich; Lohrenz, Terry M; Montague, P Read

    2014-08-01

    Computational models of reward processing suggest that foregone or fictive outcomes serve as important information sources for learning and augment those generated by experienced rewards (e.g. reward prediction errors). An outstanding question is how these learning signals interact with top-down cognitive influences, such as cognitive reappraisal strategies. Using a sequential investment task and functional magnetic resonance imaging, we show that the reappraisal strategy selectively attenuates the influence of fictive, but not reward prediction error signals on investment behavior; such behavioral effect is accompanied by changes in neural activity and connectivity in the anterior insular cortex, a brain region thought to integrate subjective feelings with high-order cognition. Furthermore, individuals differ in the extent to which their behaviors are driven by fictive errors versus reward prediction errors, and the reappraisal strategy interacts with such individual differences; a finding also accompanied by distinct underlying neural mechanisms. These findings suggest that the variable interaction of cognitive strategies with two important classes of computational learning signals (fictive, reward prediction error) represent one contributing substrate for the variable capacity of individuals to control their behavior based on foregone rewards. These findings also expose important possibilities for understanding the lack of control in addiction based on possibly foregone rewarding outcomes.

  2. Neurophysiology of Reward-Guided Behavior: Correlates Related to Predictions, Value, Motivation, Errors, Attention, and Action.

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    Bissonette, Gregory B; Roesch, Matthew R

    2016-01-01

    Many brain areas are activated by the possibility and receipt of reward. Are all of these brain areas reporting the same information about reward? Or are these signals related to other functions that accompany reward-guided learning and decision-making? Through carefully controlled behavioral studies, it has been shown that reward-related activity can represent reward expectations related to future outcomes, errors in those expectations, motivation, and signals related to goal- and habit-driven behaviors. These dissociations have been accomplished by manipulating the predictability of positively and negatively valued events. Here, we review single neuron recordings in behaving animals that have addressed this issue. We describe data showing that several brain areas, including orbitofrontal cortex, anterior cingulate, and basolateral amygdala signal reward prediction. In addition, anterior cingulate, basolateral amygdala, and dopamine neurons also signal errors in reward prediction, but in different ways. For these areas, we will describe how unexpected manipulations of positive and negative value can dissociate signed from unsigned reward prediction errors. All of these signals feed into striatum to modify signals that motivate behavior in ventral striatum and guide responding via associative encoding in dorsolateral striatum.

  3. Choice modulates the neural dynamics of prediction error processing during rewarded learning.

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    Peterson, David A; Lotz, Daniel T; Halgren, Eric; Sejnowski, Terrence J; Poizner, Howard

    2011-01-15

    Our ability to selectively engage with our environment enables us to guide our learning and to take advantage of its benefits. When facing multiple possible actions, our choices are a critical aspect of learning. In the case of learning from rewarding feedback, there has been substantial theoretical and empirical progress in elucidating the associated behavioral and neural processes, predominantly in terms of a reward prediction error, a measure of the discrepancy between actual versus expected reward. Nevertheless, the distinct influence of choice on prediction error processing and its neural dynamics remains relatively unexplored. In this study we used a novel paradigm to determine how choice influences prediction error processing and to examine whether there are correspondingly distinct neural dynamics. We recorded scalp electroencephalogram while healthy adults were administered a rewarded learning task in which choice trials were intermingled with control trials involving the same stimuli, motor responses, and probabilistic rewards. We used a temporal difference learning model of subjects' trial-by-trial choices to infer subjects' image valuations and corresponding prediction errors. As expected, choices were associated with lower overall prediction error magnitudes, most notably over the course of learning the stimulus-reward contingencies. Choices also induced a higher-amplitude relative positivity in the frontocentral event-related potential about 200 ms after reward signal onset that was negatively correlated with the differential effect of choice on the prediction error. Thus choice influences the neural dynamics associated with how reward signals are processed during learning. Behavioral, computational, and neurobiological models of rewarded learning should therefore accommodate a distinct influence for choice during rewarded learning.

  4. Dual reward prediction components yield Pavlovian sign- and goal-tracking.

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    Kaveri, Sivaramakrishnan; Nakahara, Hiroyuki

    2014-01-01

    Reinforcement learning (RL) has become a dominant paradigm for understanding animal behaviors and neural correlates of decision-making, in part because of its ability to explain Pavlovian conditioned behaviors and the role of midbrain dopamine activity as reward prediction error (RPE). However, recent experimental findings indicate that dopamine activity, contrary to the RL hypothesis, may not signal RPE and differs based on the type of Pavlovian response (e.g. sign- and goal-tracking responses). In this study, we address this discrepancy by introducing a new neural correlate for learning reward predictions; the correlate is called "cue-evoked reward". It refers to a recall of reward evoked by the cue that is learned through simple cue-reward associations. We introduce a temporal difference learning model, in which neural correlates of the cue itself and cue-evoked reward underlie learning of reward predictions. The animal's reward prediction supported by these two correlates is divided into sign and goal components respectively. We relate the sign and goal components to approach responses towards the cue (i.e. sign-tracking) and the food-tray (i.e. goal-tracking) respectively. We found a number of correspondences between simulated models and the experimental findings (i.e. behavior and neural responses). First, the development of modeled responses is consistent with those observed in the experimental task. Second, the model's RPEs were similar to dopamine activity in respective response groups. Finally, goal-tracking, but not sign-tracking, responses rapidly emerged when RPE was restored in the simulated models, similar to experiments with recovery from dopamine-antagonist. These results suggest two complementary neural correlates, corresponding to the cue and its evoked reward, form the basis for learning reward predictions in the sign- and goal-tracking rats.

  5. General functioning predicts reward and punishment learning in schizophrenia.

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    Somlai, Zsuzsanna; Moustafa, Ahmed A; Kéri, Szabolcs; Myers, Catherine E; Gluck, Mark A

    2011-04-01

    Previous studies investigating feedback-driven reinforcement learning in patients with schizophrenia have provided mixed results. In this study, we explored the clinical predictors of reward and punishment learning using a probabilistic classification learning task. Patients with schizophrenia (n=40) performed similarly to healthy controls (n=30) on the classification learning task. However, more severe negative and general symptoms were associated with lower reward-learning performance, whereas poorer general psychosocial functioning was correlated with both lower reward- and punishment-learning performances. Multiple linear regression analyses indicated that general psychosocial functioning was the only significant predictor of reinforcement learning performance when education, antipsychotic dose, and positive, negative and general symptoms were included in the analysis. These results suggest a close relationship between reinforcement learning and general psychosocial functioning in schizophrenia.

  6. Considerations for comparing radiation-induced chromosome aberration data with predictions from biophysical models

    Science.gov (United States)

    Wu, H.; Furusawa, Y.; George, K.; Kawata, T.; Cucinotta, F.

    Biophysical models addressing the formation of radiation-induced chromosome aberrations are usually based on the assumption that chromosome aberrations are formed by DNA double strand break (DSB) misrejoining, via either the homologous or the non-homologous repair pathway. However, comparing chromosome aberration data with model predictions is not always straightforward. In this paper we discuss some of the aspects that must be considered to make these comparisons meaningful. Firstly, biophysical models are usually applied to DSB rejoining and misrejoining in the G0/G1 phase of the cell cycle, while most chromosome aberration data reported in the literature are analyzed in metaphase. Since cells must progress through the cell cycle check points in order to reach mitosis, model predictions that differ from the metaphase chromosome analysis may actually agree with the aberration data in chromosomes collected in interphase. Secondly, high- LET radiation generally produces more complex aberrations involving exchanges between three or more DSB. While some models have successfully provided quantitative predictions of high-LET radiation induced complex aberrations in human lymphocytes, applying such models to other cell types requires special considerations due to the lack of geometric symmetry of the nucleus. Chromosome aberration data for non-spherical human fibroblast cells bombarded from various directions by high-LET charged particles will be presented, and their implication on physical modeling will be discussed.

  7. The predictive value of selected job rewards on occupational therapists' job satisfaction in ambulatory care settings.

    Science.gov (United States)

    Painter, J; Akroyd, D; Wilson, S; Figuers, C

    1995-01-01

    Using a perceived reward model of overall job satisfaction, this study utilized a correlational research design with multiple regression analysis to determine the predictive power of extrinsic rewards and intrinsic rewards, collectively and individually, as determinants of overall job satisfaction among registered occupational therapists (OTR) working full-time in ambulatory care settings. The intrinsic rewards (task involvement and task autonomy), collectively and individually, were perceived to be significant overall job satisfaction determinants. General working conditions was the only significant extrinsic reward. Given the demand for OTRs in ambulatory care settings, a better understanding of factors that influence overall job satisfaction among OTRs could prove beneficial in developing appropriate recruitment and retention job design strategies.

  8. Cortical delta activity reflects reward prediction error and related behavioral adjustments, but at different times.

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    Cavanagh, James F

    2015-04-15

    Recent work has suggested that reward prediction errors elicit a positive voltage deflection in the scalp-recorded electroencephalogram (EEG); an event sometimes termed a reward positivity. However, a strong test of this proposed relationship remains to be defined. Other important questions remain unaddressed: such as the role of the reward positivity in predicting future behavioral adjustments that maximize reward. To answer these questions, a three-armed bandit task was used to investigate the role of positive prediction errors during trial-by-trial exploration and task-set based exploitation. The feedback-locked reward positivity was characterized by delta band activities, and these related EEG features scaled with the degree of a computationally derived positive prediction error. However, these phenomena were also dissociated: the computational model predicted exploitative action selection and related response time speeding whereas the feedback-locked EEG features did not. Compellingly, delta band dynamics time-locked to the subsequent bandit (the P3) successfully predicted these behaviors. These bandit-locked findings included an enhanced parietal to motor cortex delta phase lag that correlated with the degree of response time speeding, suggesting a mechanistic role for delta band activities in motivating action selection. This dissociation in feedback vs. bandit locked EEG signals is interpreted as a differentiation in hierarchically distinct types of prediction error, yielding novel predictions about these dissociable delta band phenomena during reinforcement learning and decision making.

  9. Prediction-error in the context of real social relationships modulates reward system activity

    Directory of Open Access Journals (Sweden)

    Joshua ePoore

    2012-08-01

    Full Text Available The human reward system is sensitive to both social (e.g., validation and non-social rewards (e.g., money and is likely integral for relationship development and reputation building. However, data is sparse on the question of whether implicit social reward processing meaningfully contributes to explicit social representations such as trust and attachment security in pre-existing relationships. This event-related fMRI experiment examined reward system prediction-error activity in response to a potent social reward—social validation—and this activity’s relation to both attachment security and trust in the context of real romantic relationships. During the experiment, participants’ expectations for their romantic partners’ positive regard of them were confirmed (validated or violated, in either positive or negative directions. Primary analyses were conducted using predefined regions of interest, the locations of which were taken from previously published research. Results indicate that activity for mid-brain and striatal reward system regions of interest was modulated by social reward expectation violation in ways consistent with prior research on reward prediction-error. Additionally, activity in the striatum during viewing of disconfirmatory information was associated with both increases in post-scan reports of attachment anxiety and decreases in post-scan trust, a finding that follows directly from representational models of attachment and trust.

  10. Reward sensitivity predicts ice cream-related attentional bias assessed by inattentional blindness.

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    Li, Xiaoming; Tao, Qian; Fang, Ya; Cheng, Chen; Hao, Yangyang; Qi, Jianjun; Li, Yu; Zhang, Wei; Wang, Ying; Zhang, Xiaochu

    2015-06-01

    The cognitive mechanism underlying the association between individual differences in reward sensitivity and food craving is unknown. The present study explored the mechanism by examining the role of reward sensitivity in attentional bias toward ice cream cues. Forty-nine college students who displayed high level of ice cream craving (HICs) and 46 who displayed low level of ice cream craving (LICs) performed an inattentional blindness (IB) task which was used to assess attentional bias for ice cream. In addition, reward sensitivity and coping style were assessed by the Behavior Inhibition System/Behavior Activation System Scales and Simplified Coping Style Questionnaire. Results showed significant higher identification rate of the critical stimulus in the HICs than LICs, suggesting greater attentional bias for ice cream in the HICs. It was indicated that attentional bias for food cues persisted even under inattentional condition. Furthermore, a significant correlation was found between the attentional bias and reward sensitivity after controlling for coping style, and reward sensitivity predicted attentional bias for food cues. The mediation analyses showed that attentional bias mediated the relationship between reward sensitivity and food craving. Those findings suggest that the association between individual differences in reward sensitivity and food craving may be attributed to attentional bias for food-related cues.

  11. Pain in context : Cues predicting a reward decrease fear of movement related pain and avoidance behavior

    NARCIS (Netherlands)

    Claes, Nathalie; Vlaeyen, Johan W S; Crombez, Geert

    2016-01-01

    Previous research shows that goal-directed behavior might be modulated by cues that predict (dis)similar outcomes. However, the literature investigating this modulation with pain outcomes is scarce. Therefore, this experiment investigated whether environmental cues predicting pain or reward modulate

  12. Temporal dynamics of prediction error processing during reward-based decision making.

    Science.gov (United States)

    Philiastides, Marios G; Biele, Guido; Vavatzanidis, Niki; Kazzer, Philipp; Heekeren, Hauke R

    2010-10-15

    Adaptive decision making depends on the accurate representation of rewards associated with potential choices. These representations can be acquired with reinforcement learning (RL) mechanisms, which use the prediction error (PE, the difference between expected and received rewards) as a learning signal to update reward expectations. While EEG experiments have highlighted the role of feedback-related potentials during performance monitoring, important questions about the temporal sequence of feedback processing and the specific function of feedback-related potentials during reward-based decision making remain. Here, we hypothesized that feedback processing starts with a qualitative evaluation of outcome-valence, which is subsequently complemented by a quantitative representation of PE magnitude. Results of a model-based single-trial analysis of EEG data collected during a reversal learning task showed that around 220ms after feedback outcomes are initially evaluated categorically with respect to their valence (positive vs. negative). Around 300ms, and parallel to the maintained valence-evaluation, the brain also represents quantitative information about PE magnitude, thus providing the complete information needed to update reward expectations and to guide adaptive decision making. Importantly, our single-trial EEG analysis based on PEs from an RL model showed that the feedback-related potentials do not merely reflect error awareness, but rather quantitative information crucial for learning reward contingencies.

  13. Feast your eyes: hunger and trait reward drive predict attentional bias for food cues.

    Science.gov (United States)

    Tapper, Katy; Pothos, Emmanuel M; Lawrence, Andrew D

    2010-12-01

    Appraisal theories of emotion predict that the relevance of a stimulus to a person's needs and goals influences attentional allocation. We used a modified visual probe task to examine the influence of hunger and trait reward drive on food-related attentional bias. Both hunger and trait reward drive predicted degree of attentional "disengagement" from food images at short (100 ms), but not long (500, 2,000 ms) stimulus durations. Effects of hunger were found for both bland and appetizing foods, while effects of reward drive were restricted to appetizing foods. Our findings extend previous research showing delayed "disengagement" from threat-related stimuli, suggesting that both organismic- and goal-relevance are key biasing factors in attentional competition.

  14. Brief optogenetic inhibition of dopamine neurons mimics endogenous negative reward prediction errors.

    Science.gov (United States)

    Chang, Chun Yun; Esber, Guillem R; Marrero-Garcia, Yasmin; Yau, Hau-Jie; Bonci, Antonello; Schoenbaum, Geoffrey

    2016-01-01

    Correlative studies have strongly linked phasic changes in dopamine activity with reward prediction error signaling. But causal evidence that these brief changes in firing actually serve as error signals to drive associative learning is more tenuous. Although there is direct evidence that brief increases can substitute for positive prediction errors, there is no comparable evidence that similarly brief pauses can substitute for negative prediction errors. In the absence of such evidence, the effect of increases in firing could reflect novelty or salience, variables also correlated with dopamine activity. Here we provide evidence in support of the proposed linkage, showing in a modified Pavlovian over-expectation task that brief pauses in the firing of dopamine neurons in rat ventral tegmental area at the time of reward are sufficient to mimic the effects of endogenous negative prediction errors. These results support the proposal that brief changes in the firing of dopamine neurons serve as full-fledged bidirectional prediction error signals.

  15. Principal components analysis of reward prediction errors in a reinforcement learning task.

    Science.gov (United States)

    Sambrook, Thomas D; Goslin, Jeremy

    2016-01-01

    Models of reinforcement learning represent reward and punishment in terms of reward prediction errors (RPEs), quantitative signed terms describing the degree to which outcomes are better than expected (positive RPEs) or worse (negative RPEs). An electrophysiological component known as feedback related negativity (FRN) occurs at frontocentral sites 240-340ms after feedback on whether a reward or punishment is obtained, and has been claimed to neurally encode an RPE. An outstanding question however, is whether the FRN is sensitive to the size of both positive RPEs and negative RPEs. Previous attempts to answer this question have examined the simple effects of RPE size for positive RPEs and negative RPEs separately. However, this methodology can be compromised by overlap from components coding for unsigned prediction error size, or "salience", which are sensitive to the absolute size of a prediction error but not its valence. In our study, positive and negative RPEs were parametrically modulated using both reward likelihood and magnitude, with principal components analysis used to separate out overlying components. This revealed a single RPE encoding component responsive to the size of positive RPEs, peaking at ~330ms, and occupying the delta frequency band. Other components responsive to unsigned prediction error size were shown, but no component sensitive to negative RPE size was found.

  16. Impaired cross-talk between mesolimbic food reward processing and metabolic signaling predicts body mass index

    Directory of Open Access Journals (Sweden)

    Joe J Simon

    2014-10-01

    Full Text Available The anticipation of the pleasure derived from food intake drives the motivation to eat, and hence facilitate overconsumption of food which ultimately results in obesity. Brain imaging studies provide evidence that mesolimbic brain regions underlie both general as well as food related anticipatory reward processing. In light of this knowledge, the present study examined the neural responsiveness of the ventral striatum in participants with a broad BMI spectrum. The study differentiated between general (i.e. monetary and food related anticipatory reward processing. We recruited a sample of volunteers with greatly varying body weights, ranging from a low BMI (below 20 kg/m² over a normal (20 to 25 kg/m² and overweight (25 to 30 kg/m² BMI, to class I (30 to 35 kg/m² and class II (35 to 40 kg/m² obesity. A total of 24 participants underwent functional magnetic resonance imaging whilst performing both a food and monetary incentive delay task, which allows to measure neural activation during the anticipation of rewards. After the presentation of a cue indicating the amount of food or money to be won, participants had to react correctly in order to earn snack points or money coins which could then be exchanged for real food or money, respectively, at the end of the experiment. During the anticipation of both types of rewards, participants displayed activity in the ventral striatum, a region that plays a pivotal role in the anticipation of rewards. Additionally, we observed that specifically anticipatory food reward processing predicted the individual BMI (current and maximum lifetime. This relation was found to be mediated by impaired hormonal satiety signaling, i.e. increased leptin levels and insulin resistance. These findings suggest that heightened food reward motivation contributes to obesity through impaired metabolic signaling.

  17. Subjective and model-estimated reward prediction: association with the feedback-related negativity (FRN) and reward prediction error in a reinforcement learning task.

    Science.gov (United States)

    Ichikawa, Naho; Siegle, Greg J; Dombrovski, Alexandre; Ohira, Hideki

    2010-12-01

    In this study, we examined whether the feedback-related negativity (FRN) is associated with both subjective and objective (model-estimated) reward prediction errors (RPE) per trial in a reinforcement learning task in healthy adults (n=25). The level of RPE was assessed by 1) subjective ratings per trial and by 2) a computational model of reinforcement learning. As results, model-estimated RPE was highly correlated with subjective RPE (r=.82), and the grand-averaged ERP waves based on the trials with high and low model-estimated RPE showed the significant difference only in the time period of the FRN component (pcontingency.

  18. Dopamine-signalled reward predictions generated by competitive excitation and inhibition in a spiking neural network model

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    Paul eChorley

    2011-05-01

    Full Text Available Dopaminergic neurons in the mammalian substantia nigra displaycharacteristic phasic responses to stimuli which reliably predict thereceipt of primary rewards. These responses have been suggested toencode reward prediction-errors similar to those used in reinforcementlearning. Here, we propose a model of dopaminergic activity in whichprediction error signals are generated by the joint action ofshort-latency excitation and long-latency inhibition, in a networkundergoing dopaminergic neuromodulation of both spike-timing dependentsynaptic plasticity and neuronal excitability. In contrast toprevious models, sensitivity to recent events is maintained by theselective modification of specific striatal synapses, efferent tocortical neurons exhibiting stimulus-specific, temporally extendedactivity patterns. Our model shows, in the presence of significantbackground activity, (i a shift in dopaminergic response from rewardto reward predicting stimuli, (ii preservation of a response tounexpected rewards, and (iii a precisely-timed below-baseline dip inactivity observed when expected rewards are omitted.

  19. Blunted striatal response to monetary reward anticipation during smoking abstinence predicts lapse during a contingency-managed quit attempt

    Science.gov (United States)

    Sweitzer, Maggie M.; Geier, Charles F.; Denlinger, Rachel; Forbes, Erika E.; Raiff, Bethany R.; Dallery, Jesse; McClernon, F.J.; Donny, Eric C.

    2017-01-01

    Rationale Tobacco smoking is associated with dysregulated reward processing within the striatum, characterized by hypersensitivity to smoking rewards and hyposensitivity to non-smoking rewards. This bias toward smoking reward at the expense of alternative rewards is further exacerbated by deprivation from smoking, which may contribute to difficulty maintaining abstinence during a quit attempt. Objective We examined whether abstinence-induced changes in striatal processing of rewards predicted lapse likelihood during a quit attempt supported by contingency management (CM), in which abstinence from smoking was reinforced with money. Methods Thirty-six non-treatment seeking smokers participated in two fMRI sessions, one following 24-hr abstinence and one following smoking as usual. During each scan, participants completed a rewarded guessing task designed to elicit striatal activation in which they could earn smoking and monetary rewards delivered after the scan. Participants then engaged in a 3-week CM-supported quit attempt. Results As previously reported, 24-hr abstinence was associated with increased striatal activation in anticipation of smoking reward and decreased activation in anticipation of monetary reward. Individuals exhibiting greater decrements in right striatal activation to monetary reward during abstinence (controlling for activation during non-abstinence) were more likely to lapse during CM (p<.05), even when controlling for other predictors of lapse outcome (e.g., craving); no association was seen for smoking reward. Conclusions These results are consistent with a growing number of studies indicating the specific importance of disrupted striatal processing of non-drug reward in nicotine dependence, and highlight the importance of individual differences in abstinence-induced deficits in striatal function for smoking cessation. PMID:26660448

  20. Belief about nicotine selectively modulates value and reward prediction error signals in smokers.

    Science.gov (United States)

    Gu, Xiaosi; Lohrenz, Terry; Salas, Ramiro; Baldwin, Philip R; Soltani, Alireza; Kirk, Ulrich; Cinciripini, Paul M; Montague, P Read

    2015-02-24

    Little is known about how prior beliefs impact biophysically described processes in the presence of neuroactive drugs, which presents a profound challenge to the understanding of the mechanisms and treatments of addiction. We engineered smokers' prior beliefs about the presence of nicotine in a cigarette smoked before a functional magnetic resonance imaging session where subjects carried out a sequential choice task. Using a model-based approach, we show that smokers' beliefs about nicotine specifically modulated learning signals (value and reward prediction error) defined by a computational model of mesolimbic dopamine systems. Belief of "no nicotine in cigarette" (compared with "nicotine in cigarette") strongly diminished neural responses in the striatum to value and reward prediction errors and reduced the impact of both on smokers' choices. These effects of belief could not be explained by global changes in visual attention and were specific to value and reward prediction errors. Thus, by modulating the expression of computationally explicit signals important for valuation and choice, beliefs can override the physical presence of a potent neuroactive compound like nicotine. These selective effects of belief demonstrate that belief can modulate model-based parameters important for learning. The implications of these findings may be far ranging because belief-dependent effects on learning signals could impact a host of other behaviors in addiction as well as in other mental health problems.

  1. Endocannabinoid-dependent modulation of phasic dopamine signaling encodes external and internal reward-predictive cues

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    Jennifer M. Wenzel

    2014-09-01

    Full Text Available The mesolimbic dopamine (DA system plays an integral role in incentive motivation and reward seeking and a growing body of evidence identifies signal transduction at cannabinoid receptors as a critical modulator of this system. Indeed, administration of exogenous cannabinoids results in burst firing of DA neurons of the ventral tegmental area and increases extracellular DA in the nucleus accumbens (NAcc. Implementation of fast-scan cyclic voltammetry (FSCV confirms the ability of cannabinoids to augment DA within the NAcc on a subsecond timescale. The use of FSCV along with newly developed highly selective pharmacological compounds advances our understanding of how cannabinoids influence DA transmission, and highlights a role for endocannabinoid-modulated subsecond DAergic activation in the incentive motivational properties of not only external, but also internal reward-predictive cues. For example, our laboratory has recently demonstrated that in mice responding under a fixed interval (FI schedule for food reinforcement, fluctuations in NAcc DA signal the principal cue predictive of reinforcer availability – time. That is, as the interval progresses, NAcc DA levels decline leading to accelerated food seeking and the resulting characteristic FI scallop pattern of responding. Importantly, administration of WIN 55,212-2, a synthetic cannabinoid agonist, or JZL184, an indirect cannabinoid agonist, increase DA levels during the interval and disrupt this pattern of responding. Along with a wealth of other reports, these results illustrate the role of cannabinoid receptor activation in the regulation of DA transmission and the control of temporally guided reward seeking. The current review will explore the striatal beat frequency model of interval timing as it pertains cannabinoid signaling and propose a neurocircuitry through which this system modulates interoceptive time cues.

  2. Endocannabinoid-dependent modulation of phasic dopamine signaling encodes external and internal reward-predictive cues.

    Science.gov (United States)

    Wenzel, Jennifer M; Cheer, Joseph F

    2014-01-01

    The mesolimbic dopamine (DA) system plays an integral role in incentive motivation and reward seeking and a growing body of evidence identifies signal transduction at cannabinoid receptors as a critical modulator of this system. Indeed, administration of exogenous cannabinoids results in burst firing of DA neurons of the ventral tegmental area and increases extracellular DA in the nucleus accumbens (NAcc). Implementation of fast-scan cyclic voltammetry (FSCV) confirms the ability of cannabinoids to augment DA within the NAcc on a subsecond timescale. The use of FSCV along with newly developed highly selective pharmacological compounds advances our understanding of how cannabinoids influence DA transmission and highlights a role for endocannabinoid-modulated subsecond DAergic activation in the incentive motivational properties of not only external, but also internal reward-predictive cues. For example, our laboratory has recently demonstrated that in mice responding under a fixed-interval (FI) schedule for food reinforcement, fluctuations in NAcc DA signal the principal cue predictive of reinforcer availability - time. That is, as the interval progresses, NAcc DA levels decline leading to accelerated food seeking and the resulting characteristic FI scallop pattern of responding. Importantly, administration of WIN 55,212-2, a synthetic cannabinoid agonist, or JZL184, an indirect cannabinoid agonist, increases DA levels during the interval and disrupts this pattern of responding. Along with a wealth of other reports, these results illustrate the role of cannabinoid receptor activation in the regulation of DA transmission and the control of temporally guided reward seeking. The current review will explore the striatal beat frequency model of interval timing as it pertains to cannabinoid signaling and propose a neurocircuitry through which this system modulates interoceptive time cues.

  3. Autocorrelation structure at rest predicts value correlates of single neurons during reward-guided choice

    Science.gov (United States)

    Cavanagh, Sean E; Wallis, Joni D; Kennerley, Steven W; Hunt, Laurence T

    2016-01-01

    Correlates of value are routinely observed in the prefrontal cortex (PFC) during reward-guided decision making. In previous work (Hunt et al., 2015), we argued that PFC correlates of chosen value are a consequence of varying rates of a dynamical evidence accumulation process. Yet within PFC, there is substantial variability in chosen value correlates across individual neurons. Here we show that this variability is explained by neurons having different temporal receptive fields of integration, indexed by examining neuronal spike rate autocorrelation structure whilst at rest. We find that neurons with protracted resting temporal receptive fields exhibit stronger chosen value correlates during choice. Within orbitofrontal cortex, these neurons also sustain coding of chosen value from choice through the delivery of reward, providing a potential neural mechanism for maintaining predictions and updating stored values during learning. These findings reveal that within PFC, variability in temporal specialisation across neurons predicts involvement in specific decision-making computations. DOI: http://dx.doi.org/10.7554/eLife.18937.001 PMID:27705742

  4. Putting Reward in Art: A Tentative Prediction Error Account of Visual Art

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    Sander Van de Cruys

    2011-12-01

    Full Text Available The predictive coding model is increasingly and fruitfully used to explain a wide range of findings in perception. Here we discuss the potential of this model in explaining the mechanisms underlying aesthetic experiences. Traditionally art appreciation has been associated with concepts such as harmony, perceptual fluency, and the so-called good Gestalt. We observe that more often than not great artworks blatantly violate these characteristics. Using the concept of prediction error from the predictive coding approach, we attempt to resolve this contradiction. We argue that artists often destroy predictions that they have first carefully built up in their viewers, and thus highlight the importance of negative affect in aesthetic experience. However, the viewer often succeeds in recovering the predictable pattern, sometimes on a different level. The ensuing rewarding effect is derived from this transition from a state of uncertainty to a state of increased predictability. We illustrate our account with several example paintings and with a discussion of art movements and individual differences in preference. On a more fundamental level, our theorizing leads us to consider the affective implications of prediction confirmation and violation. We compare our proposal to other influential theories on aesthetics and explore its advantages and limitations.

  5. A neural reward prediction error revealed by a meta-analysis of ERPs using great grand averages.

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    Sambrook, Thomas D; Goslin, Jeremy

    2015-01-01

    Economic approaches to decision making assume that people attach values to prospective goods and act to maximize their obtained value. Neuroeconomics strives to observe these values directly in the brain. A widely used valuation term in formal learning and decision-making models is the reward prediction error: the value of an outcome relative to its expected value. An influential theory (Holroyd & Coles, 2002) claims that an electrophysiological component, feedback related negativity (FRN), codes a reward prediction error in the human brain. Such a component should be sensitive to both the prior likelihood of reward and its magnitude on receipt. A number of studies have found the FRN to be insensitive to reward magnitude, thus questioning the Holroyd and Coles account. However, because of marked inconsistencies in how the FRN is measured, a meaningful synthesis of this evidence is highly problematic. We conducted a meta-analysis of the FRN's response to both reward magnitude and likelihood using a novel method in which published effect sizes were disregarded in favor of direct measurement of the published waveforms themselves, with these waveforms then averaged to produce "great grand averages." Under this standardized measure, the meta-analysis revealed strong effects of magnitude and likelihood on the FRN, consistent with it encoding a reward prediction error. In addition, it revealed strong main effects of reward magnitude and likelihood across much of the waveform, indicating sensitivity to unsigned prediction errors or "salience." The great grand average technique is proposed as a general method for meta-analysis of event-related potential (ERP).

  6. Chronic exposure to a gambling-like schedule of reward predictive stimuli can promote sensitization to amphetamine in rats

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    Martin eZack

    2014-02-01

    Full Text Available Addiction is considered to be a brain disease caused by chronic exposure to drugs. Sensitization of brain dopamine (DA systems partly mediates this effect. Pathological gambling (PG is considered to be a behavioral addiction. Therefore, PG may be caused by chronic exposure to gambling. Identifying a gambling-induced sensitization of DA systems would support this possibility. Gambling rewards evoke DA release. One episode of slot machine play shifts the DA response from reward delivery to onset of cues (spinning reels for reward, in line with temporal difference learning principles. Thus, conditioned stimuli (CS play a key role in DA responses to gambling. In primates, DA response to a CS is strongest when reward probability is 50%. Under this schedule the CS elicits an expectancy of reward but provides no information about whether it will occur on a given trial. During gambling, a 50% schedule should elicit maximal DA release. This closely matches reward frequency (46% on a commercial slot machine. DA release can contribute to sensitization, especially for amphetamine. Chronic exposure to a CS that predicts reward 50% of the time could mimic this effect. We tested this hypothesis in 3 studies with rats. Animals received 15 x 45-min exposures to a CS that predicted reward with a probability of 0, 25, 50, 75 or 100%. The CS was a light; the reward was a 10% sucrose solution. After training, rats received a sensitizing regimen of 5 separate doses (1 mg/kg of d-amphetamine. Lastly they received a 0.5 or 1 mg/kg amphetamine challenge prior to a 90-min locomotor activity test. In all 3 studies the 50% group displayed greater activity than the other groups in response to both challenge doses. Effect sizes were modest but consistent, as reflected by a significant group x rank association ( = .986, p = .025. Chronic exposure to a gambling-like schedule of reward predictive stimuli can promote sensitization to amphetamine much like exposure to

  7. Effort-reward imbalance at work is predicted by temporal and energetic characteristics of behavior: A population-based study

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    Taina Hintsa

    2013-06-01

    Full Text Available Objective: Personality dispositions may influence perceptions of work stress. The paper examines the relationship between temperament in terms of Strelau's Regulative Theory of Temperament and the effort-reward imbalance and its components. Material and Methods: There were 890 participants (360 men aged 37.9 years on average. Temperament traits of briskness and perseveration (temporal characteristics of behavior, sensory sensitivity, emotional reactivity, endurance and activity (energetic characteristics of behavior were measured by Strelau & Zawadzki's Formal Characteristics of Behavior-Temperament Inventory (FCB-TI in 1997 and 2001. Effort and reward at work were assessed with the original effortreward imbalance (ERI questionnaire of 2007. Results: Higher ERI at work was predicted by higher emotional reactivity, higher perseveration, lower briskness, and lower endurance. Higher effort and lower rewards at work were predicted by higher perseveration and lower endurance. The FCB-TI temperament characteristics accounted for 5.2%, 4.8% and 6.5% of the variance in the ERI, effort and reward, respectively. Lower emotional reactivity, lower perseveration, higher briskness and higher endurance predicted higher esteem at work, job promotion and job security. Conclusions: Individual differences in arousability, reflected in temporal and energetic characteristics of behavior, may predispose to or to protect from an effort-reward imbalance at work. Individual differences should be acknowledged in work stress prevention and developing interventions.

  8. Midbrain volume predicts fMRI and ERP measures of reward reactivity.

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    Carlson, Joshua M; Foti, Dan; Harmon-Jones, Eddie; Proudfit, Greg H

    2015-01-01

    Ventral striatal activation measured with functional magnetic resonance imaging (fMRI) and feedback negativity amplitude measured with event-related potentials (ERPs) are each enhanced during reward processing. Recent research has found that these two neural measures of reward processing are also related to one another, such that increases in ventral striatal activity are accompanied by increases in the amplitude of the feedback negativity. Although there is a long history of research implicating the midbrain dopamine system in reward processing, there has been little research into the possibility that structural variability in the midbrain may be linked to functional variability in reward reactivity. Here, we used structural MRI to measure midbrain volumes in addition to fMRI and ERP measures of functional neural reactivity to rewards in a simple gambling task. The results suggest that as midbrain volumes increase, fMRI reward reactivity in the ventral striatum and medial prefrontal cortex also increases. A similar relationship exists between midbrain structure and the amplitude of the feedback negativity; further, this relationship is mediated specifically by activity in the ventral striatum. These data demonstrate convergence between neuroanatomical, hemodynamic, and electrophysiological measures. Thus, structural variability in the midbrain relates to variability in fMRI and ERP measures of functional reward reactivity, which may play a critical role in reward-related psychopathologies and the treatment of these disorders.

  9. Dopamine, reward learning, and active inference

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    Thomas eFitzgerald

    2015-11-01

    Full Text Available Temporal difference learning models propose phasic dopamine signalling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behaviour. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings.

  10. Girls’ challenging social experiences in early adolescence predict neural response to rewards and depressive symptoms

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    Melynda D. Casement

    2014-04-01

    Full Text Available Developmental models of psychopathology posit that exposure to social stressors may confer risk for depression in adolescent girls by disrupting neural reward circuitry. The current study tested this hypothesis by examining the relationship between early adolescent social stressors and later neural reward processing and depressive symptoms. Participants were 120 girls from an ongoing longitudinal study of precursors to depression across adolescent development. Low parental warmth, peer victimization, and depressive symptoms were assessed when the girls were 11 and 12 years old, and participants completed a monetary reward guessing fMRI task and assessment of depressive symptoms at age 16. Results indicate that low parental warmth was associated with increased response to potential rewards in the medial prefrontal cortex (mPFC, striatum, and amygdala, whereas peer victimization was associated with decreased response to potential rewards in the mPFC. Furthermore, concurrent depressive symptoms were associated with increased reward anticipation response in mPFC and striatal regions that were also associated with early adolescent psychosocial stressors, with mPFC and striatal response mediating the association between social stressors and depressive symptoms. These findings are consistent with developmental models that emphasize the adverse impact of early psychosocial stressors on neural reward processing and risk for depression in adolescence.

  11. Reward type and behavioural patterns predict dogs’ success in a delay of gratification paradigm

    Science.gov (United States)

    Brucks, Désirée; Soliani, Matteo; Range, Friederike; Marshall-Pescini, Sarah

    2017-01-01

    Inhibiting an immediate behaviour in favour of an alternative but more advantageous behaviour has been linked to individual success in life, especially in humans. Dogs, which have been living in the human environment for thousands of years, are exposed to daily situations that require inhibition different in context from other non-domesticated species. One task regularly used to study inhibitory control is the delay of gratification task, which requires individuals to choose between an immediate option of lower value and a delayed option of higher value. We tested sixteen dogs in a non-social delay of gratification task, conducting two different conditions: a quality and a quantity condition. While the majority of dogs failed to wait for more than 10 s, some dogs tolerated delays of up to 140 s, while one dog waited for 15 minutes. Moreover, dogs had more difficulties to wait if the reward increased in terms of quantity than quality. Interestingly, dogs were able to anticipate the delay duration and some dogs developed behavioural patterns that predicted waiting, which seems similar in some respects to ‘coping-strategies’ found in children, chimpanzees and parrots. Our results indicate that strategies to cope with impulsivity seem to be consistent and present across animal taxa. PMID:28272409

  12. Love to win or hate to lose? Asymmetry of dopamine D2 receptor binding predicts sensitivity to reward vs. punishment

    Science.gov (United States)

    Tomer, Rachel; Slagter, Heleen A; Christian, Bradley T; Fox, Andrew S; King, Carlye R; Murali, Dhanabalan; Gluck, Mark A; Davidson, Richard J

    2014-01-01

    Humans show consistent differences in the extent to which their behavior reflects a bias towards appetitive approach-related behavior or avoidance of aversive stimuli (Elliot, 2008). We examined the hypothesis that in healthy subjects this motivational bias (assessed by self-report and by a probabilistic learning task that allows direct comparison of the relative sensitivity to reward and punishment) reflects lateralization of dopamine signaling. Using [F-18]fallypride to measure D2/D3 binding , we found that self-reported motivational bias was predicted by the asymmetry of frontal D2 binding. Similarly, striatal and frontal asymmetries in D2 dopamine receptor binding, rather than absolute binding levels, predicted individual differences in learning from reward vs. punishment. These results suggest that normal variation in asymmetry of dopamine signaling may, in part, underlie human personality and cognition. PMID:24345165

  13. Affective personality predictors of disrupted reward learning and pursuit in major depressive disorder.

    Science.gov (United States)

    DelDonno, Sophie R; Weldon, Anne L; Crane, Natania A; Passarotti, Alessandra M; Pruitt, Patrick J; Gabriel, Laura B; Yau, Wendy; Meyers, Kortni K; Hsu, David T; Taylor, Stephen F; Heitzeg, Mary M; Herbener, Ellen; Shankman, Stewart A; Mickey, Brian J; Zubieta, Jon-Kar; Langenecker, Scott A

    2015-11-30

    Anhedonia, the diminished anticipation and pursuit of reward, is a core symptom of major depressive disorder (MDD). Trait behavioral activation (BA), as a proxy for anhedonia, and behavioral inhibition (BI) may moderate the relationship between MDD and reward-seeking. The present studies probed for reward learning deficits, potentially due to aberrant BA and/or BI, in active or remitted MDD individuals compared to healthy controls (HC). Active MDD (Study 1) and remitted MDD (Study 2) participants completed the modified monetary incentive delay task (mMIDT), a behavioral reward-seeking task whose response window parameters were individually titrated to theoretically elicit equivalent accuracy between groups. Participants completed the BI Scale and BA Reward-Responsiveness and Drive Scales. Despite individual titration, active MDD participants won significantly less money than HCs. Higher Reward-Responsiveness scores predicted more won; Drive and BI were not predictive. Remitted MDD participants' performance did not differ from controls', and trait BA and BI measures did not predict r-MDD performance. These results suggest that diminished reward-responsiveness may contribute to decreased motivation and reward pursuit during active MDD, but that reward learning is intact in remission. Understanding individual reward processing deficits in MDD may inform personalized intervention addressing anhedonia and motivation deficits in select MDD patients.

  14. Employee reward

    OpenAIRE

    2014-01-01

    Objectives: • To present the main historical and theoretical foundations underpinning contemporary employee reward practice. • To define employee reward and identify the key components of reward. • To explore the concept of reward management and the benefits and difficulties associated with introducing a strategic approach to reward. • To consider key employee reward choices facing organisations in the contemporary era. • To explore the economic and legal context for reward and the implicatio...

  15. Prefrontal cortex fails to learn from reward prediction errors in alcohol dependence

    NARCIS (Netherlands)

    Park, S.Q.; Kahnt, T.; Beck, A.; Cohen, M.X.; Dolan, R.J.; Wrase, J.; Heinz, A.

    2010-01-01

    Patients suffering from addiction persist in consuming substances of abuse, despite negative consequences or absence of positive consequences. One potential explanation is that these patients are impaired at flexibly adapting their behavior to changes in reward contingencies. A key aspect of adaptiv

  16. Lower neighborhood quality in adolescence predicts higher mesolimbic sensitivity to reward anticipation in adulthood

    Directory of Open Access Journals (Sweden)

    Marlen Z. Gonzalez

    2016-12-01

    Full Text Available Life history theory suggests that adult reward sensitivity should be best explained by childhood, but not current, socioeconomic conditions. In this functional magnetic resonance imaging (fMRI study, 83 participants from a larger longitudinal sample completed the monetary incentive delay (MID task in adulthood (∼25 years old. Parent-reports of neighborhood quality and parental SES were collected when participants were 13 years of age. Current income level was collected concurrently with scanning. Lower adolescent neighborhood quality, but neither lower current income nor parental SES, was associated with heightened sensitivity to the anticipation of monetary gain in putative mesolimbic reward areas. Lower adolescent neighborhood quality was also associated with heightened sensitivity to the anticipation of monetary loss activation in visuo-motor areas. Lower current income was associated with heightened sensitivity to anticipated loss in occipital areas and the operculum. We tested whether externalizing behaviors in childhood or adulthood could better account for neighborhood quality findings, but they did not. Findings suggest that neighborhood ecology in adolescence is associated with greater neural reward sensitivity in adulthood above the influence of parental SES or current income and not mediated through impulsivity and externalizing behaviors.

  17. Personality domains and traits that predict self-reported aberrant driving behaviours in a southeastern US university sample.

    Science.gov (United States)

    Beanland, Vanessa; Sellbom, Martin; Johnson, Alexandria K

    2014-11-01

    Personality traits are meaningful predictors of many significant life outcomes, including mortality. Several studies have investigated the relationship between specific personality traits and driving behaviours, e.g., aggression and speeding, in an attempt to identify traits associated with elevated crash risk. These studies, while valuable, are limited in that they examine only a narrow range of personality constructs and thus do not necessarily reveal which traits in constellation best predict aberrant driving behaviours. The primary aim of this study was to use a comprehensive measure of personality to investigate which personality traits are most predictive of four types of aberrant driving behaviour (Aggressive Violations, Ordinary Violations, Errors, Lapses) as indicated by the Manchester Driver Behaviour Questionnaire (DBQ). We recruited 285 young adults (67% female) from a university in the southeastern US. They completed self-report questionnaires including the DBQ and the Personality Inventory for DSM-5, which indexes 5 broad personality domains (Antagonism, Detachment, Disinhibition, Negative Affectivity, Psychoticism) and 25 specific trait facets. Confirmatory factor analysis showed adequate evidence for the DBQ internal structure. Structural regression analyses revealed that the personality domains of Antagonism and Negative Affectivity best predicted both Aggressive Violations and Ordinary Violations, whereas the best predictors of both Errors and Lapses were Negative Affectivity, Disinhibition and to a lesser extent Antagonism. A more nuanced analysis of trait facets revealed that Hostility was the best predictor of Aggressive Violations; Risk-taking and Hostility of Ordinary Violations; Irresponsibility, Separation Insecurity and Attention Seeking of Errors; and Perseveration and Irresponsibility of Lapses.

  18. Love to win or hate to Lose? Asymmetry of dopamine D2 receptor binding predicts sensitivity to reward versus punishment.

    Science.gov (United States)

    Tomer, Rachel; Slagter, Heleen A; Christian, Bradley T; Fox, Andrew S; King, Carlye R; Murali, Dhanabalan; Gluck, Mark A; Davidson, Richard J

    2014-05-01

    Humans show consistent differences in the extent to which their behavior reflects a bias toward appetitive approach-related behavior or avoidance of aversive stimuli [Elliot, A. J. Approach and avoidance motivation. In A. J. Elliot (Ed.), Handbook of approach and avoidance motivation (pp. 3-14). New York: Psychology Press, 2008]. We examined the hypothesis that in healthy participants this motivational bias (assessed by self-report and by a probabilistic learning task that allows direct comparison of the relative sensitivity to reward and punishment) reflects lateralization of dopamine signaling. Using [F-18]fallypride to measure D2/D3 binding, we found that self-reported motivational bias was predicted by the asymmetry of frontal D2 binding. Similarly, striatal and frontal asymmetries in D2 dopamine receptor binding, rather than absolute binding levels, predicted individual differences in learning from reward versus punishment. These results suggest that normal variation in asymmetry of dopamine signaling may, in part, underlie human personality and cognition.

  19. Modelling dopaminergic and other processes involved in learning from reward prediction error: Contributions from an individual differences perspective

    Directory of Open Access Journals (Sweden)

    Alan David Pickering

    2014-09-01

    Full Text Available Phasic firing changes of midbrain dopamine neurons have been widely characterised as reflecting a reward prediction error (RPE. Major personality traits (e.g. extraversion have been linked to inter-individual variations in dopaminergic neurotransmission. Consistent with these two claims, recent research (Smillie, Cooper, & Pickering, 2011; Cooper, Duke, Pickering, & Smillie, 2014 found that extraverts exhibited larger RPEs than introverts, as reflected in feedback related negativity (FRN effects in EEG recordings. Using an established, biologically-localised RPE computational model, we successfully simulated dopaminergic cell firing changes which are thought to modulate the FRN. We introduced simulated individual differences into the model: parameters were systematically varied, with stable values for each simulated individual. We explored whether a model parameter might be responsible for the observed covariance between extraversion and the FRN changes in real data, and argued that a parameter is a plausible source of such covariance if parameter variance, across simulated individuals, correlated almost perfectly with the size of the simulated dopaminergic FRN modulation, and created as much variance as possible in this simulated output. Several model parameters met these criteria, while others did not. In particular, variations in the strength of connections carrying excitatory reward drive inputs to midbrain dopaminergic cells were considered plausible candidates, along with variations in a parameter which scales the effects of dopamine cell firing bursts on synaptic modification in ventral striatum. We suggest possible neurotransmitter mechanisms underpinning these model parameters. Finally, the limitations and possible extensions of our approach are discussed.

  20. Modeling dopaminergic and other processes involved in learning from reward prediction error: contributions from an individual differences perspective.

    Science.gov (United States)

    Pickering, Alan D; Pesola, Francesca

    2014-01-01

    Phasic firing changes of midbrain dopamine neurons have been widely characterized as reflecting a reward prediction error (RPE). Major personality traits (e.g., extraversion) have been linked to inter-individual variations in dopaminergic neurotransmission. Consistent with these two claims, recent research (Smillie et al., 2011; Cooper et al., 2014) found that extraverts exhibited larger RPEs than introverts, as reflected in feedback related negativity (FRN) effects in EEG recordings. Using an established, biologically-localized RPE computational model, we successfully simulated dopaminergic cell firing changes which are thought to modulate the FRN. We introduced simulated individual differences into the model: parameters were systematically varied, with stable values for each simulated individual. We explored whether a model parameter might be responsible for the observed covariance between extraversion and the FRN changes in real data, and argued that a parameter is a plausible source of such covariance if parameter variance, across simulated individuals, correlated almost perfectly with the size of the simulated dopaminergic FRN modulation, and created as much variance as possible in this simulated output. Several model parameters met these criteria, while others did not. In particular, variations in the strength of connections carrying excitatory reward drive inputs to midbrain dopaminergic cells were considered plausible candidates, along with variations in a parameter which scales the effects of dopamine cell firing bursts on synaptic modification in ventral striatum. We suggest possible neurotransmitter mechanisms underpinning these model parameters. Finally, the limitations and possible extensions of our general approach are discussed.

  1. Hemispheric Asymmetries in Striatal Reward Responses Relate to Approach-Avoidance Learning and Encoding of Positive-Negative Prediction Errors in Dopaminergic Midbrain Regions.

    Science.gov (United States)

    Aberg, Kristoffer Carl; Doell, Kimberly C; Schwartz, Sophie

    2015-10-28

    Some individuals are better at learning about rewarding situations, whereas others are inclined to avoid punishments (i.e., enhanced approach or avoidance learning, respectively). In reinforcement learning, action values are increased when outcomes are better than predicted (positive prediction errors [PEs]) and decreased for worse than predicted outcomes (negative PEs). Because actions with high and low values are approached and avoided, respectively, individual differences in the neural encoding of PEs may influence the balance between approach-avoidance learning. Recent correlational approaches also indicate that biases in approach-avoidance learning involve hemispheric asymmetries in dopamine function. However, the computational and neural mechanisms underpinning such learning biases remain unknown. Here we assessed hemispheric reward asymmetry in striatal activity in 34 human participants who performed a task involving rewards and punishments. We show that the relative difference in reward response between hemispheres relates to individual biases in approach-avoidance learning. Moreover, using a computational modeling approach, we demonstrate that better encoding of positive (vs negative) PEs in dopaminergic midbrain regions is associated with better approach (vs avoidance) learning, specifically in participants with larger reward responses in the left (vs right) ventral striatum. Thus, individual dispositions or traits may be determined by neural processes acting to constrain learning about specific aspects of the world.

  2. Phasic dopamine as a prediction error of intrinsic and extrinsic reinforcements driving both action acquisition and reward maximization: a simulated robotic study.

    Science.gov (United States)

    Mirolli, Marco; Santucci, Vieri G; Baldassarre, Gianluca

    2013-03-01

    An important issue of recent neuroscientific research is to understand the functional role of the phasic release of dopamine in the striatum, and in particular its relation to reinforcement learning. The literature is split between two alternative hypotheses: one considers phasic dopamine as a reward prediction error similar to the computational TD-error, whose function is to guide an animal to maximize future rewards; the other holds that phasic dopamine is a sensory prediction error signal that lets the animal discover and acquire novel actions. In this paper we propose an original hypothesis that integrates these two contrasting positions: according to our view phasic dopamine represents a TD-like reinforcement prediction error learning signal determined by both unexpected changes in the environment (temporary, intrinsic reinforcements) and biological rewards (permanent, extrinsic reinforcements). Accordingly, dopamine plays the functional role of driving both the discovery and acquisition of novel actions and the maximization of future rewards. To validate our hypothesis we perform a series of experiments with a simulated robotic system that has to learn different skills in order to get rewards. We compare different versions of the system in which we vary the composition of the learning signal. The results show that only the system reinforced by both extrinsic and intrinsic reinforcements is able to reach high performance in sufficiently complex conditions.

  3. An MEG signature corresponding to an axiomatic model of reward prediction error.

    Science.gov (United States)

    Talmi, Deborah; Fuentemilla, Lluis; Litvak, Vladimir; Duzel, Emrah; Dolan, Raymond J

    2012-01-01

    Optimal decision-making is guided by evaluating the outcomes of previous decisions. Prediction errors are theoretical teaching signals which integrate two features of an outcome: its inherent value and prior expectation of its occurrence. To uncover the magnetic signature of prediction errors in the human brain we acquired magnetoencephalographic (MEG) data while participants performed a gambling task. Our primary objective was to use formal criteria, based upon an axiomatic model (Caplin and Dean, 2008a), to determine the presence and timing profile of MEG signals that express prediction errors. We report analyses at the sensor level, implemented in SPM8, time locked to outcome onset. We identified, for the first time, a MEG signature of prediction error, which emerged approximately 320 ms after an outcome and expressed as an interaction between outcome valence and probability. This signal followed earlier, separate signals for outcome valence and probability, which emerged approximately 200 ms after an outcome. Strikingly, the time course of the prediction error signal, as well as the early valence signal, resembled the Feedback-Related Negativity (FRN). In simultaneously acquired EEG data we obtained a robust FRN, but the win and loss signals that comprised this difference wave did not comply with the axiomatic model. Our findings motivate an explicit examination of the critical issue of timing embodied in computational models of prediction errors as seen in human electrophysiological data.

  4. Striatal dopamine D2 receptor availability predicts the thalamic and medial prefrontal responses to reward in cocaine abusers three years later

    Energy Technology Data Exchange (ETDEWEB)

    Asensio, S.; Goldstein, R.; Asensio, S.; Romero, M.J.; Romero, F.J.; Wong, C.T.; Alia-Klein, N.; Tomasi, D.; Wang, G.-J.; Telang, F..; Volkow, N.D.; Goldstein, R.Z.

    2010-05-01

    Low levels of dopamine (DA) D2 receptor availability at a resting baseline have been previously reported in drug addicted individuals and have been associated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to nondrug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individuals. Striatal DA D2 receptor availability was measured with [{sup 11}C]raclopride and positron emission tomography and response to monetary reward was measured (an average of three years later) with functional magnetic resonance imaging in seven cocaine-addicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a nondrug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine-addicted individuals.

  5. Striatal dopamine D2 receptor availability predicts the thalamic and medial prefrontal responses to reward in cocaine abusers three years later

    Science.gov (United States)

    Asensio, Samuel; Romero, Maria J.; Romero, Francisco J.; Wong, Christopher; Alia-Klein, Nelly; Tomasi, Dardo; Wang, Gene-Jack; Telang, Frank; Volkow, Nora D.; Goldstein, Rita Z.

    2009-01-01

    Low levels of dopamine (DA) D2 receptor availability at a resting baseline have been previously reported in drug addicted individuals and have been associated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to non-drug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individuals. Striatal DA D2 receptor availability was measured with [11C]raclopride and positron emission tomography and response to monetary reward was measured (an average of 3 years later) with functional magnetic resonance imaging in seven cocaine addicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a non-drug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine addicted individuals. PMID:20034014

  6. Orbitofrontal cortex volume in area 11/13 predicts reward devaluation, but not reversal learning performance, in young and aged monkeys.

    Science.gov (United States)

    Burke, Sara N; Thome, Alex; Plange, Kojo; Engle, James R; Trouard, Theodore P; Gothard, Katalin M; Barnes, Carol A

    2014-07-23

    The orbitofrontal cortex (OFC) and amygdala are both necessary for decisions based on expected outcomes. Although behavioral and imaging data suggest that these brain regions are affected by advanced age, the extent to which aging alters appetitive processes coordinated by the OFC and the amygdala is unknown. In the current experiment, young and aged bonnet macaques were trained on OFC- and amygdala-dependent tasks that test the degree to which response selection is guided by reward value and can be adapted when expected outcomes change. To assess whether the structural integrity of these regions varies with levels of performance on reward devaluation and object reversal tasks, volumes of areas 11/13 and 14 of the OFC, central/medial (CM), and basolateral (BL) nuclei of the amygdala were determined from high-resolution anatomical MRIs. With age, there were significant reductions in OFC, but not CM and BL, volume. Moreover, the aged monkeys showed impairments in the ability to associate an object with a higher value reward, and to reverse a previously learned association. Interestingly, greater OFC volume of area 11/13, but not 14, was significantly correlated with an animal's ability to anticipate the reward outcome associated with an object, and smaller BL volume was predictive of an animal's tendency to choose a higher value reward, but volume of neither region correlated with reversal learning. Together, these data indicate that OFC volume has an impact on monkeys' ability to guide choice behavior based on reward value but does not impact ability to reverse a previously learned association.

  7. AN EXTENDED REINFORCEMENT LEARNING MODEL OF BASAL GANGLIA TO UNDERSTAND THE CONTRIBUTIONS OF SEROTONIN AND DOPAMINE IN RISK-BASED DECISION MAKING, REWARD PREDICTION, AND PUNISHMENT LEARNING

    Directory of Open Access Journals (Sweden)

    Pragathi Priyadharsini Balasubramani

    2014-04-01

    Full Text Available Although empirical and neural studies show that serotonin (5HT plays many functional roles in the brain, prior computational models mostly focus on its role in behavioral inhibition. In this study, we present a model of risk based decision making in a modified Reinforcement Learning (RL-framework. The model depicts the roles of dopamine (DA and serotonin (5HT in Basal Ganglia (BG. In this model, the DA signal is represented by the temporal difference error (δ, while the 5HT signal is represented by a parameter (α that controls risk prediction error. This formulation that accommodates both 5HT and DA reconciles some of the diverse roles of 5HT particularly in connection with the BG system. We apply the model to different experimental paradigms used to study the role of 5HT: 1 Risk-sensitive decision making, where 5HT controls risk assessment, 2 Temporal reward prediction, where 5HT controls time-scale of reward prediction, and 3 Reward/Punishment sensitivity, in which the punishment prediction error depends on 5HT levels. Thus the proposed integrated RL model reconciles several existing theories of 5HT and DA in the BG.

  8. An extended reinforcement learning model of basal ganglia to understand the contributions of serotonin and dopamine in risk-based decision making, reward prediction, and punishment learning.

    Science.gov (United States)

    Balasubramani, Pragathi P; Chakravarthy, V Srinivasa; Ravindran, Balaraman; Moustafa, Ahmed A

    2014-01-01

    Although empirical and neural studies show that serotonin (5HT) plays many functional roles in the brain, prior computational models mostly focus on its role in behavioral inhibition. In this study, we present a model of risk based decision making in a modified Reinforcement Learning (RL)-framework. The model depicts the roles of dopamine (DA) and serotonin (5HT) in Basal Ganglia (BG). In this model, the DA signal is represented by the temporal difference error (δ), while the 5HT signal is represented by a parameter (α) that controls risk prediction error. This formulation that accommodates both 5HT and DA reconciles some of the diverse roles of 5HT particularly in connection with the BG system. We apply the model to different experimental paradigms used to study the role of 5HT: (1) Risk-sensitive decision making, where 5HT controls risk assessment, (2) Temporal reward prediction, where 5HT controls time-scale of reward prediction, and (3) Reward/Punishment sensitivity, in which the punishment prediction error depends on 5HT levels. Thus the proposed integrated RL model reconciles several existing theories of 5HT and DA in the BG.

  9. Positive priming and intentional binding: eye-blink rate predicts reward information effects on the sense of agency.

    Science.gov (United States)

    Aarts, Henk; Bijleveld, Erik; Custers, Ruud; Dogge, Myrthel; Deelder, Merel; Schutter, Dennis; Haren, Neeltje E M van

    2012-01-01

    Human society is strongly rooted in people's experiences of agency; that is, the pervasive feeling that one engages in voluntary behavior and causes one's own actions and resulting outcomes. Rewards and positive affect play an important role in the control of voluntary action. However, the role of positive reward signals in the sense of agency is poorly understood. This study examined effects of reward-related information on the sense of agency by employing the intentional binding paradigm. This paradigm measures the extent to which actions and their effects subjectively shift together across time, reflecting a crucial component of people's sense of agency. Results showed that intentional binding is stronger when participants are primed with reward-related information via brief exposure to positive pictures. Interestingly, this positive priming effect was moderated by baseline eye-blink rates (an indirect marker of striatal dopaminergic functioning); reward-related information increased intentional binding mainly for participants displaying higher baseline eye-blink rates. These findings suggest a possible role for striatal dopamine activity in the process by which reward-related information shapes the way people see themselves as agents.

  10. Prediction of alcohol drinking in adolescents: Personality-traits, behavior, brain responses, and genetic variations in the context of reward sensitivity.

    Science.gov (United States)

    Heinrich, Angela; Müller, Kathrin U; Banaschewski, Tobias; Barker, Gareth J; Bokde, Arun L W; Bromberg, Uli; Büchel, Christian; Conrod, Patricia; Fauth-Bühler, Mira; Papadopoulos, Dimitri; Gallinat, Jürgen; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Ittermann, Bernd; Mann, Karl; Martinot, Jean-Luc; Paus, Tomáš; Pausova, Zdenka; Smolka, Michael; Ströhle, Andreas; Rietschel, Marcella; Flor, Herta; Schumann, Gunter; Nees, Frauke

    2016-07-01

    Adolescence is a time that can set the course of alcohol abuse later in life. Sensitivity to reward on multiple levels is a major factor in this development. We examined 736 adolescents from the IMAGEN longitudinal study for alcohol drinking during early (mean age=14.37) and again later (mean age=16.45) adolescence. Conducting structural equation modeling we evaluated the contribution of reward-related personality traits, behavior, brain responses and candidate genes. Personality seems to be most important in explaining alcohol drinking in early adolescence. However, genetic variations in ANKK1 (rs1800497) and HOMER1 (rs7713917) play an equal role in predicting alcohol drinking two years later and are most important in predicting the increase in alcohol consumption. We hypothesize that the initiation of alcohol use may be driven more strongly by personality while the transition to increased alcohol use is more genetically influenced.

  11. Neural correlates of reward processing in healthy siblings of patients with schizophrenia

    NARCIS (Netherlands)

    Hanssen, Esther; van der Velde, Jorien; Gromann, Paula M.; Shergill, Sukhi S.; de Haan, Lieuwe; Bruggeman, Richard; Krabbendam, Lydia; Aleman, Andre; van Atteveldt, Nienke

    2015-01-01

    Deficits in motivational behavior and psychotic symptoms often observed in schizophrenia (SZ) may be driven by dysfunctional reward processing (RP). RP can be divided in two different stages; reward anticipation and reward consumption. Aberrant processing during reward anticipation seems to be relat

  12. Orienting of Attention to Gaze Direction Cues in Rhesus Macaques: Species-specificity, and Effects of Cue Motion and Reward Predictiveness

    Directory of Open Access Journals (Sweden)

    Dian eYu

    2012-06-01

    Full Text Available Primates live in complex social groups and rely on social cues to direct their attention. For example, primates react faster to an unpredictable stimulus after seeing a conspecific looking in the direction of that stimulus. In the current study we tested the specificity of facial cues (gaze direction for orienting attention and their interaction with other cues that are known to guide attention. In particular, we tested whether macaque monkeys only respond to gaze cues from conspecifics or if the effect generalizes across species. We found an attentional advantage of conspecific faces over that of other human and cartoon faces. Because gaze cues are often conveyed by gesture, we also explored the effect of image motion (a simulated glance on the orienting of attention in monkeys. We found that the simulated glance did not significantly enhance the speed of orienting for monkey face stimuli, but had a significant effect for images of human faces. Finally, because gaze cues presumably guide attention towards relevant or rewarding stimuli, we explored whether orienting of attention was modulated by reward predictiveness. When the cue predicted reward location, face and non-face cues were effective in speeding responses towards the cued location. This effect was strongest for conspecific faces. In sum, our results suggest that while conspecific gaze cues activate an intrinsic process that reflexively directs spatial attention, its effect is relatively small in comparison to other features including motion and reward predictiveness. It is possible that gaze cues are more important for decision-making and voluntary orienting than for reflexive orienting.

  13. Social reward shapes attentional biases.

    Science.gov (United States)

    Anderson, Brian A

    2016-01-01

    Paying attention to stimuli that predict a reward outcome is important for an organism to survive and thrive. When visual stimuli are associated with tangible, extrinsic rewards such as money or food, these stimuli acquire high attentional priority and come to automatically capture attention. In humans and other primates, however, many behaviors are not motivated directly by such extrinsic rewards, but rather by the social feedback that results from performing those behaviors. In the present study, I examine whether positive social feedback can similarly influence attentional bias. The results show that stimuli previously associated with a high probability of positive social feedback elicit value-driven attentional capture, much like stimuli associated with extrinsic rewards. Unlike with extrinsic rewards, however, such stimuli also influence task-specific motivation. My findings offer a potential mechanism by which social reward shapes the information that we prioritize when perceiving the world around us.

  14. Positive priming and intentional binding : Eye-blink rate predicts reward information effects on the sense of agency

    NARCIS (Netherlands)

    Aarts, Henk; Bijleveld, Erik; Custers, Ruud; Dogge, Myrthel; Deelder, Merel; Schutter, Dennis; van Haren, Neeltje E. M.

    2012-01-01

    Human society is strongly rooted in people's experiences of agency; that is, the pervasive feeling that one engages in voluntary behavior and causes one's own actions and resulting outcomes. Rewards and positive affect play an important role in the control of voluntary action. However, the role of p

  15. Positive priming and intentional binding: Eye-blink rate predicts reward information effects on the sense of agency

    NARCIS (Netherlands)

    Aarts, H.A.G.; Bijleveld, E.; Custers, R.; Dogge, M.; Deelder, M.; Schutter, D.J.L.G.; Haren, N.E.M. van

    2012-01-01

    Human society is strongly rooted in people's experiences of agency; that is, the pervasive feeling that one engages in voluntary behavior and causes one's own actions and resulting outcomes. Rewards and positive affect play an important role in the control of voluntary action. However, the role of p

  16. Reward and learning in the goldfish.

    Science.gov (United States)

    Lowes, G; Bitterman, M E

    1967-07-28

    An experiment with goldfish showed the effects of change in amount of reward that are predicted from reinforcement theory. The performance of animals shifted from small to large reward improved gradually to the level of unshifted large-reward controls, while the performance of animals shifted from large to small reward remained at the large-reward level. The difference between these results and those obtained in analogous experiments with the rat suggests that reward functions differently in the instrumental learning of the two animals.

  17. High monetary reward rates and caloric rewards decrease temporal persistence

    Science.gov (United States)

    Bode, Stefan; Murawski, Carsten

    2017-01-01

    Temporal persistence refers to an individual's capacity to wait for future rewards, while forgoing possible alternatives. This requires a trade-off between the potential value of delayed rewards and opportunity costs, and is relevant to many real-world decisions, such as dieting. Theoretical models have previously suggested that high monetary reward rates, or positive energy balance, may result in decreased temporal persistence. In our study, 50 fasted participants engaged in a temporal persistence task, incentivised with monetary rewards. In alternating blocks of this task, rewards were delivered at delays drawn randomly from distributions with either a lower or higher maximum reward rate. During some blocks participants received either a caloric drink or water. We used survival analysis to estimate participants' probability of quitting conditional on the delay distribution and the consumed liquid. Participants had a higher probability of quitting in blocks with the higher reward rate. Furthermore, participants who consumed the caloric drink had a higher probability of quitting than those who consumed water. Our results support the predictions from the theoretical models, and importantly, suggest that both higher monetary reward rates and physiologically relevant rewards can decrease temporal persistence, which is a crucial determinant for survival in many species. PMID:28228517

  18. Are persistent delusions in schizophrenia associated with aberrant salience?

    Directory of Open Access Journals (Sweden)

    Rafeef Abboud

    2016-06-01

    Conclusion: These findings do not support the hypothesis that persistent delusions are related to aberrant motivational salience processing in TRS patients. However, they do support the view that patients with schizophrenia have impaired reward learning.

  19. Analyzing the microfoundations of human violence in the DRC : intrinsic and extrinsic rewards and the prediction of appetitive aggression

    OpenAIRE

    Haer, Roos; Banholzer, Lilli; Elbert, Thomas; Weierstall, Roland

    2013-01-01

    BackgroundCivil wars are characterized by intense forms of violence, such as torture, maiming and rape. Political scientists suggest that this form of political violence is fostered through the provision of particular intrinsic and extrinsic rewards to combatants. In the field of psychology, the perpetration of this kind of cruelty is observed to be positively linked to appetitive aggression. Over time, combatants start to enjoy the fights and even the perpetration of atrocities. In this stud...

  20. Aberrant expression of nuclear HDAC3 and cytoplasmic CDH1 predict a poor prognosis for patients with pancreatic cancer.

    Science.gov (United States)

    Jiao, Feng; Hu, Hai; Han, Ting; Zhuo, Meng; Yuan, Cuncun; Yang, Haiyan; Wang, Lei; Wang, Liwei

    2016-03-29

    Previous studies showed that aberrant CDH1 or/and HDAC3 localization is essential for the progression of some human cancers. Here, we investigate the prognostic significance of aberrant CDH1 and HDAC3 localization in 84 pancreatic cancer patients. Our results show that increases in both membrane and cytoplasmic CDH1 correlate with lymph node metastasis (P = 0.026 and P 0.05). Multivariate analysis showed that nuclear HDAC3 and cytoplasmic CDH1 (P = 0.001 and P = 0.010, respectively), as well as tumor differentiation (P = 0.009) are independent prognostic factors. Most importantly, patients with high co-expression of nuclear HDAC3 and cytoplasmic CDH1 had shorter survival times (P CDH1 have independent prognostic value in pancreatic cancer and provide novel targets for prognostic therapeutics.

  1. Rewarding prayers.

    Science.gov (United States)

    Schjødt, Uffe; Stødkilde-Jørgensen, Hans; Geertz, Armin W; Roepstorff, Andreas

    2008-10-10

    We report a highly significant regional increase of the BOLD response in the caudate nucleus in a group of Danish Christians while performing silent religious prayer. The effect was found in a main-effect analysis of high-structured and low-structured religious recitals relative to comparable secular recitals and to a non-narrative baseline. This supports the hypothesis that religious prayer as a form of frequently recurring behavior is capable of stimulating the dopaminergic reward system in practicing individuals. It extends recent research which demonstrates a relation between interpersonal trust and activation in the dopaminergic system to also encompass relations to abstract entities.

  2. Chromosomal aberrations in lymphocytes predict human cancer: a report from the European Study Group on Cytogenetic Biomarkers and Health (ESCH)

    DEFF Research Database (Denmark)

    Hagmar, L; Bonassi, S; Strömberg, U;

    1998-01-01

    Chromosomal aberrations (CAs), sister chromatid exchanges (SCEs), and micronuclei (MN) in peripheral blood lymphocytes have for decades been used as cytogenetic biomarkers to survey genotoxic risks in the work environment. The conceptual basis for this application has been the idea that increased...... cytogenetic damage reflects an enhanced cancer risk. Nordic and Italian cohorts have been established to evaluate this hypothesis, and analyses presented previously have shown a positive trend between CA frequency and increased cancer risk. We now report on a pooled analysis of updated data for 3541 subjects...... examined for CAs, 2703 for SCEs, and 1496 for MN. To standardize for interlaboratory variation, the results for the various cytogenetic end points were trichotomized on the basis of the absolute value distribution within each laboratory as "low" (1-33 percentile), "medium" (34-66 percentile), or "high" (67...

  3. Optical Aberrations and Wavefront

    Directory of Open Access Journals (Sweden)

    Nihat Polat

    2014-08-01

    Full Text Available The deviation of light to create normal retinal image in the optical system is called aberration. Aberrations are divided two subgroup: low-order aberrations (defocus: spherical and cylindrical refractive errors and high-order aberrations (coma, spherical, trefoil, tetrafoil, quadrifoil, pentafoil, secondary astigmatism. Aberrations increase with aging. Spherical aberrations are compensated by positive corneal and negative lenticular spherical aberrations in youth. Total aberrations are elevated by positive corneal and positive lenticular spherical aberrations in elderly. In this study, we aimed to analyze the basic terms regarding optic aberrations which have gained significance recently. (Turk J Ophthalmol 2014; 44: 306-11

  4. Adolescent Alcohol Exposure Amplifies the Incentive Value of Reward-Predictive Cues Through Potentiation of Phasic Dopamine Signaling.

    Science.gov (United States)

    Spoelder, Marcia; Tsutsui, Kimberly T; Lesscher, Heidi M B; Vanderschuren, Louk J M J; Clark, Jeremy J

    2015-12-01

    Adolescent alcohol use remains a major public health concern due in part to well-established findings implicating the age of onset in alcohol use in the development of alcohol use disorders and persistent decision-making deficits in adults. We have previously demonstrated that moderate adolescent alcohol consumption in rats promotes suboptimal decision making and an associated perturbation in mesolimbic dopamine transmission in adulthood. Dopamine-dependent incentive learning processes are an integral component of value-based decision making and a fundamental element to many theoretical accounts of addiction. Thus we tested the hypothesis that adolescent alcohol use selectively alters incentive learning processes through perturbation of mesolimbic dopamine systems. To assess incentive learning, behavioral and neurochemical measurements were made during the acquisition, maintenance, extinction, and reacquisition of a Pavlovian conditioned approach procedure in adult rats with a history of adolescent alcohol consumption. We show that moderate adolescent alcohol consumption potentiates stimulus-evoked phasic dopamine transmission, measured in vivo by fast-scan cyclic voltammetry, in adulthood and biases individuals toward a dopamine-dependent incentive learning strategy. Moreover, we demonstrate that animals exposed to alcohol in adolescence are more sensitive to an unexpected variation in reward outcomes. This pattern of phasic dopamine signaling and the associated bias in learning may provide a mechanism for the well-documented vulnerability of individuals with early-life alcohol use for alcohol use disorders in adulthood.

  5. Cancer risk in humans predicted by increased levels of chromosomal aberrations in lymphocytes: Nordic study group on the health risk of chromosome damage

    DEFF Research Database (Denmark)

    Hagmar, L; Brøgger, A; Hansteen, I L;

    1994-01-01

    Cytogenetic assays in peripheral blood lymphocytes (PBL) have been used extensively to survey the exposure of humans to genotoxic agents. The conceptual basis for this has been the hypothesis that the extent of genetic damage in PBL reflects critical events for carcinogenic processes in target...... tissues. Until now, no follow-up studies have been performed to assess the predictive value of these methods for subsequent cancer risk. In an ongoing Nordic cohort study of cancer incidence, 3182 subjects were examined between 1970 and 1988 for chromosomal aberrations (CA), sister chromatid exchange.......0009) in CA strata with regard to subsequent cancer risk. The point estimates of the standardized incidence ratio in the three CA strata were 0.9, 0.7, and 2.1, respectively. Thus, an increased level of chromosome breakage appears to be a relevant biomarker of future cancer risk....

  6. Genetic differences and aberrant methylation in the apelin system predict the risk of high-altitude pulmonary edema

    Science.gov (United States)

    Mishra, Aastha; Kohli, Samantha; Dua, Sanchi; Thinlas, Tashi; Mohammad, Ghulam; Pasha, M. A. Qadar

    2015-01-01

    Hypoxia-inducible factor stimulates the expression of apelin, a potent vasodilator, in response to reduced blood arterial oxygen saturation. However, aberrations in the apelin system impair pulmonary vascular function, potentially resulting in the development of high-altitude (HA)-related disorders. This study aimed to elucidate the genetic and epigenetic regulation of apelin, apelin receptor (APLNR), and endothelial nitric oxide synthase (NOS3) in HA adaptation and HA pulmonary edema (HAPE). A genome-wide association study and sequencing identified variants of apelin, APLNR, and NOS3 that were validated in a larger sample size of HAPE-patients (HAPE-p), HAPE-free controls (HAPE-f), and healthy highland natives (HLs). Apelin-13 and nitrite levels and apelin and NOS3 expression were down-regulated in HAPE-p (P < 0.001). Among the several studied polymorphisms, apelin rs3761581, rs2235312, and rs3115757; APLNR rs11544374 and rs2282623; and NOS3 4b/4a, rs1799983, and rs7830 were associated with HAPE (P < 0.03). The risk allele rs3761581G was associated with a 58.6% reduction in gene expression (P = 0.017), and the risk alleles rs3761581G and rs2235312T were associated with low levels of apelin-13 and nitrite (P < 0.05). The latter two levels decreased further when both of these risk alleles were present in the patients (P < 0.05). Methylation of the apelin CpG island was significantly higher in HAPE-p at 11.92% than in HAPE-f and HLs at ≤7.1% (P < 0.05). Moreover, the methylation effect was 9% stronger in the 5′ UTR and was associated with decreased apelin expression and apelin-13 levels. The rs3761581 and rs2235312 polymorphisms and methylation of the CpG island influence the expression of apelin in HAPE. PMID:25918383

  7. The Rewards of Learning.

    Science.gov (United States)

    Chance, Paul

    1992-01-01

    Although intrinsic rewards are important, they (along with punishment and encouragement) are insufficient for efficient learning. Teachers must supplement intrinsic rewards with extrinsic rewards, such as praising, complimenting, applauding, and providing other forms of recognition for good work. Teachers should use the weakest reward required to…

  8. WE-D-BRE-05: Prediction of Late Radiation-Induced Proctitis in Prostate Cancer Patients Using Chromosome Aberration and Cell Proliferation Rate

    Energy Technology Data Exchange (ETDEWEB)

    Oh, J; Deasy, J [Memorial Sloan Kettering Cancer Center, New York, NY (United States)

    2014-06-15

    Purpose: Chromosome damage and cell proliferation rate have been investigated as potential biomarkers for the early prediction of late radiationinduced toxicity. Incorporating these endpoints, we explored the predictive power for late radiation proctitis using a machine learning method. Methods: Recently, Beaton et al. showed that chromosome aberration and cell proliferation rate could be used as biomarkers to predict late radiation proctitis (Beaton et al. (2013) Int J Rad Onc Biol Phys, 85:1346–1352). For the identification of radiosensitive biomarkers, blood samples were collected from 10 patients with grade 3 late proctitis along with 20 control patients with grade 0 proctitis. After irradiation at 6 Gy, statistically significant difference was observed between the two groups, using the number of dicentrics and excess fragments, and the number of cells in metaphase 2 (M2). However, Beaton et al. did not show the usefulness of combining these endpoints. We reanalyzed the dataset to investigate whether incorporating these endpoints can increase the predictive power of radiation proctitis, using a support vector machine (SVM). Results: Using the SVM method with the number of fragments and M2 endpoints, perfect classification was achieved. In addition, to avoid biased estimate of the classification method, leave-one-out cross-validation (LOO-CV) was performed. The best performance was achieved when all three endpoints were used with 87% accuracy, 90% sensitivity, 85% specificity, and 0.85 AUC (the area under the receiver operating characteristic (ROC) curve). The most significant endpoint was the number of fragments that obtained 83% accuracy, 70% sensitivity, 90% specificity, and 0.82 AUC. Conclusion: We demonstrated that chromosome damage and cell proliferation rate could be significant biomarkers to predict late radiation proctitis. When these endpoints were used together in conjunction with a machine learning method, the better performance was obtained

  9. Linear combination of one-step predictive information with an external reward in an episodic policy gradient setting: a critical analysis

    Directory of Open Access Journals (Sweden)

    Keyan eZahedi

    2013-11-01

    Full Text Available One of the main challenges in the field of embodied artificial intelligence is the open-ended autonomous learning of complex behaviours. Our approach is to use task-independent, information-driven intrinsic motivation(s to support task-dependent learning. The work presented here is a preliminary step in which we investigate the predictive information (the mutual information of the past and future of the sensor stream as an intrinsic drive, ideally supporting any kind of task acquisition. Previous experiments have shown that the predictive information (PI is a good candidate to support autonomous, open-ended learning of complex behaviours, because a maximisation of the PI corresponds to an exploration of morphology- and environment-dependent behavioural regularities. The idea is that these regularities can then be exploited in order to solve any given task. Three different experiments are presented and their results lead to the conclusion that the linear combination of the one-step PI with an external reward function is not generally recommended in an episodic policy gradient setting. Only for hard tasks a great speed-up can be achieved at the cost of an asymptotic performance lost.

  10. Stress and reward

    DEFF Research Database (Denmark)

    Chumbley, J R; Hulme, O; Köchli, H

    2014-01-01

    Healthy individuals tend to consume available rewards like food and sex. This tendency is attenuated or amplified in most stress-related psychiatric conditions, so we asked if it depends on endogenous levels of the 'canonical stress hormone' cortisol. We unobtrusively quantified how hard healthy...... heterosexual men would work to consume erotic images of women versus men and also measured their exposure to endogenous cortisol in the prior two months. We used linear models to predict the strength of sexual preference from cortisol level, after accounting for other potential explanations. Heterosexual...

  11. Memory Consolidation and Neural Substrate of Reward

    Directory of Open Access Journals (Sweden)

    Redolar-Ripoll, Diego

    2012-08-01

    Full Text Available The aim of this report is to analyze the relationships between reward and learning and memory processes. Different studies have described how information about rewards influences behavior and how the brain uses this reward information to control learning and memory processes. Reward nature seems to be processed in different ways by neurons in different brain structures, ranging from the detection and perception of rewards to the use of information about predicted rewards for the control of goal-directed behavior. The neural substrate underling this processing of reward information is a reliable way of improving learning and memory processes. Evidence from several studies indicates that this neural system can facilitate memory consolidation in a wide variety of learning tasks. From a molecular perspective, certain cardinal features of reward have been described as forms of memory. Studies of human addicts and studies in animal models of addiction show that chronic drug exposure produces stable changes in the brain at the cellular and molecular levels that underlie the long-lasting behavioral plasticity associated with addiction. These molecular and cellular adaptations involved in addiction are also implicated in learning and memory processes. Dopamine seems to be a critical common signal to activate different genetic mechanisms that ultimately remodel synapses and circuits. Despite memory is an active and complex process mediated by different brain areas, the neural substrate of reward is able to improve memory consolidation in a several paradigms. We believe that there are many equivalent traits between reward and learning and memory processes.

  12. Aberrant gene methylation in the peritoneal fluid is a risk factor predicting peritoneal recurrence in gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Masatsugu; Hiraki; Yoshihiko; Kitajima; Seiji; Sato; Jun; Nakamura; Kazuyoshi; Hashiguchi; Hirokazu; Noshiro; Kohji; Miyazaki

    2010-01-01

    AIM:To investigate whether gene methylation in the peritoneal fluid (PF) predicts peritoneal recurrence in gastric cancer patients.METHODS: The gene methylation of CHFR (checkpoint with forkhead and ring finger domains), p16, RUNX3 (runt-related transcription factor 3), E-cadherin, hMLH1 (mutL homolog 1), ABCG2 (ATP-binding cassette, sub-family G, member 2) and BNIP3 (BCL2/adenovirus E1B 19 kDa interacting protein 3) were analyzed in 80 specimens of PF by quantitative methylation-specific polymerase chain r...

  13. Chromosomal aberrations in lymphocytes predict human cancer independently of exposure to carcinogens. European Study Group on Cytogenetic Biomarkers and Health

    DEFF Research Database (Denmark)

    Bonassi, S; Hagmar, L; Strömberg, U;

    2000-01-01

    played by exposure to carcinogens is still uncertain because of the requisite information concerning occupation and lifestyle was lacking. We evaluated in the present study whether CAs predicted cancer because they were the result of past exposure to carcinogens or because they were an intermediate end...... by country, sex, year of birth, and year of CA test were randomly selected. Occupational exposure and smoking habit were assessed by a collaborative group of occupational hygienists. Logistic regression models indicated a statistically significant increase in risk for subjects with a high level of CAs...... compared to those with a low level in the Nordic cohort (odds ratio, 2.35; 95% confidence interval, 1.31-4.23) and in the Italian cohort (odds ratio, 2.66; 95% confidence interval, 1.26-5.62). These estimates were not affected by the inclusion of occupational exposure level and smoking habit...

  14. Non-reward neural mechanisms in the orbitofrontal cortex.

    Science.gov (United States)

    Rolls, Edmund T; Deco, Gustavo

    2016-10-01

    Single neurons in the primate orbitofrontal cortex respond when an expected reward is not obtained, and behaviour must change. The human lateral orbitofrontal cortex is activated when non-reward, or loss occurs. The neuronal computation of this negative reward prediction error is fundamental for the emotional changes associated with non-reward, and with changing behaviour. Little is known about the neuronal mechanism. Here we propose a mechanism, which we formalize into a neuronal network model, which is simulated to enable the operation of the mechanism to be investigated. A single attractor network has a reward population (or pool) of neurons that is activated by expected reward, and maintain their firing until, after a time, synaptic depression reduces the firing rate in this neuronal population. If a reward outcome is not received, the decreasing firing in the reward neurons releases the inhibition implemented by inhibitory neurons, and this results in a second population of non-reward neurons to start and continue firing encouraged by the spiking-related noise in the network. If a reward outcome is received, this keeps the reward attractor active, and this through the inhibitory neurons prevents the non-reward attractor neurons from being activated. If an expected reward has been signalled, and the reward attractor neurons are active, their firing can be directly inhibited by a non-reward outcome, and the non-reward neurons become activated because the inhibition on them is released. The neuronal mechanisms in the orbitofrontal cortex for computing negative reward prediction error are important, for this system may be over-reactive in depression, under-reactive in impulsive behaviour, and may influence the dopaminergic 'prediction error' neurons.

  15. Punished by Rewards?

    Science.gov (United States)

    Brandt, Ron

    1995-01-01

    The author of "Punished by Rewards" (1993), claims that rewards and punishments serve to manipulate behavior and destroy the potential for real learning. Praise is especially tricky, since intangible rewards can also foster compliance, not motivation. An engaging curriculum and a caring atmosphere encourage kids to exercise their natural…

  16. Motivation and reward systems

    NARCIS (Netherlands)

    van Eerde, W.; Vodosek, M.; den Hartog, D.N.; McNett, J.M.

    2014-01-01

    Reward systems are identified as one of the human resource management (HRM) practices that may impact motivation. Reward systems may consist of several components, including financial and nonfinancial rewards, in fixed and variable amounts. Reinforcement, expectancy, and equity principles are discus

  17. Pain and suicidality: insights from reward and addiction neuroscience.

    Science.gov (United States)

    Elman, Igor; Borsook, David; Volkow, Nora D

    2013-10-01

    Suicidality is exceedingly prevalent in pain patients. Although the pathophysiology of this link remains unclear, it may be potentially related to the partial congruence of physical and emotional pain systems. The latter system's role in suicide is also conspicuous during setbacks and losses sustained in the context of social attachments. Here we propose a model based on the neural pathways mediating reward and anti-reward (i.e., allostatic adjustment to recurrent activation of the reward circuitry); both are relevant etiologic factors in pain, suicide and social attachments. A comprehensive literature search on neurobiology of pain and suicidality was performed. The collected articles were critically reviewed and relevant data were extracted and summarized within four key areas: (1) physical and emotional pain, (2) emotional pain and social attachments, (3) pain- and suicide-related alterations of the reward and anti-reward circuits as compared to addiction, which is the premier probe for dysfunction of these circuits and (4) mechanistically informed treatments of co-occurring pain and suicidality. Pain-, stress- and analgesic drugs-induced opponent and proponent states of the mesolimbic dopaminergic pathways may render reward and anti-reward systems vulnerable to sensitization, cross-sensitization and aberrant learning of contents and contexts associated with suicidal acts and behaviors. These findings suggest that pain patients exhibit alterations in the brain circuits mediating reward (depressed function) and anti-reward (sensitized function) that may affect their proclivity for suicide and support pain and suicidality classification among other "reward deficiency syndromes" and a new proposal for "enhanced anti-reward syndromes". We suggest that interventions aimed at restoring the balance between the reward and anti-reward networks in patients with chronic pain may help decreasing their suicide risk.

  18. Parabolic discounting of monetary rewards by physical effort.

    Science.gov (United States)

    Hartmann, Matthias N; Hager, Oliver M; Tobler, Philippe N; Kaiser, Stefan

    2013-11-01

    When humans and other animals make decisions in their natural environments prospective rewards have to be weighed against costs. It is well established that increasing costs lead to devaluation or discounting of reward. While our knowledge about discount functions for time and probability costs is quite advanced, little is known about how physical effort discounts reward. In the present study we compared three different models in a binary choice task in which human participants had to squeeze a handgrip to earn monetary rewards: a linear, a hyperbolic, and a parabolic model. On the group as well as the individual level, the concave parabolic model explained most variance of the choice data, thus contrasting with the typical hyperbolic discounting of reward value by delay. Research on effort discounting is not only important to basic science but also holds the potential to quantify aberrant motivational states in neuropsychiatric disorders.

  19. Consolidation power of extrinsic rewards: reward cues enhance long-term memory for irrelevant past events.

    Science.gov (United States)

    Murayama, Kou; Kitagami, Shinji

    2014-02-01

    Recent research suggests that extrinsic rewards promote memory consolidation through dopaminergic modulation processes. However, no conclusive behavioral evidence exists given that the influence of extrinsic reward on attention and motivation during encoding and consolidation processes are inherently confounded. The present study provides behavioral evidence that extrinsic rewards (i.e., monetary incentives) enhance human memory consolidation independently of attention and motivation. Participants saw neutral pictures, followed by a reward or control cue in an unrelated context. Our results (and a direct replication study) demonstrated that the reward cue predicted a retrograde enhancement of memory for the preceding neutral pictures. This retrograde effect was observed only after a delay, not immediately upon testing. An additional experiment showed that emotional arousal or unconscious resource mobilization cannot explain the retrograde enhancement effect. These results provide support for the notion that the dopaminergic memory consolidation effect can result from extrinsic reward.

  20. Reward guides vision when it's your thing: trait reward-seeking in reward-mediated visual priming.

    Directory of Open Access Journals (Sweden)

    Clayton Hickey

    Full Text Available Reward-related mesolimbic dopamine is thought to play an important role in guiding animal behaviour, biasing approach towards potentially beneficial environmental stimuli and away from objects unlikely to garner positive outcome. This is considered to result in part from an impact on perceptual and attentional processes: dopamine initiates a series of cognitive events that result in the priming of reward-associated perceptual features. We have provided behavioural and electrophysiological evidence that this mechanism guides human vision in search, an effect we refer to as reward priming. We have also demonstrated that there is substantial individual variability in this effect. Here we show that behavioural differences in reward priming are predicted remarkably well by a personality index that captures the degree to which a person's behaviour is driven by reward outcome. Participants with reward-seeking personalities are found to be those who allocate visual resources to objects characterized by reward-associated visual features. These results add to a rapidly developing literature demonstrating the crucial role reward plays in attentional control. They additionally illustrate the striking impact personality traits can have on low-level cognitive processes like perception and selective attention.

  1. THC reduces the anticipatory nucleus accumbens response to reward in subjects with a nicotine addiction

    NARCIS (Netherlands)

    Jansma, J.M.; Hell, van H.H.; Vanderschuren, L.J.M.J.; Bossong, M.G.; Jager, G.; Kahn, R.S.; Ramsey, N.F.

    2013-01-01

    Recent evidence has implicated the endocannabinoid (eCB) system in nicotine addiction. The eCB system also has an important role in reward mechanisms, and nicotine addiction has been associated with aberrant reward processing. Motivated by this evidence, we tested the hypothesis that eCB modulation

  2. Chicago aberration correction work.

    Science.gov (United States)

    Beck, V D

    2012-12-01

    The author describes from his personal involvement the many improvements to electron microscopy Albert Crewe and his group brought by minimizing the effects of aberrations. The Butler gun was developed to minimize aperture aberrations in a field emission electron gun. In the 1960s, Crewe anticipated using a spherical aberration corrector based on Scherzer's design. Since the tolerances could not be met mechanically, a method of moving the center of the octopoles electrically was developed by adding lower order multipole fields. Because the corrector was located about 15 cm ahead of the objective lens, combination aberrations would arise with the objective lens. This fifth order aberration would then limit the aperture of the microscope. The transformation of the off axis aberration coefficients of a round lens was developed and a means to cancel anisotropic coma was developed. A new method of generating negative spherical aberration was invented using the combination aberrations of hexapoles. Extensions of this technique to higher order aberrations were developed. An electrostatic electron mirror was invented, which allows the cancellation of primary spherical aberration and first order chromatic aberration. A reduction of chromatic aberration by two orders of magnitude was demonstrated using such a system.

  3. Chicago aberration correction work

    Energy Technology Data Exchange (ETDEWEB)

    Beck, V.D., E-mail: vnlbeck@earthlink.net [1 Hobby Drive, Ridgefield, CT 06877-01922 (United States)

    2012-12-15

    The author describes from his personal involvement the many improvements to electron microscopy Albert Crewe and his group brought by minimizing the effects of aberrations. The Butler gun was developed to minimize aperture aberrations in a field emission electron gun. In the 1960s, Crewe anticipated using a spherical aberration corrector based on Scherzer's design. Since the tolerances could not be met mechanically, a method of moving the center of the octopoles electrically was developed by adding lower order multipole fields. Because the corrector was located about 15 cm ahead of the objective lens, combination aberrations would arise with the objective lens. This fifth order aberration would then limit the aperture of the microscope. The transformation of the off axis aberration coefficients of a round lens was developed and a means to cancel anisotropic coma was developed. A new method of generating negative spherical aberration was invented using the combination aberrations of hexapoles. Extensions of this technique to higher order aberrations were developed. An electrostatic electron mirror was invented, which allows the cancellation of primary spherical aberration and first order chromatic aberration. A reduction of chromatic aberration by two orders of magnitude was demonstrated using such a system. -- Highlights: Black-Right-Pointing-Pointer Crewe and his group made significant advances in aberration correction and reduction. Black-Right-Pointing-Pointer A deeper understanding of the quadrupole octopole corrector was developed. Black-Right-Pointing-Pointer A scheme to correct spherical aberration using hexapoles was developed. Black-Right-Pointing-Pointer Chromatic aberration was corrected using a uniform field mirror.

  4. Markov reward processes

    Science.gov (United States)

    Smith, R. M.

    1991-01-01

    Numerous applications in the area of computer system analysis can be effectively studied with Markov reward models. These models describe the behavior of the system with a continuous-time Markov chain, where a reward rate is associated with each state. In a reliability/availability model, upstates may have reward rate 1 and down states may have reward rate zero associated with them. In a queueing model, the number of jobs of certain type in a given state may be the reward rate attached to that state. In a combined model of performance and reliability, the reward rate of a state may be the computational capacity, or a related performance measure. Expected steady-state reward rate and expected instantaneous reward rate are clearly useful measures of the Markov reward model. More generally, the distribution of accumulated reward or time-averaged reward over a finite time interval may be determined from the solution of the Markov reward model. This information is of great practical significance in situations where the workload can be well characterized (deterministically, or by continuous functions e.g., distributions). The design process in the development of a computer system is an expensive and long term endeavor. For aerospace applications the reliability of the computer system is essential, as is the ability to complete critical workloads in a well defined real time interval. Consequently, effective modeling of such systems must take into account both performance and reliability. This fact motivates our use of Markov reward models to aid in the development and evaluation of fault tolerant computer systems.

  5. Interaction of Reward Seeking and Self-Regulation in the Prediction of Risk Taking: A Cross-National Test of the Dual Systems Model

    Science.gov (United States)

    Duell, Natasha; Steinberg, Laurence; Chein, Jason; Al-Hassan, Suha M.; Bacchini, Dario; Lei, Chang; Chaudhary, Nandita; Di Giunta, Laura; Dodge, Kenneth A.; Fanti, Kostas A.; Lansford, Jennifer E.; Malone, Patrick S.; Oburu, Paul; Pastorelli, Concetta; Skinner, Ann T.; Sorbring, Emma; Tapanya, Sombat; Uribe Tirado, Liliana Maria; Alampay, Liane Peña

    2016-01-01

    In the present analysis, we test the dual systems model of adolescent risk taking in a cross-national sample of over 5,200 individuals aged 10 through 30 (M = 17.05 years, SD = 5.91) from 11 countries. We examine whether reward seeking and self-regulation make independent, additive, or interactive contributions to risk taking, and ask whether…

  6. Prior fear conditioning and reward learning interact in fear and reward networks

    Directory of Open Access Journals (Sweden)

    Lisa eBulganin

    2014-03-01

    Full Text Available The ability to flexibly adapt responses to changes in the environment is important for survival. Previous research in humans separately examined the mechanisms underlying acquisition and extinction of aversive and appetitive conditioned responses. It is yet unclear how aversive and appetitive learning interact on a neural level during counterconditioning in humans. This functional magnetic resonance imaging (fMRI study investigated the interaction of fear conditioning and subsequent reward learning. In the first phase (fear acquisition, images predicted aversive electric shocks or no aversive outcome. In the second phase (counterconditioning, half of the CS+ and CS- were associated with monetary reward in the absence of electric stimulation. The third phase initiated reinstatement of fear through presentation of electric shocks, followed by CS presentation in the absence of shock or reward. Results indicate that participants were impaired at learning the reward contingencies for stimuli previously associated with shock. In the counterconditioning phase, prior fear association interacted with reward representation in the amygdala, where activation was decreased for rewarded compared to unrewarded CS- trials, while there was no reward-related difference in CS+ trials. In the reinstatement phase, an interaction of previous fear association and previous reward status was observed in a reward network consisting of substantia nigra / ventral tegmental area (SN/VTA, striatum and orbitofrontal cortex (OFC, where activation was increased by previous reward association only for CS- but not for CS+ trials. These findings suggest that during counterconditioning, prior fear conditioning interferes with reward learning, subsequently leading to lower activation of the reward network.

  7. Motivated to win: Relationship between anticipatory and outcome reward-related neural activity.

    Science.gov (United States)

    Pornpattananangkul, Narun; Nusslock, Robin

    2015-11-01

    Reward-processing involves two temporal stages characterized by two distinct neural processes: reward-anticipation and reward-outcome. Intriguingly, very little research has examined the relationship between neural processes involved in reward-anticipation and reward-outcome. To investigate this, one needs to consider the heterogeneity of reward-processing within each stage. To identify different stages of reward processing, we adapted a reward time-estimation task. While EEG data were recorded, participants were instructed to button-press 3.5s after the onset of an Anticipation-Cue and received monetary reward for good time-estimation on the Reward trials, but not on No-Reward trials. We first separated reward-anticipation into event related potentials (ERPs) occurring at three sub-stages: reward/no-reward cue-evaluation, motor-preparation and feedback-anticipation. During reward/no-reward cue-evaluation, the Reward-Anticipation Cue led to a smaller N2 and larger P3. During motor-preparation, we report, for the first time, that the Reward-Anticipation Cue enhanced the Readiness Potential (RP), starting approximately 1s before movement. At the subsequent feedback-anticipation stage, the Reward-Anticipation Cue elevated the Stimulus-Preceding Negativity (SPN). We also separated reward-outcome ERPs into different components occurring at different time-windows: the Feedback-Related Negativity (FRN), Feedback-P3 (FB-P3) and Late-Positive Potentials (LPP). Lastly, we examined the relationship between reward-anticipation and reward-outcome ERPs. We report that individual-differences in specific reward-anticipation ERPs uniquely predicted specific reward-outcome ERPs. In particular, the reward-anticipation Early-RP (1-.8s before movement) predicted early reward-outcome ERPs (FRN and FB-P3), whereas, the reward-anticipation SPN most strongly predicted a later reward-outcome ERP (LPP). Results have important implications for understanding the nature of the relationship

  8. A comparison of reward-contingent neuronal activity in monkey orbitofrontal cortex and ventral striatum: guiding actions toward rewards.

    Science.gov (United States)

    Simmons, Janine M; Ravel, Sabrina; Shidara, Munetaka; Richmond, Barry J

    2007-12-01

    We have investigated how neuronal activity in the orbitofrontal-ventral striatal circuit is related to reward-directed behavior by comparing activity in these two regions during a visually guided reward schedule task. When a set of visual cues provides information about reward contingency, that is, about whether or not a trial will be rewarded, significant subpopulations of neurons in both orbitofrontal cortex and ventral striatum encode this information. Orbitofrontal and ventral striatal neurons also differentiate between rewarding and non-rewarding trial outcomes, whether or not those outcomes were predicted. The size of the neuronal subpopulation encoding reward contingency is twice as large in orbitofrontal cortex (50% of neurons) as in ventral striatum (26%). Reward-contingency-dependent activity also appears earlier during a trial in orbitofrontal cortex than in ventral striatum. The peak reward-contingency representation in orbitofrontal cortex (31% of neurons), occurs during the wait period, a period of high anticipation prior to any action. The peak ventral striatal representation of reward contingency (18%) occurs during the go period, a time of action. We speculate that signals from orbitofrontal cortex bias ventral striatal activity, and that a flow of reward-contingency information from orbitofrontal cortex to ventral striatum serves to guide actions toward rewards.

  9. Do Substantia Nigra Dopaminergic Neurons Differentiate Between Reward and Punishment?

    Institute of Scientific and Technical Information of China (English)

    Michael J. Frank; D. James Surmeier

    2009-01-01

    The activity of dopaminergic neurons are thought to be increased by stimuli that predict reward and decreased by stimuli that predict aversive outcomes. Recent work by Matsumoto and Hikosaka challenges this model by asserting that stimuli associated with either rewarding or aversive outcomes increase the activity of dopaminergic neurons in the substantia nigra pars compacta.

  10. Anticipation of novelty recruits reward system and hippocampus while promoting recollection

    OpenAIRE

    2007-01-01

    The dopaminergic midbrain, which comprises the substantia nigra and ventral tegmental area (SN/VTA), plays a central role in reward processing. This region is also activated by novel stimuli, raising the possibility that novelty and reward have shared functional properties. It is currently unclear whether functional aspects of reward processing in the SN/VTA, namely, activation by unexpected rewards and cues that predict reward, also characterise novelty processing. To address this question, ...

  11. Assessing the construct validity of aberrant salience.

    Science.gov (United States)

    Schmidt, Kristin; Roiser, Jonathan P

    2009-01-01

    We sought to validate the psychometric properties of a recently developed paradigm that aims to measure salience attribution processes proposed to contribute to positive psychotic symptoms, the Salience Attribution Test (SAT). The "aberrant salience" measure from the SAT showed good face validity in previous results, with elevated scores both in high-schizotypy individuals, and in patients with schizophrenia suffering from delusions. Exploring the construct validity of salience attribution variables derived from the SAT is important, since other factors, including latent inhibition/learned irrelevance (LIrr), attention, probabilistic reward learning, sensitivity to probability, general cognitive ability and working memory could influence these measures. Fifty healthy participants completed schizotypy scales, the SAT, a LIrr task, and a number of other cognitive tasks tapping into potentially confounding processes. Behavioural measures of interest from each task were entered into a principal components analysis, which yielded a five-factor structure accounting for approximately 75% of the variance in behaviour. Implicit aberrant salience was found to load onto its own factor, which was associated with elevated "Introvertive Anhedonia" schizotypy, replicating our previous finding. LIrr loaded onto a separate factor, which also included implicit adaptive salience, but was not associated with schizotypy. Explicit adaptive and aberrant salience, along with a measure of probabilistic learning, loaded onto a further factor, though this also did not correlate with schizotypy. These results suggest that the measures of LIrr and implicit adaptive salience might be based on similar underlying processes, which are dissociable both from implicit aberrant salience and explicit measures of salience.

  12. Aberration Corrected Emittance Exchange

    CERN Document Server

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  13. A meta-analytic review of experiments examining the effects of extrinsic rewards on intrinsic motivation.

    Science.gov (United States)

    Deci, E L; Koestner, R; Ryan, R M

    1999-11-01

    A meta-analysis of 128 studies examined the effects of extrinsic rewards on intrinsic motivation. As predicted, engagement-contingent, completion-contingent, and performance-contingent rewards significantly undermined free-choice intrinsic motivation (d = -0.40, -0.36, and -0.28, respectively), as did all rewards, all tangible rewards, and all expected rewards. Engagement-contingent and completion-contingent rewards also significantly undermined self-reported interest (d = -0.15, and -0.17), as did all tangible rewards and all expected rewards. Positive feedback enhanced both free-choice behavior (d = 0.33) and self-reported interest (d = 0.31). Tangible rewards tended to be more detrimental for children than college students, and verbal rewards tended to be less enhancing for children than college students. The authors review 4 previous meta-analyses of this literature and detail how this study's methods, analyses, and results differed from the previous ones.

  14. Neural coding of basic reward terms of animal learning theory, game theory, microeconomics and behavioural ecology.

    Science.gov (United States)

    Schultz, Wolfram

    2004-04-01

    Neurons in a small number of brain structures detect rewards and reward-predicting stimuli and are active during the expectation of predictable food and liquid rewards. These neurons code the reward information according to basic terms of various behavioural theories that seek to explain reward-directed learning, approach behaviour and decision-making. The involved brain structures include groups of dopamine neurons, the striatum including the nucleus accumbens, the orbitofrontal cortex and the amygdala. The reward information is fed to brain structures involved in decision-making and organisation of behaviour, such as the dorsolateral prefrontal cortex and possibly the parietal cortex. The neural coding of basic reward terms derived from formal theories puts the neurophysiological investigation of reward mechanisms on firm conceptual grounds and provides neural correlates for the function of rewards in learning, approach behaviour and decision-making.

  15. Validation and extension of the reward-mountain model

    Directory of Open Access Journals (Sweden)

    Yannick-André eBreton

    2013-10-01

    Full Text Available The reward-mountain model relates the vigor of reward seeking to the strength and cost of reward. Application of this model provides information about the stage of processing at which manipulations such as drug administration, lesions, deprivation states, and optogenetic interventions act to alter reward seeking. The model has been updated by incorporation of new information about frequency following in the directly stimulated neurons responsible for brain stimulation reward and about the function that maps objective opportunity costs into subjective ones. The behavioral methods for applying the model have been updated and improved as well. To assess the impact of these changes, two related predictions of the model that were supported by earlier work have been retested: 1 altering the duration of rewarding brain stimulation should change the pulse frequency required to produce a reward of half-maximal intensity, and 2 this manipulation should not change the opportunity cost at which half-maximal performance is directed at earning a maximally intense reward. Prediction 1 was supported in all six subjects, but prediction 2 was supported in only three. The latter finding is interpreted to reflect recruitment, at some stimulation sites, of a heterogeneous reward substrate comprising dual, parallel circuits that integrate the stimulation-induced neural signals.

  16. A new scale for measuring reward responsiveness

    Directory of Open Access Journals (Sweden)

    Ivo Van Den Berg

    2010-12-01

    Full Text Available Several psychological theories assume that there are two basic brain mechanisms that guide behavior: an avoidance or inhibition system, which is responsive to signals of punishment, and an approach or activation system, which is sensitive to signals of reward. Several self-report scales have been developed to assess the sensitivity to punishment and reward, and these instruments have been shown to be useful in research on personality, psychopathology, and underlying biological substrates. However, it is also true that in particular scales for measuring reward responsiveness suffer from various inadequacies. Therefore, a new Reward Responsiveness (RR scale was developed and subjected to an extensive psychometric evaluation. The results show that this scale measures a single factor, reward responsiveness that is clearly independent of punishment sensitivity. Further, the data indicated that the internal consistency, convergent validity, discriminant validity, test-retest reliability, and predictive properties of the new scale were all adequate. It can be concluded that the RR scale is a psychometrically sound instrument that may be useful for researchers with interest in the personality construct of reward responsiveness.

  17. Epigenetic silencing of the NR4A3 tumor suppressor, by aberrant JAK/STAT signaling, predicts prognosis in gastric cancer

    Science.gov (United States)

    Yeh, Chung-Min; Chang, Liang-Yu; Lin, Shu-Hui; Chou, Jian-Liang; Hsieh, Hsiao-Yen; Zeng, Li-Han; Chuang, Sheng-Yu; Wang, Hsiao-Wen; Dittner, Claudia; Lin, Cheng-Yu; Lin, Jora M. J.; Huang, Yao-Ting; Ng, Enders K. W.; Cheng, Alfred S. L.; Wu, Shu-Fen; Lin, Jiayuh; Yeh, Kun-Tu; Chan, Michael W. Y.

    2016-08-01

    While aberrant JAK/STAT signaling is crucial to the development of gastric cancer (GC), its effects on epigenetic alterations of its transcriptional targets remains unclear. In this study, by expression microarrays coupled with bioinformatic analyses, we identified a putative STAT3 target gene, NR4A3 that was downregulated in MKN28 GC daughter cells overexpressing a constitutively activated STAT3 mutant (S16), as compared to an empty vector control (C9). Bisulphite pyrosequencing and demethylation treatment showed that NR4A3 was epigenetically silenced by promoter DNA methylation in S16 and other GC cell lines including AGS cells, showing constitutive activation of STAT3. Subsequent experiments revealed that NR4A3 promoter binding by STAT3 might repress its transcription. Long-term depletion of STAT3 derepressed NR4A3 expression, by promoter demethylation, in AGS GC cells. NR4A3 re-expression in GC cell lines sensitized the cells to cisplatin, and inhibited tumor growth in vitro and in vivo, in an animal model. Clinically, GC patients with high NR4A3 methylation, or lower NR4A3 protein expression, had significantly shorter overall survival. Intriguingly, STAT3 activation significantly associated only with NR4A3 methylation in low-stage patient samples. Taken together, aberrant JAK/STAT3 signaling epigenetically silences a potential tumor suppressor, NR4A3, in gastric cancer, plausibly representing a reliable biomarker for gastric cancer prognosis.

  18. Neural basis of reward anticipation and its genetic determinants.

    Science.gov (United States)

    Jia, Tianye; Macare, Christine; Desrivières, Sylvane; Gonzalez, Dante A; Tao, Chenyang; Ji, Xiaoxi; Ruggeri, Barbara; Nees, Frauke; Banaschewski, Tobias; Barker, Gareth J; Bokde, Arun L W; Bromberg, Uli; Büchel, Christian; Conrod, Patricia J; Dove, Rachel; Frouin, Vincent; Gallinat, Jürgen; Garavan, Hugh; Gowland, Penny A; Heinz, Andreas; Ittermann, Bernd; Lathrop, Mark; Lemaitre, Hervé; Martinot, Jean-Luc; Paus, Tomáš; Pausova, Zdenka; Poline, Jean-Baptiste; Rietschel, Marcella; Robbins, Trevor; Smolka, Michael N; Müller, Christian P; Feng, Jianfeng; Rothenfluh, Adrian; Flor, Herta; Schumann, Gunter

    2016-04-05

    Dysfunctional reward processing is implicated in various mental disorders, including attention deficit hyperactivity disorder (ADHD) and addictions. Such impairments might involve different components of the reward process, including brain activity during reward anticipation. We examined brain nodes engaged by reward anticipation in 1,544 adolescents and identified a network containing a core striatal node and cortical nodes facilitating outcome prediction and response preparation. Distinct nodes and functional connections were preferentially associated with either adolescent hyperactivity or alcohol consumption, thus conveying specificity of reward processing to clinically relevant behavior. We observed associations between the striatal node, hyperactivity, and the vacuolar protein sorting-associated protein 4A (VPS4A) gene in humans, and the causal role of Vps4 for hyperactivity was validated in Drosophila Our data provide a neurobehavioral model explaining the heterogeneity of reward-related behaviors and generate a hypothesis accounting for their enduring nature.

  19. Altered social reward and attention in anorexia nervosa

    Directory of Open Access Journals (Sweden)

    Karli K Watson

    2010-09-01

    Full Text Available Dysfunctional social reward and social orienting attend a variety of neuropsychiatric disorders including autism, schizophrenia, social anxiety, and psychopathy. Here we show that similar social reward and attention dysfunction attend anorexia nervosa, a disorder defined by avoidance of food and extreme weight loss. We measured the implicit reward value of social stimuli for female participants with (n=11 and without (n=11 anorexia nervosa using an econometric choice task and also tracked gaze patterns during free viewing of images of female faces and bodies. As predicted, the reward value of viewing bodies varied inversely with observed body weight for women with anorexia but not neurotypical women, in contrast with their explicit ratings of attractiveness. Surprisingly, women with anorexia nervosa, unlike neurotypical women, did not find female faces rewarding and avoided looking at both the face and eyes—independent of observed body weight. These findings demonstrate comorbid dysfunction in the neural circuits mediating gustatory and social reward in anorexia nervosa.

  20. Work Motivation and the Negative Effects of Extrinsic Rewards: A Reward With Implications for Theory and Practice

    Science.gov (United States)

    Notz, William W.

    1975-01-01

    Summarizes and discusses findings on two hypotheses predicting interaction between intrinsic and extrinsic motivation: extrinsic rewards are those which provide satisfaction independent of the actual activity itself and are controlled by someone other than the employee, whereas intrinsic rewards are those over which the employee has a high degree…

  1. Neural dynamics of reward probability coding: a Magnetoencephalographic study in humans

    Directory of Open Access Journals (Sweden)

    Julie eThomas

    2013-11-01

    Full Text Available Prediction of future rewards and discrepancy between actual and expected outcomes (prediction error are crucial signals for adaptive behavior. In humans, a number of fMRI studies demonstrated that reward probability modulates these two signals in a large brain network. Yet, the spatio-temporal dynamics underlying the neural coding of reward probability remains unknown. Here, using magnetoencephalography, we investigated the neural dynamics of prediction and reward prediction error computations while subjects learned to associate cues of slot machines with monetary rewards with different probabilities. We showed that event-related magnetic fields (ERFs arising from the visual cortex coded the expected reward value 155 ms after the cue, demonstrating that reward value signals emerge early in the visual stream. Moreover, a prediction error was reflected in ERF peaking 300 ms after the rewarded outcome and showing decreasing amplitude with higher reward probability. This prediction error signal was generated in a network including the anterior and posterior cingulate cortex. These findings pinpoint the spatio-temporal characteristics underlying reward probability coding. Together, our results provide insights into the neural dynamics underlying the ability to learn probabilistic stimuli-reward contingencies.

  2. A selective role for dopamine in stimulus-reward learning.

    Science.gov (United States)

    Flagel, Shelly B; Clark, Jeremy J; Robinson, Terry E; Mayo, Leah; Czuj, Alayna; Willuhn, Ingo; Akers, Christina A; Clinton, Sarah M; Phillips, Paul E M; Akil, Huda

    2011-01-01

    Individuals make choices and prioritize goals using complex processes that assign value to rewards and associated stimuli. During Pavlovian learning, previously neutral stimuli that predict rewards can acquire motivational properties, becoming attractive and desirable incentive stimuli. However, whether a cue acts solely as a predictor of reward, or also serves as an incentive stimulus, differs between individuals. Thus, individuals vary in the degree to which cues bias choice and potentially promote maladaptive behaviour. Here we use rats that differ in the incentive motivational properties they attribute to food cues to probe the role of the neurotransmitter dopamine in stimulus-reward learning. We show that intact dopamine transmission is not required for all forms of learning in which reward cues become effective predictors. Rather, dopamine acts selectively in a form of stimulus-reward learning in which incentive salience is assigned to reward cues. In individuals with a propensity for this form of learning, reward cues come to powerfully motivate and control behaviour. This work provides insight into the neurobiology of a form of stimulus-reward learning that confers increased susceptibility to disorders of impulse control.

  3. Assessing the construct validity of aberrant salience

    Directory of Open Access Journals (Sweden)

    Kristin Schmidt

    2009-12-01

    Full Text Available We sought to validate the psychometric properties of a recently developed paradigm that aims to measure salience attribution processes proposed to contribute to positive psychotic symptoms, the Salience Attribution Test (SAT. The “aberrant salience” measure from the SAT showed good face validity in previous results, with elevated scores both in high-schizotypy individuals, and in patients with schizophrenia suffering from delusions. Exploring the construct validity of salience attribution variables derived from the SAT is important, since other factors, including latent inhibition/learned irrelevance, attention, probabilistic reward learning, sensitivity to probability, general cognitive ability and working memory could influence these measures. Fifty healthy participants completed schizotypy scales, the SAT, a learned irrelevance task, and a number of other cognitive tasks tapping into potentially confounding processes. Behavioural measures of interest from each task were entered into a principal components analysis, which yielded a five-factor structure accounting for ~75% percent of the variance in behaviour. Implicit aberrant salience was found to load onto its own factor, which was associated with elevated “Introvertive Anhedonia” schizotypy, replicating our previous finding. Learned irrelevance loaded onto a separate factor, which also included implicit adaptive salience, but was not associated with schizotypy. Explicit adaptive and aberrant salience, along with a measure of probabilistic learning, loaded onto a further factor, though this also did not correlate with schizotypy. These results suggest that the measures of learned irrelevance and implicit adaptive salience might be based on similar underlying processes, which are dissociable both from implicit aberrant salience and explicit measures of salience.

  4. Alterations of the Brain Reward System in Antipsychotic Naïve Schizophrenia Patients

    DEFF Research Database (Denmark)

    Nielsen, Mette Ødegaard; Rostrup, Egill; Wulff, Sanne;

    2012-01-01

    BACKGROUND: Various schizophrenic symptoms are suggested to be linked to a dysfunction of the brain reward system. Several studies have found alterations in the reward processing in patients with schizophrenia; however, most previous findings might be confounded by medication effects. METHODS...... as arousing events) into behavioral salience (events where a predicted reward requires performance) and valence anticipation (the anticipation of a monetarily significant outcome). Furthermore, the evaluation of monetary gain and loss was assessed. RESULTS: During reward anticipation, patients had...

  5. Abnormal reward functioning across substance use disorders and major depressive disorder: Considering reward as a transdiagnostic mechanism.

    Science.gov (United States)

    Baskin-Sommers, Arielle R; Foti, Dan

    2015-11-01

    A common criticism of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2013) is that its criteria are based more on behavioral descriptions than on underlying biological mechanisms. Increasingly, calls have intensified for a more biologically-based approach to conceptualizing, studying, and treating psychological disorders, as exemplified by the Research Domain Criteria Project (RDoC). Among the most well-studied neurobiological mechanisms is reward processing. Moreover, individual differences in reward sensitivity are related to risk for substance abuse and depression. The current review synthesizes the available preclinical, electrophysiological, and neuroimaging literature on reward processing from a transdiagnostic, multidimensional perspective. Findings are organized with respect to key reward constructs within the Positive Valence Systems domain of the RDoC matrix, including initial responsiveness to reward (physiological 'liking'), approach motivation (physiological 'wanting'), and reward learning/habit formation. In the current review, we (a) describe the neural basis of reward, (b) elucidate differences in reward activity in substance abuse and depression, and (c) suggest a framework for integrating these disparate literatures and discuss the utility of shifting focus from diagnosis to process for understanding liability and co-morbidity. Ultimately, we believe that an integrative focus on abnormal reward functioning across the full continuum of clinically heterogeneous samples, rather than within circumscribed diagnostic categories, might actually help to refine the phenotypes and improve the prediction of onset and recovery of these disorders.

  6. Reward contingencies and the recalibration of task monitoring and reward systems: a high-density electrical mapping study.

    Science.gov (United States)

    Morie, K P; De Sanctis, P; Foxe, J J

    2014-07-25

    Task execution almost always occurs in the context of reward-seeking or punishment-avoiding behavior. As such, ongoing task-monitoring systems are influenced by reward anticipation systems. In turn, when a task has been executed either successfully or unsuccessfully, future iterations of that task will be re-titrated on the basis of the task outcome. Here, we examined the neural underpinnings of the task-monitoring and reward-evaluation systems to better understand how they govern reward-seeking behavior. Twenty-three healthy adult participants performed a task where they accrued points that equated to real world value (gift cards) by responding as rapidly as possible within an allotted timeframe, while success rate was titrated online by changing the duration of the timeframe dependent on participant performance. Informative cues initiated each trial, indicating the probability of potential reward or loss (four levels from very low to very high). We manipulated feedback by first informing participants of task success/failure, after which a second feedback signal indicated actual magnitude of reward/loss. High-density electroencephalography (EEG) recordings allowed for examination of event-related potentials (ERPs) to the informative cues and in turn, to both feedback signals. Distinct ERP components associated with reward cues, task-preparatory and task-monitoring processes, and reward feedback processes were identified. Unsurprisingly, participants displayed increased ERP amplitudes associated with task-preparatory processes following cues that predicted higher chances of reward. They also rapidly updated reward and loss prediction information dependent on task performance after the first feedback signal. Finally, upon reward receipt, initial reward probability was no longer taken into account. Rather, ERP measures suggested that only the magnitude of actual reward or loss was now processed. Reward and task-monitoring processes are clearly dissociable, but

  7. Do Economic Rewards Work?

    Science.gov (United States)

    Wallace, Brian D.

    2009-01-01

    The love of learning--that intrinsic desire to gain knowledge and insight into new subjects--was once its own reward. That was altered decades ago when parents started using the proverbial "stick and carrot" to motivate their children to do well in school, or even just show up. Today, educators across the country have taken hold of this approach…

  8. Commitment to self-rewards

    DEFF Research Database (Denmark)

    Koch, Alexander; Nafziger, Julia

    People often overcome self-control problems by promising to reward themselves for accomplishing a task. Such strategies based on self-administered rewards however require the person to believe that she would indeed deny herself the reward if she should fail to achieve the desired outcome. Drawing...

  9. Analog study investigating diary assessments of rewards and punishments for emotional states.

    Science.gov (United States)

    Yamamoto, Tatsuya; Shudo, Yusuke; Sakai, Makoto

    2014-12-01

    Behavioral Activation is a treatment for depression relying on rewards from activities; but it is possible that the effects of punishments should also be considered, as should its generalizability to the healthy population. Effect of rewards and punishments on emotional states and depression were investigated by using the daily diary method. Participants (7 men, 21 women; M age = 19.4 yr.) recorded their daily activities and the intensity of rewards and punishments accompanying each activity for one week. Positive and negative affects of participants were assessed using the Japanese version of the Positive Affect and Negative Affect Schedule. Multiple regression analysis indicated that both rewards and punishments predicted depressive symptoms. Moreover, rewards (but not punishments) predicted positive affect, whereas punishments predicted negative affects (and rewards did not). These preliminary results suggest that the effects of both rewards and punishments given for activities should be considered in models of behavioral activation.

  10. The impact of a total reward system of work engagement

    Directory of Open Access Journals (Sweden)

    Crystal Hoole

    2016-04-01

    Full Text Available Orientation: Work engagement is critical for both employees and employers. With the reported downward spiral of engagement levels worldwide, organisations are recognising that in order to address this, attract best talent and keep employees motivated, they need to shift their attention to total reward strategies.Research purpose: The overall purpose of this study was to explore the relationship between total rewards and work engagement in a South African context and to determine which reward categories predict work engagement. The study further endeavoured to determine whether gender and age had a moderating effect on the relationship between total rewards and engagement.Motivation for the study: Statistics report that less than 30% of all working people are optimally engaged in their work. Considering that individuals spend more than a third of their lives at work committing themselves emotionally, physically and psychologically – research indicates that employees are no longer satisfied with traditional reward systems and want to feel valued and appreciated.Research approach, design and method: In this quantitative, cross-sectional research design using a non-probability convenience and purposive sampling strategy, 318 questionnaires were collected and analysed from financial institutions in Gauteng in which opinions were sought on the importance of different types of rewards structures and preferences, and how engaged they are in their workplace. The 17-item UWES and Nienaber total reward preference model were the chosen measuring instruments.Main findings: A small statistically significant correlation (r = 0.25; p < 0.05; small effect was found between total rewards and work engagement, and 12% of the variance of work engagement was explained. Only performance and career management significantly predicted work engagement.Practical/Managerial implications: Although small, the significant correlation between total rewards and work

  11. RM-SORN: a reward-modulated self-organizing recurrent neural network.

    Science.gov (United States)

    Aswolinskiy, Witali; Pipa, Gordon

    2015-01-01

    Neural plasticity plays an important role in learning and memory. Reward-modulation of plasticity offers an explanation for the ability of the brain to adapt its neural activity to achieve a rewarded goal. Here, we define a neural network model that learns through the interaction of Intrinsic Plasticity (IP) and reward-modulated Spike-Timing-Dependent Plasticity (STDP). IP enables the network to explore possible output sequences and STDP, modulated by reward, reinforces the creation of the rewarded output sequences. The model is tested on tasks for prediction, recall, non-linear computation, pattern recognition, and sequence generation. It achieves performance comparable to networks trained with supervised learning, while using simple, biologically motivated plasticity rules, and rewarding strategies. The results confirm the importance of investigating the interaction of several plasticity rules in the context of reward-modulated learning and whether reward-modulated self-organization can explain the amazing capabilities of the brain.

  12. Aberrant TP53 detected by combining immunohistochemistry and DNA-FISH improves Barrett's esophagus progression prediction : A prospective follow-up study

    NARCIS (Netherlands)

    Davelaar, Akueni L.; Calpe, Silvia; Lau, Liana; Timmer, Margriet R.; Visser, Mike; ten Kate, Fiebo J.; Parikh, Kaushal B.; Meijer, Sybren L.; Bergman, Jacques J.; Fockens, Paul; Krishnadath, Kausilia K.

    2015-01-01

    Barrett's esophagus (BE) goes through a sequence of low grade dysplasia (LGD) and high grade dysplasia (HGD) to esophageal adenocarcinoma (EAC). The current gold standard for BE outcome prediction, histopathological staging, can be unreliable. TP53 abnormalities may serve as prognostic biomarkers. T

  13. Differential magnitude coding of gains and omitted rewards in the ventral striatum.

    Science.gov (United States)

    Pedroni, Andreas; Koeneke, Susan; Velickaite, Agne; Jäncke, Lutz

    2011-09-09

    Physiologic studies revealed that neurons in the dopaminergic midbrain of non-human primates encode reward prediction errors. It was furthermore shown that reward prediction errors are adaptively scaled with respect to the range of possible outcomes, enabling sensitive encoding for a large range of reward values. Congruently, neuroimaging studies in humans demonstrated that BOLD-responses in the ventral striatum encode reward prediction errors in similar fashion as dopaminergic midbrain neurons, suggesting that these BOLD-responses may be driven by dopaminergic midbrain activity. However, neuroimaging results are ambiguous with respect to the adaptive scaling of reward prediction errors, leading to the conjecture that under certain circumstances other than dopaminergic midbrain input may drive ventral striatal BOLD-responses. The goal of this study was to substantiate whether BOLD-responses in the ventral striatum rather respond to adaptively scaled reward prediction errors or absolute reward magnitude. In addition, we aimed to identify neuronal structures modulating activity in the ventral striatum. Sixteen healthy participants played a wheel of fortune game, where they could win three differently valued rewards while being scanned. BOLD-responses increased after gaining rewards; this gain was however independent of the absolute reward magnitude. In contrast BOLD-responses upon reward omission decreased with reward magnitude. A psychophysiological interaction analysis identified a cluster in the brainstem in proximity of the dorsal raphe nucleus, a cluster in the lateral orbitofrontal cortex, and a cluster in the rostral cingulate zone. These clusters changed their connectivity with the ventral striatum in relation to the absolute reward magnitude in reward omission trials.

  14. Neuron-type-specific signals for reward and punishment in the ventral tegmental area.

    Science.gov (United States)

    Cohen, Jeremiah Y; Haesler, Sebastian; Vong, Linh; Lowell, Bradford B; Uchida, Naoshige

    2012-01-18

    Dopamine has a central role in motivation and reward. Dopaminergic neurons in the ventral tegmental area (VTA) signal the discrepancy between expected and actual rewards (that is, reward prediction error), but how they compute such signals is unknown. We recorded the activity of VTA neurons while mice associated different odour cues with appetitive and aversive outcomes. We found three types of neuron based on responses to odours and outcomes: approximately half of the neurons (type I, 52%) showed phasic excitation after reward-predicting odours and rewards in a manner consistent with reward prediction error coding; the other half of neurons showed persistent activity during the delay between odour and outcome that was modulated positively (type II, 31%) or negatively (type III, 18%) by the value of outcomes. Whereas the activity of type I neurons was sensitive to actual outcomes (that is, when the reward was delivered as expected compared to when it was unexpectedly omitted), the activity of type II and type III neurons was determined predominantly by reward-predicting odours. We 'tagged' dopaminergic and GABAergic neurons with the light-sensitive protein channelrhodopsin-2 and identified them based on their responses to optical stimulation while recording. All identified dopaminergic neurons were of type I and all GABAergic neurons were of type II. These results show that VTA GABAergic neurons signal expected reward, a key variable for dopaminergic neurons to calculate reward prediction error.

  15. A model of food reward learning with dynamic reward exposure

    Directory of Open Access Journals (Sweden)

    Ross A Hammond

    2012-10-01

    Full Text Available The process of conditioning via reward learning is highly relevant to the study of food choice and obesity. Learning is itself shaped by environmental exposure, with the potential for such exposures to vary substantially across individuals and across place and time. In this paper, we use computational techniques to extend a well-validated standard model of reward learning, introducing both substantial heterogeneity and dynamic reward exposures. We then apply the extended model to a food choice context. The model produces a variety of individual behaviors and population-level patterns which are not evident from the traditional formulation, but which offer potential insights for understanding food reward learning and obesity. These include a lock-in effect, through which early exposure can strongly shape later reward valuation. We discuss potential implications of our results for the study and prevention of obesity, for the reward learning field, and for future experimental and computational work.

  16. Early effects of reward anticipation are modulated by dopaminergic stimulation.

    Directory of Open Access Journals (Sweden)

    Thore Apitz

    Full Text Available The abilities to predict future rewards and assess the value of reward delivery are crucial aspects of adaptive behavior. While the mesolimbic system, including dopaminergic midbrain, ventral striatum and prefrontal cortex have long been associated with reward processing, recent studies also indicate a prominent role of early visual brain regions. However, the precise underlying neural mechanisms still remain unclear. To address this issue, we presented participants with visual cues predicting rewards of high and low magnitudes and probability (2 × 2 factorial design, while neural activity was scanned using magnetoencephalography. Importantly, one group of participants received 150 mg of the dopamine precursor levodopa prior to the experiment, while another group received a placebo. For the placebo group, neural signals of reward probability (but not magnitude emerged at ∼ 100 ms after cue presentation at occipital sensors in the event-related magnetic fields. Importantly, these probability signals were absent in the levodopa group indicating a close link. Moreover, levodopa administration reduced oscillatory power in the high (20-30 Hz and low (13-20 Hz beta band during both reward anticipation and delivery. Taken together, our findings indicate that visual brain regions are involved in coding prospective reward probability but not magnitude and that these effects are modulated by dopamine.

  17. Neuronal Reward and Decision Signals: From Theories to Data.

    Science.gov (United States)

    Schultz, Wolfram

    2015-07-01

    Rewards are crucial objects that induce learning, approach behavior, choices, and emotions. Whereas emotions are difficult to investigate in animals, the learning function is mediated by neuronal reward prediction error signals which implement basic constructs of reinforcement learning theory. These signals are found in dopamine neurons, which emit a global reward signal to striatum and frontal cortex, and in specific neurons in striatum, amygdala, and frontal cortex projecting to select neuronal populations. The approach and choice functions involve subjective value, which is objectively assessed by behavioral choices eliciting internal, subjective reward preferences. Utility is the formal mathematical characterization of subjective value and a prime decision variable in economic choice theory. It is coded as utility prediction error by phasic dopamine responses. Utility can incorporate various influences, including risk, delay, effort, and social interaction. Appropriate for formal decision mechanisms, rewards are coded as object value, action value, difference value, and chosen value by specific neurons. Although all reward, reinforcement, and decision variables are theoretical constructs, their neuronal signals constitute measurable physical implementations and as such confirm the validity of these concepts. The neuronal reward signals provide guidance for behavior while constraining the free will to act.

  18. Rewarding the Multiplayer : How rewards and objectives influence Multiplayer games

    OpenAIRE

    Helin, Henry

    2014-01-01

    In this thesis I analyse the reward systems of cooperative and competitive Multiplayer games – the games I have chosen were built for a Single-player campaign with Multiplayer as additional content. My main focus is on the Multiplayer and the reward systems of that game mode. The reward systems are important to consider when designing a game for fans of Multiplayer games, as a faulty reward system might hinder the aspect which makes Multiplayer games special – to be playing together and go fo...

  19. Monetary rewards modulate inhibitory control

    Directory of Open Access Journals (Sweden)

    Paula Marcela Herrera

    2014-05-01

    Full Text Available The ability to override a dominant response, often referred to as behavioural inhibiton, is considered a key element of executive cognition. Poor behavioural inhibition is a defining characteristic of several neurological and psychiatric populations. Recently, there has been increasing interest in the motivational dimension of behavioural inhibition, with some experiments incorporating emotional contingencies in classical inhibitory paradigms such as the Go/Nogo and Stop Signal Tasks. Several studies have reported a positive modulatory effect of reward on the performance of such tasks in pathological conditions such as substance abuse, pathological gambling, and ADHD. However, experiments that directly investigate the modulatory effects of reward magnitudes on the performance of inhibitory paradigms are rare and consequently, little is known about the finer grained relationship between motivation and self-control. Here, we probed the effect of reward and reward magnitude on behavioural inhibition using two modified version of the widely used Stop Signal Task. The first task compared no reward with reward, whilst the other compared two different reward magnitudes. The reward magnitude effect was confirmed by the second study, whereas it was less compelling in the first study, possibly due to the effect of having no reward in some conditions. In addition, our results showed a kick start effect over global performance measures. More specifically, there was a long lasting improvement in performance throughout the task, when participants received the highest reward magnitudes at the beginning of the protocol. These results demonstrate that individuals’ behavioural inhibition capacities are dynamic not static because they are modulated by the reward magnitude and initial reward history of the task at hand.

  20. Imbalance in the sensitivity to different types of rewards in pathological gambling.

    Science.gov (United States)

    Sescousse, Guillaume; Barbalat, Guillaume; Domenech, Philippe; Dreher, Jean-Claude

    2013-08-01

    Pathological gambling is an addictive disorder characterized by a persistent and compulsive desire to engage in gambling activities. This maladaptive behaviour has been suggested to result from a decreased sensitivity to experienced rewards, regardless of reward type. Alternatively, pathological gambling might reflect an imbalance in the sensitivity to monetary versus non-monetary incentives. To directly test these two hypotheses, we examined how the brain reward circuit of pathological gamblers responds to different types of rewards. Using functional magnetic resonance imaging, we compared the brain responses of 18 pathological gamblers and 20 healthy control subjects while they engaged in a simple incentive task manipulating both monetary and visual erotic rewards. During reward anticipation, the ventral striatum of pathological gamblers showed a differential response to monetary versus erotic cues, essentially driven by a blunted reactivity to cues predicting erotic stimuli. This differential response correlated with the severity of gambling symptoms and was paralleled by a reduced behavioural motivation for erotic rewards. During reward outcome, a posterior orbitofrontal cortex region, responding to erotic rewards in both groups, was further recruited by monetary gains in pathological gamblers but not in control subjects. Moreover, while ventral striatal activity correlated with subjective ratings assigned to monetary and erotic rewards in control subjects, it only correlated with erotic ratings in gamblers. Our results point to a differential sensitivity to monetary versus non-monetary rewards in pathological gambling, both at the motivational and hedonic levels. Such an imbalance might create a bias towards monetary rewards, potentially promoting addictive gambling behaviour.

  1. Neural correlates of aberrant emotional salience predict psychotic symptoms and global functioning in high-risk and first-episode psychosis.

    Science.gov (United States)

    Modinos, Gemma; Tseng, Huai-Hsuan; Falkenberg, Irina; Samson, Carly; McGuire, Philip; Allen, Paul

    2015-10-01

    Neurobiological and behavioral findings suggest that psychosis is associated with corticolimbic hyperactivity during the processing of emotional salience. This has not been widely studied in the early stages of psychosis, and the impact of these abnormalities on psychotic symptoms and global functioning is unknown. We sought to address this issue in 18 patients with first-episode psychosis (FEP), 18 individuals at ultra high risk of psychosis (UHR) and 22 healthy controls (HCs). Corticolimbic response and subjective ratings to emotional and neutral scenes were measured using functional magnetic resonance imaging. The clinical and functional impact of corticolimbic abnormalities was assessed with regression analyses. The FEP and UHR groups reported increased subjective emotional arousal to neutral scenes compared with HCs. Across groups, emotional vs neutral scenes elicited activation in the dorsomedial prefrontal cortex, inferior frontal gyrus/anterior insula and amygdala. Although FEP and UHR participants showed reduced activation in these regions when viewing emotional scenes compared with controls, this was driven by increased activation to neutral scenes. Corticolimbic hyperactivity to neutral scenes predicted higher levels of positive symptoms and poorer levels of functioning. These results indicate that disruption of emotional brain systems may represent an important biological substrate for the pathophysiology of early psychosis and UHR states.

  2. The Roles of Dopamine and Hypocretin in Reward: A Electroencephalographic Study.

    Directory of Open Access Journals (Sweden)

    Armand Mensen

    Full Text Available The proper functioning of the mesolimbic reward system is largely dependent on the neurotransmitter dopamine. Recent evidence suggests that the hypocretin system has significant projections to this reward system. We examined the distinct effects of reduced dopamine or reduced hypocretin levels on reward activity in patients with Parkinson's disease, dopamine deficient, as well as patients with narcolepsy-cataplexy, hypocretin depleted, and healthy controls. Participants performed a simple game-like task while high-density electroencephalography was recorded. Topography and timing of event-related potentials for both reward cue, and reward feedback was examined across the entire dataset. While response to reward cue was similar in all groups, two distinct time points were found to distinguish patients and controls for reward feedback. Around 160 ms both patient groups had reduced ERP amplitude compared to controls. Later at 250 ms, both patient groups also showed a clear event-related potential (ERP, which was absent in controls. The initial differences show that both patient groups show a similar, blunted response to reward delivery. The second potential corresponds to the classic feedback-related negativity (FRN potential which relies on dopamine activity and reflects reward prediction-error signaling. In particular the mismatch between predicted reward and reward subsequently received was significantly higher in PD compared to NC, independent of reward magnitude and valence. The intermediate FRN response in NC highlights the contribution of hypocretin in reward processing, yet also shows that this is not as detrimental to the reward system as in Parkinson's. Furthermore, the inability to generate accurate predictions in NC may explain why hypocretin deficiency mediates cataplexy triggered by both positive and negative emotions.

  3. Rewards teach visual selective attention.

    Science.gov (United States)

    Chelazzi, Leonardo; Perlato, Andrea; Santandrea, Elisa; Della Libera, Chiara

    2013-06-07

    Visual selective attention is the brain function that modulates ongoing processing of retinal input in order for selected representations to gain privileged access to perceptual awareness and guide behavior. Enhanced analysis of currently relevant or otherwise salient information is often accompanied by suppressed processing of the less relevant or salient input. Recent findings indicate that rewards exert a powerful influence on the deployment of visual selective attention. Such influence takes different forms depending on the specific protocol adopted in the given study. In some cases, the prospect of earning a larger reward in relation to a specific stimulus or location biases attention accordingly in order to maximize overall gain. This is mediated by an effect of reward acting as a type of incentive motivation for the strategic control of attention. In contrast, reward delivery can directly alter the processing of specific stimuli by increasing their attentional priority, and this can be measured even when rewards are no longer involved, reflecting a form of reward-mediated attentional learning. As a further development, recent work demonstrates that rewards can affect attentional learning in dissociable ways depending on whether rewards are perceived as feedback on performance or instead are registered as random-like events occurring during task performance. Specifically, it appears that visual selective attention is shaped by two distinct reward-related learning mechanisms: one requiring active monitoring of performance and outcome, and a second one detecting the sheer association between objects in the environment (whether attended or ignored) and the more-or-less rewarding events that accompany them. Overall this emerging literature demonstrates unequivocally that rewards "teach" visual selective attention so that processing resources will be allocated to objects, features and locations which are likely to optimize the organism's interaction with the

  4. COMT Val(158) Met genotype is associated with reward learning: a replication study and meta-analysis.

    Science.gov (United States)

    Corral-Frías, N S; Pizzagalli, D A; Carré, J M; Michalski, L J; Nikolova, Y S; Perlis, R H; Fagerness, J; Lee, M R; Conley, E Drabant; Lancaster, T M; Haddad, S; Wolf, A; Smoller, J W; Hariri, A R; Bogdan, R

    2016-06-01

    Identifying mechanisms through which individual differences in reward learning emerge offers an opportunity to understand both a fundamental form of adaptive responding as well as etiological pathways through which aberrant reward learning may contribute to maladaptive behaviors and psychopathology. One candidate mechanism through which individual differences in reward learning may emerge is variability in dopaminergic reinforcement signaling. A common functional polymorphism within the catechol-O-methyl transferase gene (COMT; rs4680, Val(158) Met) has been linked to reward learning, where homozygosity for the Met allele (linked to heightened prefrontal dopamine function and decreased dopamine synthesis in the midbrain) has been associated with relatively increased reward learning. Here, we used a probabilistic reward learning task to asses response bias, a behavioral form of reward learning, across three separate samples that were combined for analyses (age: 21.80 ± 3.95; n = 392; 268 female; European-American: n = 208). We replicate prior reports that COMT rs4680 Met allele homozygosity is associated with increased reward learning in European-American participants (β = 0.20, t = 2.75, P learning (95% CI -0.11 to -0.03; z = 3.2; P < 0.01). These results suggest that variability in dopamine signaling associated with COMT rs4680 influences individual differences in reward which may potentially contribute to psychopathology characterized by reward dysfunction.

  5. Heightened reward learning under stress in generalized anxiety disorder: a predictor of depression resistance?

    Science.gov (United States)

    Morris, Bethany H; Rottenberg, Jonathan

    2015-02-01

    Stress-induced anhedonia is associated with depression vulnerability (Bogdan & Pizzagalli, 2006). We investigated stress-induced deficits in reward learning in a depression-vulnerable group with analogue generalized anxiety disorder (GAD, n = 34), and never-depressed healthy controls (n = 41). Utilizing a computerized signal detection task, reward learning was assessed under stressor and neutral conditions. Controls displayed intact reward learning in the neutral condition, and the expected stress-induced blunting. The GAD group as a whole also showed intact reward learning in the neutral condition. When GAD subjects were analyzed as a function of prior depression history, never-depressed GAD subjects showed heightened reward learning in the stressor condition. Better reward learning under stress among GAD subjects predicted lower depression symptoms 1 month later. Robust reward learning under stress may indicate depression resistance among anxious individuals.

  6. Reward-sensitive women overeat in a varied food environment, but only when hungry.

    Science.gov (United States)

    Guerrieri, Ramona; Stanczyk, Nicola; Nederkoorn, Chantal; Jansen, Anita

    2012-12-01

    In the current study we tried to elucidate the relationship between a personality trait, reward sensitivity, and an environmental variable; food variety. Based on scarce previous research we predicted that reward sensitivity would interact with variety in the food environment so that especially high reward sensitive individuals would be vulnerable to overeating in a varied food environment. It turned out that especially the high reward individuals did indeed overeat in a varied food environment. However, this was only the case for the highly reward sensitive individuals who experienced feelings of hunger. In other words, reward sensitivity does not affect food intake in varied food environments as long as feelings of hunger are not present. Future research should concentrate on identifying other factors that interact with the person and the environment to discourage reward-related overeating.

  7. Could Reward-Disturbances Caused by Antipsychotic Medication Lead to Weight Gain?

    DEFF Research Database (Denmark)

    Nielsen, Mette Ødegaard; Rostrup, Egill; Nørbak, Henrik

    2014-01-01

    BACKGROUND Disturbances of the brain reward system are suggested to play an important role in the development of central psychopathological symptoms in schizophrenia, and antipsychotic medication partly acts by modulating the reward system. Further, the reward system is known to be central...... putamen (r=0.541, p=0.001). There was no relation between weight gain and treatment response or medication dose. DISCUSSION As expected, antipsychotic treatment on average caused a moderate weight gain in the patients. The highest weight gain was found in the patients with the most aberrant f...... to assume that it is related to changes in dopamine transmission. Thus our results suggest that by altering the dopaminergic transmission in putamen, antipsychotic medication might through the influence on reward system affect appetite regulation and thereby, together with other mechanisms, lead to weight...

  8. ATLAS rewards industry

    CERN Multimedia

    2006-01-01

    Showing excellence in mechanics, electronics and cryogenics, three industries are honoured for their contributions to the ATLAS experiment. Representatives of the three award-wining companies after the ceremony. For contributing vital pieces to the ATLAS puzzle, three industries were recognized on Friday 5 May during a supplier awards ceremony. After a welcome and overview of the ATLAS experiment by spokesperson Peter Jenni, CERN Secretary-General Maximilian Metzger stressed the importance of industry to CERN's scientific goals. Close interaction with CERN was a key factor in the selection of each rewarded company, in addition to the high-quality products they delivered to the experiment. Alu Menziken Industrie AG, of Switzerland, was honoured for the production of 380,000 aluminium tubes for the Monitored Drift Tube Chambers (MDT). As Giora Mikenberg, the Muon System Project Leader stressed, the aluminium tubes were delivered on time with an extraordinary quality and precision. Between October 2000 and Jan...

  9. Motivating forces of human actions. Neuroimaging reward and social interaction.

    Science.gov (United States)

    Walter, Henrik; Abler, Birgit; Ciaramidaro, Angela; Erk, Susanne

    2005-11-15

    In neuroeconomics, reward and social interaction are central concepts to understand what motivates human behaviour. Both concepts are investigated in humans using neuroimaging methods. In this paper, we provide an overview about these results and discuss their relevance for economic behaviour. For reward it has been shown that a system exists in humans that is involved in predicting rewards and thus guides behaviour, involving a circuit including the striatum, the orbitofrontal cortex and the amygdala. Recent studies on social interaction revealed a mentalizing system representing the mental states of others. A central part of this system is the medial prefrontal cortex, in particular the anterior paracingulate cortex. The reward as well as the mentalizing system is engaged in economic decision-making. We will discuss implications of this study for neuromarketing as well as general implications of these results that may help to provide deeper insights into the motivating forces of human behaviour.

  10. The effects of cooperative and individualistic reward on intrinsic motivation.

    Science.gov (United States)

    Hom, H L; Berger, M; Duncan, M K; Miller, A; Blevin, A

    1994-03-01

    The effects of cooperative versus individualistic reward on students' intrinsic motivation were investigated. The controlling aspects of extrinsic reward may be heightened or produce greater ego threat in the individualistic situation when compared with a group situation. We predicted that students in the cooperative social situation would show higher levels of intrinsic motivation. Fifth-grade students from existing cooperative groups were assigned randomly to receive a tangible reward based on either cooperative or individualistic achievement for completing pattern block designs. Cooperation affected intrinsic motivation positively. Students in the cooperative dyad solved the block designs more quickly, interacted positively, and viewed the task as easier than did those in the individualistic situation, and they reported that their peers were helpful. There was little evidence that the controlling functions of reward or ego-threat were factors in producing the outcome. Some evidence supporting the importance of the social nature of cooperation was provided.

  11. Homeostatic reinforcement learning for integrating reward collection and physiological stability.

    Science.gov (United States)

    Keramati, Mehdi; Gutkin, Boris

    2014-12-02

    Efficient regulation of internal homeostasis and defending it against perturbations requires adaptive behavioral strategies. However, the computational principles mediating the interaction between homeostatic and associative learning processes remain undefined. Here we use a definition of primary rewards, as outcomes fulfilling physiological needs, to build a normative theory showing how learning motivated behaviors may be modulated by internal states. Within this framework, we mathematically prove that seeking rewards is equivalent to the fundamental objective of physiological stability, defining the notion of physiological rationality of behavior. We further suggest a formal basis for temporal discounting of rewards by showing that discounting motivates animals to follow the shortest path in the space of physiological variables toward the desired setpoint. We also explain how animals learn to act predictively to preclude prospective homeostatic challenges, and several other behavioral patterns. Finally, we suggest a computational role for interaction between hypothalamus and the brain reward system.

  12. Intolerance of uncertainty and decisions about delayed, probabilistic rewards.

    Science.gov (United States)

    Luhmann, Christian C; Ishida, Kanako; Hajcak, Greg

    2011-09-01

    Worry is the inflated concern about potential future threats and is a hallmark feature of generalized anxiety disorder. Previous theoretical work has suggested that worry may be a consequence of intolerance of uncertainty (IU). The current study seeks to explore the behavioral consequences of IU. Specifically, we examine how IU might be associated with aspects of reward-based decision making. We utilized a simple laboratory gambling task in which participants chose between small, low-probability rewards available immediately at the beginning of each trial and large, high-probability rewards only available after some variable delay. Results demonstrate that higher levels of intolerance of uncertainty were associated with a tendency to select the immediately available, but less valuable and less probable rewards. IU also predicted decision-makers' sensitivity to outcomes. We discuss the cognitive and affective mechanisms that are likely to underlie the observed decision-making behavior and the implications for anxiety disorders.

  13. Adaptive Reward Pursuit: How Effort Requirements Affect Unconscious Reward Responses and Conscious Reward Decisions

    Science.gov (United States)

    Bijleveld, Erik; Custers, Ruud; Aarts, Henk

    2012-01-01

    When in pursuit of rewards, humans weigh the value of potential rewards against the amount of effort that is required to attain them. Although previous research has generally conceptualized this process as a deliberate calculation, recent work suggests that rudimentary mechanisms--operating without conscious intervention--play an important role as…

  14. Adaptive Reward Pursuit: How Effort Requirements Affect Unconscious Reward Responses and Conscious Reward Decisions

    NARCIS (Netherlands)

    Bijleveld, E.H.; Custers, R.; Aarts, H.A.G.

    2012-01-01

    When in pursuit of rewards, humans weigh the value of potential rewards against the amount of effort that is required to attain them. Although previous research has generally conceptualized this process as a deliberate calculation, recent work suggests that rudimentary mechanisms operating without c

  15. Relief as a reward: hedonic and neural responses to safety from pain.

    Directory of Open Access Journals (Sweden)

    Siri Leknes

    Full Text Available Relief fits the definition of a reward. Unlike other reward types the pleasantness of relief depends on the violation of a negative expectation, yet this has not been investigated using neuroimaging approaches. We hypothesized that the degree of negative expectation depends on state (dread and trait (pessimism sensitivity. Of the brain regions that are involved in mediating pleasure, the nucleus accumbens also signals unexpected reward and positive prediction error. We hypothesized that accumbens activity reflects the level of negative expectation and subsequent pleasant relief. Using fMRI and two purpose-made tasks, we compared hedonic and BOLD responses to relief with responses during an appetitive reward task in 18 healthy volunteers. We expected some similarities in task responses, reflecting common neural substrates implicated across reward types. However, we also hypothesized that relief responses would differ from appetitive rewards in the nucleus accumbens, since only relief pleasantness depends on negative expectations. The results confirmed these hypotheses. Relief and appetitive reward task activity converged in the ventromedial prefrontal cortex, which also correlated with appetitive reward pleasantness ratings. In contrast, dread and pessimism scores correlated with relief but not with appetitive reward hedonics. Moreover, only relief pleasantness covaried with accumbens activation. Importantly, the accumbens signal appeared to specifically reflect individual differences in anticipation of the adverse event (dread, pessimism but was uncorrelated to appetitive reward hedonics. In conclusion, relief differs from appetitive rewards due to its reliance on negative expectations, the violation of which is reflected in relief-related accumbens activation.

  16. Relief as a Reward: Hedonic and Neural Responses to Safety from Pain

    Science.gov (United States)

    Leknes, Siri; Lee, Michael; Berna, Chantal; Andersson, Jesper; Tracey, Irene

    2011-01-01

    Relief fits the definition of a reward. Unlike other reward types the pleasantness of relief depends on the violation of a negative expectation, yet this has not been investigated using neuroimaging approaches. We hypothesized that the degree of negative expectation depends on state (dread) and trait (pessimism) sensitivity. Of the brain regions that are involved in mediating pleasure, the nucleus accumbens also signals unexpected reward and positive prediction error. We hypothesized that accumbens activity reflects the level of negative expectation and subsequent pleasant relief. Using fMRI and two purpose-made tasks, we compared hedonic and BOLD responses to relief with responses during an appetitive reward task in 18 healthy volunteers. We expected some similarities in task responses, reflecting common neural substrates implicated across reward types. However, we also hypothesized that relief responses would differ from appetitive rewards in the nucleus accumbens, since only relief pleasantness depends on negative expectations. The results confirmed these hypotheses. Relief and appetitive reward task activity converged in the ventromedial prefrontal cortex, which also correlated with appetitive reward pleasantness ratings. In contrast, dread and pessimism scores correlated with relief but not with appetitive reward hedonics. Moreover, only relief pleasantness covaried with accumbens activation. Importantly, the accumbens signal appeared to specifically reflect individual differences in anticipation of the adverse event (dread, pessimism) but was uncorrelated to appetitive reward hedonics. In conclusion, relief differs from appetitive rewards due to its reliance on negative expectations, the violation of which is reflected in relief-related accumbens activation. PMID:21490964

  17. Aberration Correction in Electron Microscopy

    CERN Document Server

    Rose, Harald H

    2005-01-01

    The resolution of conventional electron microscopes is limited by spherical and chromatic aberrations. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer theorem). Multipole correctors and electron mirrros have been designed and built, which compensate for these aberrations. The principles of correction will be demonstrated for the tetrode mirror, the quadrupole-octopole corrector and the hexapole corrector. Electron mirrors require a magnetic beam separator free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the objective lens. The hexapole corrector has the most simple structure yet eliminates only the spherical aberration, whereas the mirror and the quadrupole-octopole corrector are able to correct for both aberrations. Chromatic correction is achieved in the latter corrector by cossed electric and magnetic quadrupoles acting as first-order Wien filters. Micrographs obtaine...

  18. Camera processing with chromatic aberration.

    Science.gov (United States)

    Korneliussen, Jan Tore; Hirakawa, Keigo

    2014-10-01

    Since the refractive index of materials commonly used for lens depends on the wavelengths of light, practical camera optics fail to converge light to a single point on an image plane. Known as chromatic aberration, this phenomenon distorts image details by introducing magnification error, defocus blur, and color fringes. Though achromatic and apochromatic lens designs reduce chromatic aberration to a degree, they are complex and expensive and they do not offer a perfect correction. In this paper, we propose a new postcapture processing scheme designed to overcome these problems computationally. Specifically, the proposed solution is comprised of chromatic aberration-tolerant demosaicking algorithm and post-demosaicking chromatic aberration correction. Experiments with simulated and real sensor data verify that the chromatic aberration is effectively corrected.

  19. Random reward priming is task-contingent

    DEFF Research Database (Denmark)

    Ásgeirsson, Árni Gunnar; Kristjánsson, Árni

    2014-01-01

    Consistent financial reward of particular features influences the allocation of visual attention in many ways. More surprising are 1-trial reward priming effects on attention where reward schedules are random and reward on one trial influences attentional allocation on the next. Those findings...... for a Gabor patch of odd spatial frequency we found no evidence of reward priming, while we only partially replicate the reward priming in the exact original paradigm tested by Hickey and colleagues. The results cast doubt on the proposal that random reward enhances salience, suggested in the original papers......, and highlight the need for a more nuanced account. In many other paradigms reward effects have been found to progress gradually, becoming stronger as they build up, and we argue that for robust reward priming, reward schedules need to be more consistent than in the original 1-trial reward priming paradigm....

  20. Blunted ventral striatal responses to anticipated rewards foreshadow problematic drug use in novelty-seeking adolescents

    Science.gov (United States)

    Büchel, Christian; Peters, Jan; Banaschewski, Tobias; Bokde, Arun L. W.; Bromberg, Uli; Conrod, Patricia J.; Flor, Herta; Papadopoulos, Dimitri; Garavan, Hugh; Gowland, Penny; Heinz, Andreas; Walter, Henrik; Ittermann, Bernd; Mann, Karl; Martinot, Jean-Luc; Paillère-Martinot, Marie-Laure; Nees, Frauke; Paus, Tomas; Pausova, Zdenka; Poustka, Luise; Rietschel, Marcella; Robbins, Trevor W.; Smolka, Michael N.; Gallinat, Juergen; Schumann, Gunter; Knutson, Brian; Arroyo, Mercedes; Artiges, Eric; Aydin, Semiha; Bach, Christine; Barbot, Alexis; Barker, Gareth; Bruehl, Ruediger; Cattrell, Anna; Constant, Patrick; Crombag, Hans; Czech, Katharina; Dalley, Jeffrey; Decideur, Benjamin; Desrivieres, Sylvane; Fadai, Tahmine; Fauth-Buhler, Mira; Feng, Jianfeng; Filippi, Irinia; Frouin, Vincent; Fuchs, Birgit; Gemmeke, Isabel; Genauck, Alexander; Hanratty, Eanna; Heinrichs, Bert; Heym, Nadja; Hubner, Thomas; Ihlenfeld, Albrecht; Ing, Alex; Ireland, James; Jia, Tianye; Jones, Jennifer; Jurk, Sarah; Kaviani, Mehri; Klaassen, Arno; Kruschwitz, Johann; Lalanne, Christophe; Lanzerath, Dirk; Lathrop, Mark; Lawrence, Claire; Lemaitre, Hervé; Macare, Christine; Mallik, Catherine; Mar, Adam; Martinez-Medina, Lourdes; Mennigen, Eva; de Carvahlo, Fabiana Mesquita; Mignon, Xavier; Millenet, Sabina; Miranda, Ruben; Müller, Kathrin; Nymberg, Charlotte; Parchetka, Caroline; Pena-Oliver, Yolanda; Pentilla, Jani; Poline, Jean-Baptiste; Quinlan, Erin Burke; Rapp, Michael; Ripke, Stephan; Ripley, Tamzin; Robert, Gabriel; Rogers, John; Romanowski, Alexander; Ruggeri, Barbara; Schmäl, Christine; Schmidt, Dirk; Schneider, Sophia; Schubert, Florian; Schwartz, Yannick; Sommer, Wolfgang; Spanagel, Rainer; Speiser, Claudia; Spranger, Tade; Stedman, Alicia; Stephens, Dai; Strache, Nicole; Ströhle, Andreas; Struve, Maren; Subramaniam, Naresh; Theobald, David; Vetter, Nora; Vulser, Helene; Weiss, Katharina; Whelan, Robert; Williams, Steve; Xu, Bing; Yacubian, Juliana; Yu, Tao; Ziesch, Veronika

    2017-01-01

    Novelty-seeking tendencies in adolescents may promote innovation as well as problematic impulsive behaviour, including drug abuse. Previous research has not clarified whether neural hyper- or hypo-responsiveness to anticipated rewards promotes vulnerability in these individuals. Here we use a longitudinal design to track 144 novelty-seeking adolescents at age 14 and 16 to determine whether neural activity in response to anticipated rewards predicts problematic drug use. We find that diminished BOLD activity in mesolimbic (ventral striatal and midbrain) and prefrontal cortical (dorsolateral prefrontal cortex) regions during reward anticipation at age 14 predicts problematic drug use at age 16. Lower psychometric conscientiousness and steeper discounting of future rewards at age 14 also predicts problematic drug use at age 16, but the neural responses independently predict more variance than psychometric measures. Together, these findings suggest that diminished neural responses to anticipated rewards in novelty-seeking adolescents may increase vulnerability to future problematic drug use. PMID:28221370

  1. Evolutionary advantages of adaptive rewarding

    CERN Document Server

    Szolnoki, Attila

    2012-01-01

    Our wellbeing depends as much on our personal success, as it does on the success of our society. The realization of this fact makes cooperation a very much needed trait. Experiments have shown that rewards can elevate our readiness to cooperate, but since giving a reward inevitably entails paying a cost for it, the emergence and stability of such behavior remain elusive. Here we show that allowing for the act of rewarding to self-organize in dependence on the success of cooperation creates several evolutionary advantages that instill new ways through which collaborative efforts are promoted. Ranging from indirect territorial battle to the spontaneous emergence and destruction of coexistence, phase diagrams and the underlying spatial patterns reveal fascinatingly reach social dynamics that explains why this costly behavior has evolved and persevered. Comparisons with adaptive punishment, however, uncover an Achilles heel of adaptive rewarding that is due to over-aggression, which in turn hinders optimal utiliz...

  2. Developing a Comprehensive Reward System.

    Science.gov (United States)

    Votruba, James C.

    1979-01-01

    Providing incentives for teachers of adults is an important means of attracting, retaining, and stimulating staff. Developing a variety of extrinsic and intrinsic rewards and incentives and instituting them effectively are important administrative functions. (SK)

  3. Neural correlates of reward processing in healthy siblings of patients with schizophrenia.

    Science.gov (United States)

    Hanssen, Esther; van der Velde, Jorien; Gromann, Paula M; Shergill, Sukhi S; de Haan, Lieuwe; Bruggeman, Richard; Krabbendam, Lydia; Aleman, André; van Atteveldt, Nienke

    2015-01-01

    Deficits in motivational behavior and psychotic symptoms often observed in schizophrenia (SZ) may be driven by dysfunctional reward processing (RP). RP can be divided in two different stages; reward anticipation and reward consumption. Aberrant processing during reward anticipation seems to be related to SZ. Studies in patients with SZ have found less activation in the ventral striatum (VS) during anticipation of reward, but these findings do not provide information on effect of the genetic load on reward processing. Therefore, this study investigated RP in healthy first-degree relatives of SZ patients. The sample consisted of 94 healthy siblings of SZ patients and 57 healthy controls. Participants completed a classic RP task, the Monetary Incentive Delay task, during functional magnetic resonance imaging (fMRI). As expected, there were no behavioral differences between groups. In contrast to our expectations, we found no differences in any of the anticipatory reward related brain areas (region of interest analyses). Whole-brain analyses did reveal group differences during both reward anticipation and reward consumption; during reward anticipation siblings showed less deactivation in the insula, posterior cingulate cortex (PCC) and medial frontal gyrus (MFG) than controls. During reward consumption siblings showed less deactivation in the PCC and the right MFG compared to controls and activation in contrast to deactivation in controls in the precuneus and the left MFG. Exclusively in siblings, MFG activity correlated positively with subclinical negative symptoms. These regions are typically associated with the default mode network (DMN), which normally shows decreases in activation during task-related cognitive processes. Thus, in contrast to prior literature in patients with SZ, the results do not point to altered brain activity in classical RP brain areas, such as the VS. However, the weaker deactivation found outside the reward-related network in siblings could

  4. Phase aberration effects in elastography.

    Science.gov (United States)

    Varghese, T; Bilgen, M; Ophir, J

    2001-06-01

    In sonography, phase aberration plays a role in the corruption of sonograms. Phase aberration does not have a significant impact on elastography, if statistically similar phase errors are present in both the pre- and postcompression signals. However, if the phase errors are present in only one of the pre- or postcompression signal pairs, the precision of the strain estimation process will be reduced. In some cases, increased phase errors may occur only in the postcompression signal due to changes in the tissue structure with the applied compression. Phase-aberration effects increase with applied strain and may be viewed as an image quality derating factor, much like frequency-dependent attenuation or undesired lateral tissue motion. In this paper, we present a theoretical and simulation study of the effects of phase aberration on the elastographic strain-estimation process, using the strain filter approach.

  5. Contextual interaction between novelty and reward processing within the mesolimbic system.

    Science.gov (United States)

    Bunzeck, Nico; Doeller, Christian F; Dolan, Ray J; Duzel, Emrah

    2012-06-01

    Medial temporal lobe (MTL) dependent long-term memory for novel events is modulated by a circuitry that also responds to reward and includes the ventral striatum, dopaminergic midbrain, and medial orbitofrontal cortex (mOFC). This common neural network may reflect a functional link between novelty and reward whereby novelty motivates exploration in the search for rewards; a link also termed novelty "exploration bonus." We used fMRI in a scene encoding paradigm to investigate the interaction between novelty and reward with a focus on neural signals akin to an exploration bonus. As expected, reward related long-term memory for the scenes (after 24 hours) strongly correlated with activity of MTL, ventral striatum, and substantia nigra/ventral tegmental area (SN/VTA). Furthermore, the hippocampus showed a main effect of novelty, the striatum showed a main effect of reward, and the mOFC signalled both novelty and reward. An interaction between novelty and reward akin to an exploration bonus was found in the hippocampus. These data suggest that MTL novelty signals are interpreted in terms of their reward-predicting properties in the mOFC, which biases striatal reward responses. The striatum together with the SN/VTA then regulates MTL-dependent long-term memory formation and contextual exploration bonus signals in the hippocampus.

  6. Amphetamine Sensitization Alters Reward Processing in the Human Striatum and Amygdala

    Science.gov (United States)

    O’Daly, Owen G.; Joyce, Daniel; Tracy, Derek K.; Azim, Adnan; Stephan, Klaas E.; Murray, Robin M.; Shergill, Sukhwinder S.

    2014-01-01

    Dysregulation of mesolimbic dopamine transmission is implicated in a number of psychiatric illnesses characterised by disruption of reward processing and goal-directed behaviour, including schizophrenia, drug addiction and impulse control disorders associated with chronic use of dopamine agonists. Amphetamine sensitization (AS) has been proposed to model the development of this aberrant dopamine signalling and the subsequent dysregulation of incentive motivational processes. However, in humans the effects of AS on the dopamine-sensitive neural circuitry associated with reward processing remains unclear. Here we describe the effects of acute amphetamine administration, following a sensitising dosage regime, on blood oxygen level dependent (BOLD) signal in dopaminoceptive brain regions during a rewarded gambling task performed by healthy volunteers. Using a randomised, double-blind, parallel-groups design, we found clear evidence for sensitization to the subjective effects of the drug, while rewarded reaction times were unchanged. Repeated amphetamine exposure was associated with reduced dorsal striatal BOLD signal during decision making, but enhanced ventromedial caudate activity during reward anticipation. The amygdala BOLD response to reward outcomes was blunted following repeated amphetamine exposure. Positive correlations between subjective sensitization and changes in anticipation- and outcome-related BOLD signal were seen for the caudate nucleus and amygdala, respectively. These data show for the first time in humans that AS changes the functional impact of acute stimulant exposure on the processing of reward-related information within dopaminoceptive regions. Our findings accord with pathophysiological models which implicate aberrant dopaminergic modulation of striatal and amygdala activity in psychosis and drug-related compulsive disorders. PMID:24717936

  7. Amphetamine sensitization alters reward processing in the human striatum and amygdala.

    Directory of Open Access Journals (Sweden)

    Owen G O'Daly

    Full Text Available Dysregulation of mesolimbic dopamine transmission is implicated in a number of psychiatric illnesses characterised by disruption of reward processing and goal-directed behaviour, including schizophrenia, drug addiction and impulse control disorders associated with chronic use of dopamine agonists. Amphetamine sensitization (AS has been proposed to model the development of this aberrant dopamine signalling and the subsequent dysregulation of incentive motivational processes. However, in humans the effects of AS on the dopamine-sensitive neural circuitry associated with reward processing remains unclear. Here we describe the effects of acute amphetamine administration, following a sensitising dosage regime, on blood oxygen level dependent (BOLD signal in dopaminoceptive brain regions during a rewarded gambling task performed by healthy volunteers. Using a randomised, double-blind, parallel-groups design, we found clear evidence for sensitization to the subjective effects of the drug, while rewarded reaction times were unchanged. Repeated amphetamine exposure was associated with reduced dorsal striatal BOLD signal during decision making, but enhanced ventromedial caudate activity during reward anticipation. The amygdala BOLD response to reward outcomes was blunted following repeated amphetamine exposure. Positive correlations between subjective sensitization and changes in anticipation- and outcome-related BOLD signal were seen for the caudate nucleus and amygdala, respectively. These data show for the first time in humans that AS changes the functional impact of acute stimulant exposure on the processing of reward-related information within dopaminoceptive regions. Our findings accord with pathophysiological models which implicate aberrant dopaminergic modulation of striatal and amygdala activity in psychosis and drug-related compulsive disorders.

  8. Public praise vs. private pay: Effects of rewards on energy conservation in the workplace

    NARCIS (Netherlands)

    Handgraaf, M.J.J.; Lidth de Jeude, van M.; Appelt, K.C.

    2013-01-01

    Any solution to rising levels of CO2 depends on human behavior. One common approach to changing human behavior is rewarding desired behavior. Because financial incentives often have side effects that diminish efficacy, we predict that social rewards are more effective, because they invoke adherence

  9. Public Praise vs. Private Pay: Effects of Rewards on Energy Conservation in the Workplace

    NARCIS (Netherlands)

    Handgraaf, M.J.J.; Lidth de Jeude, van M.; Appelt, K.C.

    2011-01-01

    Any solution to rising levels of CO2 depends on human behavior. One common approach to changing human behavior is rewarding desired behavior. Because financial incentives often have side effects that diminish efficacy, we predict that more psychologically oriented social rewards are more effective,

  10. Theta-band phase locking of orbitofrontal neurons during reward expectancy

    NARCIS (Netherlands)

    van Wingerden, M.; Vinck, M.; Lankelma, J.; Pennartz, C.M.A.

    2010-01-01

    The expectancy of a rewarding outcome following actions and cues is coded by a network of brain structures including the orbitofrontal cortex. Thus far, predicted reward was considered to be coded by time-averaged spike rates of neurons. However, besides firing rate, the precise timing of action pot

  11. Enriched encoding: reward motivation organizes cortical networks for hippocampal detection of unexpected events.

    Science.gov (United States)

    Murty, Vishnu P; Adcock, R Alison

    2014-08-01

    Learning how to obtain rewards requires learning about their contexts and likely causes. How do long-term memory mechanisms balance the need to represent potential determinants of reward outcomes with the computational burden of an over-inclusive memory? One solution would be to enhance memory for salient events that occur during reward anticipation, because all such events are potential determinants of reward. We tested whether reward motivation enhances encoding of salient events like expectancy violations. During functional magnetic resonance imaging, participants performed a reaction-time task in which goal-irrelevant expectancy violations were encountered during states of high- or low-reward motivation. Motivation amplified hippocampal activation to and declarative memory for expectancy violations. Connectivity of the ventral tegmental area (VTA) with medial prefrontal, ventrolateral prefrontal, and visual cortices preceded and predicted this increase in hippocampal sensitivity. These findings elucidate a novel mechanism whereby reward motivation can enhance hippocampus-dependent memory: anticipatory VTA-cortical-hippocampal interactions. Further, the findings integrate literatures on dopaminergic neuromodulation of prefrontal function and hippocampus-dependent memory. We conclude that during reward motivation, VTA modulation induces distributed neural changes that amplify hippocampal signals and records of expectancy violations to improve predictions-a potentially unique contribution of the hippocampus to reward learning.

  12. Response of neural reward regions to food cues in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Cascio Carissa J

    2012-05-01

    Full Text Available Abstract Background One hypothesis for the social deficits that characterize autism spectrum disorders (ASD is diminished neural reward response to social interaction and attachment. Prior research using established monetary reward paradigms as a test of non-social reward to compare with social reward may involve confounds in the ability of individuals with ASD to utilize symbolic representation of money and the abstraction required to interpret monetary gains. Thus, a useful addition to our understanding of neural reward circuitry in ASD includes a characterization of the neural response to primary rewards. Method We asked 17 children with ASD and 18 children without ASD to abstain from eating for at least four hours before an MRI scan in which they viewed images of high-calorie foods. We assessed the neural reward network for increases in the blood oxygenation level dependent (BOLD signal in response to the food images Results We found very similar patterns of increased BOLD signal to these images in the two groups; both groups showed increased BOLD signal in the bilateral amygdala, as well as in the nucleus accumbens, orbitofrontal cortex, and insula. Direct group comparisons revealed that the ASD group showed a stronger response to food cues in bilateral insula along the anterior-posterior gradient and in the anterior cingulate cortex than the control group, whereas there were no neural reward regions that showed higher activation for controls than for ASD. Conclusion These results suggest that neural response to primary rewards is not diminished but in fact shows an aberrant enhancement in children with ASD.

  13. Valuing rewards to others in a prisoner's dilemma game.

    Science.gov (United States)

    Safin, Vasiliy; Locey, Matthew L; Rachlin, Howard

    2013-10-01

    People value rewards to others but discount those rewards based on social distance; rewards to a socially closer person are valued more than identical rewards to a socially more distant person (Jones and Rachlin, 2006). The concept of social discounting can explain cooperation and defection in two-player prisoner's dilemma (PD) games (Axelrod, 1980). The contingencies of a PD game are such that in any single game cooperation is costly to each player herself but beneficial to the other player. From the viewpoint of each player, the costs of cooperation are fully realized, but the benefits of cooperation are discounted by the social distance to the other player. The present experiment measured cooperation and defection in two PD-game conditions with differing reward magnitudes. In one (the 1-2-3-4 condition), the cost of cooperation exceeded its socially discounted benefit, and players were predicted to defect; in the other (the 1-2-9-10 condition), the discounted benefit of cooperation exceeded its cost, and players were predicted to cooperate. Over the course of repeated trials defection increased with the 1-2-3-4 condition but not with the 1-2-9-10 condition. Moreover, participants who rated their partners as closer, relative to random classmates, cooperated at higher rates--consistent with social discounting.

  14. Cognitive constraints on how economic rewards affect cooperation.

    Science.gov (United States)

    Furlong, Ellen E; Opfer, John E

    2009-01-01

    Cooperation often fails to spread in proportion to its potential benefits. This phenomenon is captured by prisoner's dilemma games, in which cooperation rates appear to be determined by the distinctive structure of economic incentives (e.g., $3 for mutual cooperation vs. $5 for unilateral defection). Rather than comparing economic values of cooperating versus not ($3 vs. $5), we tested the hypothesis that players simply compare numeric values (3 vs. 5), such that subjective numbers (mental magnitudes) are logarithmically scaled. Supporting our hypothesis, increasing only numeric values of rewards (from $3 to 300 cent) increased cooperation (Study 1), whereas increasing economic values increased cooperation only when there were also numeric increases (Study 2). Thus, changing rewards from 3 cent to 300 cent increased cooperation rates, but an economically identical change from 3 cent to $3 elicited no gains. Finally, logarithmically scaled reward values predicted 97% of variation in cooperation, whereas the face value of economic rewards predicted none. We conclude that representations of numeric value constrain how economic rewards affect cooperation.

  15. The role of the dorsal raphé nucleus in reward-seeking behavior

    Directory of Open Access Journals (Sweden)

    Kae eNakamura

    2013-08-01

    Full Text Available Pharmacological experiments have shown that the modulation of brain serotonin levels has a strong impact on value-based decision making. Anatomical and physiological evidence also revealed that the dorsal raphé nucleus (DRN, a major source of serotonin, and the dopamine system receive common inputs from brain regions associated with appetitive and aversive information processing. The serotonin and dopamine systems also have reciprocal functional influences on each other. However, the specific mechanism by which serotonin affects value-based decision making is not clear.To understand the information carried by the DRN for reward-seeking behavior, we measured single neuron activity in the primate DRN during the performance of saccade tasks to obtain different amounts of a reward. We found that DRN neuronal activity was characterized by tonic modulation that was altered by the expected and received reward value. Consistent reward-dependent modulation across different task periods suggested that DRN activity kept track of the reward value throughout a trial. The DRN was also characterized by modulation of its activity in the opposite direction by different neuronal subgroups, one firing strongly for the prediction and receipt of large rewards, with the other firing strongly for small rewards. Conversely, putative dopamine neurons showed positive phasic responses to reward-indicating cues and the receipt of an unexpected reward amount, which supports the reward prediction error signal hypothesis of dopamine.I suggest that the tonic reward monitoring signal of the DRN, possibly together with its interaction with the dopamine system, reports a continuous level of motivation throughout the performance of a task. Such a signal may provide reward context information to the targets of DRN projections, where it may be integrated further with incoming motivationally salient information.

  16. Aberrations in Fresnel Lenses and Mirrors

    Science.gov (United States)

    Gregory, Don

    1999-01-01

    The NASA/MSFC Shooting Star program revealed a number of technical problems that must be solved before solar thermal propulsion can become a reality. The fundamental problem of interest here is the collection of solar energy. This is the first step in the propulsion process and indeed the most important. Everything else depends on the efficiency and focusing ability of the collection lens or mirror. An initial model of Fresnel lens behavior using a wave optics approach has been completed and the results were encouraging enough to warrant an experimental investigation. This experimental investigation confirmed some of the effects predicted and produced invaluable photographic evidence of coherence based diffraction and aberration.

  17. A method of dynamic chromatic aberration correction in low-voltage scanning electron microscopes.

    Science.gov (United States)

    Khursheed, Anjam

    2005-07-01

    A time-of-flight concept that dynamically corrects for chromatic aberration effects in scanning electron microscopes (SEMs) is presented. The method is predicted to reduce the microscope's chromatic aberration by an order of magnitude. The scheme should significantly improve the spatial resolution of low-voltage scanning electron microscopes (LVSEMs). The dynamic means of correcting for chromatic aberration also allows for the possibility of obtaining high image resolution from electron guns that have relatively large energy spreads.

  18. Social stress reactivity alters reward and punishment learning

    OpenAIRE

    Cavanagh, James F.; Frank, Michael J.; Allen, John J.B.

    2010-01-01

    To examine how stress affects cognitive functioning, individual differences in trait vulnerability (punishment sensitivity) and state reactivity (negative affect) to social evaluative threat were examined during concurrent reinforcement learning. Lower trait-level punishment sensitivity predicted better reward learning and poorer punishment learning; the opposite pattern was found in more punishment sensitive individuals. Increasing state-level negative affect was directly related to punishme...

  19. Heightened sensitivity to punishment and reward in anorexia nervosa

    NARCIS (Netherlands)

    Glashouwer, Klaske A; Bloot, Lotte; Veenstra, Esther M; Franken, Ingmar H A; de Jong, Peter J

    2014-01-01

    OBJECTIVE: The aim of this study was to investigate reinforcement sensitivity in anorexia nervosa (AN). It was tested whether self-reported punishment (PS) and reward sensitivity (RS) differed between adolescents with AN and healthy controls, and/or between AN-subtypes. In addition, the predictive v

  20. The better, the bigger: The effect of graded positive performance feedback on the reward positivity.

    Science.gov (United States)

    Frömer, Romy; Stürmer, Birgit; Sommer, Werner

    2016-02-01

    In this study on skill acquisition in a computerized throwing task, we examined the effect of graded correct-related performance feedback on the reward positivity of the event-related brain potential (ERP). Theories of reinforcement learning predict effects of reward magnitude and expectancy on the reward prediction error. The later is supposed to be reflected in reward positivity, a fronto-central ERP component. A sample of 68 participants learned to throw at a beamer-projected target disk while performance accuracy, displayed as the place of impact of the projectile on the target, served as graded feedback. Effects of performance accuracy in successful trials, hit frequency, and preceding trial performance on reward positivity were analyzed simultaneously on a trial-by-trial basis by means of linear mixed models. In accord with previous findings, reward positivity increased with feedback about more accurate performance. This relationship was not linear, but cubic, with larger impact of feedback towards the end of the accuracy distribution. In line with being a measure of expectancy, the reward positivity decreased with increasing hit frequency and was larger after unsuccessful trials. The effect of hit frequency was more pronounced following successful trials. These results indicate a fast trial-by-trial adaptation of expectation. The results confirm predictions of reinforcement learning theory and extend previous findings on reward magnitude to the area of complex, goal directed skill acquisition.

  1. Goal or gold: overlapping reward processes in soccer players upon scoring and winning money.

    Directory of Open Access Journals (Sweden)

    Alexander Niklas Häusler

    Full Text Available Social rewards are important incentives for human behavior. This is especially true in team sports such as the most popular one worldwide: soccer. We investigated reward processing upon scoring a soccer goal in a standard two-versus-one situation and in comparison to winning in a monetary incentive task. The results show a strong overlap in brain activity between the two conditions in established reward regions of the mesolimbic dopaminergic system, including the ventral striatum and ventromedial pre-frontal cortex. The three main components of reward-associated learning, i.e., reward probability (RP, reward reception (RR and reward prediction errors (RPE showed highly similar activation in both con-texts, with only the RR and RPE components displaying overlapping reward activity. Passing and shooting behavior did not correlate with individual egoism scores, but we observe a positive correlation be-tween egoism and activity in the left middle frontal gyrus upon scoring after a pass versus a direct shot. Our findings suggest that rewards in the context of soccer and monetary incentives are based on similar neural processes.

  2. Motor Planning under Unpredictable Reward: Modulations of Movement Vigor and Primate Striatum Activity

    Directory of Open Access Journals (Sweden)

    Ioan eOpris

    2011-05-01

    Full Text Available Although reward probability is an important factor that shapes animal behavior, it is not well understood however, how the primate brain translates reward expectation into the vigor of movement (reaction time and speed. To address this question, we trained two monkeys in a reaction time task that required wrist movements in response to vibrotactile and visual stimuli, with a variable reward schedule. Correct performance was rewarded in 75 % of the trials. Monkeys were certain that they would be rewarded only in the trials immediately following withheld rewards. In these trials, the animals responded sooner and moved faster. Single-unit recordings from the dorsal striatum revealed that modulations in striatal neurons reflected such modulations of movement vigor. First, in the trials with certain rewards, striatal neurons modulated their firing rates earlier. Second, magnitudes of changes in neuronal firing rates depended on whether or not monkeys were certain about the reward. Third, these modulations depended on the sensory modality of the cue (visual vs. vibratory and/or movement direction (flexions vs. extensions. We conclude that dorsal striatum may be a part of the mechanism responsible for the modulation of movement vigor in response to changes of reward predictability.

  3. Effects of material and non-material rewards on remembering to do things for others

    Directory of Open Access Journals (Sweden)

    Maria A. Brandimonte

    2015-12-01

    Full Text Available Recent research has shown that pro-social prospective memory, i.e., remembering to do something for others, is negatively affected by the presence of small material rewards. While this competition between pro-social and self-gain motives leads to poor memory for the intention, people do not seem to be aware of the possible collision effects of competing motives (Brandimonte, Ferrante, Bianco, & Villani, 2010. Extending research on this general topic, in two activity-based prospective memory experiments, we explored the effects of different types and amount of rewards on pro-social prospective remembering. In Experiment 1, participants could receive no reward, a low material reward (1 euro, or a high material reward (20 euro for their pro-social prospective memory action. In Experiment 2, their pro-social prospective memory performance could be rewarded or not with an image reward (publicity of their altruistic behavior. Results revealed that introducing a small material reward (Experiment 1 or a non-material reward (Experiment 2 impaired pro-social prospective memory. However, introducing a high material reward eliminated the impairment (Experiment 1. Importantly, in Experiment 1, ongoing task performance in the pro-social condition was faster than in the No PM condition. However, in Experiment 2, ongoing task costs emerged in the presence of a non-material reward, as compared to the pro-social condition. Also, results from two independent ratings showed that people’s predictions on their future pro-social actions were at odds (Experiment 1 or in line (Experiment 2 with actual PM performance. It is suggested that, according to the nature and amount of rewards, memory for a pro-social future action may be modulated by conscious or unconscious motivational mechanisms.

  4. Effects of Material and Non-Material Rewards on Remembering to Do Things for Others.

    Science.gov (United States)

    Brandimonte, Maria A; Ferrante, Donatella

    2015-01-01

    Recent research has shown that pro-social prospective memory, i.e., remembering to do something for others, is negatively affected by the presence of small material rewards. While this competition between pro-social and self-gain motives leads to poor memory for the intention, people do not seem to be aware of the possible collision effects of competing motives (Brandimonte et al., 2010). Extending research on this general topic, in two activity-based prospective memory (PM) experiments, we explored the effects of different types and amount of rewards on pro-social prospective remembering. In Experiment 1, participants could receive no reward, a low material reward (1 euro), or a high material reward (20 euro) for their pro-social PM action. In Experiment 2, their pro-social PM performance could be rewarded or not with an image reward (disclosure of their altruistic behavior). Results revealed that introducing a small material reward (Experiment 1) or a non-material reward (Experiment 2) impaired pro-social PM. However, introducing a high material reward eliminated the impairment (Experiment 1). Importantly, in Experiment 1, ongoing task performance in the pro-social condition was faster than in the No PM condition. However, in Experiment 2, ongoing task costs emerged in the presence of a non-material reward, as compared to the pro-social condition. Also, results from two independent ratings showed that people's predictions on their future pro-social actions were at odds (Experiment 1) or in line (Experiment 2) with actual PM performance. It is suggested that, according to the nature and amount of rewards, memory for a pro-social future action may be modulated by conscious or unconscious motivational mechanisms.

  5. Signals can trump rewards in attracting seed-dispersing ants.

    Science.gov (United States)

    Turner, Kyle M; Frederickson, Megan E

    2013-01-01

    Both rewards and signals are important in mutualisms. In myrmecochory, or seed dispersal by ants, the benefits to plants are relatively well studied, but less is known about why ants pick up and move seeds. We examined seed dispersal by the ant Aphaenogaster rudis of four co-occurring species of plants, and tested whether morphology, chemical signaling, or the nutritional quality of fatty seed appendages called elaiosomes influenced dispersal rates. In removal trials, ants quickly collected diaspores (seeds plus elaiosomes) of Asarum canadense, Trillium grandiflorum, and Sanguinaria canadensis, but largely neglected those of T. erectum. This discrepancy was not explained by differences in the bulk cost-benefit ratio, as assessed by the ratio of seed to elaiosome mass. We also provisioned colonies with diaspores from one of these four plant species or no diaspores as a control. Colonies performed best when fed S. canadensis diaspores, worst when fed T. grandiflorum, and intermediately when fed A. canadense, T. erectum, or no diaspores. Thus, the nutritional rewards in elaiosomes affected colony performance, but did not completely predict seed removal. Instead, high levels of oleic acid in T. grandiflorum elaiosomes may explain why ants disperse these diaspores even though they reduce ant colony performance. We show for the first time that different elaiosome-bearing plants provide rewards of different quality to ant colonies, but also that ants appear unable to accurately assess reward quality when encountering seeds. Instead, we suggest that signals can trump rewards as attractants of ants to seeds.

  6. Signals can trump rewards in attracting seed-dispersing ants.

    Directory of Open Access Journals (Sweden)

    Kyle M Turner

    Full Text Available Both rewards and signals are important in mutualisms. In myrmecochory, or seed dispersal by ants, the benefits to plants are relatively well studied, but less is known about why ants pick up and move seeds. We examined seed dispersal by the ant Aphaenogaster rudis of four co-occurring species of plants, and tested whether morphology, chemical signaling, or the nutritional quality of fatty seed appendages called elaiosomes influenced dispersal rates. In removal trials, ants quickly collected diaspores (seeds plus elaiosomes of Asarum canadense, Trillium grandiflorum, and Sanguinaria canadensis, but largely neglected those of T. erectum. This discrepancy was not explained by differences in the bulk cost-benefit ratio, as assessed by the ratio of seed to elaiosome mass. We also provisioned colonies with diaspores from one of these four plant species or no diaspores as a control. Colonies performed best when fed S. canadensis diaspores, worst when fed T. grandiflorum, and intermediately when fed A. canadense, T. erectum, or no diaspores. Thus, the nutritional rewards in elaiosomes affected colony performance, but did not completely predict seed removal. Instead, high levels of oleic acid in T. grandiflorum elaiosomes may explain why ants disperse these diaspores even though they reduce ant colony performance. We show for the first time that different elaiosome-bearing plants provide rewards of different quality to ant colonies, but also that ants appear unable to accurately assess reward quality when encountering seeds. Instead, we suggest that signals can trump rewards as attractants of ants to seeds.

  7. Reward Contingencies and the Development of Children's Skills and Self-Efficacy.

    Science.gov (United States)

    Schunk, Dale H.

    1983-01-01

    The present study provides evidence that offering performance-contingent rewards promotes children's task accomplishments, percepts of efficacy, and skill development. These findings are consistent with predictions from Bandura's theory of self-efficacy. (Author/PN)

  8. Should Virtuous Behavior Be Rewarded?

    Institute of Scientific and Technical Information of China (English)

    Shu Shengxiang; Wu Ruowei; Fang Hua; Jin Zhen; Wan Xiaoyang; Wang Jie

    2012-01-01

    Traditionally Chinese people place much value in virtue, with a long-held belief that one should never appropriate valuable items lost by others. However, a recent regulation by the government of south China's Guangdong Province has provaked heated debate on whether such virtuaus behavior should be rewarded with money.

  9. What Rewards Do Students Want?

    Science.gov (United States)

    Ware, Barbara Ann

    1978-01-01

    In general, students ranked personal kinds of recognition high and teachers ranked tangible sources of recognition high in surveys of the kinds of rewards that motivate students. The students' top two kinds of recognition were ranked as the bottom two by teachers. (Author/IRT)

  10. Addiction: Beyond dopamine reward circuitry

    Energy Technology Data Exchange (ETDEWEB)

    Volkow, N.D.; Wang, G.; Volkow, N.D.; Wang, G.-J.; Fowler, J.S.; Tomasi, D.; Telang, F.

    2011-09-13

    Dopamine (DA) is considered crucial for the rewarding effects of drugs of abuse, but its role in addiction is much less clear. This review focuses on studies that used PET to characterize the brain DA system in addicted subjects. These studies have corroborated in humans the relevance of drug-induced fast DA increases in striatum [including nucleus accumbens (NAc)] in their rewarding effects but have unexpectedly shown that in addicted subjects, drug-induced DA increases (as well as their subjective reinforcing effects) are markedly blunted compared with controls. In contrast, addicted subjects show significant DA increases in striatum in response to drug-conditioned cues that are associated with self-reports of drug craving and appear to be of a greater magnitude than the DA responses to the drug. We postulate that the discrepancy between the expectation for the drug effects (conditioned responses) and the blunted pharmacological effects maintains drug taking in an attempt to achieve the expected reward. Also, whether tested during early or protracted withdrawal, addicted subjects show lower levels of D2 receptors in striatum (including NAc), which are associated with decreases in baseline activity in frontal brain regions implicated in salience attribution (orbitofrontal cortex) and inhibitory control (anterior cingulate gyrus), whose disruption results in compulsivity and impulsivity. These results point to an imbalance between dopaminergic circuits that underlie reward and conditioning and those that underlie executive function (emotional control and decision making), which we postulate contributes to the compulsive drug use and loss of control in addiction.

  11. The Hidden Costs of Rewards.

    Science.gov (United States)

    Deci, Edward L.

    1976-01-01

    This paper discusses ways managers can motivate their employees to work and at the same time to increase their performance. Two theories of motivation--Vroom's theory and Atkinson's theory--focus on the use of extrinsic and intrinsic rewards respectively. A managerial strategy that combines the best of both intrinsic and extrinsic approaches to…

  12. Distinct medial temporal networks encode surprise during motivation by reward versus punishment.

    Science.gov (United States)

    Murty, Vishnu P; LaBar, Kevin S; Adcock, R Alison

    2016-10-01

    Adaptive motivated behavior requires predictive internal representations of the environment, and surprising events are indications for encoding new representations of the environment. The medial temporal lobe memory system, including the hippocampus and surrounding cortex, encodes surprising events and is influenced by motivational state. Because behavior reflects the goals of an individual, we investigated whether motivational valence (i.e., pursuing rewards versus avoiding punishments) also impacts neural and mnemonic encoding of surprising events. During functional magnetic resonance imaging (fMRI), participants encountered perceptually unexpected events either during the pursuit of rewards or avoidance of punishments. Despite similar levels of motivation across groups, reward and punishment facilitated the processing of surprising events in different medial temporal lobe regions. Whereas during reward motivation, perceptual surprises enhanced activation in the hippocampus, during punishment motivation surprises instead enhanced activation in parahippocampal cortex. Further, we found that reward motivation facilitated hippocampal coupling with ventromedial PFC, whereas punishment motivation facilitated parahippocampal cortical coupling with orbitofrontal cortex. Behaviorally, post-scan testing revealed that reward, but not punishment, motivation resulted in greater memory selectivity for surprising events encountered during goal pursuit. Together these findings demonstrate that neuromodulatory systems engaged by anticipation of reward and punishment target separate components of the medial temporal lobe, modulating medial temporal lobe sensitivity and connectivity. Thus, reward and punishment motivation yield distinct neural contexts for learning, with distinct consequences for how surprises are incorporated into predictive mnemonic models of the environment.

  13. Post-learning Hippocampal Dynamics Promote Preferential Retention of Rewarding Events.

    Science.gov (United States)

    Gruber, Matthias J; Ritchey, Maureen; Wang, Shao-Fang; Doss, Manoj K; Ranganath, Charan

    2016-03-01

    Reward motivation is known to modulate memory encoding, and this effect depends on interactions between the substantia nigra/ventral tegmental area complex (SN/VTA) and the hippocampus. It is unknown, however, whether these interactions influence offline neural activity in the human brain that is thought to promote memory consolidation. Here we used fMRI to test the effect of reward motivation on post-learning neural dynamics and subsequent memory for objects that were learned in high- and low-reward motivation contexts. We found that post-learning increases in resting-state functional connectivity between the SN/VTA and hippocampus predicted preferential retention of objects that were learned in high-reward contexts. In addition, multivariate pattern classification revealed that hippocampal representations of high-reward contexts were preferentially reactivated during post-learning rest, and the number of hippocampal reactivations was predictive of preferential retention of items learned in high-reward contexts. These findings indicate that reward motivation alters offline post-learning dynamics between the SN/VTA and hippocampus, providing novel evidence for a potential mechanism by which reward could influence memory consolidation.

  14. Comparing the neural basis of monetary reward and cognitive feedback during information-integration category learning.

    Science.gov (United States)

    Daniel, Reka; Pollmann, Stefan

    2010-01-06

    The dopaminergic system is known to play a central role in reward-based learning (Schultz, 2006), yet it was also observed to be involved when only cognitive feedback is given (Aron et al., 2004). Within the domain of information-integration category learning, in which information from several stimulus dimensions has to be integrated predecisionally (Ashby and Maddox, 2005), the importance of contingent feedback is well established (Maddox et al., 2003). We examined the common neural correlates of reward anticipation and prediction error in this task. Sixteen subjects performed two parallel information-integration tasks within a single event-related functional magnetic resonance imaging session but received a monetary reward only for one of them. Similar functional areas including basal ganglia structures were activated in both task versions. In contrast, a single structure, the nucleus accumbens, showed higher activation during monetary reward anticipation compared with the anticipation of cognitive feedback in information-integration learning. Additionally, this activation was predicted by measures of intrinsic motivation in the cognitive feedback task and by measures of extrinsic motivation in the rewarded task. Our results indicate that, although all other structures implicated in category learning are not significantly affected by altering the type of reward, the nucleus accumbens responds to the positive incentive properties of an expected reward depending on the specific type of the reward.

  15. Emotional arousal predicts intertemporal choice.

    Science.gov (United States)

    Lempert, Karolina M; Johnson, Eli; Phelps, Elizabeth A

    2016-08-01

    People generally prefer immediate rewards to rewards received after a delay, often even when the delayed reward is larger. This phenomenon is known as temporal discounting. It has been suggested that preferences for immediate rewards may be due to their being more concrete than delayed rewards. This concreteness may evoke an enhanced emotional response. Indeed, manipulating the representation of a future reward to make it more concrete has been shown to heighten the reward's subjective emotional intensity, making people more likely to choose it. Here the authors use an objective measure of arousal-pupil dilation-to investigate if emotional arousal mediates the influence of delayed reward concreteness on choice. They recorded pupil dilation responses while participants made choices between immediate and delayed rewards. They manipulated concreteness through time interval framing: delayed rewards were presented either with the date on which they would be received (e.g., "$30, May 3"; DATE condition, more concrete) or in terms of delay to receipt (e.g., "$30, 7 days; DAYS condition, less concrete). Contrary to prior work, participants were not overall more patient in the DATE condition. However, there was individual variability in response to time framing, and this variability was predicted by differences in pupil dilation between conditions. Emotional arousal increased as the subjective value of delayed rewards increased, and predicted choice of the delayed reward on each trial. This study advances our understanding of the role of emotion in temporal discounting. (PsycINFO Database Record

  16. Effects of Varying Contingency and Directness of Rewards upon Children's Performance under Implicit Reward Conditions.

    Science.gov (United States)

    Sharpley, Christopher F.

    1988-01-01

    Investigated the application of verbal praise as a reward with 84 third and fourth grade children who completed a digit-symbol coding task under contingent versus noncontingent and direct versus implicit reward conditions. Noncontingent rewards possessed no significant reinforcer effect under either reward condition. (SKC)

  17. Remembering with gains and losses: effects of monetary reward and punishment on successful encoding activation of source memories.

    Science.gov (United States)

    Shigemune, Yayoi; Tsukiura, Takashi; Kambara, Toshimune; Kawashima, Ryuta

    2014-05-01

    The motivation of getting rewards or avoiding punishments reinforces learning behaviors. Although the neural mechanisms underlying the effect of rewards on episodic memory have been demonstrated, there is little evidence of the effect of punishments on this memory. Our functional magnetic resonance imaging (fMRI) study investigated the effects of monetary rewards and punishments on activation during the encoding of source memories. During encoding, participants memorized words (item) and locations of presented words (source) under 3 conditions (Reward, Punishment, and Control). During retrieval, participants retrieved item and source memories of the words and were rewarded or penalized according to their performance. Source memories encoded with rewards or punishments were remembered better than those without such encoding. fMRI data demonstrated that the ventral tegmental area and substantia nigra and nucleus accumbens activations reflected both the processes of reward and punishment, whereas insular activation increased as a linear function of punishment. Activation in the hippocampus and parahippocampal cortex predicted subsequent retrieval success of source memories. Additionally, correlations between these reward/punishment-related regions and the hippocampus were significant. The successful encoding of source memories could be enhanced by punishments and rewards, and interactions between reward/punishment-related regions and memory-related regions could contribute to memory enhancement by reward and/or punishment.

  18. What can the monetary incentive delay task tell us about the neural processing of reward and punishment?

    Directory of Open Access Journals (Sweden)

    Lutz K

    2014-04-01

    Full Text Available Kai Lutz,1–3 Mario Widmer1,2,41Department of Neurology, University Hospital Zürich, Zürich, 2Cereneo, Center for Neurology and Rehabilitation, Vitznau, 3Division of Neuropsychology, Institute of Psychology, University of Zürich, Zürich, 4Neural Control of Movement Lab, ETH Zürich, Zürich, SwitzerlandAbstract: Since its introduction in 2000, the monetary incentive delay (MID task has been used extensively to investigate changes in neural activity in response to the processing of reward and punishment in healthy, but also in clinical populations. Typically, the MID task requires an individual to react to a target stimulus presented after an incentive cue to win or to avoid losing the indicated reward. In doing so, this paradigm allows the detailed examination of different stages of reward processing like reward prediction, anticipation, outcome processing, and consumption as well as the processing of tasks under different reward conditions. This review gives an overview of different utilizations of the MID task by outlining the neuronal processes involved in distinct aspects of human reward processing, such as anticipation versus consumption, reward versus punishment, and, with a special focus, reward-based learning processes. Furthermore, literature on specific influences on reward processing like behavioral, clinical and developmental influences, is reviewed, describing current findings and possible future directions.Keywords: reward, punishment, dopamine, reward system

  19. Defining rewardable innovation in drug therapy.

    Science.gov (United States)

    Aronson, Jeffrey K; Ferner, Robin E; Hughes, Dyfrig A

    2012-03-30

    Implementing mechanisms for rewarding those who introduce innovative medicinal products requires a definition of 'rewardable innovation'. Here, we propose a definition of innovation with respect to medicinal products, accompanied by a ranking of the importance of different types of innovativeness, with the aim of providing a basis for rewarding such innovation.

  20. Chromosomal aberrations in ISS crew members

    Science.gov (United States)

    Johannes, Christian; Goedecke, Wolfgang; Antonopoulos, Alexandra

    2012-07-01

    High energy radiation is a major risk factor in manned space missions. Astronauts and cosmonauts are exposed to ionising radiations of cosmic and solar origin, while on the Earth's surface people are well protected by the atmosphere and a deflecting magnetic field. There are now data available describing the dose and the quality of ionising radiation on-board of the International Space Station (ISS). Nonetheless, the effect of increased radiation dose on mutation rates of ISS crew members are hard to predict. Therefore, direct measurements of mutation rates are required in order to better estimate the radiation risk for longer duration missions. The analysis of chromosomal aberrations in peripheral blood lymphocytes is a well established method to measure radiation-induced mutations. We present data of chromosome aberration analyses from lymphocyte metaphase spreads of ISS crew members participating in short term (10-14 days) or long term (around 6 months) missions. From each subject we received two blood samples. The first sample was drawn about 10 days before launch and a second one within 3 days after return from flight. From lymphocyte cultures metaphase plates were prepared on glass slides. Giemsa stained and in situ hybridised metaphases were scored for chromosome changes in pre-flight and post-flight blood samples and the mutation rates were compared. Results obtained in chromosomal studies on long-term flight crew members showed pronounced inter-individual differences in the response to elevated radiation levels. Overall slight but significant elevations of typical radiation induced aberrations, i.e., dicentric chromosomes and reciprocal translocations have been observed. Our data indicate no elevation of mutation rates due to short term stays on-board the ISS.

  1. Housing conditions affect rat responses to two types of ambiguity in a reward-reward discrimination cognitive bias task.

    Science.gov (United States)

    Parker, Richard M A; Paul, Elizabeth S; Burman, Oliver H P; Browne, William J; Mendl, Michael

    2014-11-01

    Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward ('optimism') or punishment ('pessimism'). We investigated whether an automated Reward-Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively 'pessimistic', whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases.

  2. An Upside to Reward Sensitivity: The Hippocampus Supports Enhanced Reinforcement Learning in Adolescence.

    Science.gov (United States)

    Davidow, Juliet Y; Foerde, Karin; Galván, Adriana; Shohamy, Daphna

    2016-10-05

    Adolescents are notorious for engaging in reward-seeking behaviors, a tendency attributed to heightened activity in the brain's reward systems during adolescence. It has been suggested that reward sensitivity in adolescence might be adaptive, but evidence of an adaptive role has been scarce. Using a probabilistic reinforcement learning task combined with reinforcement learning models and fMRI, we found that adolescents showed better reinforcement learning and a stronger link between reinforcement learning and episodic memory for rewarding outcomes. This behavioral benefit was related to heightened prediction error-related BOLD activity in the hippocampus and to stronger functional connectivity between the hippocampus and the striatum at the time of reinforcement. These findings reveal an important role for the hippocampus in reinforcement learning in adolescence and suggest that reward sensitivity in adolescence is related to adaptive differences in how adolescents learn from experience.

  3. Chromosome aberrations as biomarkers of radiation exposure: Modelling basic mechanisms

    Science.gov (United States)

    Ballarini, F.; Ottolenghi, A.

    The space radiation environment is a mixed field consisting of different particles having different energies, including high charge and energy (HZE) ions. Conventional measurements of absorbed doses may not be sufficient to completely characterise the radiation field and perform reliable estimates of health risks. Biological dosimetry, based on the observation of specific radiation-induced endpoints (typically chromosome aberrations), can be a helpful approach in case of monitored exposure to space radiation or other mixed fields, as well as in case of accidental exposure. Furthermore, various ratios of aberrations (e.g. dicentric chromosomes to centric rings and complex exchanges to simple exchanges) have been suggested as possible fingerprints of radiation quality, although all of them have been subjected to some criticisms. In this context a mechanistic model and a Monte Carlo code for the simulation of chromosome aberration induction were developed. The model, able to provide dose-responses for different aberrations (e.g. dicentrics, rings, fragments, translocations, insertions and other complex exchanges), was further developed to assess the dependence of various ratios of aberrations on radiation quality. The predictions of the model were compared with available data, whose experimental conditions were faithfully reproduced. Particular attention was devoted to the scoring criteria adopted in different laboratories and to possible biases introduced by interphase death and mitotic delay. This latter aspect was investigated by taking into account both metaphase data and data obtained with Premature Chromosome Condensation (PCC).

  4. Adolescent development of the reward system

    Directory of Open Access Journals (Sweden)

    Adriana Galván

    2010-02-01

    Full Text Available Adolescence is a developmental period characterized by increased reward-seeking behavior. Investigators have used functional magnetic resonance imaging (fMRI in conjunction with reward paradigms to test two opposing hypotheses about adolescent developmental changes in the striatum, a region implicated in reward processing. One hypothesis posits that the striatum is relatively hypo-responsive to rewards during adolescence, such that heightened reward-seeking behavior is necessary to achieve the same activation as adults. Another view suggests that during adolescence the striatal reward system is hyper-responsive, which subsequently results in greater reward-seeking. While evidence for both hypotheses has been reported, the field has generally converged on this latter hypothesis based on compelling evidence. In this review, I describe the evidence to support this notion, speculate on the disparate fMRI findings and conclude with future areas of inquiry to this fascinating question.

  5. Incremental effects of reward on creativity.

    Science.gov (United States)

    Eisenberger, R; Rhoades, L

    2001-10-01

    The authors examined 2 ways reward might increase creativity. First, reward contingent on creativity might increase extrinsic motivation. Studies 1 and 2 found that repeatedly giving preadolescent students reward for creative performance in 1 task increased their creativity in subsequent tasks. Study 3 reported that reward promised for creativity increased college students' creative task performance. Second, expected reward for high performance might increase creativity by enhancing perceived self-determination and, therefore, intrinsic task interest. Study 4 found that employees' intrinsic job interest mediated a positive relationship between expected reward for high performance and creative suggestions offered at work. Study 5 found that employees' perceived self-determination mediated a positive relationship between expected reward for high performance and the creativity of anonymous suggestions for helping the organization.

  6. Antisocial behavior, psychopathic features and abnormalities in reward and punishment processing in youth.

    Science.gov (United States)

    Byrd, Amy L; Loeber, Rolf; Pardini, Dustin A

    2014-06-01

    A better understanding of what leads youth to initially engage in antisocial behavior (ASB) and more importantly persist with such behaviors into adulthood has significant implications for prevention and intervention efforts. A considerable number of studies using behavioral and neuroimaging techniques have investigated abnormalities in reward and punishment processing as potential causal mechanisms underlying ASB. However, this literature has yet to be critically evaluated, and there are no comprehensive reviews that systematically examine and synthesize these findings. The goal of the present review is twofold. The first aim is to examine the extent to which youth with ASB are characterized by abnormalities in (1) reward processing; (2) punishment processing; or (3) both reward and punishment processing. The second aim is to evaluate whether aberrant reward and/or punishment processing is specific to or most pronounced in a subgroup of antisocial youth with psychopathic features. Studies utilizing behavioral methods are first reviewed, followed by studies using functional magnetic resonance imaging. An integration of theory and research across multiple levels of analysis is presented in order to provide a more comprehensive understanding of reward and punishment processing in antisocial youth. Findings are discussed in terms of developmental and contextual considerations, proposed future directions and implications for intervention.

  7. Using geometric algebra to study optical aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hanlon, J.; Ziock, H.

    1997-05-01

    This paper uses Geometric Algebra (GA) to study vector aberrations in optical systems with square and round pupils. GA is a new way to produce the classical optical aberration spot diagrams on the Gaussian image plane and surfaces near the Gaussian image plane. Spot diagrams of the third, fifth and seventh order aberrations for square and round pupils are developed to illustrate the theory.

  8. Reward salience and risk aversion underlie differential ACC activity in substance dependence

    Directory of Open Access Journals (Sweden)

    William H. Alexander

    2015-01-01

    Full Text Available The medial prefrontal cortex, especially the dorsal anterior cingulate cortex (ACC, has long been implicated in cognitive control and error processing. Although the association between ACC and behavior has been established, it is less clear how ACC contributes to dysfunctional behavior such as substance dependence. Evidence from neuroimaging studies investigating ACC function in substance users is mixed, with some studies showing disengagement of ACC in substance dependent individuals (SDs, while others show increased ACC activity related to substance use. In this study, we investigate ACC function in SDs and healthy individuals performing a change signal task for monetary rewards. Using a priori predictions derived from a recent computational model of ACC, we find that ACC activity differs between SDs and controls in factors related to reward salience and risk aversion between SDs and healthy individuals. Quantitative fits of a computational model to fMRI data reveal significant differences in best fit parameters for reward salience and risk preferences. Specifically, the ACC in SDs shows greater risk aversion, defined as concavity in the utility function, and greater attention to rewards relative to reward omission. Furthermore, across participants risk aversion and reward salience are positively correlated. The results clarify the role that ACC plays in both the reduced sensitivity to omitted rewards and greater reward valuation in SDs. Clinical implications of applying computational modeling in psychiatry are also discussed.

  9. Toward an autonomous brain machine interface: integrating sensorimotor reward modulation and reinforcement learning.

    Science.gov (United States)

    Marsh, Brandi T; Tarigoppula, Venkata S Aditya; Chen, Chen; Francis, Joseph T

    2015-05-13

    For decades, neurophysiologists have worked on elucidating the function of the cortical sensorimotor control system from the standpoint of kinematics or dynamics. Recently, computational neuroscientists have developed models that can emulate changes seen in the primary motor cortex during learning. However, these simulations rely on the existence of a reward-like signal in the primary sensorimotor cortex. Reward modulation of the primary sensorimotor cortex has yet to be characterized at the level of neural units. Here we demonstrate that single units/multiunits and local field potentials in the primary motor (M1) cortex of nonhuman primates (Macaca radiata) are modulated by reward expectation during reaching movements and that this modulation is present even while subjects passively view cursor motions that are predictive of either reward or nonreward. After establishing this reward modulation, we set out to determine whether we could correctly classify rewarding versus nonrewarding trials, on a moment-to-moment basis. This reward information could then be used in collaboration with reinforcement learning principles toward an autonomous brain-machine interface. The autonomous brain-machine interface would use M1 for both decoding movement intention and extraction of reward expectation information as evaluative feedback, which would then update the decoding algorithm as necessary. In the work presented here, we show that this, in theory, is possible.

  10. The Dopaminergic Midbrain Mediates an Effect of Average Reward on Pavlovian Vigor.

    Science.gov (United States)

    Rigoli, Francesco; Chew, Benjamin; Dayan, Peter; Dolan, Raymond J

    2016-09-01

    Dopamine plays a key role in motivation. Phasic dopamine response reflects a reinforcement prediction error (RPE), whereas tonic dopamine activity is postulated to represent an average reward that mediates motivational vigor. However, it has been hard to find evidence concerning the neural encoding of average reward that is uncorrupted by influences of RPEs. We circumvented this difficulty in a novel visual search task where we measured participants' button pressing vigor in a context where information (underlying an RPE) about future average reward was provided well before the average reward itself. Despite no instrumental consequence, participants' pressing force increased for greater current average reward, consistent with a form of Pavlovian effect on motivational vigor. We recorded participants' brain activity during task performance with fMRI. Greater average reward was associated with enhanced activity in dopaminergic midbrain to a degree that correlated with the relationship between average reward and pressing vigor. Interestingly, an opposite pattern was observed in subgenual cingulate cortex, a region implicated in negative mood and motivational inhibition. These findings highlight a crucial role for dopaminergic midbrain in representing aspects of average reward and motivational vigor.

  11. Phase Aberrations in Diffraction Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  12. Aberrant Gene Expression in Acute Myeloid Leukaemia

    DEFF Research Database (Denmark)

    Bagger, Frederik Otzen

    model to investigate the role of telomerase in AML, we were able to translate the observed effect into human AML patients and identify specific genes involved, which also predict survival patterns in AML patients. During these studies we have applied methods for investigating differentially expressed......Summary Acute Myeloid Leukaemia (AML) is an aggressive cancer of the bone marrow, affecting formation of blood cells during haematopoiesis. This thesis presents investigation of AML using mRNA gene expression profiles (GEP) of samples extracted from the bone marrow of healthy and diseased subjects....... Here GEPs from purified healthy haematopoietic populations, with different levels of differentiation, form the basis for comparison with diseased samples. We present a mathematical transformation of mRNA microarray data to make it possible to compare AML samples, carrying expanded aberrant...

  13. The neuroscience of investing: fMRI of the reward system.

    Science.gov (United States)

    Peterson, Richard L

    2005-11-15

    Functional magnetic resonance imaging (fMRI) has proven a useful tool for observing neural BOLD signal changes during complex cognitive and emotional tasks. Yet the meaning and applicability of the fMRI data being gathered is still largely unknown. The brain's reward system underlies the fundamental neural processes of goal evaluation, preference formation, positive motivation, and choice behavior. fMRI technology allows researchers to dynamically visualize reward system processes. Experimenters can then correlate reward system BOLD activations with experimental behavior from carefully controlled experiments. In the SPAN lab at Stanford University, directed by Brian Knutson Ph.D., researchers have been using financial tasks during fMRI scanning to correlate emotion, behavior, and cognition with the reward system's fundamental neural activations. One goal of the SPAN lab is the development of predictive models of behavior. In this paper we extrapolate our fMRI results toward understanding and predicting individual behavior in the uncertain and high-risk environment of the financial markets. The financial market price anomalies of "value versus glamour" and "momentum" may be real-world examples of reward system activation biasing collective behavior. On the individual level, the investor's bias of overconfidence may similarly be related to reward system activation. We attempt to understand selected "irrational" investor behaviors and anomalous financial market price patterns through correlations with findings from fMRI research of the reward system.

  14. A causal link between prediction errors, dopamine neurons and learning.

    Science.gov (United States)

    Steinberg, Elizabeth E; Keiflin, Ronald; Boivin, Josiah R; Witten, Ilana B; Deisseroth, Karl; Janak, Patricia H

    2013-07-01

    Situations in which rewards are unexpectedly obtained or withheld represent opportunities for new learning. Often, this learning includes identifying cues that predict reward availability. Unexpected rewards strongly activate midbrain dopamine neurons. This phasic signal is proposed to support learning about antecedent cues by signaling discrepancies between actual and expected outcomes, termed a reward prediction error. However, it is unknown whether dopamine neuron prediction error signaling and cue-reward learning are causally linked. To test this hypothesis, we manipulated dopamine neuron activity in rats in two behavioral procedures, associative blocking and extinction, that illustrate the essential function of prediction errors in learning. We observed that optogenetic activation of dopamine neurons concurrent with reward delivery, mimicking a prediction error, was sufficient to cause long-lasting increases in cue-elicited reward-seeking behavior. Our findings establish a causal role for temporally precise dopamine neuron signaling in cue-reward learning, bridging a critical gap between experimental evidence and influential theoretical frameworks.

  15. Correlations between corneal and total wavefront aberrations

    Science.gov (United States)

    Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo

    2002-06-01

    Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.

  16. Anticipation of novelty recruits reward system and hippocampus while promoting recollection.

    Science.gov (United States)

    Wittmann, Bianca C; Bunzeck, Nico; Dolan, Raymond J; Düzel, Emrah

    2007-10-15

    The dopaminergic midbrain, which comprises the substantia nigra and ventral tegmental area (SN/VTA), plays a central role in reward processing. This region is also activated by novel stimuli, raising the possibility that novelty and reward have shared functional properties. It is currently unclear whether functional aspects of reward processing in the SN/VTA, namely, activation by unexpected rewards and cues that predict reward, also characterize novelty processing. To address this question, we conducted an fMRI experiment during which subjects viewed symbolic cues that predicted either novel or familiar images of scenes with 75% validity. We show that SN/VTA was activated by cues predicting novel images as well as by unexpected novel images that followed familiarity-predictive cues, an 'unexpected novelty' response. The hippocampus, a region implicated in detecting and encoding novel stimuli, showed an anticipatory novelty response but differed from the response profile of SN/VTA in responding at outcome to expected and 'unexpected' novelty. In a behavioral extension of the experiment, recollection increased relative to familiarity when comparing delayed recognition memory for anticipated novel stimuli with unexpected novel stimuli. These data reveal commonalities in SN/VTA responses to anticipating reward and anticipating novel stimuli. We suggest that this anticipatory response codes a motivational exploratory novelty signal that, together with anticipatory activation of the hippocampus, leads to enhanced encoding of novel events. In more general terms, the data suggest that dopaminergic processing of novelty might be important in driving exploration of new environments.

  17. Dopamine and reward: the anhedonia hypothesis 30 years on.

    Science.gov (United States)

    Wise, Roy A

    2008-10-01

    The anhedonia hypothesis--that brain dopamine plays a critical role in the subjective pleasure associated with positive rewards--was intended to draw the attention of psychiatrists to the growing evidence that dopamine plays a critical role in the objective reinforcement and incentive motivation associated with food and water, brain stimulation reward, and psychomotor stimulant and opiate reward. The hypothesis called to attention the apparent paradox that neuroleptics, drugs used to treat a condition involving anhedonia (schizophrenia), attenuated in laboratory animals the positive reinforcement that we normally associate with pleasure. The hypothesis held only brief interest for psychiatrists, who pointed out that the animal studies reflected acute actions of neuroleptics whereas the treatment of schizophrenia appears to result from neuroadaptations to chronic neuroleptic administration, and that it is the positive symptoms of schizophrenia that neuroleptics alleviate, rather than the negative symptoms that include anhedonia. Perhaps for these reasons, the hypothesis has had minimal impact in the psychiatric literature. Despite its limited heuristic value for the understanding of schizophrenia, however, the anhedonia hypothesis has had major impact on biological theories of reinforcement, motivation, and addiction. Brain dopamine plays a very important role in reinforcement of response habits, conditioned preferences, and synaptic plasticity in cellular models of learning and memory. The notion that dopamine plays a dominant role in reinforcement is fundamental to the psychomotor stimulant theory of addiction, to most neuroadaptation theories of addiction, and to current theories of conditioned reinforcement and reward prediction. Properly understood, it is also fundamental to recent theories of incentive motivation.

  18. On the influence of reward on action-effect binding

    Directory of Open Access Journals (Sweden)

    Paul Simon Muhle-Karbe

    2012-11-01

    Full Text Available Ideomotor theory states that the formation of anticipatory representations about the perceptual consequences of an action (i.e. action-effect (A-E binding provides the functional basis of voluntary action control. A host of studies has demonstrated that A-E binding occurs fast and effortlessly, yet only little is known about cognitive and affective factors that influence this learning process. In the present study, we sought to test whether the motivational value of an action modulates the acquisition of A-E associations. To this end, we associated specific actions with monetary incentives during the acquisition of novel A-E mappings. In a subsequent test phase, the degree of binding was assessed by presenting the former effect stimuli as task-irrelevant response primes in a forced-choice response task in the absence of any reward. Binding, as indexed by response priming through the former action effects, was only found for reward-related A-E mappings. Moreover, the degree to which reward associations modulated the binding strength was predicted by individuals’ trait sensitivity to reward. These observations indicate that the association of actions and their immediate outcomes depends on the motivational value of the action during learning, as well as on the motivational disposition of the individual. On a larger scale, these findings also highlight the link between ideomotor theories and reinforcement-learning theories, providing an interesting perspective for future research on anticipatory regulation of behavior.

  19. Reduced Caudate and Nucleus Accumbens Response to Rewards in Unmedicated Subjects with Major Depressive Disorder

    Science.gov (United States)

    Pizzagalli, Diego A.; Holmes, Avram J.; Dillon, Daniel G.; Goetz, Elena L.; Birk, Jeffrey L.; Bogdan, Ryan; Dougherty, Darin D.; Iosifescu, Dan V.; Rauch, Scott L.; Fava, Maurizio

    2009-01-01

    Objective Major depressive disorder (MDD) is characterized by impaired reward processing, possibly due to dysfunction in the basal ganglia. However, few neuroimaging studies of depression have distinguished between anticipatory and consummatory phases of reward processing. Using functional magnetic resonance imaging (fMRI) and a task that dissociates anticipatory and consummatory phases of reward processing, the authors tested the hypothesis that MDD participants would show reduced reward-related responses in basal ganglia structures. Method A monetary incentive delay task was presented to 30 unmedicated MDD subjects and 31 healthy comparison subjects during fMRI scanning. Whole-brain analyses focused on neural responses to reward-predicting cues and rewarding outcomes (i.e., monetary gains). Secondary analyses focused on the relationship between anhedonic symptoms and basal ganglia volumes. Results Relative to comparison subjects, MDD participants showed significantly weaker responses to gains in the left nucleus accumbens and bilateral caudate. Group differences in these regions were specific to rewarding outcomes and did not generalize to neutral or negative outcomes, although relatively reduced responses to monetary penalties in MDD emerged in other caudate regions. By contrast, evidence for group differences during reward anticipation was weaker, although MDD subjects showed reduced activation to reward cues in a small sector of the left posterior putamen. Among MDD subjects, anhedonic symptoms and depression severity were associated with reduced bilateral caudate volume. Conclusions These results indicate that basal ganglia dysfunction in MDD may affect the consummatory phase of reward processing. Additionally, morphometric results suggest that anhedonia in MDD is related to caudate volume. PMID:19411368

  20. Linking reward processing to behavioral output: motor and motivational integration in the primate subthalamic nucleus

    Directory of Open Access Journals (Sweden)

    Juan-Francisco eEspinosa-Parrilla

    2013-12-01

    Full Text Available The expectation and detection of motivationally relevant events is a major determinant of goal-directed behavior and there is a strong interest in the contribution of basal ganglia in the integration of motivational processes into behavioral output. Recent research has focused on the role of the subthalamic nucleus (STN in the motivational control of action, but it remains to be determined how information about reward is encoded in this nucleus. We recorded the activity of single neurons in the STN of two behaving monkeys to examine whether activity was influenced by the delivery of reward in an instrumental task, a Pavlovian stimulus-reward association, or outside of a task context. We confirmed preliminary findings indicating that STN neurons were sensitive not only to rewards obtained during task performance, but also to the expectation of reward when its delivery was delayed in time. Most of the modulations at the onset of reaching movement were combined with modulations following reward delivery, suggesting the convergence of signals related to the animal’s movement and its outcome in the same neurons. Some neurons were also influenced by the visuomotor contingencies of the task, i.e., target location and/or movement direction. In addition, modulations were observed under conditions where reward delivery was not contingent on an instrumental response, even in the absence of a reward predictive cue. Taken as a whole, these results demonstrate a potential contribution of the STN to motivational control of behavior in the non-human primate, although problems in distinguishing neuronal signals related to reward from those related to motor behavior should be considered. Characterizing the specificity of reward processing in the STN remains challenging and could have important implications for understanding the influence of this key component of basal ganglia circuitry on emotional and motivated behaviors under normal and pathological

  1. Endocannabinoid signaling in reward and addiction

    OpenAIRE

    Parsons, Loren H.; Hurd, Yasmin L.

    2015-01-01

    Brain endocannabinoid signaling influences the motivation for natural rewards (such as palatable food, sexual activity and social interaction) and modulates the rewarding effects of addictive drugs. Pathological forms of natural and drug-induced reward are associated with dysregulated endocannabinoid signaling that may derive from pre-existing genetic factors or from prolonged drug exposure. Impaired endocannabinoid signaling contributes to dysregulated synaptic plasticity, increased stress r...

  2. Individual Differences in Music Reward Experiences

    OpenAIRE

    Mas-Herrero, E.; Marco Pallarés, Josep; Lorenzo-Seva, U.; Zatorre, R.; Rodriguez-Fornells, A.

    2013-01-01

    Music is one of the most pleasant human experiences, even though it has no direct biological advantage. However little is known about individual differences in how people experience reward in music-related activities. The goal of the present study was to describe the main facets of music experience that could explain the variance observed in how people experience reward associated with music. To this end we developed the Barcelona Music Reward Questionnaire (BMRQ), which was administrated to ...

  3. Chromosome aberrations induced by zebularine in triticale.

    Science.gov (United States)

    Ma, Xuhui; Wang, Qing; Wang, Yanzhi; Ma, Jieyun; Wu, Nan; Ni, Shuang; Luo, Tengxiao; Zhuang, Lifang; Chu, Chenggen; Cho, Seong-Woo; Tsujimoto, Hisashi; Qi, Zengjun

    2016-07-01

    Chromosome engineering is an important approach for generating wheat germplasm. Efficient development of chromosome aberrations will facilitate the introgression and application of alien genes in wheat. In this study, zebularine, a DNA methylation transferase inhibitor, was successfully used to induce chromosome aberrations in the octoploid triticale cultivar Jinghui#1. Dry seeds were soaked in zebularine solutions (250, 500, and 750 μmol/L) for 24 h, and the 500 μmol/L treatment was tested in three additional treatment times, i.e., 12, 36, and 48 h. All treatments induced aberrations involving wheat and rye chromosomes. Of the 920 cells observed in 67 M1 plants, 340 (37.0%) carried 817 aberrations with an average of 0.89 aberrations per cell (range: 0-12). The aberrations included probable deletions, telosomes and acentric fragments (49.0%), large segmental translocations (28.9%), small segmental translocations (17.1%), intercalary translocations (2.6%), long chromosomes that could carry more than one centromere (2.0%), and ring chromosomes (0.5%). Of 510 M2 plants analyzed, 110 (21.6%) were found to carry stable aberrations. Such aberrations included 79 with varied rye chromosome numbers, 7 with wheat and rye chromosome translocations, 15 with possible rye telosomes/deletions, and 9 with complex aberrations involving variation in rye chromosome number and wheat-rye translocations. These indicated that aberrations induced by zebularine can be steadily transmitted, suggesting that zebularine is a new efficient agent for chromosome manipulation.

  4. Lights, Camembert, Action! The Role of Human Orbitofrontal Cortex in Encoding Stimuli, Rewards, and Choices

    OpenAIRE

    O'Doherty, John P.

    2007-01-01

    This review outlines some of the main conclusions about the contributions of the orbitofrontal cortex to reward learning and decision making arising from functional neuroimaging studies in humans. It will be argued that human orbitofrontal cortex is involved in a number of distinct functions: signaling the affective value of stimuli as they are perceived, encoding expectations of future reward, and updating these expectations, either by making use of prediction error signals generated in the ...

  5. The Social Rewards of Engagement

    DEFF Research Database (Denmark)

    Robison, Joshua

    2017-01-01

    Political interest is a crucial precursor to political engagement, but little is known about how to stimulate greater interest. The article explores the role social motives have in generating interest. A laboratory experiment is used in which it is possible to manipulate beliefs about the social...... particularly strong among individuals with low levels of external efficacy. Ultimately, the data provide clear evidence that political interest can be positively stimulated with social rewards mobilisation techniques and that it is rooted in beliefs about the potential motives pursuable through politics...

  6. Neural processing of reward in adolescent rodents

    Directory of Open Access Journals (Sweden)

    Nicholas W. Simon

    2015-02-01

    Full Text Available Immaturities in adolescent reward processing are thought to contribute to poor decision making and increased susceptibility to develop addictive and psychiatric disorders. Very little is known; however, about how the adolescent brain processes reward. The current mechanistic theories of reward processing are derived from adult models. Here we review recent research focused on understanding of how the adolescent brain responds to rewards and reward-associated events. A critical aspect of this work is that age-related differences are evident in neuronal processing of reward-related events across multiple brain regions even when adolescent rats demonstrate behavior similar to adults. These include differences in reward processing between adolescent and adult rats in orbitofrontal cortex and dorsal striatum. Surprisingly, minimal age related differences are observed in ventral striatum, which has been a focal point of developmental studies. We go on to discuss the implications of these differences for behavioral traits affected in adolescence, such as impulsivity, risk-taking, and behavioral flexibility. Collectively, this work suggests that reward-evoked neural activity differs as a function of age and that regions such as the dorsal striatum that are not traditionally associated with affective processing in adults may be critical for reward processing and psychiatric vulnerability in adolescents.

  7. Atom lens without chromatic aberrations

    CERN Document Server

    Efremov, Maxim A; Schleich, Wolfgang P

    2012-01-01

    We propose a lens for atoms with reduced chromatic aberrations and calculate its focal length and spot size. In our scheme a two-level atom interacts with a near-resonant standing light wave formed by two running waves of slightly different wave vectors, and a far-detuned running wave propagating perpendicular to the standing wave. We show that within the Raman-Nath approximation and for an adiabatically slow atom-light interaction, the phase acquired by the atom is independent of the incident atomic velocity.

  8. Aspherical surfaces design for extreme ultraviolet lithographic objective with correction of thermal aberration

    Science.gov (United States)

    Liu, Yan; Li, Yanqiu

    2016-09-01

    At present, few projection objectives for extreme ultraviolet (EUV) lithography pay attention to correct thermal aberration in optical design phase, which would lead to poor image quality in a practical working environment. We present an aspherical modification method for helping the EUV lithographic objective additionally correct the thermal aberration. Based on the thermal aberration and deformation predicted by integrated optomechanical analysis, the aspherical surfaces in an objective are modified by an iterative algorithm. The modified aspherical surfaces could correct the thermal aberration and maintain the initial high image quality in a practical working environment. A six-mirror EUV lithographic objective with 0.33-numerical aperture is taken as an example to illustrate the presented method. The results show that the thermal aberration can be corrected effectively, and the image quality of the thermally deformed system is improved to the initial design level, which proves the availability of the method.

  9. Distinct linear and non-linear trajectories of reward and punishment reversal learning during development: relevance for dopamine's role in adolescent decision making.

    Science.gov (United States)

    van der Schaaf, Marieke E; Warmerdam, Eveline; Crone, Eveline A; Cools, Roshan

    2011-10-01

    Abnormalities in value-based decision making during adolescence have often been attributed to non-linear, inverted-U shaped development of reward-related processes. This hypothesis is strengthened by functional imaging work revealing an inverted-U shaped relationship between age and reward-related activity in the striatum. However, behavioural studies have mostly reported linear rather than non-linear increases in reward-related performance. In the present study, we investigated the mechanisms underlying the development of reward- and punishment-related processing across four age groups using a reversal learning task previously shown to depend on striatal dopamine. We demonstrate both linear and non-linear age effects on distinct components of reversal learning. Specifically, results revealed a linear shift with age in terms of valence-dependent reversal learning, with children exhibiting better punishment than reward reversal learning, adults exhibiting better reward than punishment reversal learning and adolescents exhibiting an intermediate performance pattern. In addition, we also observed a non-linear, inverted-U shaped relationship between age and valence-independent reversal learning, which was due to aberrant ability of adolescents to update behaviour in response to negative performance feedback. These findings indicate that the (linear or nonlinear) nature of the relationship between age and reward learning depends on the type of reward learning under study.

  10. Social Influences on Creativity: Interactive Effects of Reward and Choice.

    Science.gov (United States)

    Amabile, Teresa M.

    In a test of intrinsic motivation hypothesis of creativity, 60 undergraduate women did an artistic creativity task with either the expectation of receiving a reward or no expectation of reward. Reward was crossed with choice in task engagement, such that half of the reward Ss contracted to do the task in order to receive reward, and half simply…

  11. Reward and non-reward learning of flower colours in the butterfly Byasa alcinous (Lepidoptera: Papilionidae)

    Science.gov (United States)

    Kandori, Ikuo; Yamaki, Takafumi

    2012-09-01

    Learning plays an important role in food acquisition for a wide range of insects. To increase their foraging efficiency, flower-visiting insects may learn to associate floral cues with the presence (so-called reward learning) or the absence (so-called non-reward learning) of a reward. Reward learning whilst foraging for flowers has been demonstrated in many insect taxa, whilst non-reward learning in flower-visiting insects has been demonstrated only in honeybees, bumblebees and hawkmoths. This study examined both reward and non-reward learning abilities in the butterfly Byasa alcinous whilst foraging among artificial flowers of different colours. This butterfly showed both types of learning, although butterflies of both sexes learned faster via reward learning. In addition, females learned via reward learning faster than males. To the best of our knowledge, these are the first empirical data on the learning speed of both reward and non-reward learning in insects. We discuss the adaptive significance of a lower learning speed for non-reward learning when foraging on flowers.

  12. Cognitive processing of food rewards.

    Science.gov (United States)

    Higgs, Suzanne

    2016-09-01

    Cues associated with tasty foods, such as their smell or taste, are strong motivators of eating, but the power of food cues on behaviour varies from moment to moment and from person to person. Variation in the rewarding value of a food with metabolic state explains why food cues are more attractive when hungry. However, cognitive processes are also important determinants of our responses to food cues. An urge to consume a tempting food may be resisted if, for example, a person has a longer term goal of weight loss. There is also evidence that responses to food cues can be facilitated or inhibited by memory processes. The aim of this review is to add to the literature on cognitive control of eating by reviewing recent evidence on the influence of working memory and episodic memory processes on responses to food cues. It is argued that processing of food information in working memory affects how much attention is paid to food cues in the environment and promotes the motivation to seek out food in the absence of direct contact with food cues. It is further argued that memories of specific recent eating episodes play an important role in directing food choices and influencing when and how much we eat. However, these memory processes are prone to disruption. When this happens, eating behaviour may become more cue-driven and less flexible. In the modern food environment, disruption of cognitive processing of food reward cues may lead to overconsumption and obesity.

  13. Looking for reward in all the wrong places: dopamine receptor gene polymorphisms indirectly affect aggression through sensation-seeking.

    Science.gov (United States)

    Chester, David S; DeWall, C Nathan; Derefinko, Karen J; Estus, Steven; Lynam, Donald R; Peters, Jessica R; Jiang, Yang

    2016-10-01

    Individuals with genotypes that code for reduced dopaminergic brain activity often exhibit a predisposition toward aggression. However, it remains largely unknown how dopaminergic genotypes may increase aggression. Lower-functioning dopamine systems motivate individuals to seek reward from external sources such as illicit drugs and other risky experiences. Based on emerging evidence that aggression is a rewarding experience, we predicted that the effect of lower-functioning dopaminergic functioning on aggression would be mediated by tendencies to seek the environment for rewards. Caucasian female and male undergraduates (N = 277) were genotyped for five polymorphisms of the dopamine D2 receptor (DRD2) gene; they reported their previous history of aggression and their dispositional reward-seeking. Lower-functioning DRD2 profiles were associated with greater sensation-seeking, which then predicted greater aggression. Our findings suggest that lower-functioning dopaminergic activity puts individuals at risk for violence because it motivates them to experience aggression's hedonically rewarding qualities.

  14. Neural signal during immediate reward anticipation in schizophrenia: Relationship to real-world motivation and function.

    Science.gov (United States)

    Subramaniam, Karuna; Hooker, Christine I; Biagianti, Bruno; Fisher, Melissa; Nagarajan, Srikantan; Vinogradov, Sophia

    2015-01-01

    Amotivation in schizophrenia is a central predictor of poor functioning, and is thought to occur due to deficits in anticipating future rewards, suggesting that impairments in anticipating pleasure can contribute to functional disability in schizophrenia. In healthy comparison (HC) participants, reward anticipation is associated with activity in frontal-striatal networks. By contrast, schizophrenia (SZ) participants show hypoactivation within these frontal-striatal networks during this motivated anticipatory brain state. Here, we examined neural activation in SZ and HC participants during the anticipatory phase of stimuli that predicted immediate upcoming reward and punishment, and during the feedback/outcome phase, in relation to trait measures of hedonic pleasure and real-world functional capacity. SZ patients showed hypoactivation in ventral striatum during reward anticipation. Additionally, we found distinct differences between HC and SZ groups in their association between reward-related immediate anticipatory neural activity and their reported experience of pleasure. HC participants recruited reward-related regions in striatum that significantly correlated with subjective consummatory pleasure, while SZ patients revealed activation in attention-related regions, such as the IPL, which correlated with consummatory pleasure and functional capacity. These findings may suggest that SZ patients activate compensatory attention processes during anticipation of immediate upcoming rewards, which likely contribute to their functional capacity in daily life.

  15. Neural signal during immediate reward anticipation in schizophrenia: Relationship to real-world motivation and function

    Directory of Open Access Journals (Sweden)

    Karuna Subramaniam

    2015-01-01

    Full Text Available Amotivation in schizophrenia is a central predictor of poor functioning, and is thought to occur due to deficits in anticipating future rewards, suggesting that impairments in anticipating pleasure can contribute to functional disability in schizophrenia. In healthy comparison (HC participants, reward anticipation is associated with activity in frontal–striatal networks. By contrast, schizophrenia (SZ participants show hypoactivation within these frontal–striatal networks during this motivated anticipatory brain state. Here, we examined neural activation in SZ and HC participants during the anticipatory phase of stimuli that predicted immediate upcoming reward and punishment, and during the feedback/outcome phase, in relation to trait measures of hedonic pleasure and real-world functional capacity. SZ patients showed hypoactivation in ventral striatum during reward anticipation. Additionally, we found distinct differences between HC and SZ groups in their association between reward-related immediate anticipatory neural activity and their reported experience of pleasure. HC participants recruited reward-related regions in striatum that significantly correlated with subjective consummatory pleasure, while SZ patients revealed activation in attention-related regions, such as the IPL, which correlated with consummatory pleasure and functional capacity. These findings may suggest that SZ patients activate compensatory attention processes during anticipation of immediate upcoming rewards, which likely contribute to their functional capacity in daily life.

  16. Reward sensitivity is associated with brain activity during erotic stimulus processing.

    Directory of Open Access Journals (Sweden)

    Victor Costumero

    Full Text Available The behavioral approach system (BAS from Gray's reinforcement sensitivity theory is a neurobehavioral system involved in the processing of rewarding stimuli that has been related to dopaminergic brain areas. Gray's theory hypothesizes that the functioning of reward brain areas is modulated by BAS-related traits. To test this hypothesis, we performed an fMRI study where participants viewed erotic and neutral pictures, and cues that predicted their appearance. Forty-five heterosexual men completed the Sensitivity to Reward scale (from the Sensitivity to Punishment and Sensitivity to Reward Questionnaire to measure BAS-related traits. Results showed that Sensitivity to Reward scores correlated positively with brain activity during reactivity to erotic pictures in the left orbitofrontal cortex, left insula, and right ventral striatum. These results demonstrated a relationship between the BAS and reward sensitivity during the processing of erotic stimuli, filling the gap of previous reports that identified the dopaminergic system as a neural substrate for the BAS during the processing of other rewarding stimuli such as money and food.

  17. Chromatic aberration measurement for transmission interferometric testing.

    Science.gov (United States)

    Seong, Kibyung; Greivenkamp, John E

    2008-12-10

    A method of chromatic aberration measurement is described based on the transmitted wavefront of an optical element obtained from a Mach-Zehnder interferometer. The chromatic aberration is derived from transmitted wavefronts measured at five different wavelengths. Reverse ray tracing is used to remove induced aberrations associated with the interferometer from the measurement. In the interferometer, the wavefront transmitted through the sample is tested against a plano reference, allowing for the absolute determination of the wavefront radius of curvature. The chromatic aberrations of a singlet and a doublet have been measured.

  18. Video Game Training and the Reward System

    Directory of Open Access Journals (Sweden)

    Robert C. Lorenz

    2015-02-01

    Full Text Available Video games contain elaborate reinforcement and reward schedules that have the potential to maximize motivation. Neuroimaging studies suggest that video games might have an influence on the reward system. However, it is not clear whether reward-related properties represent a precondition, which biases an individual towards playing video games, or if these changes are the result of playing video games. Therefore, we conducted a longitudinal study to explore reward-related functional predictors in relation to video gaming experience as well as functional changes in the brain in response to video game training.Fifty healthy participants were randomly assigned to a video game training (TG or control group (CG. Before and after training/control period, functional magnetic resonance imaging (fMRI was conducted using a non-video game related reward task.At pretest, both groups showed strongest activation in ventral striatum (VS during reward anticipation. At posttest, the TG showed very similar VS activity compared to pretest. In the CG, the VS activity was significantly attenuated.This longitudinal study revealed that video game training may preserve reward responsiveness in the ventral striatum in a retest situation over time. We suggest that video games are able to keep striatal responses to reward flexible, a mechanism which might be of critical value for applications such as therapeutic cognitive training.

  19. Performance-Based Rewards and Work Stress

    Science.gov (United States)

    Ganster, Daniel C.; Kiersch, Christa E.; Marsh, Rachel E.; Bowen, Angela

    2011-01-01

    Even though reward systems play a central role in the management of organizations, their impact on stress and the well-being of workers is not well understood. We review the literature linking performance-based reward systems to various indicators of employee stress and well-being. Well-controlled experiments in field settings suggest that certain…

  20. Reward Magnitude Effects on Temporal Discrimination

    Science.gov (United States)

    Galtress, Tiffany; Kirkpatrick, Kimberly

    2010-01-01

    Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment…

  1. Status Characteristics, Reward Allocation, and Equity

    Science.gov (United States)

    Parcel, Toby L.; Cook, Karen S.

    1977-01-01

    The relationship between a group's power and prestige or status hierarchy and group members' patterns of reward allocation was investigated. The addition of evidence concerning actual task performance results in the alignment of reward and status rankings and encourages the use of distribution rules stressing equity as opposed to equality.…

  2. The Risks and Rewards of Sexual Debut

    Science.gov (United States)

    Golden, Rachel Lynn; Furman, Wyndol; Collibee, Charlene

    2016-01-01

    The sex-positive framework of sexual development hypothesizes that healthy sexual experiences can be developmentally appropriate and rewarding for adolescents despite the risks involved. Research has not examined whether risky behaviors and rewarding cognitions actually change with sexual debut at a normative or late age. This study measured the…

  3. Modelling and analysis of Markov reward automata

    NARCIS (Netherlands)

    Guck, Dennis; Timmer, Mark; Hatefi, Hassan; Ruijters, Enno; Stoelinga, Mariëlle

    2014-01-01

    Costs and rewards are important ingredients for many types of systems, modelling critical aspects like energy consumption, task completion, repair costs, and memory usage. This paper introduces Markov reward automata, an extension of Markov automata that allows the modelling of systems incorporating

  4. Resource Allocation Problems with Concave Reward Functions

    NARCIS (Netherlands)

    Grundel, S.; Borm, P.E.M.; Hamers, H.J.M.

    2013-01-01

    Abstract: In a resource allocation problem there is a common-pool resource, which has to be divided among agents. Each agent is characterized by a claim on this pool and an individual concave reward function on assigned resources. An assignment of resources is optimal if the total joint reward is ma

  5. Video game training and the reward system.

    Science.gov (United States)

    Lorenz, Robert C; Gleich, Tobias; Gallinat, Jürgen; Kühn, Simone

    2015-01-01

    Video games contain elaborate reinforcement and reward schedules that have the potential to maximize motivation. Neuroimaging studies suggest that video games might have an influence on the reward system. However, it is not clear whether reward-related properties represent a precondition, which biases an individual toward playing video games, or if these changes are the result of playing video games. Therefore, we conducted a longitudinal study to explore reward-related functional predictors in relation to video gaming experience as well as functional changes in the brain in response to video game training. Fifty healthy participants were randomly assigned to a video game training (TG) or control group (CG). Before and after training/control period, functional magnetic resonance imaging (fMRI) was conducted using a non-video game related reward task. At pretest, both groups showed strongest activation in ventral striatum (VS) during reward anticipation. At posttest, the TG showed very similar VS activity compared to pretest. In the CG, the VS activity was significantly attenuated. This longitudinal study revealed that video game training may preserve reward responsiveness in the VS in a retest situation over time. We suggest that video games are able to keep striatal responses to reward flexible, a mechanism which might be of critical value for applications such as therapeutic cognitive training.

  6. Self-rewards and personal motivation

    DEFF Research Database (Denmark)

    Koch, Alexander Karl; Nafziger, Julia; Suvorov, Anton

    2014-01-01

    Self-administered rewards are ubiquitous. They serve as incentives for personal accomplishments and are widely recommended to increase personal motivation. We show that in a model with time-inconsistent and reference-dependent preferences, self-rewards can be a credible and effective tool to over...

  7. Self-Rewards and Personal Motivation

    DEFF Research Database (Denmark)

    Koch, Alexander Karl; Nafziger, Julia; Suvorov, Anton

    Self-administered rewards are ubiquitous. They serve as incentives for personal accomplishments and are widely recommended to increase personal motivation. We show that in a model with time-inconsistent and reference-dependent preferences, self-rewards can be a credible and effective tool to over...

  8. Effects of Extrinsic Rewards on Intrinsic Motivation in the Classroom.

    Science.gov (United States)

    Workman, Edward A.; Williams, Robert L.

    1980-01-01

    Reviews classroom behavior management studies to see if extrinsic rewards affect intrinsic reinforcement value of appropriate classroom behaviors. Conclusion indicates extrinsic rewards are useful. Teachers need not avoid the use of rewards in fear of undermining intrinsic interest. (LAB)

  9. Electrophysiological ratio markers for the balance between reward and punishment.

    Science.gov (United States)

    Schutter, Dennis J L G; Van Honk, Jack

    2005-08-01

    It has been argued that prototypical forms of psychopathology result from an imbalance in reward and punishment systems. Recent studies suggest that the ratios between slower and faster waves of the electroencephalogram (EEG) index this motivational balance and might therefore have diagnostic value for psychopathology. To scrutinize this notion, the present study investigated whether resting state EEG ratios would predict decision making on the Iowa gambling task (Iowa-GT), a well-known marker for motivational imbalance. A resting state EEG recording was acquired followed by the Iowa-GT in twenty-eight healthy right-handed volunteers. Results showed that higher versus lower EEG ratios were associated with disadvantageous versus advantageous decision making strategies indicating motivational imbalances in reward- and punishment-driven behavior, respectively. This finding provides the first direct evidence that the electrophysiologically derived EEG ratios can serve as biological markers for balance and imbalance in motivation.

  10. Serotonergic modulation of reward and punishment

    DEFF Research Database (Denmark)

    Macoveanu, Julian

    2014-01-01

    Until recently, the bulk of research on the human reward system was focused on studying the dopaminergic and opioid neurotransmitter systems. However, extending the initial data from animal studies on reward, recent pharmacological brain imaging studies on human participants bring a new line...... of evidence on the key role serotonin plays in reward processing. The reviewed research has revealed how central serotonin availability and receptor specific transmission modulates the neural response to both appetitive (rewarding) and aversive (punishing) stimuli in putative reward-related brain regions......-related processing and may also provide a neural correlated for the emotional blunting observed in the clinical treatment of psychiatric disorders with selective serotonin reuptake inhibitors. Given the unique profile of action of each serotonergic receptor subtype, future pharmacological studies may favor receptor...

  11. Artificial neural network for the determination of Hubble Space Telescope aberration from stellar images

    Science.gov (United States)

    Barrett, Todd K.; Sandler, David G.

    1993-01-01

    An artificial-neural-network method, first developed for the measurement and control of atmospheric phase distortion, using stellar images, was used to estimate the optical aberration of the Hubble Space Telescope. A total of 26 estimates of distortion was obtained from 23 stellar images acquired at several secondary-mirror axial positions. The results were expressed as coefficients of eight orthogonal Zernike polynomials: focus through third-order spherical. For all modes other than spherical the measured aberration was small. The average spherical aberration of the estimates was -0.299 micron rms, which is in good agreement with predictions obtained when iterative phase-retrieval algorithms were used.

  12. Aberrations of Gradient-Index Lenses.

    Science.gov (United States)

    Matthews, A. L.

    Available from UMI in association with The British Library. In this thesis, the primary aberrations of lenses with a radial focussing gradient-of-index are analysed. Such a lens has a refractive index profile which decreases continuously and radially outward from the optical axis, so that the surfaces of constant refractive index are circular cylinders which are coaxial with the optical axis. Current applications of these lenses include photocopiers, medical endoscopes, telecommunications systems and compact disc systems. Closed formulae for the primary wavefront aberrations for a gradient-index lens with curved or plane entry and exit faces are obtained from the differential equations of such a lens to assess the primary transverse ray aberrations that it introduces. Identical expressions are then obtained by using the difference in optical path length produced between two rays by the lens. This duplication of the derivations of the primary wavefront aberrations acts as a confirmation of the validity of the expressions. One advantage of these equations is that the contributions due to the primary spherical aberration, coma, astigmatism, field curvature and distortion can be assessed individually. A Fortran 77 program has been written to calculate each of these individual contributions, the total primary wavefront aberrations and the primary transverse ray aberrations. Further confirmation of the validity of the expressions is obtained by using this program to show that the coma and distortion were both zero for fully symmetric systems working at unit magnification. The program is then used to assess the primary wavefront aberrations for a gradient-index lens which is currently of interest to the telecommunications industry. These results are compared with values obtained using a finite ray-tracing program for the total wavefront aberrations. This shows that the primary wavefront aberrations are the completely dominant contribution to the total wavefront

  13. Reward sensitivity and food addiction in women.

    Science.gov (United States)

    Loxton, Natalie J; Tipman, Renée J

    2016-10-15

    Sensitivity to the rewarding properties of appetitive substances has long been implicated in excessive consumption of palatable foods and drugs of abuse. Previous research focusing on individual differences in reward responsiveness has found heightened trait reward sensitivity to be associated with binge-eating, hazardous drinking, and illicit substance use. Food addiction has been proposed as an extreme form of compulsive-overeating and has been associated with genetic markers of heightened reward responsiveness. However, little research has explicitly examined the association between reward sensitivity and food addiction. Further, the processes by which individual differences in this trait are associated with excessive over-consumption has not been determined. A total of 374 women from the community completed an online questionnaire assessing reward sensitivity, food addiction, emotional, externally-driven, and hedonic eating. High reward sensitivity was significantly associated with greater food addiction symptoms (r = 0.31). Bootstrapped tests of indirect effects found the relationship between reward sensitivity and food addiction symptom count to be uniquely mediated by binge-eating, emotional eating, and hedonic eating (notably, food availability). These indirect effects held even when controlling for BMI, anxiety, depression, and trait impulsivity. This study further supports the argument that high levels of reward sensitivity may offer a trait marker of vulnerability to excessive over-eating, beyond negative affect and impulse-control deficits. That the hedonic properties of food (especially food availability), emotional, and binge-eating behavior act as unique mediators suggest that interventions for reward-sensitive women presenting with food addiction may benefit from targeting food availability in addition to management of negative affect.

  14. Touch massage, a rewarding experience.

    Science.gov (United States)

    Lindgren, Lenita; Jacobsson, Maritha; Lämås, Kristina

    2014-12-01

    This study aims to describe and analyze healthy individuals' expressed experiences of touch massage (TM). Fifteen healthy participants received whole body touch massage during 60 minutes for two separate occasions. Interviews were analyzed by narrative analysis. Four identifiable storyline was found, Touch massage as an essential need, in this storyline the participants talked about a desire and need for human touch and TM. Another storyline was about, Touch massage as a pleasurable experience and the participants talked about the pleasure of having had TM. In the third storyline Touch massage as a dynamic experience, the informants talked about things that could modulate the experience of receiving TM. In the last storyline, Touch massage influences self-awareness, the participants described how TM affected some of their psychological and physical experiences. Experiences of touch massage was in general described as pleasant sensations and the different storylines could be seen in the light of rewarding experiences.

  15. Floral reward in Ranunculaceae species

    Directory of Open Access Journals (Sweden)

    Bożena Denisow

    2016-04-01

    Full Text Available Floral reward is important in ecological and evolutionary perspectives and essential in pollination biology. For example, floral traits, nectar and pollen features are essential for understanding the functional ecology, the dynamics of pollen transport, competition for pollinator services, and patterns of specialization and generalization in plant–pollinator interactions. We believe to present a synthetic description in the field of floral reward in Ranunculaceae family important in pollination biology and indicating connections between ecological and evolutionary approaches. The links between insect visitors’ behaviour and floral reward type and characteristics exist. Ranunculaceae is a family of aboot 1700 species (aboot 60 genera, distributed worldwide, however the most abundant representatives are in temperate and cool regions of the northern and southern hemispheres. The flowers are usually radially symmetric (zygomorphic and bisexual, but in Aconitum, Aquilegia are bilaterally symmetric (zygomorphic. Most Ranunculaceae flowers offer no nectar, only pollen (e.g., Ranunculus, Adonis vernalis, Thalictrum, but numerous species create trophic niches for different wild pollinators (e.g. Osmia, Megachile, Bombus, Andrena (Denisow et al. 2008. Pollen is a source of protein, vitamins, mineral salts, organic acids and hormones, but the nutritional value varies greatly between different plant species. The pollen production can differ significantly between Ranunculacea species. The mass of pollen produced in anthers differ due to variations in the number of developed anthers. For example, interspecies differences are considerable, 49 anthers are noted in Aquilegia vulgaris, 70 anthers in Ranunculus lanuginosus, 120 in Adonis vernalis. A significant intra-species differences’ in the number of anthers are also noted (e.g. 41 to 61 in Aquilegia vulgaris, 23-45 in Ranunculus cassubicus. Pollen production can be up to 62 kg per ha for Ranunculus acer

  16. Modulation of impulsivity and reward sensitivity in intertemporal choice by striatal and midbrain dopamine synthesis in healthy adults.

    Science.gov (United States)

    Smith, Christopher T; Wallace, Deanna L; Dang, Linh C; Aarts, Esther; Jagust, William J; D'Esposito, Mark; Boettiger, Charlotte A

    2016-03-01

    Converging evidence links individual differences in mesolimbic and mesocortical dopamine (DA) to variation in the tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or "Now bias." However, to date, no study of healthy young adults has evaluated the relationship between Now bias and DA with positron emission tomography (PET). Sixteen healthy adults (ages 24-34 yr; 50% women) completed a delay-discounting task that quantified aspects of intertemporal reward choice, including Now bias and reward magnitude sensitivity. Participants also underwent PET scanning with 6-[(18)F]fluoro-l-m-tyrosine (FMT), a radiotracer that measures DA synthesis capacity. Lower putamen FMT signal predicted elevated Now bias, a more rapidly declining discount rate with increasing delay time, and reduced willingness to accept low-interest-rate delayed rewards. In contrast, lower FMT signal in the midbrain predicted greater sensitivity to increasing magnitude of the Later reward. These data demonstrate that intertemporal reward choice in healthy humans varies with region-specific measures of DA processing, with regionally distinct associations with sensitivity to delay and to reward magnitude.

  17. Individual differences in the time course of reward processing: Stage-specific links with depression and impulsivity.

    Science.gov (United States)

    Novak, Brittni K; Novak, Keisha D; Lynam, Donald R; Foti, Dan

    2016-09-01

    Reward dysfunction has been implicated in a wide range of psychological disorders, including internalizing and externalizing psychopathology. Basic neuroscience research has shown that reward is a multistage process, yet it is unclear how specific stages relate to individual differences in reward sensitivity. The current study utilized event-related potentials elicited during a monetary incentive task to parse sub-stages within anticipatory and consummatory reward processing. Effects of depressive symptoms and trait impulsivity were examined at each sub-stage (N=92). Reward anticipation modulated neural activity across three sub-stages: cue detection (cue-P3), approach behavior (contingent negative variation, CNV), and outcome anticipation (stimulus preceding negativity). Reward delivery modulated activity across two sub-stages: initial evaluation (reward positivity, RewP), and allocation of attention (feedback-P3). Sensation seeking predicted faster reaction times, as well as cue-P3 and RewP amplitudes. Depression and lack of premeditation interacted to predict CNV and RewP amplitudes. Results demonstrate that individual differences in reward functioning are stage-specific.

  18. Quantifying individual variation in the propensity to attribute incentive salience to reward cues.

    Science.gov (United States)

    Meyer, Paul J; Lovic, Vedran; Saunders, Benjamin T; Yager, Lindsay M; Flagel, Shelly B; Morrow, Jonathan D; Robinson, Terry E

    2012-01-01

    If reward-associated cues acquire the properties of incentive stimuli they can come to powerfully control behavior, and potentially promote maladaptive behavior. Pavlovian incentive stimuli are defined as stimuli that have three fundamental properties: they are attractive, they are themselves desired, and they can spur instrumental actions. We have found, however, that there is considerable individual variation in the extent to which animals attribute Pavlovian incentive motivational properties ("incentive salience") to reward cues. The purpose of this paper was to develop criteria for identifying and classifying individuals based on their propensity to attribute incentive salience to reward cues. To do this, we conducted a meta-analysis of a large sample of rats (N = 1,878) subjected to a classic Pavlovian conditioning procedure. We then used the propensity of animals to approach a cue predictive of reward (one index of the extent to which the cue was attributed with incentive salience), to characterize two behavioral phenotypes in this population: animals that approached the cue ("sign-trackers") vs. others that approached the location of reward delivery ("goal-trackers"). This variation in Pavlovian approach behavior predicted other behavioral indices of the propensity to attribute incentive salience to reward cues. Thus, the procedures reported here should be useful for making comparisons across studies and for assessing individual variation in incentive salience attribution in small samples of the population, or even for classifying single animals.

  19. Quantifying individual variation in the propensity to attribute incentive salience to reward cues.

    Directory of Open Access Journals (Sweden)

    Paul J Meyer

    Full Text Available If reward-associated cues acquire the properties of incentive stimuli they can come to powerfully control behavior, and potentially promote maladaptive behavior. Pavlovian incentive stimuli are defined as stimuli that have three fundamental properties: they are attractive, they are themselves desired, and they can spur instrumental actions. We have found, however, that there is considerable individual variation in the extent to which animals attribute Pavlovian incentive motivational properties ("incentive salience" to reward cues. The purpose of this paper was to develop criteria for identifying and classifying individuals based on their propensity to attribute incentive salience to reward cues. To do this, we conducted a meta-analysis of a large sample of rats (N = 1,878 subjected to a classic Pavlovian conditioning procedure. We then used the propensity of animals to approach a cue predictive of reward (one index of the extent to which the cue was attributed with incentive salience, to characterize two behavioral phenotypes in this population: animals that approached the cue ("sign-trackers" vs. others that approached the location of reward delivery ("goal-trackers". This variation in Pavlovian approach behavior predicted other behavioral indices of the propensity to attribute incentive salience to reward cues. Thus, the procedures reported here should be useful for making comparisons across studies and for assessing individual variation in incentive salience attribution in small samples of the population, or even for classifying single animals.

  20. Midbrain dopamine neurons signal aversion in a reward-context-dependent manner

    Science.gov (United States)

    Matsumoto, Hideyuki; Tian, Ju; Uchida, Naoshige; Watabe-Uchida, Mitsuko

    2016-01-01

    Dopamine is thought to regulate learning from appetitive and aversive events. Here we examined how optogenetically-identified dopamine neurons in the lateral ventral tegmental area of mice respond to aversive events in different conditions. In low reward contexts, most dopamine neurons were exclusively inhibited by aversive events, and expectation reduced dopamine neurons’ responses to reward and punishment. When a single odor predicted both reward and punishment, dopamine neurons’ responses to that odor reflected the integrated value of both outcomes. Thus, in low reward contexts, dopamine neurons signal value prediction errors (VPEs) integrating information about both reward and aversion in a common currency. In contrast, in high reward contexts, dopamine neurons acquired a short-latency excitation to aversive events that masked their VPE signaling. Our results demonstrate the importance of considering the contexts to examine the representation in dopamine neurons and uncover different modes of dopamine signaling, each of which may be adaptive for different environments. DOI: http://dx.doi.org/10.7554/eLife.17328.001 PMID:27760002

  1. Low cortisol levels and the balance between punishment sensitivity and reward dependency.

    Science.gov (United States)

    van Honk, Jack; Schutter, Dennis J L G; Hermans, Erno J; Putman, Peter

    2003-10-27

    The neuro-endocrinological basis of psychopathy, a disorder characterized by lack of fear, is relatively unknown. However, low levels of cortisol may result in fearlessness and have been observed in individuals with psychopathic tendencies. Low fear models state that psychopaths are not motivated to avoid punishment, especially when reward is pending. In agreement, disadvantageous decision making on the IOWA gambling task in psychopaths and psychopathic analogous, indicates low punishment sensitivity and high reward dependency. Here, it was investigated whether low basal cortisol levels predicted the balance between punishment sensitivity and reward dependency in the same manner. As hypothesized, the most disadvantageous pattern of decision making was found in the subjects with the lowest cortisol levels. These findings suggest that low levels of cortisol may set the balance between the sensitivity for punishment and reward dependency towards a pre-disposition for psychopathy.

  2. Reward, dopamine and the control of food intake: implications for obesity

    Energy Technology Data Exchange (ETDEWEB)

    Volkow N. D.; Wang G.; Volkow, N.D.; Wang, G.-J.; Baler, R.D.

    2011-10-01

    The ability to resist the urge to eat requires the proper functioning of neuronal circuits involved in top-down control to oppose the conditioned responses that predict reward from eating the food and the desire to eat the food. Imaging studies show that obese subjects might have impairments in dopaminergic pathways that regulate neuronal systems associated with reward sensitivity, conditioning and control. It is known that the neuropeptides that regulate energy balance (homeostatic processes) through the hypothalamus also modulate the activity of dopamine cells and their projections into regions involved in the rewarding processes underlying food intake. It is postulated that this could also be a mechanism by which overeating and the resultant resistance to homoeostatic signals impairs the function of circuits involved in reward sensitivity, conditioning and cognitive control.

  3. Planning activity for internally generated reward goals in monkey amygdala neurons.

    Science.gov (United States)

    Hernádi, István; Grabenhorst, Fabian; Schultz, Wolfram

    2015-03-01

    The best rewards are often distant and can only be achieved by planning and decision-making over several steps. We designed a multi-step choice task in which monkeys followed internal plans to save rewards toward self-defined goals. During this self-controlled behavior, amygdala neurons showed future-oriented activity that reflected the animal's plan to obtain specific rewards several trials ahead. This prospective activity encoded crucial components of the animal's plan, including value and length of the planned choice sequence. It began on initial trials when a plan would be formed, reappeared step by step until reward receipt, and readily updated with a new sequence. It predicted performance, including errors, and typically disappeared during instructed behavior. Such prospective activity could underlie the formation and pursuit of internal plans characteristic of goal-directed behavior. The existence of neuronal planning activity in the amygdala suggests that this structure is important in guiding behavior toward internally generated, distant goals.

  4. Intense sweetness surpasses cocaine reward.

    Directory of Open Access Journals (Sweden)

    Magalie Lenoir

    Full Text Available BACKGROUND: Refined sugars (e.g., sucrose, fructose were absent in the diet of most people until very recently in human history. Today overconsumption of diets rich in sugars contributes together with other factors to drive the current obesity epidemic. Overconsumption of sugar-dense foods or beverages is initially motivated by the pleasure of sweet taste and is often compared to drug addiction. Though there are many biological commonalities between sweetened diets and drugs of abuse, the addictive potential of the former relative to the latter is currently unknown. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that when rats were allowed to choose mutually-exclusively between water sweetened with saccharin-an intense calorie-free sweetener-and intravenous cocaine-a highly addictive and harmful substance-the large majority of animals (94% preferred the sweet taste of saccharin. The preference for saccharin was not attributable to its unnatural ability to induce sweetness without calories because the same preference was also observed with sucrose, a natural sugar. Finally, the preference for saccharin was not surmountable by increasing doses of cocaine and was observed despite either cocaine intoxication, sensitization or intake escalation-the latter being a hallmark of drug addiction. CONCLUSIONS: Our findings clearly demonstrate that intense sweetness can surpass cocaine reward, even in drug-sensitized and -addicted individuals. We speculate that the addictive potential of intense sweetness results from an inborn hypersensitivity to sweet tastants. In most mammals, including rats and humans, sweet receptors evolved in ancestral environments poor in sugars and are thus not adapted to high concentrations of sweet tastants. The supranormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a supranormal reward signal in the brain, with the potential to override self

  5. Reward Experience, Socioeconomic Status, and Sex: Exploring Parameters of the Overjustification Effect.

    Science.gov (United States)

    Schilling, Deanna E.

    The overjustification hypothesis predicts decreased intrinsic motivation when persons are paid to perform an interesting task. The factors of reward experience, socioeconomic status (SES), and sex are examined while testing conflicting predictions of the hypothesis and reinforcement theory. Children from grade 1 at two public elementary schools…

  6. Aberration coefficients of curved holographic optical elements

    Science.gov (United States)

    Verboven, P. E.; Lagasse, P. E.

    1986-11-01

    A general formula is derived that gives all aberration terms of holographic optical elements on substrates of any shape. The spherical substrate shape and the planar substrate shape are treated as important special cases. A numerical example illustrates the need of including higher-order aberrations.

  7. Psychometric Characteristics of the Aberrant Behavior Checklist.

    Science.gov (United States)

    Aman, Michael G.; And Others

    1985-01-01

    Information is presented on the psychometric characteristics of the Aberrant Behavior Checklist, a measure of psychotropic drug effects. Internal consistency and test-retest reliability of the checklist appeared very good. Interrater reliability was generally in the moderate range. In general, validity was established for most Aberrant Behavior…

  8. Higher-Order Aberrations in Myopic Eyes

    Directory of Open Access Journals (Sweden)

    Farid Karimian

    2010-01-01

    Full Text Available Purpose: To evaluate the correlation between refractive error and higher-order aberrations (HOAs in patients with myopic astigmatism. Methods: HOAs were measured using the Zywave II aberrometer over a 6 mm pupil. Correlations between HOAs and myopia, astigmatism, and age were analyzed. Results: One hundred and twenty-six eyes of 63 subjects with mean age of 26.4±5.9 years were studied. Mean spherical equivalent refractive error and refractive astigmatism were -4.94±1.63 D and 0.96±1.06 D, respectively. The most common higher-order aberration was primary horizontal trefoil with mean value of 0.069±0.152 μm followed by spherical aberration (-0.064±0.130 μm and primary vertical coma (-0.038±0.148 μm. As the order of aberration increased from third to fifth, its contribution to total HOA decreased: 53.9% for third order, 31.9% for fourth order, and 14.2% for fifth order aberrations. Significant correlations were observed between spherical equivalent refractive error and primary horizontal coma (R=0.231, P=0.022, and root mean square (RMS of spherical aberration (R=0.213, P=0.031; between astigmatism and RMS of total HOA (R=0.251, P=0.032, RMS of fourth order aberration (R=0.35, P<0.001, and primary horizontal coma (R=0.314, P=0.004. Spherical aberration (R=0.214, P=0.034 and secondary vertical coma (R=0.203, P=0.031 significantly increased with age. Conclusion: Primary horizontal trefoil, spherical aberration and primary vertical coma are the predominant higher-order aberrations in eyes with myopic astigmatism.

  9. Prosocial reward learning in children and adolescents

    Directory of Open Access Journals (Sweden)

    Youngbin Kwak

    2016-10-01

    Full Text Available Adolescence is a period of increased sensitivity to social contexts. To evaluate how social context sensitivity changes over development – and influences reward learning – we investigated how children and adolescents perceive and integrate rewards for oneself and others during a dynamic risky-decision-making task. Children and adolescents (N=75, 8-16 yrs performed the Social Gambling Task (SGT, (Kwak et al., 2014 and completed a set of questionnaires measuring other-regarding behavior. In the SGT, participants choose amongst four card decks that have different payout structures for oneself and for a charity. We examined patterns of choices, overall decision strategies, and how reward outcomes led to trial-by-trial adjustments in behavior, as estimated using a reinforcement-learning model. Performance of children and adolescents was compared to data from a previously collected sample of adults (N=102 performing the identical task. We found that that children/adolescents were not only more sensitive to rewards directed to the charity than self but also showed greater prosocial tendencies on independent measures of other-regarding behavior. Children and adolescents also showed less use of a strategy that prioritizes rewards for self at the expense of rewards for others. These results support the conclusion that, compared to adults, children and adolescents show greater sensitivity to outcomes for others when making decisions and learning about potential rewards.

  10. Acute stress selectively reduces reward sensitivity

    Directory of Open Access Journals (Sweden)

    Lisa H Berghorst

    2013-04-01

    Full Text Available Stress may promote the onset of psychopathology by disrupting reward processing. However, the extent to which stress impairs reward processing, rather than incentive processing more generally, is unclear. To evaluate the specificity of stress-induced reward processing disruption, 100 psychiatrically healthy females were administered a probabilistic stimulus selection task enabling comparison of sensitivity to reward-driven (Go and punishment-driven (NoGo learning under either ‘no stress’ or ‘stress’ (threat-of-shock conditions. Cortisol samples and self-report measures were collected. Contrary to hypotheses, the groups did not differ significantly in task performance or cortisol reactivity. However, further analyses focusing only on individuals under ‘stress’ who were high responders with regard to both cortisol reactivity and self-reported negative affect revealed reduced reward sensitivity relative to individuals tested in the ‘no stress’ condition; importantly, these deficits were reward-specific. Overall, findings provide preliminary evidence that stress-reactive individuals show diminished sensitivity to reward but not punishment under stress. While such results highlight the possibility that stress-induced anhedonia might be an important mechanism linking stress to affective disorders, future studies are necessary to confirm this conjecture.

  11. Reinforcement Learning by Comparing Immediate Reward

    CERN Document Server

    Pandey, Punit; Kumar, Shishir

    2010-01-01

    This paper introduces an approach to Reinforcement Learning Algorithm by comparing their immediate rewards using a variation of Q-Learning algorithm. Unlike the conventional Q-Learning, the proposed algorithm compares current reward with immediate reward of past move and work accordingly. Relative reward based Q-learning is an approach towards interactive learning. Q-Learning is a model free reinforcement learning method that used to learn the agents. It is observed that under normal circumstances algorithm take more episodes to reach optimal Q-value due to its normal reward or sometime negative reward. In this new form of algorithm agents select only those actions which have a higher immediate reward signal in comparison to previous one. The contribution of this article is the presentation of new Q-Learning Algorithm in order to maximize the performance of algorithm and reduce the number of episode required to reach optimal Q-value. Effectiveness of proposed algorithm is simulated in a 20 x20 Grid world dete...

  12. Detection of epigenetic aberrations in the development of hepatocellular carcinoma.

    Science.gov (United States)

    Zhang, Yujing

    2015-01-01

    Hepatocellular carcinoma (HCC) is the third most common cause of cancer death worldwide. Hepatocarcinogenesis is a complex, multistep process. It is now recognized that HCC is a both genetic and epigenetic disease; genetic and epigenetic components cooperate at all stages of hepatocarcinogenesis. Epigenetic changes involve aberrant DNA methylation, posttranslational histone modifications and aberrant expression of microRNAs all of which can affect the expression of oncogenes, tumor suppressor genes and other tumor-related genes and alter the pathways in cancer development. Several risk factors for HCC, including hepatitis B and C virus infections and exposure to the chemical carcinogen aflatoxin B1 have been found to influence epigenetic changes. Their interactions could play an important role in the initiation and progression of HCC. Discovery and detection of biomarkers for epigenetic changes is a promising area for early diagnosis and risk prediction of HCC.

  13. Endocannabinoid signalling in reward and addiction.

    Science.gov (United States)

    Parsons, Loren H; Hurd, Yasmin L

    2015-10-01

    Brain endocannabinoid (eCB) signalling influences the motivation for natural rewards (such as palatable food, sexual activity and social interaction) and modulates the rewarding effects of addictive drugs. Pathological forms of natural and drug-induced reward are associated with dysregulated eCB signalling that may derive from pre-existing genetic factors or from prolonged drug exposure. Impaired eCB signalling contributes to dysregulated synaptic plasticity, increased stress responsivity, negative emotional states and cravings that propel addiction. Understanding the contributions of eCB disruptions to behavioural and physiological traits provides insight into the eCB influence on addiction vulnerability.

  14. Forebrain substrates of reward and motivation.

    Science.gov (United States)

    Wise, Roy A

    2005-12-01

    Electrical stimulation of the medial forebrain bundle can reward arbitrary acts or motivate biologically primitive, species-typical behaviors like feeding or copulation. The subsystems involved in these behaviors are only partially characterized, but they appear to transsynaptically activate the mesocorticolimbic dopamine system. Basal function of the dopamine system is essential for arousal and motor function; phasic activation of this system is rewarding and can potentiate the effectiveness of reward-predictors that guide learned behaviors. This system is phasically activated by most drugs of abuse and such activation contributes to the habit-forming actions of these drugs.

  15. Adverse health effects of high-effort/low-reward conditions.

    Science.gov (United States)

    Siegrist, J

    1996-01-01

    In addition to the person-environment fit model (J. R. French, R. D. Caplan, & R. V. Harrison, 1982) and the demand-control model (R. A. Karasek & T. Theorell, 1990), a third theoretical concept is proposed to assess adverse health effects of stressful experience at work: the effort-reward imbalance model. The focus of this model is on reciprocity of exchange in occupational life where high-cost/low-gain conditions are considered particularly stressful. Variables measuring low reward in terms of low status control (e.g., lack of promotion prospects, job insecurity) in association with high extrinsic (e.g., work pressure) or intrinsic (personal coping pattern, e.g., high need for control) effort independently predict new cardiovascular events in a prospective study on blue-collar men. Furthermore, these variables partly explain prevalence of cardiovascular risk factors (hypertension, atherogenic lipids) in 2 independent studies. Studying adverse health effects of high-effort/low-reward conditions seems well justified, especially in view of recent developments of the labor market.

  16. Analysis of the Aberration in Directly-writing Atom Lithography

    Institute of Scientific and Technical Information of China (English)

    LI Chuanwen; CAI Weiquan; WANG Yuzhu

    2000-01-01

    After deriving the approximation solution which describes the motion of neutral atoms in an optical standing wave field with large detuning, the spherical aberration and the chromatic aberration are analyzed and possible methods to reduce these aberrations are discussed.

  17. Epigenetic aberrations and therapeutic implications in gliomas.

    Science.gov (United States)

    Natsume, Atsushi; Kondo, Yutaka; Ito, Motokazu; Motomura, Kazuya; Wakabayashi, Toshihiko; Yoshida, Jun

    2010-06-01

    Almost all cancer cells have multiple epigenetic abnormalities, which combine with genetic changes to affect many cellular processes, including cell proliferation and invasion, by silencing tumor-suppressor genes. In this review, we focus on the epigenetic mechanisms of DNA hypomethylation and CpG island hypermethylation in gliomas. Aberrant hypermethylation in promoter CpG islands has been recognized as a key mechanism involved in the silencing of cancer-associated genes and occurs at genes with diverse functions related to tumorigenesis and tumor progression. Such promoter hypermethylation can modulate the sensitivity of glioblastomas to drugs and radiotherapy. As an example, the methylation of the O6-methylguanine DNA methyltransferase (MGMT) promoter is a specific predictive biomarker of tumor responsiveness to chemotherapy with alkylating agents. Further, we reviewed reports on pyrosequencing - a simple technique for the accurate and quantitative analysis of DNA methylation. We believe that the quantification of MGMT methylation by pyrosequencing might enable the selection of patients who are most likely to benefit from chemotherapy. Finally, we also evaluated the potential of de novo NY-ESO-1, the most immunogenic cancer/testis antigen (CTA) discovered thus far, as an immunotherapy target. The use of potent epigenetics-based therapy for cancer cells might restore the abnormally regulated epigenomes to a more normal state through epigenetic reprogramming. Thus, epigenetic therapy may be a promising and potent treatment for human neoplasia.

  18. State-based versus reward-based motivation in younger and older adults.

    Science.gov (United States)

    Worthy, Darrell A; Cooper, Jessica A; Byrne, Kaileigh A; Gorlick, Marissa A; Maddox, W Todd

    2014-12-01

    Recent decision-making work has focused on a distinction between a habitual, model-free neural system that is motivated toward actions that lead directly to reward and a more computationally demanding goal-directed, model-based system that is motivated toward actions that improve one's future state. In this article, we examine how aging affects motivation toward reward-based versus state-based decision making. Participants performed tasks in which one type of option provided larger immediate rewards but the alternative type of option led to larger rewards on future trials, or improvements in state. We predicted that older adults would show a reduced preference for choices that led to improvements in state and a greater preference for choices that maximized immediate reward. We also predicted that fits from a hybrid reinforcement-learning model would indicate greater model-based strategy use in younger than in older adults. In line with these predictions, older adults selected the options that maximized reward more often than did younger adults in three of the four tasks, and modeling results suggested reduced model-based strategy use. In the task where older adults showed similar behavior to younger adults, our model-fitting results suggested that this was due to the utilization of a win-stay-lose-shift heuristic rather than a more complex model-based strategy. Additionally, within older adults, we found that model-based strategy use was positively correlated with memory measures from our neuropsychological test battery. We suggest that this shift from state-based to reward-based motivation may be due to age related declines in the neural structures needed for more computationally demanding model-based decision making.

  19. Image-based EUVL aberration metrology

    Science.gov (United States)

    Fenger, Germain Louis

    A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberration. As resolution of nanolithography systems increases, effects of wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate in-situ aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials.

  20. Chromosome aberration assays in Allium

    Energy Technology Data Exchange (ETDEWEB)

    Grant, W.F.

    1982-01-01

    The common onion (Allium cepa) is an excellent plant for the assay of chromosome aberrations after chemical treatment. Other species of Allium (A. cepa var. proliferum, A. carinatum, A. fistulosum and A. sativum) have also been used but to a much lesser extent. Protocols have been given for using root tips from either bulbs or seeds of Allium cepa to study the cytological end-points, such as chromosome breaks and exchanges, which follow the testing of chemicals in somatic cells. It is considered that both mitotic and meiotic end-points should be used to a greater extent in assaying the cytogenetic effects of a chemical. From a literature survey, 148 chemicals are tabulated that have been assayed in 164 Allium tests for their clastogenic effect. Of the 164 assays which have been carried out, 75 are reported as giving a positive reaction, 49 positive and with a dose response, 1 positive and temperature-related, 9 borderline positive, and 30 negative; 76% of the chemicals gave a definite positive response. It is proposed that the Allium test be included among those tests routinely used for assessing chromosomal damage induced by chemicals.

  1. On aberration in gravitational lensing

    CERN Document Server

    Sereno, M

    2008-01-01

    It is known that a relative translational motion between the deflector and the observer affects gravitational lensing. In this paper, a lens equation is obtained to describe such effects on actual lensing observables. Results can be easily interpreted in terms of aberration of light-rays. Both radial and transverse motions with relativistic velocities are considered. The lens equation is derived by first considering geodesic motion of photons in the rest-frame Schwarzschild spacetime of the lens, and, then, light-ray detection in the moving observer's frame. Due to the transverse motion images are displaced and distorted in the observer's celestial sphere, whereas the radial velocity along the line of sight causes an effective re-scaling of the lens mass. The Einstein ring is distorted to an ellipse whereas the caustics in the source plane are still point-like. Either for null transverse motion or up to linear order in velocities, the critical curve is still a circle with its radius corrected by a factor (1+z...

  2. Reward and punishment effects on error processing and conflict control

    Directory of Open Access Journals (Sweden)

    Birgit eStürmer

    2011-11-01

    Full Text Available Recently, positive mood has been shown to reduce cognitive conflicts and adaptation related to conflict control. Van Steenbergen et al. (2009 proposed that short-term adaptation after conflict is driven by the aversive quality of the conflict. They reasoned that monetary gain and its positive emotional consequences might counteract the aversive quality of the preceding conflict and hence reduce subsequent conflict-driven adaptation processes. According to Ashby et al. (1999, however, positive affect increases cognitive flexibility and might, therefore, support cognitive conflict control.In two experiments, we combined Simon-type conflicts with monetary gains and losses in between trials and analyzed event-related brain potentials (ERPs. In Experiment 1 gains and losses were applied randomly as a lottery in between two Simon trials whereas in the second experiment gains and losses were related to behavioral performance. Either the 25 % fastest responses were rewarded or the 25 % slowest responses were penalized. In Experiment 1 conflict adaptation was not at all modulated by gains and losses and in Experiment 2 conflict adaptation increased after a gain. In addition we analyzed the error-related negativity (ERN in Experiment 2 – a brain signal proposed to be related to the reward prediction error and response conflicts. The ERN and post-error slowing were enlarged in the context of reward. We conclude that a context of reward increases the subjective value of an error, thus, enhancing error adaptation. However, modulatory effects of affective states on cognitive conflict control are much more limited as previously asserted.

  3. Transitionality in addiction: A "temporal continuum" hypotheses involving the aberrant motivation, the hedonic dysregulation, and the aberrant learning.

    Science.gov (United States)

    Patrono, Enrico; Gasbarri, Antonella; Tomaz, Carlos; Nishijo, Hisao

    2016-08-01

    Addiction is a chronic compulsion and relapsing disorder. It involves several brain areas and circuits, which encode vary functions such as reward, motivation, and memory. Drug addiction is defined as a "pathological pattern of use of a substance", characterized by the loss of control on drug-taking-related behaviors, the pursuance of those behaviors even in the presence of negative consequences, and a strong motivated activity to assume substances. Three different theories guide experimental research on drug addiction. Each of these theories consider singles features, such as an aberrant motivation, a hedonic dysregulation, and an aberrant habit learning as the main actor to explain the entire process of the addictive behaviors. The major goal of this study is to present a new hypotheses of transitionality from a controlled use to abuse of addictive substances trough the overview of the three different theories, considering all the single features of each single theory together on the same "temporal continuum" from use to abuse of addictive substances. Recently, it has been suggested that common neural systems may be activated by natural and pharmacological stimuli, raising the hypotheses that binge-eating disorders could be considered as addictive behaviors. The second goal of this study is to present evidences in order to highlight a possible psycho-bio-physiological superimposition between drug and "food addiction". Finally, interesting questions are brought up starting from last findings about a theoretical/psycho-bio-physiological superimposition between drug and "food addiction" and their possibly same transitionality along the same "temporal continuum" from use to abuse of addictive substances in order to investigate new therapeutic strategies based on new therapeutic strategies based on the individual moments characterizing the transition from the voluntary intake of substances to the maladaptive addictive behavior.

  4. Brain Reward Circuits in Morphine Addiction

    Science.gov (United States)

    Kim, Juhwan; Ham, Suji; Hong, Heeok; Moon, Changjong; Im, Heh-In

    2016-01-01

    Morphine is the most potent analgesic for chronic pain, but its clinical use has been limited by the opiate’s innate tendency to produce tolerance, severe withdrawal symptoms and rewarding properties with a high risk of relapse. To understand the addictive properties of morphine, past studies have focused on relevant molecular and cellular changes in the brain, highlighting the functional roles of reward-related brain regions. Given the accumulated findings, a recent, emerging trend in morphine research is that of examining the dynamics of neuronal interactions in brain reward circuits under the influence of morphine action. In this review, we highlight recent findings on the roles of several reward circuits involved in morphine addiction based on pharmacological, molecular and physiological evidences. PMID:27506251

  5. TOTAL REWARDS MODEL IN ROMANIAN COMPANIES

    Directory of Open Access Journals (Sweden)

    Elena-Sabina HODOR

    2014-04-01

    Full Text Available Total Rewards Management is a subject of major importance for companies, because, by using models for this, firms can achieve their objectives of high performance. In order to analyse a validated total rewards model in Romanian Accounting and Consulting Companies, it is used The WorldatWork Total Rewards Model, which depict what contributes to applicant attraction and employee motivation and retention. Thus, the methodology of the previous survey is adjusted to the local context. The conclusions for the methodological aspects illustrate that the present research involves three strategic steps in order to achieve the objectives presented: the analysis of organizational environment of the companies from the sample, checking if Total Rewards Model proposed in the previous research is applicable for the same romanian companies from the previous survey, the analysing of the differences between results, and, if necessary, the adaptation of the model for Romania.

  6. Reward reveals dissociable aspects of sustained attention.

    Science.gov (United States)

    Esterman, Michael; Reagan, Andrew; Liu, Guanyu; Turner, Caroline; DeGutis, Joseph

    2014-12-01

    Although reward is known to have a powerful influence on performance, its effects on the ability to continuously sustain performance over time are poorly understood. The current study examines multiple measures of sustained attention (accuracy and variability) and their decrements over time, while introducing reward in the form of a monetary incentive or the promise of early completion. Compared with unrewarded participants, rewarded participants demonstrated greater overall accuracy and lower reaction time variability. However, rewarded and unrewarded participants displayed nearly identical decrements in performance over time, suggesting that these aspects of sustained attention are far less malleable by enhanced effort. This study helps to resolve conflicting models of sustained attention as it reveals that some aspects of performance are due to motivational lapses whereas others are due to the depletion of cognitive resources that cannot be easily overcome.

  7. Analysis of Bitcoin Pooled Mining Reward Systems

    CERN Document Server

    Rosenfeld, Meni

    2011-01-01

    In this paper we describe the various scoring systems used to calculate rewards of participants in Bitcoin pooled mining, explain the problems each were designed to solve and analyze their respective advantages and disadvantages.

  8. Dopamine Signaling in reward-related behaviors

    Directory of Open Access Journals (Sweden)

    Ja-Hyun eBaik

    2013-10-01

    Full Text Available Dopamine (DA regulates emotional and motivational behavior through the mesolimbic dopaminergic pathway. Changes in DAmesolimbic neurotransmission have been found to modify behavioral responses to various environmental stimuli associated with reward behaviors. Psychostimulants, drugs of abuse, and natural rewards such as food can cause substantial synaptic modifications to the mesolimbic DA system. Recent studies using optogenetics and DREADDs, together with neuron-specific or circuit-specific genetic manipulations have improved our understanding of DA signaling in the reward circuit, and provided a means to identify the neural substrates of complex behaviors such as drug addiction and eating disorders. This review focuses on the role of the DA system in drug addiction and food motivation, with an overview of the role of D1 and D2 receptors in the control of reward-associated behaviors.

  9. Performance insurance: rewarding managers for better service

    NARCIS (Netherlands)

    Zetland, D.J.

    2012-01-01

    Water utilities need to improve their performance in ways that are transparent and obvious to customers. David Zetland explains how performance insurance can improve outcomes for customers, ease the workload on regulators, and reward good managers

  10. EuroPlus+ Reward / Alar Hammer

    Index Scriptorium Estoniae

    Hammer, Alar

    2000-01-01

    EuroPlus+ Reward on mitmes versioonis ilmunud inglise keele õppeprogramm, milles on ühendatud multimeedia võimalused ning distantsõpe ning mis loob täiesti uued võimalused keele omandamiseks arvuti abil

  11. Dopamine signaling in reward-related behaviors.

    Science.gov (United States)

    Baik, Ja-Hyun

    2013-01-01

    Dopamine (DA) regulates emotional and motivational behavior through the mesolimbic dopaminergic pathway. Changes in DA mesolimbic neurotransmission have been found to modify behavioral responses to various environmental stimuli associated with reward behaviors. Psychostimulants, drugs of abuse, and natural reward such as food can cause substantial synaptic modifications to the mesolimbic DA system. Recent studies using optogenetics and DREADDs, together with neuron-specific or circuit-specific genetic manipulations have improved our understanding of DA signaling in the reward circuit, and provided a means to identify the neural substrates of complex behaviors such as drug addiction and eating disorders. This review focuses on the role of the DA system in drug addiction and food motivation, with an overview of the role of D1 and D2 receptors in the control of reward-associated behaviors.

  12. When is it adaptive to be patient? A general framework for evaluating delayed rewards.

    Science.gov (United States)

    Fawcett, Tim W; McNamara, John M; Houston, Alasdair I

    2012-02-01

    The tendency of animals to seek instant gratification instead of waiting for greater long-term benefits has been described as impatient, impulsive or lacking in self-control. How can we explain the evolution of such seemingly irrational behaviour? Here we analyse optimal behaviour in a variety of simple choice situations involving delayed rewards. We show that preferences for more immediate rewards should depend on a variety of factors, including whether the choice is a one-off or is likely to be repeated, the information the animal has about the continuing availability of the rewards and the opportunity to gain rewards through alternative activities. In contrast to the common assertion that rational animals should devalue delayed rewards exponentially, we find that this pattern of discounting is optimal only under restricted circumstances. We predict preference reversal whenever waiting for delayed rewards entails loss of opportunities elsewhere, but the direction of this reversal depends on whether the animal will face the same choice repeatedly. Finally, we question the ecological relevance of standard laboratory tests for impulsive behaviour, arguing that animals rarely face situations analogous to the self-control paradigm in their natural environment. To understand the evolution of impulsiveness, a more promising strategy would be to identify decision rules that are adaptive in a realistic ecological setting, and examine how these rules determine patterns of behaviour in simultaneous choice tests.

  13. Subanesthetic ketamine decreases the incentive-motivational value of reward-related cues.

    Science.gov (United States)

    Fitzpatrick, Christopher J; Morrow, Jonathan D

    2017-01-01

    The attribution of incentive-motivational value to reward-related cues contributes to cue-induced craving and relapse in addicted patients. Recently, it was demonstrated that subanesthetic ketamine increases motivation to quit and decreases cue-induced craving in cocaine-dependent individuals. Although the underlying mechanism of this effect is currently unknown, one possibility is that subanesthetic ketamine decreases the incentive-motivational value of reward-related cues. In the present study, we used a Pavlovian conditioned approach procedure to identify sign-trackers, rats that attribute incentive-motivational value to reward-related cues, and goal-trackers, rats that assign only predictive value to reward-related cues. This model is of interest because sign-trackers are more vulnerable to cue-induced reinstatement of drug-seeking behavior and will persist in this drug-seeking behavior despite adverse consequences. We tested the effect of subanesthetic ketamine on the expression of Pavlovian conditioned approach behavior and the conditioned reinforcing properties of a reward-related cue in sign- and goal-trackers. We found that subanesthetic ketamine decreased sign-tracking and increased goal-tracking behavior in sign-trackers, though it had no effect on conditioned reinforcement. These results suggest that subanesthetic ketamine may be a promising pharmacotherapy for addiction that acts by decreasing the incentive-motivational value of reward-related cues.

  14. Dorsomedial striatum lesions affect adjustment to reward uncertainty, but not to reward devaluation or omission.

    Science.gov (United States)

    Torres, Carmen; Glueck, Amanda C; Conrad, Shannon E; Morón, Ignacio; Papini, Mauricio R

    2016-09-22

    The dorsomedial striatum (DMS) has been implicated in the acquisition of reward representations, a proposal leading to the hypothesis that it should play a role in situations involving reward loss. We report the results of an experiment in which the effects of DMS excitotoxic lesions were tested in consummatory successive negative contrast (reward devaluation), autoshaping training with partial vs. continuous reinforcement (reward uncertainty), and appetitive extinction (reward omission). Animals with DMS lesions exhibited reduced lever pressing responding, but enhanced goal entries, during partial reinforcement training in autoshaping. However, they showed normal negative contrast, acquisition under continuous reinforcement (CR), appetitive extinction, and response facilitation in early extinction trials. Open-field testing also indicated normal motor behavior. Thus, DMS lesions selectively affected the behavioral adjustment to a situation involving reward uncertainty, producing a behavioral reorganization according to which goal tracking (goal entries) became predominant at the expense of sign tracking (lever pressing). This pattern of results shows that the function of the DMS in situations involving reward loss is not general, but restricted to reward uncertainty. We suggest that a nonassociative, drive-related process induced by reward uncertainty requires normal output from DMS neurons.

  15. Individual differences in sensitivity to reward and punishment and neural activity during reward and avoidance learning.

    Science.gov (United States)

    Kim, Sang Hee; Yoon, HeungSik; Kim, Hackjin; Hamann, Stephan

    2015-09-01

    In this functional neuroimaging study, we investigated neural activations during the process of learning to gain monetary rewards and to avoid monetary loss, and how these activations are modulated by individual differences in reward and punishment sensitivity. Healthy young volunteers performed a reinforcement learning task where they chose one of two fractal stimuli associated with monetary gain (reward trials) or avoidance of monetary loss (avoidance trials). Trait sensitivity to reward and punishment was assessed using the behavioral inhibition/activation scales (BIS/BAS). Functional neuroimaging results showed activation of the striatum during the anticipation and reception periods of reward trials. During avoidance trials, activation of the dorsal striatum and prefrontal regions was found. As expected, individual differences in reward sensitivity were positively associated with activation in the left and right ventral striatum during reward reception. Individual differences in sensitivity to punishment were negatively associated with activation in the left dorsal striatum during avoidance anticipation and also with activation in the right lateral orbitofrontal cortex during receiving monetary loss. These results suggest that learning to attain reward and learning to avoid loss are dependent on separable sets of neural regions whose activity is modulated by trait sensitivity to reward or punishment.

  16. The Circadian Clock, Reward, and Memory

    OpenAIRE

    Urs eAlbrecht

    2011-01-01

    During our daily activities, we experience variations in our cognitive performance, which is often accompanied by cravings for small rewards, such as consuming coffee or chocolate. This indicates that the time of day, cognitive performance, and reward may be related to one another. This review will summarize data that describe the influence of the circadian clock on addiction and mood-related behavior and put the data into perspective in relation to memory processes.

  17. The circadian clock, reward and memory

    Directory of Open Access Journals (Sweden)

    Urs eAlbrecht

    2011-11-01

    Full Text Available During our daily activities, we experience variations in our cognitive performance, which is often accompanied by cravings for small rewards, such as consuming coffee or chocolate. This indicates that the time of day, cognitive performance and reward may be related to one another. This review will summarize data that describes the influence of the circadian clock on addiction and mood-related behavior and put the data into perspective in relation to memory processes.

  18. Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict.

    Science.gov (United States)

    van den Berg, Berry; Krebs, Ruth M; Lorist, Monicque M; Woldorff, Marty G

    2014-06-01

    The prospect of gaining money is an incentive widely at play in the real world. Such monetary motivation might have particularly strong influence when the cognitive system is challenged, such as when needing to process conflicting stimulus inputs. Here, we employed manipulations of reward-prospect and attentional-preparation levels in a cued-Stroop stimulus conflict task, along with the high temporal resolution of electrical brain recordings, to provide insight into the mechanisms by which reward-prospect and attention interact and modulate cognitive task performance. In this task, the cue indicated whether or not the participant needed to prepare for an upcoming Stroop stimulus and, if so, whether there was the potential for monetary reward (dependent on performance on that trial). Both cued attention and cued reward-prospect enhanced preparatory neural activity, as reflected by increases in the hallmark attention-related negative-polarity ERP slow wave (contingent negative variation [CNV]) and reductions in oscillatory Alpha activity, which was followed by enhanced processing of the subsequent Stroop stimulus. In addition, similar modulations of preparatory neural activity (larger CNVs and reduced Alpha) predicted shorter versus longer response times (RTs) to the subsequent target stimulus, consistent with such modulations reflecting trial-to-trial variations in attention. Particularly striking were the individual differences in the utilization of reward-prospect information. In particular, the size of the reward effects on the preparatory neural activity correlated across participants with the degree to which reward-prospect both facilitated overall task performance (shorter RTs) and reduced conflict-related behavioral interference. Thus, the prospect of reward appears to recruit attentional preparation circuits to enhance processing of task-relevant target information.

  19. Synchrony Can Destabilize Reward-Sensitive Networks

    Directory of Open Access Journals (Sweden)

    Michael eChary

    2014-04-01

    Full Text Available When exposed to rewarding stimuli, only some animals develop persistent craving. Others are resilient and do not. How the activity of neural populations relates to the development of persistent craving behavior is not fully understood. Previous computational studies suggest that synchrony helps a network embed certain patterns of activity, although the role of synchrony in reward-dependent learning has been less studied. Increased synchrony has been reported as a marker for both susceptibility and resilience to developing persistent craving. Here we use computational simulations to study the effect of reward salience on the ability of synchronous input to embed a new pattern of activity into a neural population. Our main finding is that weak stimulus-reward correlations can facilitate the short-term repetition of a pattern of neural activity, while blocking long-term embedding of that pattern. Interestingly, synchrony did not have this dual effect on all patterns, which suggests that synchrony is more effective at embedding some patterns of activity than others. Our results demonstrate that synchrony can have opposing effects in networks sensitive to the correlation structure of their inputs, in this case the correlation between stimulus and reward. This work contributes to an understanding of the interplay between synchrony and reward-dependent plasticity.

  20. Increases in rewards promote flexible behavior.

    Science.gov (United States)

    Shen, Y Jeremy; Chun, Marvin M

    2011-04-01

    Offering reward for performance can motivate people to perform a task better, but better preparation for one task usually means decreased flexibility to perform different tasks. In six experiments in which reward varied between low and high levels, we found that reward can encourage people to prepare more flexibly for different tasks, but only as it increased from the level on the previous trial. When the same high rewards were offered continuously trial after trial, people were more inclined to simply stick with doing what had worked previously. We demonstrated such enhancements in flexibility in task switching, a difficult visual search task, and an easier priming of pop-out search task, which shows that this effect generalizes from executive tasks to perceptual processes that require relatively little executive control. These findings suggest that relative, transient changes in reward can exert more potent effects on behavioral flexibility than can the absolute amount of reward, whether it consists of money or points in a social competition.

  1. Aberrations in square pore micro-channel optics used for x-ray lobster eye telescopes

    Science.gov (United States)

    Willingale, R.; Pearson, J. F.; Martindale, A.; Feldman, C. H.; Fairbend, R.; Schyns, E.; Petit, S.; Osborne, J. P.; O'Brien, P. T.

    2016-07-01

    We identify all the significant aberrations that limit the performance of square pore micro-channel plate optics (MPOs) used as an X-ray lobster eye. These include aberrations intrinsic to the geometry, intrinsic errors associated with the slumping process used to introduce a spherical form to the plates and imperfections associated with the plate manufacturing process. The aberrations are incorporated into a comprehensive software model of the X-ray response of the optics and the predicted imaging response is compared with the measured X-ray performance obtained from a breadboard lobster eye. The results reveal the manufacturing tolerances which limit the current performance of MPOs and enable us to identify particular intrinsic aberrations which will limit the ultimate performance we can expect from MPO-lobster eye telescopes.

  2. Novelty increases the mesolimbic functional connectivity of the substantia nigra/ventral tegmental area (SN/VTA) during reward anticipation: Evidence from high-resolution fMRI.

    Science.gov (United States)

    Krebs, R M; Heipertz, D; Schuetze, H; Duzel, E

    2011-09-15

    Reward and novelty are potent learning signals that critically rely on dopaminergic midbrain responses. Recent findings suggest that although reward and novelty are likely to interact, both functions may be subserved by distinct neuronal clusters. We used high-resolution functional magnetic resonance imaging (fMRI) to isolate neural responses to reward and novelty within the human substantia nigra/ventral tegmental area (SN/VTA) complex to investigate the spatial delineation and integration of reward- and novelty-related activity clusters. We demonstrate that distinct clusters within the caudal portion of the medial SN/VTA and the lateral portion of the right SN are predominantly modulated by the anticipation of reward, while a more rostral part of the medial SN/VTA was exclusively modulated by novelty. In addition, the caudal medial SN/VTA cluster embodied an interaction between novelty and reward where novelty selectively increased reward-anticipation responses. This interaction, in turn, was paralleled by differences in the functional-connectivity patterns of these SN/VTA regions. Specifically, novel as compared to familiar reward-predictive stimuli increased the functional connectivity of the medial SN/VTA with mesolimbic regions, including the nucleus accumbens and the hippocampus, as well as with the primary visual cortex. This functional correlation may highlight how afferents of the medial SN/VTA provide integrative information about novelty and reward, or, alternatively, how medial SN/VTA activity may modulate memory processes for novel events associated with rewards.

  3. Reward Comparison: The Achilles’ heel and hope for addiction

    OpenAIRE

    Grigson, Patricia Sue

    2008-01-01

    In the words of the late Charles Flaherty, reward comparison is commonplace. Rats and man, it appears, compare all rewards and this capacity likely contributes to our ability to select the most appropriate reward/behavior (food, water, salt, sex), at the most ideal level (e.g., a certain sweetness), at any given time. A second advantage of our predisposition for reward comparison is that the availability of rich alternative rewards can protect against our becoming addicted to any single rewar...

  4. Catadioptric aberration correction in cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  5. Flow cytometric detection of aberrant chromosomes

    Energy Technology Data Exchange (ETDEWEB)

    Gray, J.W.; Lucas, J.; Yu, L.C.; Langlois, R.

    1983-05-11

    This report describes the quantification of chromosomal aberrations by flow cytometry. Both homogeneously and heterogeneously occurring chromosome aberrations were studied. Homogeneously occurring aberrations were noted in chromosomes isolated from human colon carcinoma (LoVo) cells, stained with Hoechst 33258 and chromomycin A3 and analyzed using dual beam flow cytometry. The resulting bivariate flow karyotype showed a homogeneously occurring marker chromosome of intermediate size. Heterogeneously occurring aberrations were quantified by slit-scan flow cytometry in chromosomes isolated from control and irradiated Chinese hamster cells and stained with propidium iodide. Heterogeneously occurring dicentric chromosomes were detected by their shapes (two centrometers). The frequencies of such chromosomes estimated by slit-scan flow cytometry correlated well with the frequencies determined by visual microscopy.

  6. Timing and expectation of reward: a neuro-computational model of the afferents to the ventral tegmental area

    Directory of Open Access Journals (Sweden)

    Julien eVitay

    2014-01-01

    Full Text Available Neural activity in dopaminergic areas such as the ventral tegmental area is influenced by timing processes, in particular by the temporal expectation of rewards during Pavlovian conditioning. Receipt of a reward at the expected time allows to compute reward-prediction errors which can drive learning in motor or cognitive structures. Reciprocally, dopamine plays an important role in the timing of external events. Several models of the dopaminergic system exist, but the substrate of temporal learning is rather unclear. In this article, we propose a neuro-computational model of the afferent network to the ventral tegmental area, including the lateral hypothalamus, the pedunculopontine nucleus, the amygdala, the ventromedial prefrontal cortex, the ventral basal ganglia (including the nucleus accumbens and the ventral pallidum, as well as the lateral habenula and the rostromedial tegmental nucleus. Based on a plausible connectivity and realistic learning rules, this neuro-computational model reproduces several experimental observations, such as the progressive cancellation of dopaminergic bursts at reward delivery, the appearance of bursts at the onset of reward-predicting cues or the influence of reward magnitude on activity in the amygdala and ventral tegmental area. While associative learning occurs primarily in the amygdala, learning of the temporal relationship between the cue and the associated reward is implemented as a dopamine-modulated coincidence detection mechanism in the nucleus accumbens.

  7. Reward sensitivity for a palatable food reward peaks during pubertal developmental in rats

    Directory of Open Access Journals (Sweden)

    Chris M Friemel

    2010-07-01

    Full Text Available Puberty is a critical period for the initiation of drug use and abuse. Because early drug use onset often accounts for a more severe progression of addiction, it is of importance to understand the underlying mechanisms and neurodevelopmental changes during puberty that are contributing to enhanced reward processing in teenagers. The present study investigated the progression of reward sensitivity towards a natural food reward over the whole course of adolescence in male rats (postnatal days 30–90 by monitoring consummatory, motivational behavior and neurobiological correlates of reward. Using a limited-free intake paradigm, consumption of sweetened condensed milk (SCM was measured repeatedly in adolescent and adult rats. Additionally, early- and mid-pubertal animals were tested in Progressive Ratio responding for SCM and c-fos protein expression in reward-associated brain structures was examined after odor-conditioning for SCM. We found a transient increase in SCM consumption and motivational incentive for SCM during puberty. This increased reward sensitivity was most pronounced around mid-puberty. The behavioral findings are paralleled by enhanced c-fos staining in reward-related structures revealing an intensified neuronal response after reward-cue presentation, distinctive for pubertal animals. Taken together, these data indicate an increase in reward sensitivity during adolescence accompanied by enhanced responsiveness of reward associated brain structures to incentive stimuli, and it seems that both is strongly pronounced around mid-puberty. Therefore, higher reward sensitivity during pubertal maturation might contribute to the enhanced vulnerability of teenagers for the initiation of experimental drug use.

  8. Sensing Phase Aberrations behind Lyot Coronagraphs

    Science.gov (United States)

    Sivaramakrishnan, Anand; Soummer, Rémi; Pueyo, Laurent; Wallace, J. Kent; Shao, Michael

    2008-11-01

    Direct detection of young extrasolar planets orbiting nearby stars can be accomplished from the ground with extreme adaptive optics and coronagraphy in the near-infrared, as long as this combination can provide an image with a dynamic range of 107 after the data are processed. Slowly varying speckles due to residual phase aberrations that are not measured by the primary wave-front sensor are the primary obstacle to achieving such a dynamic range. In particular, non-common optical path aberrations occurring between the wave-front sensor and the coronagraphic occulting spot degrade performance the most. We analyze the passage of both low and high spatial frequency phase ripples, as well as low-order Zernike aberrations, through an apodized pupil Lyot coronagraph in order to demonstrate the way coronagraphic filtering affects various aberrations. We derive the coronagraphically induced cutoff frequency of the filtering and estimate coronagraphic contrast losses due to low-order Zernike aberrations: tilt, astigmatism, defocus, coma, and spherical aberration. Such slowly varying path errors can be measured behind a coronagraph and corrected by a slowly updated optical path delay precompensation or offset asserted on the wave front by the adaptive optics (AO) system. We suggest ways of measuring and correcting all but the lowest spatial frequency aberrations using Lyot plane wave-front data, in spite of the complex interaction between the coronagraph and those mid-spatial frequency aberrations that cause image plane speckles near the coronagraphic focal plane mask occulter's edge. This investigation provides guidance for next-generation coronagraphic instruments currently under construction.

  9. Nucleus accumbens response to rewards and testosterone levels are related to alcohol use in adolescents and young adults

    Directory of Open Access Journals (Sweden)

    Barbara R. Braams

    2016-02-01

    Full Text Available During adolescence there is a normative increase in risk-taking behavior, which is reflected in, for example, increases in alcohol consumption. Prior research has demonstrated a link between testosterone and alcohol consumption, and between testosterone and neural responses to rewards. Yet, no study to date tested how testosterone levels and neural responses to rewards relate to and predict individual differences in alcohol use. The current study aimed to investigate this by assessing alcohol use, testosterone levels and neural responses to rewards in adolescents (12–17 years old and young adults (18–26 years old. Participants were measured twice with a two-year interval between testing sessions. Cross-sectional analysis showed that at the second time point higher neural activity to rewards, but not testosterone levels, explained significant variance above age in reported alcohol use. Predictive analyses showed that, higher testosterone level at the first time point, but not neural activity to rewards at the first time point, was predictive of more alcohol use at the second time point. These results suggest that neural responses to rewards are correlated with current alcohol consumption, and that testosterone level is predictive of future alcohol consumption. These results are interpreted in the context of trajectory models of adolescent development.

  10. Nucleus accumbens response to rewards and testosterone levels are related to alcohol use in adolescents and young adults.

    Science.gov (United States)

    Braams, Barbara R; Peper, Jiska S; van der Heide, Dianne; Peters, Sabine; Crone, Eveline A

    2016-02-01

    During adolescence there is a normative increase in risk-taking behavior, which is reflected in, for example, increases in alcohol consumption. Prior research has demonstrated a link between testosterone and alcohol consumption, and between testosterone and neural responses to rewards. Yet, no study to date tested how testosterone levels and neural responses to rewards relate to and predict individual differences in alcohol use. The current study aimed to investigate this by assessing alcohol use, testosterone levels and neural responses to rewards in adolescents (12-17 years old) and young adults (18-26 years old). Participants were measured twice with a two-year interval between testing sessions. Cross-sectional analysis showed that at the second time point higher neural activity to rewards, but not testosterone levels, explained significant variance above age in reported alcohol use. Predictive analyses showed that, higher testosterone level at the first time point, but not neural activity to rewards at the first time point, was predictive of more alcohol use at the second time point. These results suggest that neural responses to rewards are correlated with current alcohol consumption, and that testosterone level is predictive of future alcohol consumption. These results are interpreted in the context of trajectory models of adolescent development.

  11. Individual eye model based on wavefront aberration

    Science.gov (United States)

    Guo, Huanqing; Wang, Zhaoqi; Zhao, Qiuling; Quan, Wei; Wang, Yan

    2005-03-01

    Based on the widely used Gullstrand-Le Grand eye model, the individual human eye model has been established here, which has individual corneal data, anterior chamber depth and the eyeball depth. Furthermore, the foremost thing is that the wavefront aberration calculated from the individual eye model is equal to the eye's wavefront aberration measured with the Hartmann-shack wavefront sensor. There are four main steps to build the model. Firstly, the corneal topography instrument was used to measure the corneal surfaces and depth. And in order to input cornea into the optical model, high-order aspheric surface-Zernike Fringe Sag surface was chosen to fit the corneal surfaces. Secondly, the Hartmann-shack wavefront sensor, which can offer the Zernike polynomials to describe the wavefront aberration, was built to measure the wavefront aberration of the eye. Thirdly, the eye's axial lengths among every part were measured with A-ultrasonic technology. Then the data were input into the optical design software-ZEMAX and the crystalline lens's shapes were optimized with the aberration as the merit function. The individual eye model, which has the same wavefront aberrations with the real eye, is established.

  12. Neuroendocrinology and brain imaging of reward in eating disorders: A possible key to the treatment of anorexia nervosa and bulimia nervosa.

    Science.gov (United States)

    Monteleone, Alessio Maria; Castellini, Giovanni; Volpe, Umberto; Ricca, Valdo; Lelli, Lorenzo; Monteleone, Palmiero; Maj, Mario

    2017-03-01

    Anorexia nervosa and bulimia nervosa are severe eating disorders whose etiopathogenesis is still unknown. Clinical features suggest that eating disorders may develop as reward-dependent syndromes, since eating less food is perceived as rewarding in anorexia nervosa while consumption of large amounts of food during binge episodes in bulimia nervosa aims at reducing the patient's negative emotional states. Therefore, brain reward mechanisms have been a major focus of research in the attempt to contribute to the comprehension of the pathophysiology of these disorders. Structural brain imaging data provided the evidence that brain reward circuits may be altered in patients with anorexia or bulimia nervosa. Similarly, functional brain imaging studies exploring the activation of brain reward circuits by food stimuli as well as by stimuli recognized to be potentially rewarding for eating disordered patients, such as body image cues or stimuli related to food deprivation and physical hyperactivity, showed several dysfunctions in ED patients. Moreover, very recently, it has been demonstrated that some of the biochemical homeostatic modulators of eating behavior are also implicated in the regulation of food-related and non-food-related reward, representing a possible link between the aberrant behaviors of ED subjects and their hypothesized deranged reward processes. In particular, changes in leptin and ghrelin occur in patients with anorexia or bulimia nervosa and have been suggested to represent not only homeostatic adaptations to an altered energy balance but to contribute also to the acquisition and/or maintenance of persistent starvation, binge eating and physical hyperactivity, which are potentially rewarding for ED patients. On the basis of such findings new pathogenetic models of EDs have been proposed, and these models may provide new theoretical basis for the development of innovative treatment strategies, either psychological and pharmacological, with the aim to

  13. Is sensitivity to reward associated with the malleability of implicit inclinations toward high-fat food?

    Science.gov (United States)

    Ashby, Casey R; Stritzke, Werner G K

    2013-08-01

    Two experiments examined the effect of positive and negative priming on implicit approach and avoidance inclinations toward high-fat food stimuli in participants high or low in reward sensitivity, using personalized unipolar variants of the Implicit Association Test (IAT; A. G. Greenwald, D. E. McGhee, & J. L. K. Schwartz, 1998, "Measuring individual differences in implicit cognition: The Implicit Association Test," Journal of Personality and Social Psychology, Vol. 74, pp. 1464-1480). Participants high in reward sensitivity showed an automatic processing bias that is characterized by a dual vulnerability of being particularly susceptible to priming of the rewarding aspects of high-fat foods, while being unaffected by priming of the negative aspects of those foods. In contrast, participants low in reward sensitivity generally showed no facilitation of implicit-approach inclinations following positive priming, but consistently showed facilitation of implicit-avoidance inclinations following negative priming. These results are consistent with the revised reinforcement sensitivity theory ( J. A. Gray & N. McNaughton, 2000, The neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system, 2nd ed., New York, NY, Oxford University Press.) and suggest that the systems mediating reward sensitivity and punishment sensitivity are not orthogonal, as predicted by the separable subsystems hypothesis, but can be interdependent, as predicted by the joint subsystems hypothesis.

  14. Anger is associated with reward-related electrocortical activity: Evidence from the reward positivity

    NARCIS (Netherlands)

    Angus, D.J.; Kemkes, K.; Schutter, D.J.L.G.; Harmon-Jones, E.

    2015-01-01

    Previous research indicates that the reward positivity (RewP), an electrophysiological correlate of sensitivity and biases towards rewarding stimuli, is modulated by affective and motivational variables. Studies have provided evidence that states and traits associated with negative affect and reduce

  15. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  16. The Timing Effects of Reward, Business Longevity, and Involvement on Consumers’ Responses to a Reward Program

    Directory of Open Access Journals (Sweden)

    Badri Munir Sukoco

    2015-06-01

    Full Text Available Managers could elicit customers’ repeat purchase behavior through a well-designed reward program. This study examines two extrinsic cues - business longevity and timing effects of reward – to determine the consumers’ perceived risk and intention to participate in this kind of program. Moreover, this study discusses how different levels of involvement might interact with these two cues. An experiment with a 2 (business longevity: long vs. short x 2 (timing of reward: delayed vs. immediate x 2 (involvement: high vs. low between-subject factorial design is conducted to validate the proposed research hypotheses. The results show that an immediate reward offered by an older, more established, firm for a highly-involved product, make loyalty programs less risky and consequently attract consumers to participate. Interestingly, immediate rewards that are offered by older firms for a product that customers are less involved in has the opposite effects. Managerial and academic implications are further presented in this study.

  17. Single pulse TMS differentially modulates reward behavior.

    Science.gov (United States)

    Stanford, Arielle D; Luber, Bruce; Unger, Layla; Cycowicz, Yael M; Malaspina, Dolores; Lisanby, Sarah H

    2013-12-01

    Greater knowledge of cortical brain regions in reward processing may set the stage for using transcranial magnetic stimulation (TMS) as a treatment in patients with avolition, apathy or other drive-related symptoms. This study examined the effects of single pulse (sp) TMS to two reward circuit targets on drive in healthy subjects. Fifteen healthy subjects performed the monetary incentive delay task (MID) while receiving fMRI-guided spTMS to either inferior parietal lobe (IPL) or supplemental motor area (SMA). The study demonstrated decreasing reaction times (RT) for increasing reward. It also showed significant differences in RT modulation for TMS pulses to the IPL versus the SMA. TMS pulses during the delay period produced significantly more RT slowing when targeting the IPL than those to the SMA. This RT slowing carried over into subsequent trials without TMS stimulation, with significantly slower RTs in sessions that had targeted the IPL compared to those targeting SMA. The results of this study suggest that both SMA and IPL are involved in reward processing, with opposite effects on RT in response to TMS stimulation. TMS to these target cortical regions may be useful in modulating reward circuit deficits in psychiatric populations.

  18. Prediction

    CERN Document Server

    Sornette, Didier

    2010-01-01

    This chapter first presents a rather personal view of some different aspects of predictability, going in crescendo from simple linear systems to high-dimensional nonlinear systems with stochastic forcing, which exhibit emergent properties such as phase transitions and regime shifts. Then, a detailed correspondence between the phenomenology of earthquakes, financial crashes and epileptic seizures is offered. The presented statistical evidence provides the substance of a general phase diagram for understanding the many facets of the spatio-temporal organization of these systems. A key insight is to organize the evidence and mechanisms in terms of two summarizing measures: (i) amplitude of disorder or heterogeneity in the system and (ii) level of coupling or interaction strength among the system's components. On the basis of the recently identified remarkable correspondence between earthquakes and seizures, we present detailed information on a class of stochastic point processes that has been found to be particu...

  19. Listening to music in a risk-reward context: The roles of the temporoparietal junction and the orbitofrontal/insular cortices in reward-anticipation, reward-gain, and reward-loss.

    Science.gov (United States)

    Li, Chia-Wei; Chen, Jyh-Horng; Tsai, Chen-Gia

    2015-12-10

    Artificial rewards, such as visual arts and music, produce pleasurable feelings. Popular songs in the verse-chorus form provide a useful model for understanding the neural mechanisms underlying the processing of artificial rewards, because the chorus is usually the most rewarding element of a song. In this functional magnetic resonance imaging (fMRI) study, the stimuli were excerpts of 10 popular songs with a tensioned verse-to-chorus transition. We examined the neural correlates of three phases of reward processing: (1) reward-anticipation during the verse-to-chorus transition, (2) reward-gain during the first phrase of the chorus, and (3) reward-loss during the unexpected noise followed by the verse-to-chorus transition. Participants listened to these excerpts in a risk-reward context because the verse was followed by either the chorus or noise with equal probability. The results showed that reward-gain and reward-loss were associated with left- and right-biased temporoparietal junction activation, respectively. The bilateral temporoparietal junctions were active during reward-anticipation. Moreover, we observed left-biased lateral orbitofrontal activation during reward-anticipation, whereas the medial orbitofrontal cortex was activated during reward-gain. The findings are discussed in relation to the cognitive and emotional aspects of reward processing.

  20. Withholding a Reward-driven Action: Studies of the Rise and Fall of Motor Activation and the Effect of Cognitive Depletion.

    Science.gov (United States)

    Freeman, Scott M; Aron, Adam R

    2016-02-01

    Controlling an inappropriate response tendency in the face of a reward-predicting stimulus likely depends on the strength of the reward-driven activation, the strength of a putative top-down control process, and their relative timing. We developed a rewarded go/no-go paradigm to investigate such dynamics. Participants made rapid responses (on go trials) to high versus low reward-predicting stimuli and sometimes had to withhold responding (on no-go trials) in the face of the same stimuli. Behaviorally, for high versus low reward stimuli, responses were faster on go trials, and there were more errors of commission on no-go trials. We used single-pulse TMS to map out the corticospinal excitability dynamics, especially on no-go trials where control is needed. For successful no-go trials, there was an early rise in motor activation that was then sharply reduced beneath baseline. This activation-reduction pattern was more pronounced for high- versus low-reward trials and in individuals with greater motivational drive for reward. A follow-on experiment showed that, when participants were fatigued by an effortful task, they made more errors on no-go trials for high versus low reward stimuli. Together, these studies show that, when a response is inappropriate, reward-predicting stimuli induce early motor activation, followed by a top-down effortful control process (which we interpret as response suppression) that depends on the strength of the preceding activation. Our findings provide novel information about the activation-suppression dynamics during control over reward-driven actions, and they illustrate how fatigue or depletion leads to control failures in the face of reward.

  1. Mathematical treatment of condenser aberrations and their impact on linewidth control

    Science.gov (United States)

    Krautschik, Christof G.; Shibuya, Masato; Toh, Kenny K.

    1999-07-01

    While condenser aberrations under Koehler illumination were previously treated in the literature their mathematical derivation did not take conservation of radiance into consideration. Here we make use of a more rigorous derivation of the mutual intensity where the source deformation term is treated in the context of radiance conservation. The derivation predicts that condenser aberrations lead to radiance invariance while aberrations have a direct bearing on illumination uniformity and the angular extent of the local effective source. This result significantly contrasts with the previously established conclusion in the literature that condenser aberrations lead to a modification of the source radiance but preserves irradiance in the reticle plane. Source aberrations of first and third order are derived and then systematically explored both analytically and numerically. Aberration impact on linewidth control are further considered and quantified from the aerial image perspective. It is shown that third order coma has the most significant impact on CD control as a result of the asymmetry in the deformation of the source shape. Similarly coma also significantly impacts overall mask illumination uniformity.

  2. Deep Brain Stimulation of the Subthalamic Nucleus improves Reward-based decision-learning in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Nelleke Corine Van Wouwe

    2011-04-01

    Full Text Available Recently, the subthalamic nucleus (STN has been shown to be critically involved in decision-making, action selection, and motor control. Here we investigate the effect of deep brain stimulation (DBS of the STN on reward-based decision-learning in patients diagnosed with Parkinson’s disease (PD. We determined computational measures of outcome evaluation and reward prediction from PD patients who performed a probabilistic reward-based decision-learning task. In previous work, these measures covaried with activation in the nucleus caudatus (outcome evaluation during the early phases of learning and the putamen (reward prediction during later phases of learning. We observed that stimulation of the STN motor regions in PD patients served to improve reward-based decision-learning, probably through its effect on activity in frontostriatal motor loops (prominently involving the putamen and, hence, reward prediction. In a subset of relatively younger patients with relatively shorter disease duration, the effects of DBS appeared to spread to more cognitive regions of the STN, benefitting loops that connect the caudate to various prefrontal areas important for outcome evaluation. These results highlight positive effects of STN stimulation on cognitive functions that may benefit PD patients in daily-life association-learning situations.

  3. A tribute to Charlie Chaplin: Induced positive affect improves reward-based decision-learning in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    K. Richard eRidderinkhof

    2012-06-01

    Full Text Available Reward-based decision-learning refers to the process of learning to select those actions that lead to rewards while avoiding actions that lead to punishments. This process, known to rely on dopaminergic activity in striatal brain regions, is compromised in Parkinson’s disease (PD. We hypothesized that such decision-learning deficits are alleviated by induced positive affect, which is thought to incur transient boosts in midbrain and striatal dopaminergic activity. Computational measures of probabilistic reward-based decision-learning were determined for 51 patients diagnosed with PD. Previous work has shown these measures to rely on the nucleus caudatus (outcome evaluation during the early phases of learning and the putamen (reward prediction during later phases of learning. We observed that induced positive affect facilitated learning, through its effects on reward prediction rather than outcome evaluation. Viewing a few minutes of comedy clips served to remedy dopamine-related problems in putamen-based frontostriatal circuitry and, consequently, in learning to predict which actions will yield reward.

  4. Increased risk of cancer in radon-exposed miners with elevated frequency of chromosomal aberrations.

    Science.gov (United States)

    Smerhovsky, Zdenek; Landa, Karel; Rössner, Pavel; Juzova, Dagmar; Brabec, Marek; Zudova, Zdena; Hola, Nora; Zarska, Hana; Nevsimalova, Emilie

    2002-02-15

    In spite of the extensive use of cytogenetic analysis of human peripheral blood lymphocytes in the biomonitoring of exposure to various mutagens and carcinogens, the long-term effects of an increased frequency of chromosomal aberrations in individuals are still uncertain. Few epidemiologic studies have addressed this issue, and a moderate risk of cancer in individuals with an elevated frequency of chromosomal aberrations has been observed. In the present study, we analyzed data on 1323 cytogenetic assays and 225 subjects examined because of occupational exposures to radon (range of exposure from 1.7 to 662.3 working level month (WLM)). Seventy-five subjects were non-smokers. We found 36 cases of cancer in this cohort. Chromatid breaks were the most frequently observed type of aberrations (mean frequency 1.2 per 100 cells), which statistically significantly correlated with radon exposure (Spearman's correlation coefficient R=0.22, P<0.001). Also, the frequency of aberrant cells (median of 2.5%) correlated with radon exposure (Spearman's correlation coefficient R=0.16, P<0.02). Smoking and silicosis were not associated with results of cytogenetic analyses. The Cox regression models, which accounted for the age at time of first cytogenetic assay, radon exposure, and smoking showed strong and statistically significant associations between cancer incidence and frequency of chromatid breaks and frequency of aberrant cells, respectively. A 1% increase in the frequency of aberrant cells was paralleled by a 62% increase in risk of cancer (P<0.000). An increase in frequency of chromatid breaks by 1 per 100 cells was followed by a 99% increase in risk of cancer (P<0.000). We obtained similar results when we analyzed the incidence of lung cancer and the incidence other than lung cancer separately. Contrary to frequency of chromatid breaks and frequency of aberrant cells, the frequency of chromatid exchanges, and chromosome-type aberrations were not predictive of cancer.

  5. Beyond simple reinforcement learning: the computational neurobiology of reward-learning and valuation.

    Science.gov (United States)

    O'Doherty, John P

    2012-04-01

    Neural computational accounts of reward-learning have been dominated by the hypothesis that dopamine neurons behave like a reward-prediction error and thus facilitate reinforcement learning in striatal target neurons. While this framework is consistent with a lot of behavioral and neural evidence, this theory fails to account for a number of behavioral and neurobiological observations. In this special issue of EJN we feature a combination of theoretical and experimental papers highlighting some of the explanatory challenges faced by simple reinforcement-learning models and describing some of the ways in which the framework is being extended in order to address these challenges.

  6. Vigor in the face of fluctuating rates of reward: an experimental examination.

    Science.gov (United States)

    Guitart-Masip, Marc; Beierholm, Ulrik R; Dolan, Raymond; Duzel, Emrah; Dayan, Peter

    2011-12-01

    Two fundamental questions underlie the expression of behavior, namely what to do and how vigorously to do it. The former is the topic of an overwhelming wealth of theoretical and empirical work particularly in the fields of reinforcement learning and decision-making, with various forms of affective prediction error playing key roles. Although vigor concerns motivation, and so is the subject of many empirical studies in diverse fields, it has suffered a dearth of computational models. Recently, Niv et al. [Niv, Y., Daw, N. D., Joel, D., & Dayan, P. Tonic dopamine: Opportunity costs and the control of response vigor. Psychopharmacology (Berlin), 191, 507-520, 2007] suggested that vigor should be controlled by the opportunity cost of time, which is itself determined by the average rate of reward. This coupling of reward rate and vigor can be shown to be optimal under the theory of average return reinforcement learning for a particular class of tasks but may also be a more general, perhaps hard-wired, characteristic of the architecture of control. We, therefore, tested the hypothesis that healthy human participants would adjust their RTs on the basis of the average rate of reward. We measured RTs in an odd-ball discrimination task for rewards whose magnitudes varied slowly but systematically. Linear regression on the subjects' individual RTs using the time varying average rate of reward as the regressor of interest, and including nuisance regressors such as the immediate reward in a round and in the preceding round, showed that a significant fraction of the variance in subjects' RTs could indeed be explained by the rate of experienced reward. This validates one of the key proposals associated with the model, illuminating an apparently mandatory form of coupling that may involve tonic levels of dopamine.

  7. Optimization of rewards in single machine scheduling in the rewards-driven systems

    Directory of Open Access Journals (Sweden)

    Abolfazl Gharaei

    2015-06-01

    Full Text Available The single machine scheduling problem aims at obtaining the best sequence for a set of jobs in a manufacturing system with a single machine. In this paper, we optimize rewards in single machine scheduling in rewards-driven systems such that total reward is maximized while the constraints contains of limitation in total rewards for earliness and learning, independent of earliness and learning and etc. are satisfied. In mentioned systems as for earliness and learning the bonus is awarded to operators, we consider only rewards in mentioned systems and it will not be penalized under any circumstances. Our objective is to optimize total rewards in mentioned system by taking the rewards in the form of quadratic for both learning and earliness. The recently-developed sequential quadratic programming (SQP, is used by solve the problem. Results show that SQP had satisfactory performance in terms of optimum solutions, number of iterations, infeasibility and optimality error. Finally, a sensitivity analysis is performed on the change rate of the objective function obtained based on the change rate of the “amount of earliness for jobs (Ei parameter”.

  8. Impaired learning of social compared to monetary rewards in autism

    Directory of Open Access Journals (Sweden)

    Alice eLin

    2012-10-01

    Full Text Available A leading hypothesis to explain the social dysfunction in people with autism spectrum disorders (ASD is that they exhibit a deficit in reward processing and motivation specific to social stimuli.  However, there have been few direct tests of this hypothesis to date.  Here we used an instrumental reward learning task that contrasted learning with social rewards (pictures of positive and negative faces against learning with monetary reward (winning and losing money. The two tasks were structurally identical except for the type of reward, permitting direct comparisons.  We tested ten high-functioning people with ASD (7M, 3F and ten healthy controls who were matched on gender, age and education.  We found no significant differences between the two groups in terms of overall ability behaviorally to discriminate positive from negative slot machines, reaction-times, and valence ratings,  However, there was a specific impairment in the ASD group in learning to choose social rewards, compared to monetary rewards: they had a significantly lower cumulative number of choices of the most rewarding social slot machine, and had a significantly slower initial learning rate for the socially rewarding slot machine, compared to the controls.  The findings show a deficit in reward learning in ASD that is greater for social rewards than for monetary rewards, and support the hypothesis of a disproportionate impairment in social reward processing in ASD.

  9. The relationship between personality types and reward preferences

    Directory of Open Access Journals (Sweden)

    R. Nienaber

    2011-12-01

    Full Text Available Orientation: Research has shown that total rewards models structured according to individual preferences, positively influence efforts to attract, retain and motivate key employees. Yet, this is seldom done. Structuring total rewards models according to the preferences of employee segments is a viable alternative to accommodate individual preferences. Research purpose: The primary aim of the study was to determine the relationship between personality types and reward preferences. The secondary aim was to determine the reward preferences for different demographic groups. Motivation for the study: An enhanced understanding of reward preferences for different employee segments will enable employers to offer more competitive reward options to their employees. This may, in turn, have a positive impact on retention. Research design, approach and method: Two measuring instruments, the MBTI® Form GRV and the Rewards Preferences Questionnaire, were distributed electronically to 5 000 potential respondents. The results from 589 sets of questionnaires were used in the data analyses. Primary and secondary factor analyses were done on the items in the Rewards Preferences Questionnaire. Main findings/results: The study confirmed that individuals with certain personality types and personality preferences, have different preferences for certain reward categories. There was a stronger relationship between reward preferences and personality preferences than for reward preferences and personality types. Preferences for reward categories by different demographic groups were confirmed. The significant difference in reward preferences between Black and White respondents in particular was noteworthy, with Black respondents indicating significantly higher mean scores for all reward categories than White respondents. Finally, a total rewards framework influenced by the most prominent preferences for reward categories, was designed. Practical/Managerial implications

  10. Undervaluing delayed rewards explains adolescents' impulsivity in inter-temporal choice: an ERP study.

    Science.gov (United States)

    Huang, Yunyun; Hu, Ping; Li, Xueting

    2017-02-15

    Adolescence has frequently been characterized as a period of choice impulsivity relative to adulthood. According to the control-integrated valuation model of inter-temporal choice, this choice impulsivity may be driven partly by an age-related difference in reward processing. We hypothesized that, compared to adults, adolescents would undervalue delayed rewards during reward processing and would thus be more impulsive in inter-temporal choice. To test this hypothesis at the behavioural and neural levels, we first measured the choice impulsivity of 18 adolescents and 19 adults using a delay discounting task (DDT). Then, we recorded event-related potentials (ERPs) from the participants while they were performing the valuation task, in which monetary gains and losses were either immediate or delayed. The behavioural results showed that adolescents were more impulsive than adults in the DDT. The ERP results showed that, whilst both groups valued immediate rewards, implied by a similarly strong feedback-related negativity (FRN) effect associated with immediate outcomes, adolescents devalued delayed rewards more than adults did, as they produced a significantly smaller FRN effect associated with delayed outcomes. As predicted, the mediation analysis revealed that the adolescents' lower FRN effect of delayed outcomes underpinned their stronger impulsive decision making in the DDT.

  11. Neural representation of reward probability: evidence from the illusion of control.

    Science.gov (United States)

    Kool, Wouter; Getz, Sarah J; Botvinick, Matthew M

    2013-06-01

    To support reward-based decision-making, the brain must encode potential outcomes both in terms of their incentive value and their probability of occurrence. Recent research has made it clear that the brain bears multiple representations of reward magnitude, meaning that a single choice option may be represented differently-and even inconsistently-in different brain areas. There are some hints that the same may be true for reward probability. Preliminary evidence hints that, even as systematic distortions of probability are expressed in behavior, these may not always be uniformly reflected at the neural level: Some neural representations of probability may be immune from such distortions. This study provides new evidence consistent with this possibility. Participants in a behavioral experiment displayed a classic "illusion of control," providing higher estimates of reward probability for gambles they had chosen than for identical gambles that were imposed on them. However, an fMRI study of the same task revealed that neural prediction error signals, arising when gamble outcomes were revealed, were unaffected by the illusion of control. The resulting behavioral-neural dissociation reinforces the case for multiple, inconsistent internal representations of reward probability, while also prompting a reinterpretation of the illusion of control effect itself.

  12. Undervaluing delayed rewards explains adolescents’ impulsivity in inter-temporal choice: an ERP study

    Science.gov (United States)

    Huang, Yunyun; Hu, Ping; Li, Xueting

    2017-01-01

    Adolescence has frequently been characterized as a period of choice impulsivity relative to adulthood. According to the control-integrated valuation model of inter-temporal choice, this choice impulsivity may be driven partly by an age-related difference in reward processing. We hypothesized that, compared to adults, adolescents would undervalue delayed rewards during reward processing and would thus be more impulsive in inter-temporal choice. To test this hypothesis at the behavioural and neural levels, we first measured the choice impulsivity of 18 adolescents and 19 adults using a delay discounting task (DDT). Then, we recorded event-related potentials (ERPs) from the participants while they were performing the valuation task, in which monetary gains and losses were either immediate or delayed. The behavioural results showed that adolescents were more impulsive than adults in the DDT. The ERP results showed that, whilst both groups valued immediate rewards, implied by a similarly strong feedback-related negativity (FRN) effect associated with immediate outcomes, adolescents devalued delayed rewards more than adults did, as they produced a significantly smaller FRN effect associated with delayed outcomes. As predicted, the mediation analysis revealed that the adolescents’ lower FRN effect of delayed outcomes underpinned their stronger impulsive decision making in the DDT. PMID:28198452

  13. Parameters of rewards on choice behavior in Siamese fighting fish (Betta splendens).

    Science.gov (United States)

    Shapiro, Martin S; Jensen, Ashley L

    2009-09-01

    Five experiments were conducted with Siamese fighting fish (Betta splendens) to investigate how choices in a T-maze were affected by parameters of a social reward (aggression display to another male): presence or absence, amount, delay and distance traveled. Bettas showed a preference for the side associated with the presence of another male rather than the side associated with nothing (Exp 1), a greater length of time of the reward (Exp 2) and shorter delay (Exp 3). The animals were indifferent when one side offered a longer delay to a longer reward time compared with a shorter delay to a shorter reward time (Exp 4). What was most surprising, however, was that fish preferred to choose the side that was associated with swimming a greater distance to reach an opponent male (Exp 5). These experiments demonstrate that, while some parameters of a visual reward affect behavior in predictable ways (greater amount, shorter delay), the complex motivations underlying inter-male aggression can produce what appear to be paradoxical results.

  14. Probabilistic reward learning in adults with Attention Deficit Hyperactivity Disorder--an electrophysiological study.

    Science.gov (United States)

    Thoma, Patrizia; Edel, Marc-Andreas; Suchan, Boris; Bellebaum, Christian

    2015-01-30

    Attention Deficit Hyperactivity Disorder (ADHD) is hypothesized to be characterized by altered reinforcement sensitivity. The main aim of the present study was to assess alterations in the electrophysiological correlates of monetary reward processing in adult patients with ADHD of the combined subtype. Fourteen adults with ADHD of the combined subtype and 14 healthy control participants performed an active and an observational probabilistic reward-based learning task while an electroencephalogramm (EEG) was recorded. Regardless of feedback valence, there was a general feedback-related negativity (FRN) enhancement in combination with reduced learning performance during both active and observational reward learning in patients with ADHD relative to healthy controls. Other feedback-locked potentials such as the P200 and P300 and response-locked potentials were unaltered in the patients. There were no significant correlations between learning performance, FRN amplitudes and clinical symptoms, neither in the overall group involving all participants, nor in patients or controls considered separately. This pattern of findings might reflect generally impaired reward prediction in adults with ADHD of the combined subtype. We demonstrated for the first time that patients with ADHD of the combined subtype show not only deficient active reward learning but are also impaired when learning by observing other people׳s outcomes.

  15. Response of the REWARD detection system to the presence of a Radiological Dispersal Device

    Energy Technology Data Exchange (ETDEWEB)

    Luis, R.; Baptista, M.; Barros, S.; Marques, J.; Vaz, P. [IST - Campus Tecnologico e Nuclear, Estrada Nacional 10 - km 139.7, 2695-066, Bobadela LRS (Portugal); Balbuena, J.; Disch, C. [Physical Institut, University of Freiburg Hermann-Herder-Str. 3 D-79104 Freiburg (Germany); Fleta, C.; Jumilla, C.; Lozano, M. [Instituto de Microelectronica de Barcelona - IMB-CNM, CSIC, E-08193 Bellaterra, Barcelona (Spain)

    2015-07-01

    In recent years an increased international concern has emerged about the radiological and nuclear (RN) threats associated with the illicit trafficking of nuclear and radioactive materials that could be potentially used for terrorist attacks. The objective of the REWARD (Real Time Wide Area Radiation Surveillance System) project, co-funded by the European Union 7. Framework Programme Security, consisted in building a mobile system for real time, wide area radiation surveillance, using a CdZnTe detector for gamma radiation and a neutron detector based on novel silicon technologies. The sensing unit includes a GPS system and a wireless communication interface to send the data remotely to a monitoring base station, where it will be analyzed in real time and correlated with historical data from the tag location, in order to generate an alarm when an abnormal situation is detected. Due to its portability and accuracy, the system will be extremely useful in many different scenarios such as nuclear terrorism, lost radioactive sources, radioactive contamination or nuclear accidents. This paper shortly introduces the REWARD detection system, depicts some terrorist threat scenarios involving radioactive sources and special nuclear materials and summarizes the simulation work undertaken during the past three years in the framework of the REWARD project. The main objective consisted in making predictions regarding the behavior of the REWARD system in the presence of a Radiological Dispersion Device (RDD), one of the reference scenarios foreseen for REWARD, using the Monte Carlo simulation program MCNP6. The reference scenario is characterized in detail, from the i) radiological protection, ii) radiation detection requirements and iii) communications points of view. Experimental tests were performed at the Fire Brigades Facilities in Rome and at the Naples Fire Brigades, and the results, which validate the simulation work, are presented and analyzed. The response of the REWARD

  16. Reward and cooperation in the spatial public goods game

    CERN Document Server

    Szolnoki, Attila

    2010-01-01

    The promise of punishment and reward in promoting public cooperation is debatable. While punishment is traditionally considered more successful than reward, the fact that the cost of punishment frequently fails to offset gains from enhanced cooperation has lead some to reconsider reward as the main catalyst behind collaborative efforts. Here we elaborate on the "stick versus carrot" dilemma by studying the evolution of cooperation in the spatial public goods game, where besides the traditional cooperators and defectors, rewarding cooperators supplement the array of possible strategies. The latter are willing to reward cooperative actions at a personal cost, thus effectively downgrading pure cooperators to second-order free-riders due to their unwillingness to bear these additional costs. Consequently, we find that defection remains viable, especially if the rewarding is costly. Rewards, however, can promote cooperation, especially if the synergetic effects of cooperation are low. Surprisingly, moderate reward...

  17. Reward: From Basic Reinforcers to Anticipation of Social Cues.

    Science.gov (United States)

    Rademacher, Lena; Schulte-Rüther, Martin; Hanewald, Bernd; Lammertz, Sarah

    2017-01-01

    Reward processing plays a major role in goal-directed behavior and motivation. On the neural level, it is mediated by a complex network of brain structures called the dopaminergic reward system. In the last decade, neuroscientific researchers have become increasingly interested in aspects of social interaction that are experienced as rewarding. Recent neuroimaging studies have provided evidence that the reward system mediates the processing of social stimuli in a manner analogous to nonsocial rewards and thus motivates social behavior. In this context, the neuropeptide oxytocin is assumed to play a key role by activating dopaminergic reward pathways in response to social cues, inducing the rewarding quality of social interactions. Alterations in the dopaminergic reward system have been found in several psychiatric disorders that are accompanied by social interaction and motivation problems, for example autism, attention deficit/hyperactivity disorder, addiction disorders, and schizophrenia.

  18. Improvement of Brain Reward Abnormalities by Antipsychotic Monotherapy in Schizophrenia

    DEFF Research Database (Denmark)

    Nielsen, Mette Ødegaard; Rostrup, Egill; Wulff, Sanne;

    2012-01-01

    CONTEXT Schizophrenic symptoms are linked to a dysfunction of dopamine neurotransmission and the brain reward system. However, it remains unclear whether antipsychotic treatment, which blocks dopamine transmission, improves, alters, or even worsens the reward-related abnormalities. OBJECTIVE To i...

  19. Modelling and analysis of Markov reward automata (extended version)

    NARCIS (Netherlands)

    Guck, Dennis; Timmer, Mark; Hatefi, Hassan; Ruijters, Enno; Stoelinga, Mariëlle

    2014-01-01

    Costs and rewards are important ingredients for cyberphysical systems, modelling critical aspects like energy consumption, task completion, repair costs, and memory usage. This paper introduces Markov reward automata, an extension of Markov automata that allows the modelling of systems incorporating

  20. Regret-based Reward Elicitation for Markov Decision Processes

    CERN Document Server

    Regan, Kevin

    2012-01-01

    The specification of aMarkov decision process (MDP) can be difficult. Reward function specification is especially problematic; in practice, it is often cognitively complex and time-consuming for users to precisely specify rewards. This work casts the problem of specifying rewards as one of preference elicitation and aims to minimize the degree of precision with which a reward function must be specified while still allowing optimal or near-optimal policies to be produced. We first discuss how robust policies can be computed for MDPs given only partial reward information using the minimax regret criterion. We then demonstrate how regret can be reduced by efficiently eliciting reward information using bound queries, using regret-reduction as a means for choosing suitable queries. Empirical results demonstrate that regret-based reward elicitation offers an effective way to produce near-optimal policies without resorting to the precise specification of the entire reward function.

  1. Social and monetary reward processing in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Delmonte Sonja

    2012-09-01

    Full Text Available Abstract Background Social motivation theory suggests that deficits in social reward processing underlie social impairments in autism spectrum disorders (ASD. However, the extent to which abnormalities in reward processing generalize to other classes of stimuli remains unresolved. The aim of the current study was to examine if reward processing abnormalities in ASD are specific to social stimuli or can be generalized to other classes of reward. Additionally, we sought to examine the results in the light of behavioral impairments in ASD. Methods Participants performed adapted versions of the social and monetary incentive delay tasks. Data from 21 unmedicated right-handed male participants with ASD and 21 age- and IQ-matched controls were analyzed using a factorial design to examine the blood-oxygen-level-dependent (BOLD response during the anticipation and receipt of both reward types. Results Behaviorally, the ASD group showed less of a reduction in reaction time (RT for rewarded compared to unrewarded trials than the control group. In terms of the fMRI results, there were no significant group differences in reward circuitry during reward anticipation. During the receipt of rewards, there was a significant interaction between group and reward type in the left dorsal striatum (DS. The ASD group showed reduced activity in the DS compared to controls for social rewards but not monetary rewards and decreased activation for social rewards compared to monetary rewards. Controls showed no significant difference between the two reward types. Increased activation in the DS during social reward processing was associated with faster response times for rewarded trials, compared to unrewarded trials, in both groups. This is in line with behavioral results indicating that the ASD group showed less of a reduction in RT for rewarded compared to unrewarded trials. Additionally, de-activation to social rewards was associated with increased repetitive behavior in

  2. EFFECT OF EXTRINSIC REWARDS ON MOTIVATION.

    Science.gov (United States)

    GLADSTONE, ROY

    THE SPECIFIC PROBLEM WAS WHETHER HUMANS, AFTER HAVING BEEN TRAINED ON A GIVEN REWARD SCHEDULE TO ACT IN A GIVEN WAY IN GIVEN CIRCUMSTANCES, WILL EXHIBIT FIXED EXTINCTION BEHAVIOR REGARDLESS OF THE DIFFERENCES BETWEEN THE TRAINING AND THE EXTINCTION PERIODS. SUBJECTS WERE 360 COLLEGE STUDENTS WHO HAD VOLUNTEERED FOR THE EXPERIMENT. AN APPARATUS WAS…

  3. Competitive Pressure on China : Factor Rewards Migration

    NARCIS (Netherlands)

    Ten Raa, T.; Pan, H.

    2001-01-01

    Our objective is to assess personal income under perfect competition, when factors are rewarded according to their productivities, and to contrast the ensuing distribution with the status quo.Competition will yield winners and losers, both in terms of factor claims and in terms of regions or provinc

  4. Motivating Intrapreneurs: The Relevance of Rewards

    Science.gov (United States)

    de Villiers-Scheepers, M. J.

    2011-01-01

    A challenge faced by management graduates in promoting intrapreneurship to achieve competitive advantage is the use of motivational techniques that build commitment to entrepreneurial behaviour. Despite the acknowledged importance of rewards to encourage innovation, there is surprisingly little empirical evidence to provide guidance on which…

  5. Should Voluntary Services Be Financially Rewarded?

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ The city of Suqian in east China's Jiangsu Province, put a new regulation into practice six months ago whereby police authorities reward residents who volunteer to make peace in neighborhood quarrels, mediate in civil disputes or, for that matter, help in put-ring out fires.

  6. Should Voluntary Services Be Financially Rewarded?

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The city of Suqian in east China’s Jiangsu Province,put a new regulation into practice six months ago whereby police authorities reward residents who volunteer to make peace in neighborhood quarrels,mediate in civil disputes or,for that matter,help in putting out fires.

  7. Encouraging Classroom Participation with Empty Extrinsic Rewards

    Science.gov (United States)

    Guinee, William

    2012-01-01

    In this article, the author talks about how to encourage classroom participation with empty extrinsic rewards. He uses "bonus points" in awarding students for particularly interesting or well thought-out contributions to the class discussion. These bonus points have absolutely no effect on the student's course grade. But the students respond…

  8. Sensitivity and bias in decision-making under risk: evaluating the perception of reward, its probability and value.

    Directory of Open Access Journals (Sweden)

    Madeleine E Sharp

    Full Text Available BACKGROUND: There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. OBJECTIVE: We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. DESIGN/METHODS: Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. RESULTS: Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a 'risk premium' of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. CONCLUSIONS: This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia.

  9. Brain mechanisms of drug reward and euphoria.

    Science.gov (United States)

    Wise, R A; Bozarth, M A

    1985-01-01

    Drugs of abuse have in common the fact that they serve as biological rewards. They presumably do so because of their ability to activate endogenous brain circuitry. By determining the brain circuitry activated by rewarding drug injections, much can be learned about the degree to which there is a common basis for the abuse liability of seemingly different drugs. The brain circuitry activated by two classes of abused drugs, psychomotor stimulants and opiates, is now partially understood; the current evidence suggests a shared mechanism of stimulant reward and opiate reward. The identified portion of the circuitry involves dopamine-containing cells of the ventral tegmental area and their fiber projections to the cells of the nucleus accumbens. Morphine activates these cells in the region of the cell bodies; it may have direct actions on receptors imbedded in the dopaminergic cell membrane, or it may act on afferent terminals that synapse on the dopaminergic cell bodies or dendrites. Cocaine and amphetamine act at the terminals of the dopaminergic fibers to nucleus accumbens and perhaps other structures. The shared activation of the dopaminergic input to nucleus accumbens accounts for the behaviorally activating and the rewarding effects of both stimulants and opiates (the opiate stimulant action is not widely known because it is usually masked by depressant actions of opiates in other, antagonistic, brain circuits). The activation of dopaminergic systems also accounts for amphetamine euphoria; it almost certainly accounts for cocaine euphoria and it probably accounts for opiate euphoria as well. Opiates and psychomotor stimulants clearly have many other actions which are not shared; nonshared actions must account for the well-known differences in the subjective effects of opiates and stimulants. One of the major nonshared actions is physical dependence. Opiates gain access to a major component of the circuitry mediating opiate physical dependence through opiate

  10. Chromosomal aberration frequency in lymphocytes predicts the risk of cancer

    DEFF Research Database (Denmark)

    Bonassi, Stefano; Norppa, Hannu; Ceppi, Marcello

    2008-01-01

    studies and to evaluate the strength of this association, a pooled analysis was carried out. The pooled database included 11 national cohorts and a total of 22 358 cancer-free individuals who underwent genetic screening with CA for biomonitoring purposes during 1965-2002 and were followed up for cancer...... for stomach cancer [RR(medium) = 1.17 (95% CI = 0.37-3.70), RR(high) = 3.13 (95% CI = 1.17-8.39)]. Exposure to carcinogens did not modify the effect of CA levels on overall cancer risk. These results reinforce the evidence of a link between CA frequency and cancer risk and provide novel information...

  11. Agent Reward Shaping for Alleviating Traffic Congestion

    Science.gov (United States)

    Tumer, Kagan; Agogino, Adrian

    2006-01-01

    Traffic congestion problems provide a unique environment to study how multi-agent systems promote desired system level behavior. What is particularly interesting in this class of problems is that no individual action is intrinsically "bad" for the system but that combinations of actions among agents lead to undesirable outcomes, As a consequence, agents need to learn how to coordinate their actions with those of other agents, rather than learn a particular set of "good" actions. This problem is ubiquitous in various traffic problems, including selecting departure times for commuters, routes for airlines, and paths for data routers. In this paper we present a multi-agent approach to two traffic problems, where far each driver, an agent selects the most suitable action using reinforcement learning. The agent rewards are based on concepts from collectives and aim to provide the agents with rewards that are both easy to learn and that if learned, lead to good system level behavior. In the first problem, we study how agents learn the best departure times of drivers in a daily commuting environment and how following those departure times alleviates congestion. In the second problem, we study how agents learn to select desirable routes to improve traffic flow and minimize delays for. all drivers.. In both sets of experiments,. agents using collective-based rewards produced near optimal performance (93-96% of optimal) whereas agents using system rewards (63-68%) barely outperformed random action selection (62-64%) and agents using local rewards (48-72%) performed worse than random in some instances.

  12. Neurophysiological differences in reward processing in anhedonics.

    Science.gov (United States)

    Padrão, Gonçalo; Mallorquí, Aida; Cucurell, David; Marco-Pallares, Josep; Rodriguez-Fornells, Antoni

    2013-03-01

    Anhedonia is characterized by a reduced capacity to experience pleasure in response to rewarding stimuli and has been considered a possible candidate endophenotype in depression and schizophrenia. However, it is still not well understood whether these reward deficits are confined to anticipatory and/or to consummatory experiences of pleasure. In the present study, we recorded electrophysiological responses (event-related brain potentials [ERPs] and oscillatory activity) to monetary gains and losses in extreme groups of anhedonic and nonanhedonic participants. The anhedonic participants showed reduced motivation to incur risky decisions, especially after monetary rewards. These sequential behavioral effects were correlated with an increased sensitivity to punishment, which psychometrically characterized the anhedonic group. In contrast, both electrophysiological measures associated with the impacts of monetary losses and gains--the feedback-related negativity (FRN) and the beta-gamma oscillatory component--clearly revealed preserved consummatory responses in anhedonic participants. However, anhedonics showed a drastic increase in frontal medial theta power after receiving the maximum monetary gain. This increase in theta oscillatory activity could be associated with an increase in conflict and cognitive control for unexpected large positive rewards, thus indexing the violation of default negative expectations built up across the task in anhedonic participants. Thus, the present results showed that participants with elevated scores on Chapman's Physical Anhedonia Scale were more sensitive to possible punishments, showed deficits in the correct integration of response outcomes in their actions, and evidenced deficits in sustaining positive expectations of future rewards. This overall pattern suggests an effect of anhedonia in the motivational aspects of approach behavior rather than in consummatory processes.

  13. Framing Reinforcement Learning from Human Reward: Reward Positivity, Temporal Discounting, Episodicity, and Performance

    Science.gov (United States)

    2014-09-29

    value function approximation is an active area of research ( Parr et al., 2008; Mahadevan, 2009; Taylor and Parr , 2009; Boots and Gordon, 2010), but it is...Publishers Inc. Ng, A., Harada, D., Russell , S., 1999. Policy invariance under reward transfor- mations: Theory and application to reward shaping. ICML...strategy. In: Proceedings of the IEEE/ACM International Conference on Human-Robot Interaction. 43 Parr , R., Li, L., Taylor, G., Painter-Wakefield, C

  14. Neural response to reward anticipation is modulated by Gray's impulsivity.

    Science.gov (United States)

    Hahn, Tim; Dresler, Thomas; Ehlis, Ann-Christine; Plichta, Michael M; Heinzel, Sebastian; Polak, Thomas; Lesch, Klaus-Peter; Breuer, Felix; Jakob, Peter M; Fallgatter, Andreas J

    2009-07-15

    According to the Reinforcement Sensitivity Theory (RST), Gray's dimension of impulsivity, reflecting human trait reward sensitivity, determines the extent to which stimuli activate the Behavioural Approach System (BAS). The potential neural underpinnings of the BAS, however, remain poorly understood. In the present study, we examined the association between Gray's impulsivity as defined by the RST and event-related fMRI BOLD-response to anticipation of reward in twenty healthy human subjects in brain regions previously associated with reward processing. Anticipation of reward during a Monetary Incentive Delay Task elicited activation in key components of the human reward circuitry such as the ventral striatum, the amygdala and the orbitofrontal cortex. Interindividual differences in Gray's impulsivity accounted for a significant amount of variance of the reward-related BOLD-response in the ventral striatum and the orbitofrontal cortex. Specifically, higher trait reward sensitivity was associated with increased activation in response to cues indicating potential reward. Extending previous evidence, here we show that variance in functional brain activation during anticipation of reward is attributed to interindividual differences regarding Gray's dimension of impulsivity. Thus, trait reward sensitivity contributes to the modulation of responsiveness in major components of the human reward system which thereby display a core property of the BAS. Generally, fostering our understanding of the neural underpinnings of the association of reward-related interindividual differences in affective traits might aid researchers in quest for custom-tailored treatments of psychiatric disorders, further disentangling the complex relationship between personality traits, emotion, and health.

  15. Rewards versus Learning: A Response to Paul Chance.

    Science.gov (United States)

    Kohn, Alfie

    1993-01-01

    Responding to Paul Chance's November 1992 "Kappan" article on motivational value of rewards, this article argues that manipulating student behavior with either punishments or rewards is unnecessary and counterproductive. Extrinsic rewards can never buy more than short-term compliance because they are inherently controlling and…

  16. Changes in reward-induced brain activation in opiate addicts

    NARCIS (Netherlands)

    Martin-Soelch, C; Chevalley, AF; Kunig, G; Missimer, J; Magyar, S; Mino, A; Schultz, W; Leenders, KL

    2001-01-01

    Many studies indicate a role of the cerebral dopaminergic reward system in addiction. Motivated by these findings, we examined in opiate addicts whether brain regions involved in the reward circuitry also react to human prototypical rewards. We measured regional cerebral blood flow (rCBF) with (H2O)

  17. Motivating Inhibition--Reward Prospect Speeds up Response Cancellation

    Science.gov (United States)

    Boehler, Carsten N.; Hopf, Jens-Max; Stoppel, Christian M.; Krebs, Ruth M.

    2012-01-01

    Reward prospect has been demonstrated to facilitate various cognitive and behavioral operations, particularly by enhancing the speed and vigor of processes linked to approaching reward. Studies in this domain typically employed task regimes in which participants' overt responses are facilitated by prospective rewards. In contrast, we demonstrate…

  18. Should Rewards Have a Place in Early Childhood Programs?

    Science.gov (United States)

    Shiller, Virginia M.; O'Flynn, Janet C.; Reineke, June; Sonsteng, Kathleen; Gartrell, Dan

    2008-01-01

    Does the use of rewards to motivate children to learn or to follow classroom rules run counter to fostering a true desire for mastery? This column, which consists of two separate articles, provides the opposing opinions of the authors regarding the appropriateness of giving rewards in an early childhood classroom. In "Using Rewards in the Early…

  19. Extending Markov Automata with State and Action Rewards

    NARCIS (Netherlands)

    Guck, Dennis; Timmer, Mark; Blom, Stefan; Bertrand, N.; Bortolussi, L.

    2014-01-01

    This presentation introduces the Markov Reward Automaton (MRA), an extension of the Markov automaton that allows the modelling of systems incorporating rewards in addition to nondeterminism, discrete probabilistic choice and continuous stochastic timing. Our models support both rewards that are acqu

  20. Extrinsic Rewards Undermine Altruistic Tendencies in 20-Month-Olds

    Science.gov (United States)

    Warneken, Felix; Tomasello, Michael

    2008-01-01

    The current study investigated the influence of rewards on very young children's helping behavior. After 20-month-old infants received a material reward during a treatment phase, they subsequently were less likely to engage in further helping during a test phase as compared with infants who had previously received social praise or no reward at…

  1. Using Rewards To Teach Students with Disabilities: Implications for Motivation.

    Science.gov (United States)

    Witzel, Bradley S.; Mercer, Cecil D.

    2003-01-01

    This article presents and compares current research practices surrounding the use of rewards in classroom management. A motivational model emerges of the use of extrinsic rewards with special needs learners to build intrinsic motivation. Teachers' use of praise as the focal point to multiple rewards and students' need for equity are also…

  2. Managing Simultaneous Renewal: Reward Structures for School and University Faculty.

    Science.gov (United States)

    Carnes, Nate; Schwager, Susan

    2000-01-01

    Examined the impact of rewards and reward structures for mentor teachers and university faculty engaged in preparing teachers and the ongoing professional development of veteran teachers within Professional Development Schools. School faculty cited extrinsic reward structures as inadequate, emphasizing their importance as incentives for…

  3. Crash risk and aberrant driving behaviors among bus drivers: the role of personality and attitudes towards traffic safety.

    Science.gov (United States)

    Mallia, Luca; Lazuras, Lambros; Violani, Cristiano; Lucidi, Fabio

    2015-06-01

    Several studies have shown that personality traits and attitudes toward traffic safety predict aberrant driving behaviors and crash involvement. However, this process has not been adequately investigated in professional drivers, such as bus drivers. The present study used a personality-attitudes model to assess whether personality traits predicted aberrant self-reported driving behaviors (driving violations, lapses, and errors) both directly and indirectly, through the effects of attitudes towards traffic safety in a large sample of bus drivers. Additionally, the relationship between aberrant self-reported driving behaviors and crash risk was also assessed. Three hundred and one bus drivers (mean age=39.1, SD=10.7 years) completed a structured and anonymous questionnaire measuring personality traits, attitudes toward traffic safety, self-reported aberrant driving behaviors (i.e., errors, lapses, and traffic violations), and accident risk in the last 12 months. Structural equation modeling analysis revealed that personality traits were associated to aberrant driving behaviors both directly and indirectly. In particular altruism, excitement seeking, and normlessness directly predicted bus drivers' attitudes toward traffic safety which, in turn, were negatively associated with the three types of self-reported aberrant driving behaviors. Personality traits relevant to emotionality directly predicted bus drivers' aberrant driving behaviors, without any mediation of attitudes. Finally, only self-reported violations were related to bus drivers' accident risk. The present findings suggest that the hypothesized personality-attitudes model accounts for aberrant driving behaviors in bus drivers, and provide the empirical basis for evidence-based road safety interventions in the context of public transport.

  4. Dopamine in the Brain: Hypothesizing Surfeit or Deficit Links to Reward and Addiction

    Science.gov (United States)

    Blum, Kenneth; Thanos, Peter K.; Oscar-Berman, Marlene; Febo, Marcelo; Baron, David; Badgaiyan, Rajendra D.; Gardner, Eliot; Demetrovics, Zsolt; Fahlke, Claudia; Haberstick, Brett C.; Dushaj, Kristina; Gold, Mark S.

    2016-01-01

    Recently there has been debate concerning the role of brain dopamine in reward and addiction. David Nutt and associates eloquently proposed that dopamine (DA) may be central to psycho stimulant dependence and some what important for alcohol, but not important for opiates, nicotine or even cannabis. Others have also argued that surfeit theories can explain for example cocaine seeking behavior as well as non-substance-related addictive behaviors. It seems prudent to distinguish between what constitutes “surfeit” compared to” deficit” in terms of short-term (acute) and long-term (chronic) brain reward circuitry responsivity. In an attempt to resolve controversy regarding the contributions of mesolimbic DA systems to reward, we review the three main competing explanatory categories: “liking”, “learning”, and “wanting”. They are (a) the hedonic impact -liking reward, (b) the ability to predict rewarding effects-learning and (c) the incentive salience of reward-related stimuli -wanting. In terms of acute effects, most of the evidence seems to favor the “surfeit theory”. Due to preferential dopamine release at mesolimbic-VTA-caudate-accumbens loci most drugs of abuse and Reward Deficiency Syndrome (RDS) behaviors have been linked to heightened feelings of well-being and hyperdopaminergic states.The “dopamine hypotheses” originally thought to be simple, is now believed to be quite complex and involves encoding the set point of hedonic tone, encoding attention, reward expectancy, and incentive motivation. Importantly, Willuhn et al. shows that in a self-administration paradigm, (chronic) excessive use of cocaine is caused by decreased phasic dopamine signaling in the striatum. In terms of chronic addictions, others have shown a blunted responsivity at brain reward sites with food, nicotine, and even gambling behavior. Finally, we are cognizant of the differences in dopaminergic function as addiction progresses and argue that relapse may be tied

  5. The left hemisphere learns what is right: Hemispatial reward learning depends on reinforcement learning processes in the contralateral hemisphere.

    Science.gov (United States)

    Aberg, Kristoffer Carl; Doell, Kimberly Crystal; Schwartz, Sophie

    2016-08-01

    Orienting biases refer to consistent, trait-like direction of attention or locomotion toward one side of space. Recent studies suggest that such hemispatial biases may determine how well people memorize information presented in the left or right hemifield. Moreover, lesion studies indicate that learning rewarded stimuli in one hemispace depends on the integrity of the contralateral striatum. However, the exact neural and computational mechanisms underlying the influence of individual orienting biases on reward learning remain unclear. Because reward-based behavioural adaptation depends on the dopaminergic system and prediction error (PE) encoding in the ventral striatum, we hypothesized that hemispheric asymmetries in dopamine (DA) function may determine individual spatial biases in reward learning. To test this prediction, we acquired fMRI in 33 healthy human participants while they performed a lateralized reward task. Learning differences between hemispaces were assessed by presenting stimuli, assigned to different reward probabilities, to the left or right of central fixation, i.e. presented in the left or right visual hemifield. Hemispheric differences in DA function were estimated through differential fMRI responses to positive vs. negative feedback in the left vs. right ventral striatum, and a computational approach was used to identify the neural correlates of PEs. Our results show that spatial biases favoring reward learning in the right (vs. left) hemifield were associated with increased reward responses in the left hemisphere and relatively better neural encoding of PEs for stimuli presented in the right (vs. left) hemifield. These findings demonstrate that trait-like spatial biases implicate hemisphere-specific learning mechanisms, with individual differences between hemispheres contributing to reinforcing spatial biases.

  6. Metering, settlement and export reward options for micro-generation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report presents the results of a study carried out as part of the Department of Trade and Industry's New and Renewable Energy Programme to evaluate the costs and benefits of various metering, settlement and export reward opportunities for both renewable and non-renewable forms of microgeneration based on existing projections to 2020. The technologies studied included single and three-phase applications of: solar photovoltaic (rated at 1 kW per installation); small-scale wind generation (rated at 1 kW per installation); micro-CHP (combined heat and power) (rated at 1.1 kW per installation); and micro-hydropower (rated at 3.7 and 6.4 kW per installation). The report outlines a number of different options for metering, settlement and export rewards, and describes the development of an economic model to quantify their costs and benefits. This model is then used to predict the future costs and benefits of the various options. The potential value of the options to the UK economy and any environmental benefits are discussed and a commentary on possible barriers to implementation is provided.

  7. Associations between sensitivity to punishment, sensitivity to reward, and gambling.

    Science.gov (United States)

    Gaher, Raluca M; Hahn, Austin M; Shishido, Hanako; Simons, Jeffrey S; Gaster, Sam

    2015-03-01

    The majority of individuals gamble during their lifetime; however only a subset of these individuals develops problematic gambling. Gray's Reinforcement Sensitivity Theory may be relevant to understanding gambling problems. Differences in sensitivity to punishments and rewards can influence an individual's behavior and may be pertinent to the development of gambling problems. This study examined the functional associations between sensitivity to punishment (SP), sensitivity to reward (SR), and gambling problems in a sample of 2254 college students. Zero-inflated negative binomial regression was used to predict gambling problems as well as the absence of gambling problems. Gambling problems were hypothesized to be positively associated with SR and inversely associated with SP. In addition, SP was hypothesized to moderate the association between SR and gambling problems, attenuating the strength of the association. As hypothesized, SR was positively associated with gambling problems. However, SP did not moderate the relationship between SR and gambling problems. SP did, however, moderate the relationship between SR and the likelihood of never experiencing gambling problems. The results demonstrate that individual differences in SP and SR are functionally associated with gambling problems.

  8. Anti-forensics of chromatic aberration

    Science.gov (United States)

    Mayer, Owen; Stamm, Matthew C.

    2015-03-01

    Over the past decade, a number of information forensic techniques have been developed to identify digital image manipulation and falsification. Recent research has shown, however, that an intelligent forger can use anti-forensic countermeasures to disguise their forgeries. In this paper, an anti-forensic technique is proposed to falsify the lateral chromatic aberration present in a digital image. Lateral chromatic aberration corresponds to the relative contraction or expansion between an image's color channels that occurs due to a lens's inability to focus all wavelengths of light on the same point. Previous work has used localized inconsistencies in an image's chromatic aberration to expose cut-and-paste image forgeries. The anti-forensic technique presented in this paper operates by estimating the expected lateral chromatic aberration at an image location, then removing deviations from this estimate caused by tampering or falsification. Experimental results are presented that demonstrate that our anti-forensic technique can be used to effectively disguise evidence of an image forgery.

  9. Optical advantages of astigmatic aberration corrected heliostats

    Science.gov (United States)

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  10. [Aberrant pancreas with a double intestinal location].

    Science.gov (United States)

    Yenon, K; Lethurgie, C; Bokobza, B

    2005-01-01

    The authors report one exceptional case of aberrant pancreas with a double intestinal location (jejunum and Meckel's diverticulum) in a thirty-year-old patient. Digestive haemorrhage and the abdominal colic were the revealing clinical signs. The enteroscopy guided by the enteroscanner, was the indicated complementary investigation for the preoperative diagnosis. The research of other locations during the operation should be systematic.

  11. Functional Analysis and Treatment of Aberrant Behavior.

    Science.gov (United States)

    Mace, F. Charles; And Others

    1991-01-01

    This article reviews general classes of variables which help to maintain aberrant behavior including attention seeking, sensory and perceptual consequences, and access to materials or activities. Suggestions for a methodology providing a comprehensive functional analysis are offered which include descriptive analysis, hypothesis forming,…

  12. The correction of electron lens aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hawkes, P.W., E-mail: peter.hawkes@cemes.fr

    2015-09-15

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. - Highlights: • Geometrical aberration correction. • Chromatic aberration correction. • 50 pm resolution. • High-resolution electron energy-loss spectroscopy. • Extensive bibliographies.

  13. Prenatal hydronephrosis caused by aberrant renal vessels

    DEFF Research Database (Denmark)

    Lenz, K; Thorup, Jørgen Mogens; Rabol, A;

    1996-01-01

    With routine use of obstetric ultrasonography, fetal low-grade hydronephrosis is commonly detected, but may resolve spontaneously after birth. Two cases are presented to illustrate that in some cases such findings can express intermittent hydronephrosis caused by aberrant renal vessels. Renal...

  14. Aberrant Force Processing in Schizophrenia.

    Science.gov (United States)

    Martinelli, Cristina; Rigoli, Francesco; Shergill, Sukhwinder S

    2016-07-06

    Initially considered as mere side effects of antipsychotic medication, there is now evidence that motor and somatosensory disturbances precede the onset of the illness and can be found in drug-naive patients. However, research on the topic is scarce. Here, we were interested in assessing the accuracy of the neural signal in detecting parametric variations of force linked to a voluntary motor act and a received tactile sensation, either self-generated or externally generated. Patients with a diagnosis of schizophrenia and healthy controls underwent functional magnetic resonance imaging while asked to press, or abstain from pressing, a lever in order to match a visual target force. Forces, exerted and received, varied on 10 levels from 0.5 N to 5 N in 0.5 N increments. Healthy participants revealed a positive correlation between force and activity in contralateral primary somatosensory area (S1) when performing a movement as well as when receiving a tactile sensation but only when this was externally, and not self-, generated. Patients showed evidence of altered force signaling in both motor and tactile conditions, as well as increased correlation with force when tactile sensation was self-generated. Findings are interpreted in line with accounts of predictive and sensory integration mechanisms and point toward alterations in the encoding of parametric forces in the motor and somatosensory domain in patients affected by schizophrenia.

  15. A collateral effect of reward predicted by matching theory.

    OpenAIRE

    Mace, F C; McCurdy, B; Quigley, E A

    1990-01-01

    Matching theory describes a process by which organisms distribute their behavior between two or more concurrent schedules of reinforcement (Herrnstein, 1961). In an attempt to determine the generality of matching theory to applied settings, 2 students receiving special education were provided with academic response alternatives. Using a combined simultaneous treatments design and reversal design, unequal ratio schedules of reinforcement were varied across two academic responses. Findings indi...

  16. The role of fair treatment and rewards in perceptions of organizational support and leader-member exchange.

    Science.gov (United States)

    Wayne, Sandy J; Shore, Lynn M; Bommer, William H; Tetrick, Lois E

    2002-06-01

    This study examined a model of the antecedents and consequences of perceived organizational support (POS) and leader-member exchange (LMX). It was predicted that organizational justice (procedural and distributive justice) and organizational practices that provide recognition to the employee (feelings of inclusion and recognition from upper management) would influence POS. For LMX, it was predicted that leader reward (distributive justice and contingent rewards) and punishment behavior would be important antecedents. Results based on a sample of 211 employee-supervisor dyads indicated that organizational justice, inclusion, and recognition were related to POS and contingent rewards were related to LMX. In terms of consequences, POS was related to employee commitment and organizational citizenship behavior, whereas LMX predicted performance ratings.

  17. Identity-Specific Reward Representations in Orbitofrontal Cortex Are Modulated by Selective Devaluation.

    Science.gov (United States)

    Howard, James D; Kahnt, Thorsten

    2017-03-08

    Goal-directed behavior is sensitive to the current value of expected outcomes. This requires independent representations of specific rewards, which have been linked to orbitofrontal cortex (OFC) function. However, the mechanisms by which the human brain updates specific goals on the fly, and translates those updates into choices, have remained unknown. Here we implemented selective devaluation of appetizing food odors in combination with pattern-based neuroimaging and a decision-making task. We found that in a hungry state, participants chose to smell high-intensity versions of two value-matched food odor rewards. After eating a meal corresponding to one of the two odors, participants switched choices toward the low intensity of the sated odor but continued to choose the high intensity of the nonsated odor. This sensory-specific behavioral effect was mirrored by pattern-based changes in fMRI signal in lateral posterior OFC, where specific reward identity representations were altered after the meal for the sated food odor but retained for the nonsated counterpart. In addition, changes in functional connectivity between the OFC and general value coding in ventromedial prefrontal cortex (vmPFC) predicted individual differences in satiety-related choice behavior. These findings demonstrate how flexible representations of specific rewards in the OFC are updated by devaluation, and how functional connections to vmPFC reflect the current value of outcomes and guide goal-directed behavior.SIGNIFICANCE STATEMENT The orbitofrontal cortex (OFC) is critical for goal-directed behavior. A recent proposal is that OFC fulfills this function by representing a variety of state and task variables ("cognitive maps"), including a conjunction of expected reward identity and value. Here we tested how identity-specific representations of food odor reward are updated by satiety. We found that fMRI pattern-based signatures of reward identity in lateral posterior OFC were modulated after

  18. Finding intrinsic rewards by embodied evolution and constrained reinforcement learning.

    Science.gov (United States)

    Uchibe, Eiji; Doya, Kenji

    2008-12-01

    Understanding the design principle of reward functions is a substantial challenge both in artificial intelligence and neuroscience. Successful acquisition of a task usually requires not only rewards for goals, but also for intermediate states to promote effective exploration. This paper proposes a method for designing 'intrinsic' rewards of autonomous agents by combining constrained policy gradient reinforcement learning and embodied evolution. To validate the method, we use Cyber Rodent robots, in which collision avoidance, recharging from battery packs, and 'mating' by software reproduction are three major 'extrinsic' rewards. We show in hardware experiments that the robots can find appropriate 'intrinsic' rewards for the vision of battery packs and other robots to promote approach behaviors.

  19. The role of the orbitofrontal cortex in the pursuit of happiness and more specific rewards.

    Science.gov (United States)

    Burke, Kathryn A; Franz, Theresa M; Miller, Danielle N; Schoenbaum, Geoffrey

    2008-07-17

    Cues that reliably predict rewards trigger the thoughts and emotions normally evoked by those rewards. Humans and other animals will work, often quite hard, for these cues. This is termed conditioned reinforcement. The ability to use conditioned reinforcers to guide our behaviour is normally beneficial; however, it can go awry. For example, corporate icons, such as McDonald's Golden Arches, influence consumer behaviour in powerful and sometimes surprising ways, and drug-associated cues trigger relapse to drug seeking in addicts and animals exposed to addictive drugs, even after abstinence or extinction. Yet, despite their prevalence, it is not known how conditioned reinforcers control human or other animal behaviour. One possibility is that they act through the use of the specific rewards they predict; alternatively, they could control behaviour directly by activating emotions that are independent of any specific reward. In other words, the Golden Arches may drive business because they evoke thoughts of hamburgers and fries, or instead, may be effective because they also evoke feelings of hunger or happiness. Moreover, different brain circuits could support conditioned reinforcement mediated by thoughts of specific outcomes versus more general affective information. Here we have attempted to address these questions in rats. Rats were trained to learn that different cues predicted different rewards using specialized conditioning procedures that controlled whether the cues evoked thoughts of specific outcomes or general affective representations common to different outcomes. Subsequently, these rats were given the opportunity to press levers to obtain short and otherwise unrewarded presentations of these cues. We found that rats were willing to work for cues that evoked either outcome-specific or general affective representations. Furthermore the orbitofrontal cortex, a prefrontal region important for adaptive decision-making, was critical for the former but not for

  20. DNA Copy Number Aberrations in Breast Cancer by Array Comparative Genomic Hybridization

    Institute of Scientific and Technical Information of China (English)

    Jian Li; Kai Wang; Shengting Li; Vera Timmermans-Wielenga; Fritz Rank; Carsten Wiuf; Xiuqing Zhang; Huanming Yang; Lars Bolund

    2009-01-01

    Array comparative genomic hybridization (CGH) has been popularly used for an-alyzing DNA copy number variations in diseases like cancer. In this study, we investigated 82 sporadic samples from 49 breast cancer patients using 1-Mb reso-lution bacterial artificial chromosome CGH arrays. A number of highly frequent genomic aberrations were discovered, which may act as "drivers" of tumor pro-gression. Meanwhile, the genomic profiles of four "normal" breast tissue samples taken at least 2 cm away from the primary tumor sites were also found to have some genomic aberrations that recurred with high frequency in the primary tu-mors, which may have important implications for clinical therapy. Additionally, we performed class comparison and class prediction for various clinicopathological pa-rameters, and a list of characteristic genomic aberrations associated with different clinicopathological phenotypes was compiled. Our study provides clues for further investigations of the underlying mechanisms of breast carcinogenesis.

  1. Exploring the depth range for three-dimensional laser machining with aberration correction.

    Science.gov (United States)

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  2. Exoplanet detection with simultaneous spectral differential imaging: effects of out-of-pupil-plane optical aberrations

    CERN Document Server

    Marois, C; Marois, Christian; Macintosh, Don W. Phillion & Bruce

    2006-01-01

    Imaging faint companions (exoplanets and brown dwarfs) around nearby stars is currently limited by speckle noise. To efficiently attenuate this noise, a technique called simultaneous spectral differential imaging (SSDI) can be used. This technique consists of acquiring simultaneously images of the field of view in several adjacent narrow bands and in combining these images to suppress speckles. Simulations predict that SSDI can achieve, with the acquisition of three wavelengths, speckle noise attenuation of several thousands. These simulations are usually performed using the Fraunhofer approximation, i.e. considering that all aberrations are located in the pupil plane. We have performed wavefront propagation simulations to evaluate how out-of-pupil-plane aberrations affect SSDI speckle noise attenuation performance. The Talbot formalism is used to give a physical insight of the problem; results are confirmed using a proper wavefront propagation algorithm. We will show that near-focal-plane aberrations can sig...

  3. Effort-reward imbalance and burnout among German nurses in medical compared with psychiatric hospital settings.

    Science.gov (United States)

    Schulz, M; Damkröger, A; Heins, C; Wehlitz, L; Löhr, M; Driessen, M; Behrens, J; Wingenfeld, K

    2009-04-01

    The aim of this study was to investigate whether nurses' efforts and rewards, as well as the effort-reward imbalance (ERI) and burnout, differ between subjects working in psychiatric vs. medical hospitals and between nurses under education and examined nurses respectively. Furthermore, the relationship between ERI and burnout was evaluated. Nursing is associated with high levels of emotional strain and heavy workloads. Burnout and a negative ERI can result in high absenteeism and turnover and have been identified as reasons why nurses leave their profession. In the last decade, working conditions of the nursing profession have changed in Germany, but somatic and psychiatric hospitals developed in different ways. This development may lead to different profiles. A sample of 389 nurses (78.8% female) in four German hospitals was investigated. A total of 147 nurses worked in psychiatric hospitals and 236 nurses worked in medical (somatic) hospitals. Fifty participants were still under education. The Effort-Reward Imbalance Inventory measures effort, reward and overcommitment at job and provides an imbalance score between effort and reward. The Maslach Burnout Inventory with the subscales, emotional exhaustion, lack of accomplishment and depersonalization, was also used. Nurses working in medical hospitals reported more burnout and had higher ERI scores. Subjects under education were comparable to examined nurses in terms of burnout but had lower ERI scores. Multiple regression analyses showed all ERI scales to be significant predictors for emotional exhaustion, while age, field of work and educational status further predict effort or ERI respectively. At present, the working situation of nurses in different settings appears to be characterized by a perceived imbalance of effort and reward and is associated with a high risk of developing burnout symptoms.

  4. Reward system and temporal pole contributions to affective evaluation during a first person shooter video game

    Directory of Open Access Journals (Sweden)

    Weber René

    2011-07-01

    Full Text Available Abstract Background Violent content in video games evokes many concerns but there is little research concerning its rewarding aspects. It was demonstrated that playing a video game leads to striatal dopamine release. It is unclear, however, which aspects of the game cause this reward system activation and if violent content contributes to it. We combined functional Magnetic Resonance Imaging (fMRI with individual affect measures to address the neuronal correlates of violence in a video game. Results Thirteen male German volunteers played a first-person shooter game (Tactical Ops: Assault on Terror during fMRI measurement. We defined success as eliminating opponents, and failure as being eliminated themselves. Affect was measured directly before and after game play using the Positive and Negative Affect Schedule (PANAS. Failure and success events evoked increased activity in visual cortex but only failure decreased activity in orbitofrontal cortex and caudate nucleus. A negative correlation between negative affect and responses to failure was evident in the right temporal pole (rTP. Conclusions The deactivation of the caudate nucleus during failure is in accordance with its role in reward-prediction error: it occurred whenever subject missed an expected reward (being eliminated rather than eliminating the opponent. We found no indication that violence events were directly rewarding for the players. We addressed subjective evaluations of affect change due to gameplay to study the reward system. Subjects reporting greater negative affect after playing the game had less rTP activity associated with failure. The rTP may therefore be involved in evaluating the failure events in a social context, to regulate the players' mood.

  5. Associations among smoking, anhedonia, and reward learning in depression.

    Science.gov (United States)

    Liverant, Gabrielle I; Sloan, Denise M; Pizzagalli, Diego A; Harte, Christopher B; Kamholz, Barbara W; Rosebrock, Laina E; Cohen, Andrew L; Fava, Maurizio; Kaplan, Gary B

    2014-09-01

    Depression and cigarette smoking co-occur at high rates. However, the etiological mechanisms that contribute to this relationship remain unclear. Anhedonia and associated impairments in reward learning are key features of depression, which also have been linked to the onset and maintenance of cigarette smoking. However, few studies have investigated differences in anhedonia and reward learning among depressed smokers and depressed nonsmokers. The goal of this study was to examine putative differences in anhedonia and reward learning in depressed smokers (n=36) and depressed nonsmokers (n=44). To this end, participants completed self-report measures of anhedonia and behavioral activation (BAS reward responsiveness scores) and as well as a probabilistic reward task rooted in signal detection theory, which measures reward learning (Pizzagalli, Jahn, & O'Shea, 2005). When considering self-report measures, depressed smokers reported higher trait anhedonia and reduced BAS reward responsiveness scores compared to depressed nonsmokers. In contrast to self-report measures, nicotine-satiated depressed smokers demonstrated greater acquisition of reward-based learning compared to depressed nonsmokers as indexed by the probabilistic reward task. Findings may point to a potential mechanism underlying the frequent co-occurrence of smoking and depression. These results highlight the importance of continued investigation of the role of anhedonia and reward system functioning in the co-occurrence of depression and nicotine abuse. Results also may support the use of treatments targeting reward learning (e.g., behavioral activation) to enhance smoking cessation among individuals with depression.

  6. Dose-Response Curve of Chromosome Aberrations in Human Lymphocytes Induced by Gamma-Rays

    Directory of Open Access Journals (Sweden)

    Y. Lusiyanti

    2013-12-01

    Full Text Available Chromosome aberration is a biomarker to predict the level of cell damage caused by exposure to ionizing radiation on human body. Dicentric chromosome is a specific chromosome aberration caused by ionizing radiation and is used as a gold standard biodosimetry of individuals over exposed to ionizing radiation. In radiation accident the dicentric assays has been applied as biological dosimetry to estimate radiation absorbed dose and also to confirm the radiation dose received to radiation workers.The purpose of this study was to generate a dose response curve of chromosome aberration (dicentric in human lymphocyte induced by gamma radiation. Peripheral blood samples from three non smoking healthy volunteers aged between 25-48 years old with informed consent were irradiated with dose between 0.1-4.0 Gy and a control using gamma teletherapy source. The culture procedure was conducted following the IAEA standard procedures with slight modifications. Analysis of dose-response curves used was LQ model Y = a + αD + βD2. The result showed that α and β values of the curve obtained were 0.018 ± 0.006 and 0.013 ± 0.002, respectively. Dose response calibration curve for dicentric chromosome aberrations in human lymphocytes induced by gamma-radiation fitted to linear quadratic model. In order to apply the dose response curve of chromosome aberration disentric for biodosimetry, this standar curve still need to be validated.

  7. Influence of dopaminergically mediated reward on somatosensory decision-making.

    Directory of Open Access Journals (Sweden)

    Burkhard Pleger

    2009-07-01

    Full Text Available Reward-related dopaminergic influences on learning and overt behaviour are well established, but any influence on sensory decision-making is largely unknown. We used functional magnetic resonance imaging (fMRI while participants judged electric somatosensory stimuli on one hand or other, before being rewarded for correct performance at trial end via a visual signal, at one of four anticipated financial levels. Prior to the procedure, participants received either placebo (saline, a dopamine agonist (levodopa, or an antagonist (haloperidol.higher anticipated reward improved tactile decisions. Visually signalled reward reactivated primary somatosensory cortex for the judged hand, more strongly for higher reward. After receiving a higher reward on one trial, somatosensory activations and decisions were enhanced on the next trial. These behavioural and neural effects were all enhanced by levodopa and attenuated by haloperidol, indicating dopaminergic dependency. Dopaminergic reward-related influences extend even to early somatosensory cortex and sensory decision-making.

  8. Role of delay-based reward in the spatial cooperation

    Science.gov (United States)

    Wang, Xu-Wen; Nie, Sen; Jiang, Luo-Luo; Wang, Bing-Hong; Chen, Shi-Ming

    2017-01-01

    Strategy selection in games, a typical decision making, usually brings noticeable reward for players which have discounted value if the delay appears. The discounted value is measure: earning sooner with a small reward or later with a delayed larger reward. Here, we investigate effects of delayed rewards on the cooperation in structured population. It is found that delayed reward supports the spreading of cooperation in square lattice, small-world and random networks. In particular, intermediate reward differences between delays impel the highest cooperation level. Interestingly, cooperative individuals with the same delay time steps form clusters to resist the invasion of defects, and cooperative individuals with lowest delay reward survive because they form the largest clusters in the lattice.

  9. The Effects of Rewarding User Engagement

    DEFF Research Database (Denmark)

    Claussen, Jörg; Kretschmer, Tobias; Mayrhofer, Philip

    2013-01-01

    We study the market for apps on Facebook, the dominant social networking platform, and make use of a rule change by Facebook by which highly engaging apps were rewarded with further opportunities to engage users. The rule change led to new applications with significantly higher user ratings being...... declined less rapidly with age. Our results show that social media channels do not necessarily have to be managed through hard exclusion of participants but can also be steered through “softer” changes in reward and incentive systems....... developed. Moreover, user ratings became more important drivers of app success. Other drivers of app success are also affected by the rule change; sheer network size became a less important driver for app success, update frequency benefitted apps more in staying successful, and active users of Facebook apps...

  10. Social stress reactivity alters reward and punishment learning.

    Science.gov (United States)

    Cavanagh, James F; Frank, Michael J; Allen, John J B

    2011-06-01

    To examine how stress affects cognitive functioning, individual differences in trait vulnerability (punishment sensitivity) and state reactivity (negative affect) to social evaluative threat were examined during concurrent reinforcement learning. Lower trait-level punishment sensitivity predicted better reward learning and poorer punishment learning; the opposite pattern was found in more punishment sensitive individuals. Increasing state-level negative affect was directly related to punishment learning accuracy in highly punishment sensitive individuals, but these measures were inversely related in less sensitive individuals. Combined electrophysiological measurement, performance accuracy and computational estimations of learning parameters suggest that trait and state vulnerability to stress alter cortico-striatal functioning during reinforcement learning, possibly mediated via medio-frontal cortical systems.

  11. The taxonomic structure of rewards as work outcomes

    Directory of Open Access Journals (Sweden)

    W. I. Myburgh

    1986-04-01

    Full Text Available Contemporary cognitive process theories of motivation, specifically expectancy/valence theory, use rewards as an important work outcome variable, to explain and predict the interaction processes between motivation and other variables. To date, relatively little attention has been given to define and describe work outcomes empirically. Use is currently made of a hierarchical extrinsic/intrinsic structure, representing outcomes grouped together with universal valence and related to each other. This investigation aims to investigate this taxonomy. Opsomming In kontemporere kognitiewe prosesteoriee van motivering en veral verwagtingsteorie, word verwys na werksuitkomstes (vergoeding as 'n belangrike veranderlike in die verklaring en voorspelling van die interaksieprosesse tussen ander motiveringsfaktore. Tot dusver is relatiefmin aandag bestee om werksuitkomstes empiries te ontleed en te beskryfen teoretici gebruik tans 'n hierargiese struktuur om, uitkomstes wat oor universiele valensie beskik en onderling met mekaar verband hou, te groepeer in ekstrinsieke en intrinsieke uitkomstes of vergoedings. In hierdie ondersoek word gepoog om hierdie taksonomie empirics na te vors.

  12. Specific genomic aberrations in primary colorectal cancer are associated with liver metastases

    Directory of Open Access Journals (Sweden)

    Wessels Lodewyk F

    2010-12-01

    Full Text Available Abstract Background Accurate staging of colorectal cancer (CRC with clinicopathological parameters is important for predicting prognosis and guiding treatment but provides no information about organ site of metastases. Patterns of genomic aberrations in primary colorectal tumors may reveal a chromosomal signature for organ specific metastases. Methods Array Comparative Genomic Hybridization (aCGH was employed to asses DNA copy number changes in primary colorectal tumors of three distinctive patient groups. This included formalin-fixed, paraffin-embedded tissue of patients who developed liver metastases (LM; n = 36, metastases (PM; n = 37 and a group that remained metastases-free (M0; n = 25. A novel statistical method for identifying recurrent copy number changes, KC-SMART, was used to find specific locations of genomic aberrations specific for various groups. We created a classifier for organ specific metastases based on the aCGH data using Prediction Analysis for Microarrays (PAM. Results Specifically in the tumors of primary CRC patients who subsequently developed liver metastasis, KC-SMART analysis identified genomic aberrations on chromosome 20q. LM-PAM, a shrunken centroids classifier for liver metastases occurrence, was able to distinguish the LM group from the other groups (M0&PM with 80% accuracy (78% sensitivity and 86% specificity. The classification is predominantly based on chromosome 20q aberrations. Conclusion Liver specific CRC metastases may be predicted with a high accuracy based on specific genomic aberrations in the primary CRC tumor. The ability to predict the site of metastases is important for improvement of personalized patient management.

  13. Hypoalgesia Induced by Reward Devaluation in Rats.

    Science.gov (United States)

    Jiménez-García, Ana María; Ruíz-Leyva, Leandro; Cendán, Cruz Miguel; Torres, Carmen; Papini, Mauricio R; Morón, Ignacio

    2016-01-01

    Reduced sensitivity to physical pain (hypoalgesia) has been reported after events involving reward devaluation. Reward devaluation was implemented in a consummatory successive negative contrast (cSNC) task. Food-deprived Wistar rats had access to 32% sucrose during 16 sessions followed by access to 4% sucrose during 3 additional sessions. An unshifted control group had access to 4% sucrose throughout the 19 sessions. Pain sensitivity was measured using von Frey filaments (Experiment 1) and Hargreaves thermal stimuli (Experiment 2) in pretraining baseline, 5 min, and 300 min after either the first (session 17) or second (session 18) devaluation session in the cSNC situation. Sucrose consumption was lower in downshifted groups relative to unshifted groups during postshift sessions-the cSNC effect. Hypoalgesia was observed in downshifted groups relative to unshifted controls when pain sensitivity was assessed 5 min after either the first or second devaluation session, regardless of the pain sensitivity test used. Both pain sensitivity tests yielded evidence of hypoalgesia 300 min after the second downshift session, but not 300 min after the first devaluation session. Whereas hypoalgesia was previously shown only after the second devaluation session, here we report evidence of hypoalgesia after both the first and second devaluation sessions using mechanical and thermal nociceptive stimuli. Moreover, the hypoalgesia observed 300 min after the second devaluation session in both experiments provides unique evidence of the effects of reward loss on sensitivity to physical pain 5 hours after the loss episode. The underlying neurobehavioral mechanisms remain to be identified.

  14. Rewarding safe behavior: strategies for change.

    Science.gov (United States)

    Fell-Carlson, Deborah

    2004-12-01

    Effective, sustainable safety incentives are integrated into a performance management system designed to encourage long term behavior change. Effective incentive program design integrates the fundamental considerations of compensation (i.e., valence, instrumentality, expectancy, equity) with behavior change theory in the context of a strong merit based performance management system. Clear expectations are established and communicated from the time applicants apply for the position. Feedback and social recognition are leveraged and used as rewards, in addition to financial incentives built into the compensation system and offered periodically as short term incentives. Rewards are tied to specific objectives intended to influence specific behaviors. Objectives are designed to challenge employees, providing opportunities to grow and enhance their sense of belonging. Safety contests and other awareness activities are most effective when used to focus safety improvement efforts on specific behaviors or processes, for a predetermined period of time, in the context of a comprehensive safety system. Safety incentive programs designed around injury outcomes can result in unintended, and undesirable, consequences. Safety performance can be leveraged by integrating safety into corporate cultural indicators. Symbols of safety remind employees of corporate safety goals and objectives (e.g., posted safety goals and integrating safety into corporate mission and vision). Rites and ceremonies provide opportunities for social recognition and feedback and demonstrate safety is a corporate value. Feedback opportunities, rewards, and social recognition all provide content for corporate legends, those stories embellished over time, that punctuate the overall system of organizational norms, and provide examples of the organizational safety culture in action.

  15. Extinction Can Reduce the Impact of Reward Cues on Reward-Seeking Behavior.

    Science.gov (United States)

    Lovibond, Peter F; Satkunarajah, Michelle; Colagiuri, Ben

    2015-07-01

    Reward-associated cues are thought to promote relapse after treatment of appetitive disorders such as drug-taking, binge eating, and gambling. This process has been modelled in the laboratory using a Pavlovian-instrumental transfer (PIT) design in which Pavlovian cues facilitate instrumental reward-directed action. Attempts to reduce facilitation by cue exposure (extinction) have produced mixed results. We tested the effect of extinction in a recently developed PIT procedure using a natural reward, chocolate, in human participants. Facilitation of instrumental responding was only observed in participants who were aware of the Pavlovian contingencies. Pavlovian extinction successfully reduced, but did not completely eliminate, expectancy of reward and facilitation of instrumental responding. The results indicate that exposure can reduce the ability of cues to promote reward-directed behavior in the laboratory. However, the residual potency of extinguished cues means that additional active strategies may be needed in clinical practice to train patients to resist the impact of these cues in their environment.

  16. Developmental changes in the reward positivity: an electrophysiological trajectory of reward processing.

    Science.gov (United States)

    Lukie, Carmen N; Montazer-Hojat, Somayyeh; Holroyd, Clay B

    2014-07-01

    Children and adolescents learn to regulate their behavior by utilizing feedback from the environment but exactly how this ability develops remains unclear. To investigate this question, we recorded the event-related brain potential (ERP) from children (8-13 years), adolescents (14-17 years) and young adults (18-23 years) while they navigated a "virtual maze" in pursuit of monetary rewards. The amplitude of the reward positivity, an ERP component elicited by feedback stimuli, was evaluated for each age group. A current theory suggests the reward positivity is produced by the impact of reinforcement learning signals carried by the midbrain dopamine system on anterior cingulate cortex, which utilizes the signals to learn and execute extended behaviors. We found that the three groups produced a reward positivity of comparable size despite relatively longer ERP component latencies for the children, suggesting that the reward processing system reaches maturity early in development. We propose that early development of the midbrain dopamine system facilitates the development of extended goal-directed behaviors in anterior cingulate cortex.

  17. Neural networks involved in adolescent reward processing: An activation likelihood estimation meta-analysis of functional neuroimaging studies.

    Science.gov (United States)

    Silverman, Merav H; Jedd, Kelly; Luciana, Monica

    2015-11-15

    Behavioral responses to, and the neural processing of, rewards change dramatically during adolescence and may contribute to observed increases in risk-taking during this developmental period. Functional MRI (fMRI) studies suggest differences between adolescents and adults in neural activation during reward processing, but findings are contradictory, and effects have been found in non-predicted directions. The current study uses an activation likelihood estimation (ALE) approach for quantitative meta-analysis of functional neuroimaging studies to: (1) confirm the network of brain regions involved in adolescents' reward processing, (2) identify regions involved in specific stages (anticipation, outcome) and valence (positive, negative) of reward processing, and (3) identify differences in activation likelihood between adolescent and adult reward-related brain activation. Results reveal a subcortical network of brain regions involved in adolescent reward processing similar to that found in adults with major hubs including the ventral and dorsal striatum, insula, and posterior cingulate cortex (PCC). Contrast analyses find that adolescents exhibit greater likelihood of activation in the insula while processing anticipation relative to outcome and greater likelihood of activation in the putamen and amygdala during outcome relative to anticipation. While processing positive compared to negative valence, adolescents show increased likelihood for activation in the posterior cingulate cortex (PCC) and ventral striatum. Contrasting adolescent reward processing with the existing ALE of adult reward processing reveals increased likelihood for activation in limbic, frontolimbic, and striatal regions in adolescents compared with adults. Unlike adolescents, adults also activate executive control regions of the frontal and parietal lobes. These findings support hypothesized elevations in motivated activity during adolescence.

  18. Cosmological parameter estimation: impact of CMB aberration

    CERN Document Server

    Catena, Riccardo

    2012-01-01

    The peculiar motion of an observer with respect to the CMB rest frame induces an apparent deflection of the observed CMB photons, i.e. aberration, and a shift in their frequency, i.e. Doppler effect. Both effects distort the temperature multipoles a_lm's via a mixing matrix at any l. The common lore when performing a CMB based cosmological parameter estimation is to consider that Doppler affects only the l=1 multipole, and neglect any other corrections. In this paper we reconsider the validity of this assumption, showing that it is actually not robust when sky cuts are included to model CMB foreground contaminations. Assuming a simple fiducial cosmological model with five parameters, we simulated CMB temperature maps of the sky in a WMAP-like and in a Planck-like experiment and added aberration and Doppler effects to the maps. We then analyzed with a MCMC in a Bayesian framework the maps with and without aberration and Doppler effects in order to assess the ability of reconstructing the parameters of the fidu...

  19. [Familial, structural aberration of the Y chromosome with fertility disorders].

    Science.gov (United States)

    Gall, H; Schmid, M; Schmidtke, J; Schempp, W; Weber, L

    1985-11-01

    Cytogenetic studies on a patient with Klinefelter's syndrome revealed an inherited, structural aberration of the Y-chromosome which has not been described before. The aberrant Y-chromosome was characterized by eight different banding methods. The value of individual staining techniques in studies on Y-heterochromatin aberrations is emphasized. Analysis of the cytogenetic studies (banding methods, restriction endonuclease of DNA, and measurement of the length of the Y-chromosome) permits an interpretation to be made on how the aberrant Y-chromosome originated. The functions of the Y-chromosome are discussed. The decrease in fertility (cryptozoospermia) in the two brothers with the same aberrant Y-chromosome was striking.

  20. Trust versus paranoia: abnormal response to social reward in psychotic illness.

    Science.gov (United States)

    Gromann, Paula M; Heslenfeld, Dirk J; Fett, Anne-Kathrin; Joyce, Dan W; Shergill, Sukhi S; Krabbendam, Lydia

    2013-06-01

    Psychosis is characterized by an elementary lack of trust in others. Trust is an inherently rewarding aspect of successful social interactions and can be examined using neuroeconomic paradigms. This study was aimed at investigating the underlying neural basis of diminished trust in psychosis. Functional magnetic resonance imaging data were acquired from 20 patients with psychosis and 20 healthy control subjects during two multiple-round trust games; one with a cooperative and the other with a deceptive counterpart. An a priori region of interest analysis of the right caudate nucleus, right temporo-parietal junction and medial prefrontal cortex was performed focusing on the repayment phase of the games. For regions with group differences, correlations were calculated between the haemodynamic signal change, behavioural outcomes and patients' symptoms. Patients demonstrated reduced levels of baseline trust, indicated by smaller initial investments. For the caudate nucleus, there was a significant game × group interaction, with controls showing stronger activation for the cooperative game than patients, and no differences for the deceptive game. The temporo-parietal junction was significantly more activated in control subjects than in patients during cooperative and deceptive repayments. There were no significant group differences for the medial prefrontal cortex. Patients' reduced activation within the caudate nucleus correlated negatively with paranoia scores. The temporo-parietal junction signal was positively correlated with positive symptom scores during deceptive repayments. Reduced sensitivity to social reward may explain the basic loss of trust in psychosis, mediated by aberrant activation of the caudate nucleus and the temporo-parietal junction.

  1. Differentiating neural reward responsiveness in autism versus ADHD

    Directory of Open Access Journals (Sweden)

    Gregor Kohls

    2014-10-01

    Full Text Available Although attention deficit hyperactivity disorders (ADHD and autism spectrum disorders (ASD share certain neurocognitive characteristics, it has been hypothesized to differentiate the two disorders based on their brain's reward responsiveness to either social or monetary reward. Thus, the present fMRI study investigated neural activation in response to both reward types in age and IQ-matched boys with ADHD versus ASD relative to typically controls (TDC. A significant group by reward type interaction effect emerged in the ventral striatum with greater activation to monetary versus social reward only in TDC, whereas subjects with ADHD responded equally strong to both reward types, and subjects with ASD showed low striatal reactivity across both reward conditions. Moreover, disorder-specific neural abnormalities were revealed, including medial prefrontal hyperactivation in response to social reward in ADHD versus ventral striatal hypoactivation in response to monetary reward in ASD. Shared dysfunction was characterized by fronto-striato-parietal hypoactivation in both clinical groups when money was at stake. Interestingly, lower neural activation within parietal circuitry was associated with higher autistic traits across the entire study sample. In sum, the present findings concur with the assumption that both ASD and ADHD display distinct and shared neural dysfunction in response to reward.

  2. Reward associations impact both iconic and visual working memory.

    Science.gov (United States)

    Infanti, Elisa; Hickey, Clayton; Turatto, Massimo

    2015-02-01

    Reward plays a fundamental role in human behavior. A growing number of studies have shown that stimuli associated with reward become salient and attract attention. The aim of the present study was to extend these results into the investigation of iconic memory and visual working memory. In two experiments we asked participants to perform a visual-search task where different colors of the target stimuli were paired with high or low reward. We then tested whether the pre-established feature-reward association affected performance on a subsequent visual memory task, in which no reward was provided. In this test phase participants viewed arrays of 8 objects, one of which had unique color that could match the color associated with reward during the previous visual-search task. A probe appeared at varying intervals after stimulus offset to identify the to-be-reported item. Our results suggest that reward biases the encoding of visual information such that items characterized by a reward-associated feature interfere with mnemonic representations of other items in the test display. These results extend current knowledge regarding the influence of reward on early cognitive processes, suggesting that feature-reward associations automatically interact with the encoding and storage of visual information, both in iconic memory and visual working memory.

  3. A non-reward attractor theory of depression.

    Science.gov (United States)

    Rolls, Edmund T

    2016-09-01

    A non-reward attractor theory of depression is proposed based on the operation of the lateral orbitofrontal cortex and supracallosal cingulate cortex. The orbitofrontal cortex contains error neurons that respond to non-reward for many seconds in an attractor state that maintains a memory of the non-reward. The human lateral orbitofrontal cortex is activated by non-reward during reward reversal, and by a signal to stop a response that is now incorrect. Damage to the human orbitofrontal cortex impairs reward reversal learning. Not receiving reward can produce depression. The theory proposed is that in depression, this lateral orbitofrontal cortex non-reward system is more easily triggered, and maintains its attractor-related firing for longer. This triggers negative cognitive states, which in turn have positive feedback top-down effects on the orbitofrontal cortex non-reward system. Treatments for depression, including ketamine, may act in part by quashing this attractor. The mania of bipolar disorder is hypothesized to be associated with oversensitivity and overactivity in the reciprocally related reward system in the medial orbitofrontal cortex and pregenual cingulate cortex.

  4. DNA Repair Defects and Chromosomal Aberrations

    Science.gov (United States)

    Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

  5. Radiotherapeutical chromosomal aberrations in laryngeal cancer patients

    Directory of Open Access Journals (Sweden)

    Stošić-Divjak Svetlana L.

    2009-01-01

    Full Text Available Introduction. The authors present the results of cytogenetic analysis of 21 patients with laryngeal carcinomas diagnosed and treated in the period 1995-2000 at the Institute of Otorhinolaryngology and Maxillofacial Surgery, Clinical Center of Serbia and Clinical Center of Novi Sad. Material and methods. The patients were specially monitored and the material was analyzed at the Institute of Human Genetics of the School of Medicine in Belgrade as well as in the Laboratory for Radiological Protection of the Institute of Occupational and Radiological Health 'Dr Dragomir Karajovic' in Belgrade. Results. The incidence of chromosomal aberrations and incidence of exchange of material between sister chromatids were observed in the preparation of the metaphasic lymphocyte chromosomes of the peripheral blood obtained in the culture. Structural aberrations were found on the chromosomes in the form of breakups, rings, translocations and dicentrics as early as after a single exposure of patients to tumor radiation dose of 2 Gy in the field sized 5x7. Out of the total number of 35 cultivated blood samples obtained from 13 patients, 21 were successfully cultivated and they were proved to contain chromosomal aberrations. Some of the peripheral blood samples failed to show cell growth in vitro due to the lethal cell damages in vivo. Discussion.. We have consluded that the number of structural aberrations cannot be used as a biological measure of the absorbed ionizing radiation dose. The presence of aberrations per se is indicative of the mutagenic effect of the ionizing radiation, which was also confirmed in our series on the original model by cultivation of the peripheral blood lymphocytes in the culture of the cells of the volunteer donors upon in vitro radiation. Using the method of bromdeoxyuridylreductase, the increased incidence of SCE as a mutagenic effect was registered. Conclusion. It has been concluded that the increase of absorbed radiation dose in

  6. GABAA receptor drugs and neuronal plasticity in reward and aversion: focus on the ventral tegmental area

    Directory of Open Access Journals (Sweden)

    Elena eVashchinkina

    2014-11-01

    Full Text Available GABAA receptors are the main fast inhibitory neurotransmitter receptors in the mammalian brain, and targets for many clinically important drugs widely used in the treatment of anxiety disorders, insomnia and in anesthesia. Nonetheless, there are significant risks associated with the long-term use of these drugs particularly related to development of tolerance and addiction. Addictive mechanisms of GABAA receptor drugs are poorly known, but recent findings suggest that those drugs may induce aberrant neuroadaptations in the brain reward circuitry. Recently, benzodiazepines, acting on synaptic GABAA receptors, and modulators of extrasynaptic GABAA receptors (THIP and neurosteroids have been found to induce plasticity in the ventral tegmental area (VTA dopamine neurons and their main target projections. Furthermore, depending whether synaptic or extrasynaptic GABAA receptor populations are activated, the behavioral outcome of repeated administration seems to correlate with rewarding or aversive behavioral responses, respectively. The VTA dopamine neurons project to forebrain centers such as the nucleus accumbens and medial prefrontal cortex, and receive afferent projections from these brain regions and especially from the extended amygdala and lateral habenula, forming the major part of the reward and aversion circuitry. Both synaptic and extrasynaptic GABAA drugs inhibit the VTA GABAergic interneurons, thus activating the VTA DA neurons by disinhibition and this way inducing glutamatergic synaptic plasticity. However, the GABAA drugs failed to alter synaptic spine numbers as studied from Golgi-Cox-stained VTA dendrites. Since the GABAergic drugs are known to depress the brain metabolism and gene expression, their likely way of inducing neuroplasticity in mature neurons is by disinhibiting the principal neurons, which remains to be rigorously tested for a number of clinically important anxiolytics, sedatives and anesthetics in different parts of

  7. Chromatic variation of aberration: the role of induced aberrations and raytrace direction

    Science.gov (United States)

    Berner, A.; Nobis, T.; Shafer, D.; Gross, H.

    2015-09-01

    The design and optimization process of an optical system contains several first order steps. The definition of the appropriate lens type and the fixation of the raytrace direction are some of them. The latter can be understood as a hidden assumption rather than an aware design step. This is usually followed by the determination of the paraxial lens layout calculated for the primary wavelength. It is obvious, that for this primary wavelength the paraxial calculations are independent of raytrace direction. Today, most of the lens designs are specified not to work only for one wavelength, but in a certain wavelength range. Considering such rays of other wavelengths, one can observe that depending on the direction there will already occur differences in the first order chromatic aberrations and additionally in the chromatic variation of the third-order aberrations. The reason for this effect are induced aberrations emerging from one surface to the following surfaces by perturbed ray heights and ray angles. It can be shown, that the total amount of surface-resolved first order chromatic aberrations and the chromatic variation of the five primary aberrations can be split into an intrinsic part and an induced part. The intrinsic part is independent of the raytrace direction whereas the induced part is not.

  8. Chromosome aberrations and cell death by ionizing radiation: Evolution of a biophysical model

    Science.gov (United States)

    Ballarini, Francesca; Carante, Mario P.

    2016-11-01

    effectiveness for a proton SOBP used to treat eye melanoma in Catania, Italy. The survival of AG01522 cells at different depths was reproduced, and the survival of V79 cells was predicted. For both cell lines, the simulations also predicted yields of chromosome aberrations, some of which can be regarded as indicators of the risk to normal tissues.

  9. Nodal aberration theory for wild-filed asymmetric optical systems

    Science.gov (United States)

    Chen, Yang; Cheng, Xuemin; Hao, Qun

    2016-10-01

    Nodal Aberration Theory (NAT) was used to calculate the zero field position in Full Field Display (FFD) for the given aberration term. Aiming at wide-filed non-rotational symmetric decentered optical systems, we have presented the nodal geography behavior of the family of third-order and fifth-order aberrations. Meanwhile, we have calculated the wavefront aberration expressions when one optical element in the system is tilted, which was not at the entrance pupil. By using a three-piece-cellphone lens example in optical design software CodeV, the nodal geography is testified under several situations; and the wavefront aberrations are calculated when the optical element is tilted. The properties of the nodal aberrations are analyzed by using Fringe Zernike coefficients, which are directly related with the wavefront aberration terms and usually obtained by real ray trace and wavefront surface fitting.

  10. Who, what, where, when (and maybe even why)? How the experience of sexual reward connects sexual desire, preference, and performance.

    Science.gov (United States)

    Pfaus, James G; Kippin, Tod E; Coria-Avila, Genaro A; Gelez, Hélène; Afonso, Veronica M; Ismail, Nafissa; Parada, Mayte

    2012-02-01

    Although sexual behavior is controlled by hormonal and neurochemical actions in the brain, sexual experience induces a degree of plasticity that allows animals to form instrumental and Pavlovian associations that predict sexual outcomes, thereby directing the strength of sexual responding. This review describes how experience with sexual reward strengthens the development of sexual behavior and induces sexually-conditioned place and partner preferences in rats. In both male and female rats, early sexual experience with partners scented with a neutral or even noxious odor induces a preference for scented partners in subsequent choice tests. Those preferences can also be induced by injections of morphine or oxytocin paired with a male rat's first exposure to scented females, indicating that pharmacological activation of opioid or oxytocin receptors can "stand in" for the sexual reward-related neurochemical processes normally activated by sexual stimulation. Conversely, conditioned place or partner preferences can be blocked by the opioid receptor antagonist naloxone. A somatosensory cue (a rodent jacket) paired with sexual reward comes to elicit sexual arousal in male rats, such that paired rats with the jacket off show dramatic copulatory deficits. We propose that endogenous opioid activation forms the basis of sexual reward, which also sensitizes hypothalamic and mesolimbic dopamine systems in the presence of cues that predict sexual reward. Those systems act to focus attention on, and activate goal-directed behavior toward, reward-related stimuli. Thus, a critical period exists during an individual's early sexual experience that creates a "love map" or Gestalt of features, movements, feelings, and interpersonal interactions associated with sexual reward.

  11. Neural evidence for description dependent reward processing in the framing effect.

    Science.gov (United States)

    Yu, Rongjun; Zhang, Ping

    2014-01-01

    Human decision making can be influenced by emotionally valenced contexts, known as the framing effect. We used event-related brain potentials to investigate how framing influences the encoding of reward. We found that the feedback related negativity (FRN), which indexes the "worse than expected" negative prediction error in the anterior cingulate cortex (ACC), was more negative for the negative frame than for the positive frame in the win domain. Consistent with previous findings that the FRN is not sensitive to "better than expected" positive prediction error, the FRN did not differentiate the positive and negative frame in the loss domain. Our results provide neural evidence that the description invariance principle which states that reward representation and decision making are not influenced by how options are presented is violated in the framing effect.

  12. Transient analysis of some rewarded Markov models using randomization with quasistationarity detection

    OpenAIRE

    Carrasco, Juan A.

    2004-01-01

    Rewarded homogeneous continuous-time Markov chain (CTMC) models can be used to analyze performance, dependability and performability attributes of computer and telecommunication systems. In this paper, we consider rewarded CTMC models with a reward structure including reward rates associated with states and two measures summarizing the behavior in time of the resulting reward rate random variable: the expected transient reward rate at time t and the expected averaged reward rate in the tim...

  13. Deficits in cognitive control, timing and reward sensitivity appear to be dissociable in ADHD.

    Directory of Open Access Journals (Sweden)

    Patrick de Zeeuw

    Full Text Available Recent neurobiological models of ADHD suggest that deficits in different neurobiological pathways may independently lead to symptoms of this disorder. At least three independent pathways may be involved: a dorsal frontostriatal pathway involved in cognitive control, a ventral frontostriatal pathway involved in reward processing and a frontocerebellar pathway related to temporal processing. Importantly, we and others have suggested that disruptions in these three pathways should lead to separable deficits at the cognitive level. Furthermore, if these truly represent separate biological pathways to ADHD, these cognitive deficits should segregate between individuals with ADHD. The present study tests these hypotheses in a sample of children, adolescents and young adults with ADHD and controls. 149 Subjects participated in a short computerized battery assessing cognitive control, timing and reward sensitivity. We used Principal Component Analysis to find independent components underlying the variance in the data. The segregation of deficits between individuals was tested using Loglinear Analysis. We found four components, three of which were predicted by the model: Cognitive control, reward sensitivity and timing. Furthermore, 80% of subjects with ADHD that had a deficit were deficient on only one component. Loglinear Analysis statistically confirmed the independent segregation of deficits between individuals. We therefore conclude that cognitive control, timing and reward sensitivity were separable at a cognitive level and that deficits on these components segregated between individuals with ADHD. These results support a neurobiological framework of separate biological pathways to ADHD with separable cognitive deficits.

  14. Cannabinoid modulation of drug reward and the implications of marijuana legalization.

    Science.gov (United States)

    Covey, Dan P; Wenzel, Jennifer M; Cheer, Joseph F

    2015-12-02

    Marijuana is the most popular illegal drug worldwide. Recent trends indicate that this may soon change; not due to decreased marijuana use, but to an amendment in marijuana's illegal status. The cannabinoid type 1 (CB1) receptor mediates marijuana's psychoactive and reinforcing properties. CB1 receptors are also part of the brain endocannabinoid (eCB) system and support numerous forms of learning and memory, including the conditioned reinforcing properties of cues predicting reward or punishment. This is accomplished via eCB-dependent alterations in mesolimbic dopamine function, which plays an obligatory role in reward learning and motivation. Presynaptic CB1 receptors control midbrain dopamine neuron activity and thereby shape phasic dopamine release in target regions, particularly the nucleus accumbens (NAc). By also regulating synaptic input to the NAc, CB1 receptors modulate NAc output onto downstream neurons of the basal ganglia motor circuit, and thereby support goal-directed behaviors. Abused drugs promote short- and long-term adaptations in eCB-regulation of mesolimbic dopamine function, and thereby hijack neural systems related to the pursuit of rewards to promote drug abuse. By pharmacologically targeting the CB1 receptors, marijuana has preferential access to this neuronal system and can potently alter eCB-dependent processing of reward-related stimuli. As marijuana legalization progresses, greater access to this drug should increase the utility of marijuana as a research tool to better understand the eCB system, which has the potential to advance cannabinoid-based treatments for drug addiction.

  15. Decisions in Motion: Decision Dynamics during Intertemporal Choice reflect Subjective Evaluation of Delayed Rewards.

    Science.gov (United States)

    O'Hora, Denis; Carey, Rachel; Kervick, Aoife; Crowley, David; Dabrowski, Maciej

    2016-01-01

    People tend to discount rewards or losses that occur in the future. Such delay discounting has been linked to many behavioral and health problems, since people choose smaller short-term gains over greater long-term gains. We investigated whether the effect of delays on the subjective value of rewards is expressed in how people move when they make choices. Over 600 patrons of the RISK LAB exhibition hosted by the Science Gallery Dublin(TM) played a short computer game in which they used a computer mouse to choose between amounts of money at various delays. Typical discounting effects were observed and decision dynamics indicated that choosing smaller short-term rewards became easier (i.e., shorter response times, tighter trajectories, less vacillation) as the delays until later rewards increased. Based on a sequence of choices, subjective values of delayed outcomes were estimated and decision dynamics during initial choices predicted these values. Decision dynamics are affected by subjective values of available options and thus provide a means to estimate such values.

  16. Deficits in cognitive control, timing and reward sensitivity appear to be dissociable in ADHD.

    Science.gov (United States)

    de Zeeuw, Patrick; Weusten, Juliette; van Dijk, Sarai; van Belle, Janna; Durston, Sarah

    2012-01-01

    Recent neurobiological models of ADHD suggest that deficits in different neurobiological pathways may independently lead to symptoms of this disorder. At least three independent pathways may be involved: a dorsal frontostriatal pathway involved in cognitive control, a ventral frontostriatal pathway involved in reward processing and a frontocerebellar pathway related to temporal processing. Importantly, we and others have suggested that disruptions in these three pathways should lead to separable deficits at the cognitive level. Furthermore, if these truly represent separate biological pathways to ADHD, these cognitive deficits should segregate between individuals with ADHD. The present study tests these hypotheses in a sample of children, adolescents and young adults with ADHD and controls. 149 Subjects participated in a short computerized battery assessing cognitive control, timing and reward sensitivity. We used Principal Component Analysis to find independent components underlying the variance in the data. The segregation of deficits between individuals was tested using Loglinear Analysis. We found four components, three of which were predicted by the model: Cognitive control, reward sensitivity and timing. Furthermore, 80% of subjects with ADHD that had a deficit were deficient on only one component. Loglinear Analysis statistically confirmed the independent segregation of deficits between individuals. We therefore conclude that cognitive control, timing and reward sensitivity were separable at a cognitive level and that deficits on these components segregated between individuals with ADHD. These results support a neurobiological framework of separate biological pathways to ADHD with separable cognitive deficits.

  17. Diverse sources of reward value signals in the basal ganglia nuclei transmitted to the lateral habenula in the monkey

    Directory of Open Access Journals (Sweden)

    Simon eHong

    2013-11-01

    Full Text Available The lateral habenula (LHb plays an important role in motivational decision making. Neurons in the primate LHb signal negative ‘reward prediction errors’ and inhibit midbrain dopamine (DA neurons. These negative reward prediction error signals in the LHb are, at least partly, provided by a distinct group of neurons in the border region of the globus pallidus internal segment (GPb. However, it is still unclear whether other basal ganglia nuclei provide the LHb with reward signals, either through the GPb or through different circuits. As a first step to answer this question, we electrically stimulated various parts of the basal ganglia and monitored the neural activity in the LHb in the awake monkey. First, we found that low intensity stimulations in the GPb and the internal segment of the globus pallidus (GPi evoked a short latency (5 ms excitatory response in LHb neurons. Second, LHb neurons were inhibited by stimulations in the ventral pallidum (VP. These results suggest that reward-related signals are transmitted to the LHb mainly through excitatory connections from the GPb and inhibitory connections from the VP. Finally, excitations or inhibitions are induced in LHb neurons from diverse but patchy regions in the striatum. These effects have considerably longer latencies, suggesting that they may be mediated by the GPb or the VP. The patchy nature of the stimulation effect raises the possibility that the striosomes are the source of reward-related signals transmitted to the LHb.

  18. Dopamine and extinction: A convergence of theory with fear and reward circuitry

    OpenAIRE

    Abraham, Antony D.; Neve, Kim A.; Lattal, K. Matthew

    2013-01-01

    Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine’s function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks...

  19. Cannabinoid modulation of drug reward and the implications of marijuana legalization

    OpenAIRE

    Covey, Dan P.; Wenzel, Jennifer M.; Cheer, Joseph F.

    2014-01-01

    Marijuana is the most popular illegal drug worldwide. Recent trends indicate that this may soon change; not due to decreased marijuana use, but to an amendment in marijuana’s illegal status. The cannabinoid type 1 (CB1) receptor mediates marijuana’s psychoactive and reinforcing properties. CB1 receptors are also part of the brain endocannabinoid (eCB) system and support numerous forms of learning and memory, including the conditioned reinforcing properties of cues predicting reward or punishm...

  20. Negative symptoms in schizophrenia are associated with aberrant striato-cortical connectivity in a rewarded perceptual decision-making task

    Directory of Open Access Journals (Sweden)

    Greg E. Reckless

    2015-01-01

    Conclusions: The present findings suggest that there is a link between dysfunctional striato-cortical connectivity and negative symptom severity, and offer a possible explanation as to why negative symptoms persist after treatment with antipsychotics.

  1. Effects of monetary reward and punishment on information checking behaviour.

    Science.gov (United States)

    Li, Simon Y W; Cox, Anna L; Or, Calvin; Blandford, Ann

    2016-03-01

    Two experiments were conducted to examine whether checking one's own work can be motivated by monetary reward and punishment. Participants were randomly assigned to one of three conditions: a flat-rate payment for completing the task (Control); payment increased for error-free performance (Reward); payment decreased for error performance (Punishment). Experiment 1 (N = 90) was conducted with liberal arts students, using a general data-entry task. Experiment 2 (N = 90) replicated Experiment 1 with clinical students and a safety-critical 'cover story' for the task. In both studies, Reward and Punishment resulted in significantly fewer errors, more frequent and longer checking, than Control. No such differences were obtained between the Reward and Punishment conditions. It is concluded that error consequences in terms of monetary reward and punishment can result in more accurate task performance and more rigorous checking behaviour than errors without consequences. However, whether punishment is more effective than reward, or vice versa, remains inconclusive.

  2. Positive emotions and brain reward circuits in chronic pain.

    Science.gov (United States)

    Navratilova, Edita; Morimura, Kozo; Xie, Jennifer Y; Atcherley, Christopher W; Ossipov, Michael H; Porreca, Frank

    2016-06-01

    Chronic pain is an important public health problem that negatively impacts the quality of life of affected individuals and exacts enormous socioeconomic costs. Chronic pain is often accompanied by comorbid emotional disorders including anxiety, depression, and possibly anhedonia. The neural circuits underlying the intersection of pain and pleasure are not well understood. We summarize recent human and animal investigations and demonstrate that aversive aspects of pain are encoded in brain regions overlapping with areas processing reward and motivation. We highlight findings revealing anatomical and functional alterations of reward/motivation circuits in chronic pain. Finally, we review supporting evidence for the concept that pain relief is rewarding and activates brain reward/motivation circuits. Adaptations in brain reward circuits may be fundamental to the pathology of chronic pain. Knowledge of brain reward processing in the context of pain could lead to the development of new therapeutics for the treatment of emotional aspects of pain and comorbid conditions.

  3. Reward networks in the brain as captured by connectivity measures

    Directory of Open Access Journals (Sweden)

    Estela Camara

    2009-12-01

    Full Text Available An assortment of human behaviors is thought to be driven by rewards including reinforcement learning, novelty processing, learning, decision making, economic choice, incentive motivation, and addiction. In each case the ventral tegmental area / ventral striatum (Nucleus accumbens system (VTA-VS has been implicated as a key structure by functional imaging studies, mostly on the basis of standard, univariate analyses. Here we propose that standard fMRI analysis needs to be complemented by methods that take into account the differential connectivity of the VTA-VS system in the different behavioral contexts in order to describe reward based processes more appropriately. We first consider the wider network for reward processing as it emerged from animal experimentation. Subsequently, an example for a method to assess functional connectivity is given. Finally, we illustrate the usefulness of such analyses by examples regarding reward valuation, reward expectation and the role of reward in addiction.

  4. Rewards modulate saccade latency but not exogenous spatial attention.

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    Stephen eDunne

    2015-07-01

    Full Text Available The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behaviour induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor IOR. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for 3 blocks of extinction trials. However this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

  5. Extrinsic Rewards Diminish Costly Sharing in 3-Year-Olds.

    Science.gov (United States)

    Ulber, Julia; Hamann, Katharina; Tomasello, Michael

    2016-07-01

    Two studies investigated the influence of external rewards and social praise in young children's fairness-related behavior. The motivation of ninety-six 3-year-olds' to equalize unfair resource allocations was measured in three scenarios (collaboration, windfall, and dictator game) following three different treatments (material reward, verbal praise, and neutral response). In all scenarios, children's willingness to engage in costly sharing was negatively influenced when they had received a reward for equal sharing during treatment than when they had received praise or no reward. The negative effect of material rewards was not due to subjects responding in kind to their partner's termination of rewards. These results provide new evidence for the intrinsic motivation of prosociality-in this case, costly sharing behavior-in preschool children.

  6. Pain and suicidality: Insights from reward and addiction neuroscience

    OpenAIRE

    Elman, Igor; Borsook, David; Nora D Volkow

    2013-01-01

    Suicidality is exceedingly prevalent in pain patients. Although the pathophysiology of this link remains unclear, it may be potentially related to the partial congruence of physical and emotional pain systems. The latter system’s role in suicide is also conspicuous during setbacks and losses sustained in the context of social attachments. Here we propose a model based on the neural pathways mediating reward and anti-reward (i.e., allostatic adjustment to recurrent activation of the reward cir...

  7. Dopamine and Reward: The Anhedonia Hypothesis 30 years on

    OpenAIRE

    Wise, Roy A.

    2008-01-01

    The anhedonia hypothesis – that brain dopamine plays a critical role in the subjective pleasure associated with positive rewards – was intended to draw the attention of psychiatrists to the growing evidence that dopamine plays a critical role in the objective reinforcement and incentive motivation associated with food and water, brain stimulation reward, and psychomotor stimulant and opiate reward. The hypothesis called to attention the apparent paradox that neuroleptics, drugs used to treat ...

  8. Neuropsychology of reward learning and negative symptoms in schizophrenia

    OpenAIRE

    2014-01-01

    We used the Iowa Gambling Test (IGT) to examine the relationship of reward learning to both neuropsychological functioning and symptom formation in 65 individuals with schizophrenia. Results indicated that compared to controls, participants with schizophrenia showed significantly reduced reward learning, which in turn correlated with reduced intelligence, memory and executive function, and increased negative symptoms. The current findings suggested that a disease-related disturbance in reward...

  9. Neuropsychology of Reward Learning and Negative Symptoms in Schizophrenia

    OpenAIRE

    2014-01-01

    We used the Iowa Gambling Test (IGT) to examine the relationship of reward learning to both neuropsychological functioning and symptom formation in 65 individuals with schizophrenia. Results indicated that compared to controls, participants with schizophrenia showed significantly reduced reward learning, which in turn correlated with reduced intelligence, memory and executive function, and increased negative symptoms. The current findings suggested that a disease-related disturbance in reward...

  10. Extrinsic Rewards: An Adventist Curriculum Perspective for Classroom Management

    OpenAIRE

    Nadine A. Joseph

    2014-01-01

    Extrinsic rewards refer to gifts used as a form of motivation for students’ to attain an academic goal, or given when that particular goal is reached. Though the use of extrinsic rewards have been proven to have some impact on’ behavior change, such as academic performance, the absence of rewards can cause students’ to revert to the initial unwanted behavior. Consequently, the curricula focus in the Adventist classroom should address the deeper issues that affect behavior and implement the us...

  11. Hypoalgesia Induced by Reward Devaluation in Rats

    Science.gov (United States)

    Jiménez-García, Ana María; Ruíz-Leyva, Leandro; Cendán, Cruz Miguel; Torres, Carmen; Papini, Mauricio R.; Morón, Ignacio

    2016-01-01

    Reduced sensitivity to physical pain (hypoalgesia) has been reported after events involving reward devaluation. Reward devaluation was implemented in a consummatory successive negative contrast (cSNC) task. Food-deprived Wistar rats had access to 32% sucrose during 16 sessions followed by access to 4% sucrose during 3 additional sessions. An unshifted control group had access to 4% sucrose throughout the 19 sessions. Pain sensitivity was measured using von Frey filaments (Experiment 1) and Hargreaves thermal stimuli (Experiment 2) in pretraining baseline, 5 min, and 300 min after either the first (session 17) or second (session 18) devaluation session in the cSNC situation. Sucrose consumption was lower in downshifted groups relative to unshifted groups during postshift sessions—the cSNC effect. Hypoalgesia was observed in downshifted groups relative to unshifted controls when pain sensitivity was assessed 5 min after either the first or second devaluation session, regardless of the pain sensitivity test used. Both pain sensitivity tests yielded evidence of hypoalgesia 300 min after the second downshift session, but not 300 min after the first devaluation session. Whereas hypoalgesia was previously shown only after the second devaluation session, here we report evidence of hypoalgesia after both the first and second devaluation sessions using mechanical and thermal nociceptive stimuli. Moreover, the hypoalgesia observed 300 min after the second devaluation session in both experiments provides unique evidence of the effects of reward loss on sensitivity to physical pain 5 hours after the loss episode. The underlying neurobehavioral mechanisms remain to be identified. PMID:27764142

  12. Dopaminergic balance between reward maximization and policy complexity

    Directory of Open Access Journals (Sweden)

    Naama eParush

    2011-05-01

    Full Text Available Previous reinforcement-learning models of the basal ganglia network have highlighted the role of dopamine in encoding the mismatch between prediction and reality. Far less attention has been paid to the computational goals and algorithms of the main-axis (actor. Here, we construct a top-down model of the basal ganglia with emphasis on the role of dopamine as both a reinforcement learning signal and as a pseudo-temperature signal controlling the general level of basal ganglia excitability and motor vigilance of the acting agent. We argue that the basal ganglia endow the thalamic-cortical networks with the optimal dynamic tradeoff between two constraints: minimizing the policy complexity (cost and maximizing the expected future reward (gain. We show that this multi-dimensional optimization processes results in an experience-modulated version of the softmax behavioral policy. Thus, as in classical softmax behavioral policies, probability of actions are selected according to their estimated values and the pseudo-temperature, but in addition also vary according to the frequency of previous choices of these actions. We conclude that the computational goal of the basal ganglia is not to maximize cumulative (positive and negative reward. Rather, the basal ganglia aim at optimization of independent gain and cost functions. Unlike previously suggested single-variable maximization processes, this multi-dimensional optimization process leads naturally to a softmax-like behavioral policy. We suggest that beyond its role in the modulation of the efficacy of the cortico-striatal synapses, dopamine directly affects striatal excitability and thus provides a pseudo-temperature signal that modulates the trade-off between gain and cost. The resulting experience and dopamine modulated softmax policy can then serve as a theoretical framework to account for the broad range of behaviors and clinical states governed by the basal ganglia and dopamine systems.

  13. Is avolition in schizophrenia associated with a deficit of dorsal caudate activity? A functional magnetic resonance imaging study during reward anticipation and feedback

    OpenAIRE

    Mucci, A.; D. Dima; Soricelli, A; Volpe, U.; Bucci, P.; Frangou, S.; Prinster, A.; Salvatore, M; Galderisi, S.; Maj, M.

    2015-01-01

    BACKGROUND: The neurobiological underpinnings of avolition in schizophrenia remain unclear. Most brain imaging research has focused on reward prediction deficit and on ventral striatum dysfunction, but findings are not consistent. In the light of accumulating evidence that both ventral striatum and dorsal caudate play a key role in motivation, we investigated ventral striatum and dorsal caudate activation during processing of reward or loss in patients with schizophrenia. METHOD: We used ...

  14. Generalized Orienteering Problem with Resource Dependent Rewards

    Science.gov (United States)

    2013-02-19

    Feb. 2008. [15] G. Laporte and S. Martello. The selective traveling salesman problem . Discrete Applied Math- ematics, 26:193–207, 1990. [16] H. D...the following convex NLP produces the minimum travel distance between them. Problem D δ∗i,j = min t ||(ρi + (t− τi)ui)− (ρj + (t− τj)uj)|| s.t. max...Generalized Orienteering Problem with Resource Dependent Rewards Jesse Pietz, Johannes O. Royset Operations Research Department, Naval Postgraduate

  15. A Typology Framework of Loyalty Reward Programs

    Science.gov (United States)

    Cao, Yuheng; Nsakanda, Aaron Luntala; Mann, Inder Jit Singh

    Loyalty reward programs (LRPs), initially developed as marketing programs to enhance customer retention, have now become an important part of customer-focused business strategy. With the proliferation and increasing economy impact of the programs, the management complexity in the programs has also increased. However, despite widespread adoption of LRPs in business, academic research in the field seems to lag behind its practical application. Even the fundamental questions such as what LRPs are and how to classify them have not yet been fully addressed. In this paper, a comprehensive framework for LRP classification is proposed, which provides a foundation for further study of LRP design and planning issues.

  16. Should Charity Fundraisers Be Rewarded With Commission?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With China’s economic boom have come a host of new occupations not seen before in the country.One such job category,that of professional charity fundraiser,on the face of it,seems a more than worthwhile addition to a country where the many needy can benefit in volumes from profit-reeking enterprises and the rise in nouveau riche. Yet when the Hunan Charity Federation initiated a big fundraising campaign,giving financial incentives to volunteer fundraisers,it became a major bone of contention,focusing on the ethics of charity institutes and the con- troversial"rewards"for funds collected.

  17. Communicating total rewards to the generations.

    Science.gov (United States)

    Reynolds, Leah A

    2005-01-01

    This is the first time in American history that four distinct generations have been in the workforce at the same time. Because employers have finite resources with which to compete for talent, they must understand the generations, what matters most to them and what they can do to motivate different generations of workers. Perhaps surprisingly, the author argues that the generations share in most valuing "soft cost" rewards over "hard dollar cost" items. This article advises employers on how to make their company a great place to work for all generations.

  18. Reward optimization of a repairable system

    Energy Technology Data Exchange (ETDEWEB)

    Castro, I.T. [Departamento de Matematicas, Facultad de Veterinaria, Universidad de Extremadura, Avenida de la Universidad, s/n. 10071 Caceres (Spain)]. E-mail: inmatorres@unex.es; Perez-Ocon, R. [Departamento de Estadistica e Investigacion Operativa, Facultad de Ciencias, Universidad de Granada, Avenida de Severo Ochoa, s/n. 18071 Granada (Spain)]. E-mail: rperezo@ugr.es

    2006-03-15

    This paper analyzes a system subject to repairable and non-repairable failures. Non-repairable failures lead to replacement of the system. Repairable failures, first lead to repair but they lead to replacement after a fixed number of repairs. Operating and repair times follow phase type distributions (PH-distributions) and the pattern of the operating times is modelled by a geometric process. In this context, the problem is to find the optimal number of repairs, which maximizes the long-run average reward per unit time. To this end, the optimal number is determined and it is obtained by efficient numerical procedures.

  19. Wavefront aberrations of x-ray dynamical diffraction beams.

    Science.gov (United States)

    Liao, Keliang; Hong, Youli; Sheng, Weifan

    2014-10-01

    The effects of dynamical diffraction in x-ray diffractive optics with large numerical aperture render the wavefront aberrations difficult to describe using the aberration polynomials, yet knowledge of them plays an important role in a vast variety of scientific problems ranging from optical testing to adaptive optics. Although the diffraction theory of optical aberrations was established decades ago, its application in the area of x-ray dynamical diffraction theory (DDT) is still lacking. Here, we conduct a theoretical study on the aberration properties of x-ray dynamical diffraction beams. By treating the modulus of the complex envelope as the amplitude weight function in the orthogonalization procedure, we generalize the nonrecursive matrix method for the determination of orthonormal aberration polynomials, wherein Zernike DDT and Legendre DDT polynomials are proposed. As an example, we investigate the aberration evolution inside a tilted multilayer Laue lens. The corresponding Legendre DDT polynomials are obtained numerically, which represent balanced aberrations yielding minimum variance of the classical aberrations of an anamorphic optical system. The balancing of classical aberrations and their standard deviations are discussed. We also present the Strehl ratio of the primary and secondary balanced aberrations.

  20. Measuring Social Motivation Using Signal Detection and Reward Responsiveness

    Science.gov (United States)

    Chevallier, Coralie; Tonge, Natasha; Safra, Lou; Kahn, David; Kohls, Gregor; Miller, Judith; Schultz, Robert T.

    2016-01-01

    Background Recent trends in psychiatry have emphasized the need for a shift from categorical to dimensional approaches. Of critical importance to this transformation is the availability of tools to objectively quantify behaviors dimensionally. The present study focuses on social motivation, a dimension of behavior that is central to a range of psychiatric conditions but for which a particularly small number of assays currently exist. Methods In Study 1 (N = 48), healthy adults completed a monetary reward task and a social reward task, followed by completion of the Chapman Physical and Social Anhedonia Scales. In Study 2 (N = 26), an independent sample was recruited to assess the robustness of Study 1’s findings. Results The reward tasks were analyzed using signal detection theory to quantify how much reward cues bias participants’ responses. In both Study 1 and Study 2, social anhedonia scores were negatively correlated with change in response bias in the social reward task but not in the monetary reward task. A median split on social anhedonia scores confirmed that participants with high social anhedonia showed less change in response bias in the social reward task compared to participants with low social anhedonia. Conclusions This study confirms that social anhedonia selectively affects how much an individual changes their behavior based on the presence of socially rewarding cues and establishes a tool to quantify social reward responsiveness dimensionally. PMID:27907025

  1. The Cooperative Multi-agent Learning with Random Reward Values

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua-xiang; HUANG Shang-teng

    2005-01-01

    This paper investigated how to learn the optimal action policies in cooperative multiagent systems if the agents' rewards are random variables, and proposed a general two-stage learning algorithm for cooperative multiagent decision processes. The algorithm first calculates the averaged immediate rewards, and considers these learned rewards as the agents' immediate action rewards to learn the optimal action policies. It is proved that the learning algorithm can find the optimal policies in stochastic environment. Extending the algorithm to stochastic Markov decision processes was also discussed.

  2. Reward Comparison: The Achilles' heel and hope for addiction.

    Science.gov (United States)

    Grigson, Patricia Sue

    2008-01-01

    In the words of the late Charles Flaherty, reward comparison is commonplace. Rats and man, it appears, compare all rewards and this capacity likely contributes to our ability to select the most appropriate reward/behavior (food, water, salt, sex), at the most ideal level (e.g., a certain sweetness), at any given time. A second advantage of our predisposition for reward comparison is that the availability of rich alternative rewards can protect against our becoming addicted to any single reward/behavior. Thus, the potential protective effects of natural rewards/enrichment are addressed. Despite this, behavior can become inflexible when, through the development of addiction, stress, drug, or cues elicit craving, withdrawal, and ultimately, drug-seeking. Drug-seeking corresponds with a 'window of inopportunity', when even potent natural rewards have little or no impact on behavior. During this time, there is a unitary solution to the need state, and that solution is drug. The present animal model explores this 'window of inopportunity' when natural rewards are devalued and drug-seeking is engaged and considers a mode of possible intervention.

  3. Charging versus rewarding : A comparison of road-pricing and rewarding peak avoidance in the Netherlands

    NARCIS (Netherlands)

    Tillema, Taede; Ben-Elia, Eran; Ettema, Dick; van Delden, Janet

    2013-01-01

    The aim of this paper is to compare two congestion management schemes road-pricing and peak avoidance rewarding and their impact on commuter behaviour, based on two studies that were conducted in the Netherlands. The road-pricing study is based on stated preference data, whereas the study involving

  4. Reward expectancy promotes generalized increases in attentional bias for rewarding stimuli.

    Science.gov (United States)

    Jones, Andrew; Hogarth, Lee; Christiansen, Paul; Rose, Abigail K; Martinovic, Jasna; Field, Matt

    2012-01-01

    Expectations of drug availability increase the magnitude of attentional biases for drug-related cues. However, it is unknown whether these effects are outcome specific, or whether expectation of a specific reinforcer produces a general enhancement of attentional bias for other types of rewarding cues. In the present study, 31 social drinkers completed an eye-tracking task in which attentional bias for alcohol- and chocolate-related cues was assessed while the expectation of receiving alcohol and chocolate was manipulated on a trial-by-trial basis. Participants showed attentional bias for alcohol and chocolate cues (relative to neutral cues) overall. Importantly, these attentional biases for reward cues were magnified when participants expected to receive alcohol and chocolate, but effects were not outcome specific: The expectation of receiving either alcohol or chocolate increased attentional bias for both alcohol and chocolate cues. Results suggest that anticipation of reward produces a general rather than an outcome-specific enhancement of attentional bias for reward-related stimuli.

  5. Neural coding of reward magnitude in the orbitofrontal cortex of the rat during a five-odor olfactory discrimination task.

    NARCIS (Netherlands)

    E. van Duuren; F.A.N. Escamez; R.N.J.M.A. Joosten; R. Visser; A.B. Mulder; C.M.A. Pennartz

    2007-01-01

    The orbitofrontal cortex (OBFc) has been suggested to code the motivational value of environmental stimuli and to use this information for the flexible guidance of goal-directed behavior. To examine whether information regarding reward prediction is quantitatively represented in the rat OBFc, neural

  6. Neural Coding of Reward Magnitude in the Orbitofrontal Cortex of the Rat during a Five-Odor Olfactory Discrimination Task

    Science.gov (United States)

    van Duuren, Esther; Nieto Escamez, Francisco A.; Joosten, Ruud N. J. M. A.; Visser, Rein; Mulder, Antonius B.; Pennartz, Cyriel M. A.

    2007-01-01

    The orbitofrontal cortex (OBFc) has been suggested to code the motivational value of environmental stimuli and to use this information for the flexible guidance of goal-directed behavior. To examine whether information regarding reward prediction is quantitatively represented in the rat OBFc, neural activity was recorded during an olfactory…

  7. Cannabinoids reward sensitivity in a neurodevelopmental animal model of schizophrenia: a brain stimulation reward study.

    Science.gov (United States)

    Gallo, Alexandra; Bouchard, Claude; Fortier, Emmanuel; Ducrot, Charles; Rompré, Pierre-Paul

    2014-09-01

    The comorbidity schizophrenia and cannabis has a high prevalence. The consumption of cannabis is ten times higher among schizophrenia patients, suggesting that these patients could be differentially sensitive to its motivational effects. To study this question, we investigated the motivational effects of cannabinoid agonists using the brain stimulation reward paradigm and a neurodevelopmental model of schizophrenia: neonatal ventral hippocampus lesions (NVHL). Using the curve-shift paradigm, we first compared the effect single dose (0.75mg/kg) of amphetamine in sham and NVHL rats on reward and operant responding. Then, in different groups of NVHL and sham rats, we studied the effect of delta-9-tetrahydrocannabinnol (THC, 0.5mg/kg, i.p.) and WIN55,212-2 (WIN, 1 and 3mg/kg, i.p.) Rats were initially trained to self-administer an electrical stimulation to the posterio-medial mesencephalon. Once responding was stable, reward threshold defined as the frequency required to induce a half maximum response rate was measured before and after injection of the drug or the vehicle. Results show that amphetamine enhanced reward in sham and NVHL rats, an effect that was shorter in duration in NVHL rats. THC produced a weak attenuation of reward in sham rats while WIN produced a dose-dependent attenuation in NVHL; the attenuation effect of WIN was blocked by the cannabinoid antagonist, AM251. WIN also produced an attenuation of performance in sham and NVHL rats, and this effect was partially prevented by AM251. These results provide the additional evidence that the motivational effect of cannabinoids is altered in animals with a schizophrenia-like phenotype.

  8. Optogenetic activation of dorsal raphe serotonin neurons enhances patience for future rewards.

    Science.gov (United States)

    Miyazaki, Kayoko W; Miyazaki, Katsuhiko; Tanaka, Kenji F; Yamanaka, Akihiro; Takahashi, Aki; Tabuchi, Sawako; Doya, Kenji

    2014-09-08

    Serotonin is a neuromodulator that is involved extensively in behavioral, affective, and cognitive functions in the brain. Previous recording studies of the midbrain dorsal raphe nucleus (DRN) revealed that the activation of putative serotonin neurons correlates with the levels of behavioral arousal [1], rhythmic motor outputs [2], salient sensory stimuli [3-6], reward, and conditioned cues [5-8]. The classic theory on serotonin states that it opposes dopamine and inhibits behaviors when aversive events are predicted [9-14]. However, the therapeutic effects of serotonin signal-enhancing medications have been difficult to reconcile with this theory [15, 16]. In contrast, a more recent theory states that serotonin facilitates long-term optimal behaviors and suppresses impulsive behaviors [17-21]. To test these theories, we developed optogenetic mice that selectively express channelrhodopsin in serotonin neurons and tested how the activation of serotonergic neurons in the DRN affects animal behavior during a delayed reward task. The activation of serotonin neurons reduced the premature cessation of waiting for conditioned cues and food rewards. In reward omission trials, serotonin neuron stimulation prolonged the time animals spent waiting. This effect was observed specifically when the animal was engaged in deciding whether to keep waiting and was not due to motor inhibition. Control experiments showed that the prolonged waiting times observed with optogenetic stimulation were not due to behavioral inhibition or the reinforcing effects of serotonergic activation. These results show, for the first time, that the timed activation of serotonin neurons during waiting promotes animals' patience to wait for a delayed reward.

  9. Chromosomal aberrations related to metastasis of human solid tumors

    Institute of Scientific and Technical Information of China (English)

    Lun-Xiu Qin

    2002-01-01

    between the chromosomal aberrations and the metastatic phenotype of cancer. As the progression of human genome project and the establishment of more and more new techniques, it is hopeful to make clear the genetic mechanisms involved in the tumor metastasis in a not very long future, and provide new clues to predicting and controlling the metastasis.

  10. Aberration measurement from specific photolithographic images: a different approach.

    Science.gov (United States)

    Nomura, H; Tawarayama, K; Kohno, T

    2000-03-01

    Techniques for measurement of higher-order aberrations of a projection optical system in photolithographic exposure tools have been established. Even-type and odd-type aberrations are independently obtained from printed grating patterns on a wafer by three-beam interference under highly coherent illumination. Even-type aberrations, i.e., spherical aberration and astigmatism, are derived from the best focus positions of vertical, horizontal, and oblique grating patterns by an optical microscope. Odd-type aberrations, i.e., coma and three-foil, are obtained by detection of relative shifts of a fine grating pattern to a large pattern by an overlay inspection tool. Quantitative diagnosis of lens aberrations with a krypton fluoride (KrF) excimer laser scanner is demonstrated.

  11. Calibration and removal of lateral chromatic aberration in images

    OpenAIRE

    Mallon, John; Whelan, Paul F.

    2007-01-01

    This paper addresses the problem of compensating for lateral chromatic aberration in digital images through colour plane realignment. Two main contributions are made: the derivation of a model for lateral chromatic aberration in images, and the subsequent calibration of this model from a single view of a chess pattern. These advances lead to a practical and accurate alternative for the compensation of lateral chromatic aberrations. Experimental results validate the proposed models and calibra...

  12. Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels

    Energy Technology Data Exchange (ETDEWEB)

    J.A. Maloney, B. Erdelyi, A. Afanaciev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov

    2011-03-01

    Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

  13. The impact of work rewards on radiographers' organizational commitment.

    Science.gov (United States)

    Akroyd, D; Mulkey, W; Utley-Smith, Q

    1995-01-01

    Organizational commitment is an affective work outcome that has been used to predict work-related behaviors such as turnover, absenteeism and intent-to-leave. There has been little research in organizational commitment for the allied health professions and no empirical studies in the radiologic sciences. The purpose of this study was to examine the predictive value of selected intrinsic and extrinsic work reward variables--involvement, significance, autonomy, general working conditions, supervision and salary--on staff radiographers' organizational commitment. In this study of 600 full-time staff radiographers in North and South Carolina, supervision (for ages 20-37 years) and involvement (for ages 38-66 years) were significant predictors of organizational commitment. The results of the study indicate that healthcare organizations should provide potential supervisors with managerial training, especially for radiographers who move to supervisory positions based on clinical skills and years of experience. In the long run, such programs are much less expensive than costs associated with replacing employees who leave the organization because of low organizational commitment. Also, management strategies and programs to redesign and enhance job tasks may help maintain or increase organizational commitment.

  14. Changes in Astigmatism, Densitometry, and Aberrations After SMILE for Low to High Myopic Astigmatism

    DEFF Research Database (Denmark)

    Pedersen, Iben Bach; Ivarsen, Anders; Hjortdal, Jesper

    2017-01-01

    PURPOSE: To evaluate 12-month changes in refraction, visual outcome, corneal densitometry, and postoperative aberrations after small incision lenticule extraction (SMILE) for myopic astigmatism. METHODS: This 12-month prospective clinical trial comprised 101 eyes (101 patients) treated with SMILE...... be identified. CONCLUSIONS: Treatment of astigmatism with SMILE seems to be predictable and effective, but with an astigmatic undercorrection of approximately 11% and a small counterclockwise rotation of the axis. [J Refract Surg. 2017;33(1):11-17.]....

  15. Cellular origin of prognostic chromosomal aberrations in AML patients

    DEFF Research Database (Denmark)

    Mora-Jensen, H.; Jendholm, J.; Rapin, N.;

    2015-01-01

    karyotype have demonstrated the presence of prognostic driver aberrations (that is, NPM1, FLT3-ITD and FLT3-TKD) in committed HPCs but not in multipotent HSCs. However, the HSC populations lacking the prognostic driver aberrations contained preleukemic clones harboring a series of recurrent molecular...... aberrations that were present in the fully transformed committed HPCs together with the prognostic driver aberration. Adding to this vast heterogeneity and complexity of AML genomes and their clonal evolution, a recent study of a murine AML model demonstrated that t(9;11) AML originating from HSCs responded...

  16. Evidence that Illness-Compatible Cues Are Rewarding in Women Recovered from Anorexia Nervosa: A Study of the Effects of Dopamine Depletion on Eye-Blink Startle Responses

    Science.gov (United States)

    O’Hara, Caitlin B.; Keyes, Alexandra; Renwick, Bethany; Giel, Katrin E.; Campbell, Iain C.; Schmidt, Ulrike

    2016-01-01

    In anorexia nervosa (AN), motivational salience is attributed to illness-compatible cues (e.g., underweight and active female bodies) and this is hypothesised to involve dopaminergic reward circuitry. We investigated the effects of reducing dopamine (DA) transmission on the motivational processing of AN-compatible cues in women recovered from AN (AN REC, n = 17) and healthy controls (HC, n = 15). This involved the acute phenylalanine and tyrosine depletion (APTD) procedure and a startle eye-blink modulation (SEM) task. In a balanced amino acid state, AN REC showed an increased appetitive response (decreased startle potentiation) to illness-compatible cues (underweight and active female body pictures (relative to neutral and non-active cues, respectively)). The HC had an aversive response (increased startle potentiation) to the same illness-compatible stimuli (relative to neutral cues). Importantly, these effects, which may be taken to resemble symptoms observed in the acute stage of illness and healthy behaviour respectively, were not present when DA was depleted. Thus, AN REC implicitly appraised underweight and exercise cues as more rewarding than did HC and the process may, in part, be DA-dependent. It is proposed that the positive motivational salience attributed to cues of emaciation and physical activity is, in part, mediated by dopaminergic reward processes and this contributes to illness pathology. These observations are consistent with the proposal that, in AN, aberrant reward-based learning contributes to the development of habituation of AN-compatible behaviours. PMID:27764214

  17. Acute Stress Influences Neural Circuits of Reward Processing

    Directory of Open Access Journals (Sweden)

    Anthony John Porcelli

    2012-11-01

    Full Text Available People often make decisions under aversive conditions such as acute stress. Yet, less is known about the process in which acute stress can influence decision-making. A growing body of research has established that reward-related information associated with the outcomes of decisions exerts a powerful influence over the choices people make and that an extensive network of brain regions, prominently featuring the striatum, is involved in the processing of this reward-related information. Thus, an important step in research on the nature of acute stress’ influence over decision-making is to examine how it may modulate responses to rewards and punishments within reward-processing neural circuitry. In the current experiment, we employed a simple reward processing paradigm – where participants received monetary rewards and punishments – known to evoke robust striatal responses. Immediately prior to performing each of two task runs, participants were exposed to acute stress (i.e., cold pressor or a no stress control procedure in a between-subjects fashion. No stress group participants exhibited a pattern of activity within the dorsal striatum and orbitofrontal cortex consistent with past research on outcome processing – specifically, differential responses for monetary rewards over punishments. In contrast, acute stress group participants’ dorsal striatum and orbitofrontal cortex demonstrated decreased sensitivity to monetary outcomes and a lack of differential activity. These findings provide insight into how neural circuits may process rewards and punishments associated with simple decisions under acutely stressful conditions.

  18. Learning from Human Reward Benefits from Socio-competitive Feedback

    NARCIS (Netherlands)

    Li, G.; Hung, H.; Whiteson, S.; Knox, W.B.

    2014-01-01

    Learning from rewards generated by a human trainer observing an agent in action has proven to be a powerful method for non-experts in autonomous agents to teach such agents to perform challenging tasks. Since the efficacy of this approach depends critically on the reward the trainer provides, we con

  19. The Use of Rewards and Punishment in Early Childhood Classrooms

    Science.gov (United States)

    Moberly, Deborah A.; Waddle, Jerry L.; Duff, R. Eleanor

    2005-01-01

    Much has been written about the problems associated with reliance on extrinsic rewards and punishment in controlling behavior and motivating students. This study explores the use of extrinsic rewards and punishment by prekindergarten-grade 3 teachers in Missouri. The purpose of the study was to (a) determine the most common motivational practices…

  20. The Use of Different Rules to Allocate Reward and Punishment.

    Science.gov (United States)

    Mueller, Charles W.

    Much research has been conducted about how and when individuals allocate rewards, yet little research exists concerning the allocation of punishment. The process of allocating negative outcomes may be different from the decision making process for positive outcomes. To examine the decision making process for allocating rewards and punishment,…

  1. 31 CFR 103.62 - Rewards for informants.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Rewards for informants. 103.62 Section 103.62 Money and Finance: Treasury Regulations Relating to Money and Finance FINANCIAL RECORDKEEPING AND REPORTING OF CURRENCY AND FOREIGN TRANSACTIONS General Provisions § 103.62 Rewards...

  2. Cognitive regulation of saccadic velocity by reward prospect.

    Science.gov (United States)

    Chen, Lewis L; Hung, Leroy Y; Quinet, Julie; Kosek, Kevin

    2013-08-01

    It is known that expectation of reward speeds up saccades. Past studies have also shown the presence of a saccadic velocity bias in the orbit, resulting from a biomechanical regulation over varying eccentricities. Nevertheless, whether and how reward expectation interacts with the biomechanical regulation of saccadic velocities over varying eccentricities remains unknown. We addressed this question by conducting a visually guided double-step saccade task. The role of reward expectation was tested in monkeys performing two consecutive horizontal saccades, one associated with reward prospect and the other not. To adequately assess saccadic velocity and avoid adaptation, we systematically varied initial eye positions, saccadic directions and amplitudes. Our results confirmed the existence of a velocity bias in the orbit, i.e., saccadic peak velocity decreased linearly as the initial eye position deviated in the direction of the saccade. The slope of this bias increased as saccadic amplitudes increased. Nevertheless, reward prospect facilitated velocity to a greater extent for saccades away from than for saccades toward the orbital centre, rendering an overall reduction in the velocity bias. The rate (slope) and magnitude (intercept) of reward modulation over this velocity bias were linearly correlated with amplitudes, similar to the amplitude-modulated velocity bias without reward prospect, which presumably resulted from a biomechanical regulation. Small-amplitude (≤ 5°) saccades received little modulation. These findings together suggest that reward expectation modulated saccadic velocity not as an additive signal but as a facilitating mechanism that interacted with the biomechanical regulation.

  3. Reward association facilitates distractor suppression in human visual search.

    Science.gov (United States)

    Gong, Mengyuan; Yang, Feitong; Li, Sheng

    2016-04-01

    Although valuable objects are attractive in nature, people often encounter situations where they would prefer to avoid such distraction while focusing on the task goal. Contrary to the typical effect of attentional capture by a reward-associated item, we provide evidence for a facilitation effect derived from the active suppression of a high reward-associated stimulus when cuing its identity as distractor before the display of search arrays. Selection of the target is shown to be significantly faster when the distractors were in high reward-associated colour than those in low reward-associated or non-rewarded colours. This behavioural reward effect was associated with two neural signatures before the onset of the search display: the increased frontal theta oscillation and the strengthened top-down modulation from frontal to anterior temporal regions. The former suggests an enhanced working memory representation for the reward-associated stimulus and the increased need for cognitive control to override Pavlovian bias, whereas the latter indicates that the boost of inhibitory control is realized through a frontal top-down mechanism. These results suggest a mechanism in which the enhanced working memory representation of a reward-associated feature is integrated with task demands to modify attentional priority during active distractor suppression and benefit behavioural performance.

  4. Developmental continuity in reward-related enhancement of cognitive control

    Directory of Open Access Journals (Sweden)

    Nicole M. Strang

    2014-10-01

    Full Text Available Adolescents engage in more risky behavior than children or adults. The most prominent hypothesis for this phenomenon is that brain systems governing reward sensitivity and brain systems governing self-regulation mature at different rates. Those systems governing reward sensitivity mature in advance of those governing self-control. This hypothesis has substantial empirical support, however, the evidence supporting this theory has been exclusively derived from contexts where self-control systems are required to regulate reward sensitivity in order to promote adaptive behavior. In adults, reward promotes a shift to a proactive control strategy and better cognitive control performance. It is unclear whether children and adolescents will respond to reward in the same way. Using fMRI methodology, we explored whether children and adolescents would demonstrate a shift to proactive control in the context of reward. We tested 22 children, 20 adolescents, and 23 adults. In contrast to our hypothesis, children, adolescents, and adults all demonstrated a shift to proactive cognitive control in the context of reward. In light of the results, current neurobiological theories of adolescent behavior need to be refined to reflect that in certain contexts there is continuity in the manner reward and cognitive control systems interact across development.

  5. Immunizing Children against the Negative Effects of Reward.

    Science.gov (United States)

    Amabile, Teresa M.; And Others

    To determine whether training could counter deleterious effects of reward on intrinsic motivation and creativity, 68 students in grades 3, 4, and 5 at a parochial school in Massachusetts were assigned to one of four conditions in which intrinsic motivation training and rewards were either provided or withheld. In the intrinsic motivation training…

  6. Effort reward imbalance, and salivary cortisol in the morning

    DEFF Research Database (Denmark)

    Eller, Nanna Hurwitz; Nielsen, Søren Feodor; Blønd, Morten

    2012-01-01

    Effort reward imbalance (ERI) is suggested to increase risk for stress and is hypothesized to increase cortisol levels, especially the awakening cortisol response, ACR.......Effort reward imbalance (ERI) is suggested to increase risk for stress and is hypothesized to increase cortisol levels, especially the awakening cortisol response, ACR....

  7. Representation of Reward Feedback in Primate Auditory Cortex

    Directory of Open Access Journals (Sweden)

    Michael eBrosch

    2011-02-01

    Full Text Available It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1 the reward expectancy for each trial, (2 the reward size received and (3 the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

  8. Reward Retroactively Enhances Memory Consolidation for Related Items

    Science.gov (United States)

    Patil, Anuya; Murty, Vishnu P.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.; Davachi, Lila

    2017-01-01

    Reward motivation has been shown to modulate episodic memory processes in order to support future adaptive behavior. However, for a memory system to be truly adaptive, it should enhance memory for rewarded events as well as for neutral events that may seem inconsequential at the time of encoding but can gain importance later. Here, we investigated…

  9. Effects of Teacher Rewards on Recognition and Job Enrichment.

    Science.gov (United States)

    Frase, Larry E.

    1989-01-01

    Implications of Herzberg's motivation-hygiene theory for teacher reward programs were tested by comparing changes in teachers' (N=38) job-enrichment opportunities and recognition after the teachers had chosen one of two rewards (travel to professional training conferences or cash). Results were consistent with the motivation-hygiene theory. (IAH)

  10. Rewards for Reading: Their Effects on Reading Motivation

    Science.gov (United States)

    Chen, Pin-Hwa; Wu, Jen-Rung

    2010-01-01

    In recent years, many Taiwanese elementary schools have implemented extensive reading activities in their respective campuses. In order to motivate pupils to read, teachers and parents would offer pupils contingent rewards. As we know, the use of rewards in educational settings as a way to improve motivation is a controversial issue. Previous…

  11. Representation of reward feedback in primate auditory cortex.

    Science.gov (United States)

    Brosch, Michael; Selezneva, Elena; Scheich, Henning

    2011-01-01

    It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

  12. The Effects of Extrinsic Rewards on Admissions Counselors' Performance

    Science.gov (United States)

    Gardner-Engel, Miriam

    2010-01-01

    This study examines the best ways to motivate college admissions counselors. A review of literature revealed multiple perspectives on intrinsic and extrinsic as well as tangible and intangible rewards. Primary research was designed to examine the impact of tangible rewards and verbal reinforcements with a convenience sample of nine college…

  13. Marine Corps Promotion System: Rewarding Merit or Seniority?

    Science.gov (United States)

    2013-04-23

    battlefields. PME is both an extrinsic and intrinsic reward . The majority of schools offer the ability to earn an advanced degree in conjunction...intrinsic and extrinsic motivators is key to rewarding leaders who have earned the right to be at the front of the line. In-zone reordering would...

  14. Recruiter-Applicant Differences in Perceptions of Extrinsic Rewards.

    Science.gov (United States)

    David, Kermit R., Jr.; And Others

    1991-01-01

    Examined how accurate recruiters would be in estimating relative preferences of college seniors for important category of extrinsic rewards. Compared preferences of 602 graduating college seniors for 11 extrinsic rewards with preference estimates of 486 recruiters. Recruiters underestimated importance of medical and life insurance, pension plans,…

  15. Extrinsic Rewards Are Education's Past, Not Its Future.

    Science.gov (United States)

    Schaps, Eric; Lewis, Catherine

    1991-01-01

    Robert Slavin's position--that extrinsic rewards promote student motivation and learning--may be valid within the context of a "facts-and-skills" curriculum. However, extrinsic rewards are unnecessary when schools offer engaging learning activities; programs addressing social, ethical, and cognitive development; and a supportive…

  16. Opportunity NYC--Family Rewards: Qualitative Study of Family Communication

    Science.gov (United States)

    Fraker, Carolyn A.; Greenberg, David

    2011-01-01

    Aimed at low-income families in six of New York City's highest-poverty communities, the Family Rewards program ties cash rewards to a pre-specified set of activities. This paper presents the qualitative findings from interviews with 77 families. It examines how families incorporated the program into their households, and specifically the…

  17. Neurobiology of hyperactivity and reward : Agreeable restlessness in Anorexia Nervosa

    NARCIS (Netherlands)

    Scheurink, Anton J. W.; Boersma, Gretha J.; Nergardh, Ricard; Sodersten, Per; Nergårdh, Ricard; Södersten, Per

    2010-01-01

    Restricted food intake is associated with increased physical activity, very likely an evolutionary advantage, initially both functional and rewarding. The hyperactivity of patients with Anorexia Nervosa, however, is a main problem for recovery. This seemingly paradoxical reward of hyperactivity in A

  18. The nucleus accumbens is involved in both the pursuit of social reward and the avoidance of social punishment.

    Science.gov (United States)

    Kohls, Gregor; Perino, Michael T; Taylor, James M; Madva, Elizabeth N; Cayless, Sarah J; Troiani, Vanessa; Price, Elinora; Faja, Susan; Herrington, John D; Schultz, Robert T

    2013-09-01

    Human social motivation is characterized by the pursuit of social reward and the avoidance of social punishment. The ventral striatum/nucleus accumbens (VS/Nacc), in particular, has been implicated in the reward component of social motivation, i.e., the 'wanting' of social incentives like approval. However, it is unclear to what extent the VS/Nacc is involved in avoiding social punishment like disapproval, an intrinsically pleasant outcome. Thus, we conducted an event-related functional magnetic resonance imaging (fMRI) study using a social incentive delay task with dynamic video stimuli instead of static pictures as social incentives in order to examine participants' motivation for social reward gain and social punishment avoidance. As predicted, the anticipation of avoidable social punishment (i.e., disapproval) recruited the VS/Nacc in a manner that was similar to VS/Nacc activation observed during the anticipation of social reward gain (i.e., approval). Stronger VS/Nacc activity was accompanied by faster reaction times of the participants to obtain those desired outcomes. This data support the assumption that dynamic social incentives elicit robust VS/Nacc activity, which likely reflects motivation to obtain social reward and to avoid social punishment. Clinical implications regarding the involvement of the VS/Nacc in social motivation dysfunction in autism and social phobia are discussed.

  19. U.S. Geological Survey Rewarding Environment Culture Study, 2002

    Science.gov (United States)

    Nash, Janis C.; Paradise-Tornow, Carol A.; Gray, Vicki K.; Griffin-Bemis, Sarah P.; Agnew, Pamela R.; Bouchet, Nicole M.

    2010-01-01

    In its 2001 review of the U.S. Geological Survey (USGS), the National Research Council (NRC, p. 126) cautioned that ?high-quality personnel are essential for developing high-quality science information? and urged the USGS to ?devote substantial efforts to recruiting and retaining excellent staff.? Recognizing the importance of the NRC recommendation, the USGS has committed time and resources to create a rewarding work environment with the goal of achieving the following valued outcomes: ? USGS science vitality ? Customer satisfaction with USGS products and services ? Employee perceptions of the USGS as a rewarding place to work ? Heightened employee morale and commitment ? The ability to recruit and retain employees with critical skills To determine whether this investment of time and resources was proving to be successful, the USGS Human Resources Office conducted a Rewarding Environment Culture Study to answer the following four questions. ? Question 1: Does a rewarding work environment lead to the valued outcomes (identified above) that the USGS is seeking? ? Question 2: Which management, supervisory, and leadership behaviors contribute most to creating a rewarding work environment and to achieving the valued outcomes that the USGS is seeking? ? Question 3: Do USGS employees perceive that the USGS is a rewarding place to work? ? Question 4: What actions can and should be taken to enhance the USGS work environment? To begin the study, a conceptual model of a rewarding USGS environment was developed to test assumptions about a rewarding work environment. The Rewarding Environment model identifies the key components that are thought to contribute to a rewarding work environment and the valued outcomes that are thought to result from having a rewarding work environment. The 2002 Organizational Assessment Survey (OAS) was used as the primary data source for the study because it provided the most readily available data. Additional survey data were included as they

  20. Exit, punishment and rewards in commons dilemmas: an experimental study.

    Directory of Open Access Journals (Sweden)

    Giangiacomo Bravo

    Full Text Available Commons dilemmas are interaction situations where a common good is provided or exploited by a group of individuals so that optimal collective outcomes clash with private interests. Although in these situations, social norms and institutions exist that might help individuals to cooperate, little is known about the interaction effects between positive and negative incentives and exit options by individuals. We performed a modified public good game experiment to examine the effect of exit, rewards and punishment, as well as the interplay between exit and rewards and punishment. We found that punishment had a stronger effect than rewards on cooperation if considered by itself, whereas rewards had a stronger effect when combined with voluntary participation. This can be explained in terms of the 'framing effect', i.e., as the combination of exit and rewards might induce people to attach higher expected payoffs to cooperative strategies and expect better behaviour from others.

  1. Exit, punishment and rewards in commons dilemmas: an experimental study.

    Science.gov (United States)

    Bravo, Giangiacomo; Squazzoni, Flaminio

    2013-01-01

    Commons dilemmas are interaction situations where a common good is provided or exploited by a group of individuals so that optimal collective outcomes clash with private interests. Although in these situations, social norms and institutions exist that might help individuals to cooperate, little is known about the interaction effects between positive and negative incentives and exit options by individuals. We performed a modified public good game experiment to examine the effect of exit, rewards and punishment, as well as the interplay between exit and rewards and punishment. We found that punishment had a stronger effect than rewards on cooperation if considered by itself, whereas rewards had a stronger effect when combined with voluntary participation. This can be explained in terms of the 'framing effect', i.e., as the combination of exit and rewards might induce people to attach higher expected payoffs to cooperative strategies and expect better behaviour from others.

  2. Motivating inhibition - reward prospect speeds up response cancellation.

    Science.gov (United States)

    Boehler, Carsten N; Hopf, Jens-Max; Stoppel, Christian M; Krebs, Ruth M

    2012-12-01

    Reward prospect has been demonstrated to facilitate various cognitive and behavioral operations, particularly by enhancing the speed and vigor of processes linked to approaching reward. Studies in this domain typically employed task regimes in which participants' overt responses are facilitated by prospective rewards. In contrast, we demonstrate here that even the cancellation of a motor response can be accelerated by reward prospect, thus signifying reward-related benefits on restraint rather than approach behavior. Importantly, this facilitation occurred independent of strategy-related adjustments of response speed, which are known to systematically distort the estimation of response-cancellation speed. The fact that motivational factors can indeed facilitate response inhibition is not only relevant for understanding how motivation and response inhibition interact in healthy participants but also for work on various patient groups that display response-inhibition deficits, suggesting that core differences in the ability to inhibit motor responses have to be differentiated from motivational factors.

  3. Decision-Theoretic Planning with non-Markovian Rewards

    CERN Document Server

    Gretton, C; Price, D; Slaney, J; Thiebaux, S

    2011-01-01

    A decision process in which rewards depend on history rather than merely on the current state is called a decision process with non-Markovian rewards (NMRDP). In decision-theoretic planning, where many desirable behaviours are more naturally expressed as properties of execution sequences rather than as properties of states, NMRDPs form a more natural model than the commonly adopted fully Markovian decision process (MDP) model. While the more tractable solution methods developed for MDPs do not directly apply in the presence of non-Markovian rewards, a number of solution methods for NMRDPs have been proposed in the literature. These all exploit a compact specification of the non-Markovian reward function in temporal logic, to automatically translate the NMRDP into an equivalent MDP which is solved using efficient MDP solution methods. This paper presents NMRDPP (Non-Markovian Reward Decision Process Planner), a software platform for the development and experimentation of methods for decision-theoretic planning...

  4. Optogenetics in Freely Moving Mammals: Dopamine and Reward.

    Science.gov (United States)

    Zhang, Feng; Tsai, Hsing-Chen; Airan, Raag D; Stuber, Garret D; Adamantidis, Antoine R; de Lecea, Luis; Bonci, Antonello; Deisseroth, Karl

    2015-08-03

    Brain reward systems play a central role in the cognitive and hedonic behaviors of mammals. Multiple neuron types and brain regions are involved in reward processing, posing fascinating scientific questions, and major experimental challenges. Using diverse approaches including genetics, electrophysiology, imaging, and behavioral analysis, a large body of research has focused on both normal functioning of the reward circuitry and on its potential significance in neuropsychiatric diseases. In this introduction, we illustrate a real-world application of optogenetics to mammalian behavior and physiology, delineating procedures and technologies for optogenetic control of individual components of the reward circuitry. We describe the experimental setup and protocol for integrating optogenetic modulation of dopamine neurons with fast-scan cyclic voltammetry, conditioned place preference, and operant conditioning to assess the causal role of well-defined electrical and biochemical signals in reward-related behavior.

  5. Effort-reward imbalance and depression in Japanese medical residents.

    Science.gov (United States)

    Sakata, Yumi; Wada, Koji; Tsutsumi, Akizumi; Ishikawa, Hiroyasu; Aratake, Yutaka; Watanabe, Mayumi; Katoh, Noritada; Aizawa, Yoshiharu; Tanaka, Katsutoshi

    2008-01-01

    The effort-reward imbalance is an important psychosocial factor which is related to poor health among employees. However, there are few studies that have evaluated effort-reward imbalance among medical residents. The present study was done to determine the association between psychosocial factors at work as defined by the effort-reward imbalance model and depression among Japanese medical residents. We distributed a questionnaire to 227 medical residents at 16 teaching hospitals in Japan at the end of August 2005. We asked participants to answer questions which included demographic information, depressive symptoms, effort-reward imbalance, over-commitment and social support. Depression was evaluated using the Japanese version of the Center for Epidemiologic Studies-Depression (CES-D) scale. The effort-reward imbalance and over-commitment were assessed by the Effort-Reward Imbalance (ERI) questionnaire which Siegrist developed. Social support was determined on a visual analog scale. Logistic regression analysis was performed to determine the associations between effort-reward imbalance and depressive symptoms. Depressive symptoms were found in 35 (29.2%) 1st-year residents and 21 (27.6%) 2nd-year residents. The effort-reward ratio >1 (OR, 8.83; 95% CI, 2.87-27.12) and low social support score (OR, 2.77, 95% CI, 1.36-5.64) were associated with depressive symptoms among medical residents. Effort-reward imbalance was independently related to depression among Japanese medical residents. The present study suggests that balancing between effort and reward at work is important for medical residents' mental health.

  6. Motivational orientation modulates the neural response to reward.

    Science.gov (United States)

    Linke, Julia; Kirsch, Peter; King, Andrea V; Gass, Achim; Hennerici, Michael G; Bongers, André; Wessa, Michèle

    2010-02-01

    Motivational orientation defines the source of motivation for an individual to perform a particular action and can either originate from internal desires (e.g., interest) or external compensation (e.g., money). To this end, motivational orientation should influence the way positive or negative feedback is processed during learning situations and this might in turn have an impact on the learning process. In the present study, we thus investigated whether motivational orientation, i.e., extrinsic and intrinsic motivation modulates the neural response to reward and punishment as well as learning from reward and punishment in 33 healthy individuals. To assess neural responses to reward, punishment and learning of reward contingencies we employed a probabilistic reversal learning task during functional magnetic resonance imaging. Extrinsic and intrinsic motivation were assessed with a self-report questionnaire. Rewarding trials fostered activation in the medial orbitofrontal cortex and anterior cingulate gyrus (ACC) as well as the amygdala and nucleus accumbens, whereas for punishment an increased neural response was observed in the medial and inferior prefrontal cortex, the superior parietal cortex and the insula. High extrinsic motivation was positively correlated to increased neural responses to reward in the ACC, amygdala and putamen, whereas a negative relationship between intrinsic motivation and brain activation in these brain regions was observed. These findings show that motivational orientation indeed modulates the responsiveness to reward delivery in major components of the human reward system and therefore extends previous results showing a significant influence of individual differences in reward-related personality traits on the neural processing of reward.

  7. Lateral hypothalamic circuits for feeding and reward.

    Science.gov (United States)

    Stuber, Garret D; Wise, Roy A

    2016-02-01

    In experiments conducted over 60 years ago, the lateral hypothalamic area (LHA) was identified as a critical neuroanatomical substrate for motivated behavior. Electrical stimulation of the LHA induces voracious feeding even in well-fed animals. In the absence of food, animals will work tirelessly, often lever-pressing thousands of times per hour, for electrical stimulation at the same site that provokes feeding, drinking and other species-typical motivated behaviors. Here we review the classic findings from electrical stimulation studies and integrate them with more recent work that has used contemporary circuit-based approaches to study the LHA. We identify specific anatomically and molecularly defined LHA elements that integrate diverse information arising from cortical, extended amygdala and basal forebrain networks to ultimately generate a highly specified and invigorated behavioral state conveyed via LHA projections to downstream reward and feeding-specific circuits.

  8. On Principle of Rewards in English Learning

    Institute of Scientific and Technical Information of China (English)

    熊莉芸

    2004-01-01

    There is no question that learning a foreign language like English is different from learning other subjects, mainly be cause it is new to us Chinese and there is no enough enviroment. But that doesn't mean we have no way to learn it and do it well .If asked to identify the most powerful influences on learning, motivation would probably be high on most teachers' and learners' lists. It seens only sensible to assume that English learning is most likely to occur when the learners want to learn. That is, when motivation such as interest, curiosity, or a desire achieves, the learners would be engaged in learning. However, how do we teachers motivate our students to like learning and learn well? Here, rewards both extrinsic and intrinsic are of great value and play a vital role in English learning.

  9. Strategies for reward-based crowdfunding campaigns

    DEFF Research Database (Denmark)

    Kraus, Sascha; Richter, Christian; Brem, Alexander

    2016-01-01

    Crowdfunding represents an alternative way of funding entrepreneurial ventures – and is attracting a high amount of interest in research as well as practice. Against this back- ground, this paper analyzes reward-based crowdfunding campaign strategies and their communication tools. To do this, 446...... crowdfunding projects were gathered and empirically analyzed. Three different paths of successful crowdfunding projects could be identified and are described in detail. Practical implications of crowdfunding strategies are derived, and are dependent on the required sales effort and the project added value....... The terms communicator, networker and self-runner are created for this crowdfunding strategy and filled with practi- cal examples. This paper contributes to the literature in different ways: first, it sheds more light on the developing concept of crowdfunding, with an overview of current academic dis...

  10. CMS rewards eight of its suppliers

    CERN Multimedia

    2002-01-01

    At the third awards ceremony to honour its top suppliers, the CMS collaboration presented awards to eight firms. Seven of them are involved in the manufacture of the magnet. The winners of the third CMS suppliers' awards visit the assembly site for the detector. Unsurprisingly, the CMS magnet was once again in the limelight at the third awards ceremony in honour of the collaboration's top suppliers. 'Unsurprisingly', because this magnet, which must produce an intense field of 4 Tesla inside an enormous volume (12 metres in diameter and 13 metres in length) is the detector's key component. As a result, many firms are involved in its construction. The CMS suppliers' awards are an annual event aimed at rewarding the exceptional efforts of certain companies. Firms are only eligible once they have delivered at least 50% of their supplies. This year, the collaboration honoured eight firms at a ceremony held on Monday 4 March in the main auditorium. Seven of th...

  11. Flavor vs Energy Sensing in Brain Reward Circuits

    Directory of Open Access Journals (Sweden)

    Ivan E De Araujo

    2014-07-01

    Full Text Available Sweetness functions as a potent natural reinforcer in several species, from flies to rodents to primates including humans. The appreciation of flavored stimuli is greatly enhanced when sweetness is added, the obvious example being sugar-sweetened flavored beverages (the major source of excess added calories in US diets. Different sweet substances are nevertheless attributed greater incentive value than others, with glucose-containing sugars appearing as the uppermost sweet reward. Food choices are indeed prominently determined by nutritional value, with caloric content being highly predictive of both preference and intake. Specifically, for most species studied, glucose-containing sugars are known to exert exquisitely strong effects on food choice via post-ingestive signals. Despite the relevance of the issue to public health, the identity of the physiological signals underlying glucose’s rewarding effects remains incompletely understood. Recently, however, some progress has been achieved in this front: the concept is emerging that the metabolic utilization of glucose moieties contained in sugars drives activity in brain reward circuitries (thereby presumably driving robust intake. Specifically, disruption of glucose utilization in mice was shown to produce an enduring inhibitory effect on artificial (non-nutritive sweetener intake, an effect that did not depend on sweetness perception or aversion [1]. Indeed, such an effect was not observed in mice presented with a less palatable, yet caloric, glucose solution. It is also remarkable that hungry mice shift their preferences away from artificial sweeteners in favor of glucose solutions, especially when the sugar is experienced in a food-depleted state. However, the most striking effect associated with sweet appetite appears to be the strong selectivity of certain brain circuitries to the energy content of the solutions, irrespective of sweetness per se. Indeed, it has been shown that glucose

  12. Modeling the violation of reward maximization and invariance in reinforcement schedules.

    Directory of Open Access Journals (Sweden)

    Giancarlo La Camera

    Full Text Available It is often assumed that animals and people adjust their behavior to maximize reward acquisition. In visually cued reinforcement schedules, monkeys make errors in trials that are not immediately rewarded, despite having to repeat error trials. Here we show that error rates are typically smaller in trials equally distant from reward but belonging to longer schedules (referred to as "schedule length effect". This violates the principles of reward maximization and invariance and cannot be predicted by the standard methods of Reinforcement Learning, such as the method of temporal differences. We develop a heuristic model that accounts for all of the properties of the behavior in the reinforcement schedule task but whose predictions are not different from those of the standard temporal difference model in choice tasks. In the modification of temporal difference learning introduced here, the effect of schedule length emerges spontaneously from the sensitivity to the immediately preceding trial. We also introduce a policy for general Markov Decision Processes, where the decision made at each node is conditioned on the motivation to perform an instrumental action, and show that the application of our model to the reinforcement schedule task and the choice task are special cases of this general theoretical framework. Within this framework, Reinforcement Learning can approach contextual learning with the mixture of empirical findings and principled assumptions that seem to coexist in the best descriptions of animal behavior. As examples, we discuss two phenomena observed in humans that often derive from the violation of the principle of invariance: "framing," wherein equivalent options are treated differently depending on the context in which they are presented, and the "sunk cost" effect, the greater tendency to continue an endeavor once an investment in money, effort, or time has been made. The schedule length effect might be a manifestation of these

  13. Underconnectivity between voice-selective cortex and reward circuitry in children with autism.

    Science.gov (United States)

    Abrams, Daniel A; Lynch, Charles J; Cheng, Katherine M; Phillips, Jennifer; Supekar, Kaustubh; Ryali, Srikanth; Uddin, Lucina Q; Menon, Vinod

    2013-07-16

    Individuals with autism spectrum disorders (ASDs) often show insensitivity to the human voice, a deficit that is thought to play a key role in communication deficits in this population. The social motivation theory of ASD predicts that impaired function of reward and emotional systems impedes children with ASD from actively engaging with speech. Here we explore this theory by investigating distributed brain systems underlying human voice perception in children with ASD. Using resting-state functional MRI data acquired from 20 children with ASD and 19 age- and intelligence quotient-matched typically developing children, we examined intrinsic functional connectivity of voice-selective bilateral posterior superior temporal sulcus (pSTS). Children with ASD showed a striking pattern of underconnectivity between left-hemisphere pSTS and distributed nodes of the dopaminergic reward pathway, including bilateral ventral tegmental areas and nucleus accumbens, left-hemisphere insula, orbitofrontal cortex, and ventromedial prefrontal cortex. Children with ASD also showed underconnectivity between right-hemisphere pSTS, a region known for processing speech prosody, and the orbitofrontal cortex and amygdala, brain regions critical for emotion-related associative learning. The degree of underconnectivity between voice-selective cortex and reward pathways predicted symptom severity for communication deficits in children with ASD. Our results suggest that weak connectivity of voice-selective cortex and brain structures involved in reward and emotion may impair the ability of children with ASD to experience speech as a pleasurable stimulus, thereby impacting language and social skill development in this population. Our study provides support for the social motivation theory of ASD.

  14. Need for cognition and desire for control as moderators of extrinsic reward effects: a person x situation approach to the study of intrinsic motivation.

    Science.gov (United States)

    Thompson, E P; Chaiken, S; Hazlewood, J D

    1993-06-01

    Seventy-four Ss in extrinsic-reward or no-reward conditions completed a brainstorming task and then were left alone with the option to engage in additional versions of this task. If the Need for Cognition (NFC) Scale taps intrinsic motivation for effortful cognition (J. T. Cacioppo & R. E. Petty, 1982), the optional task engagement of high-NFCSs, but not low-NFCSs, should be undermined by extrinsic reward. Results confirmed this hypothesis, but regression analyses showed that NFC scores' moderation of reward effects was due to their covariation with scores on J. M. Burger and H. M. Cooper's (1979) Desire for Control Scale. The data suggest that (a) NFC involves intrinsic motivation for effortful cognitive processing, (b) NFC may predict such processing mainly in contexts with minimal extrinsic incentives for processing, and (c) control motivation may be related causally both to extrinsic undermining effects and to individual differences in NFC.

  15. Aberrant angiogenesis: The gateway to diabetic complications

    Directory of Open Access Journals (Sweden)

    Sunil K Kota

    2012-01-01

    Full Text Available Diabetes Mellitus is a metabolic cum vascular syndrome with resultant abnormalities in both micro- and macrovasculature. The adverse long-term effects of diabetes mellitus have been described to involve many organ systems. Apart from hyperglycemia, abnormalities of angiogenesis may cause or contribute toward many of the clinical manifestations of diabetes. These are implicated in the pathogenesis of vascular abnormalities of the retina, kidneys, and fetus, impaired wound healing, increased risk of rejection of transplanted organs, and impaired formation of coronary collaterals. A perplexing feature of the aberrant angiogenesis is that excessive and insufficient angiogenesis can occur in different organs in the same individual. The current article hereby reviews the molecular mechanisms including abnormalities in growth factors, cytokines, and metabolic derangements, clinical implications, and therapeutic options of dealing with abnormal angiogenesis in diabetes.

  16. RACK1 affects morphine reward via BDNF.

    Science.gov (United States)

    Wan, Lihong; Xie, Yizhou; Su, Lan; Liu, Yanyou; Wang, Yuhui; Wang, Zhengrong

    2011-10-06

    Chronic morphine addiction may trigger functional changes in the mesolimbic dopamine system, which is believed to be the neurobiological substrate of opiate addiction. Brain derived neurotrophic factor (BDNF) has been implicated in addiction-related pathology in animal studies. Our previous studies have shown that RACK1 is involved in morphine reward in mice. The recent research indicates nuclear RACK1 by localizing at the promoter IV region of the BDNF gene and the subsequent chromatin modifications leads to the activation of the promoter and transcription of BDNF. The present study was designed to investigate if shRACK1 (a short hairpin RNA of RACK1) could reverse the mice's behavioral responses to morphine and BDNF expression in hippocampus and prefrontal cortex. No significant changes were observed in vehicle-infused mice which received no morphine treatment (CONC) and shRACK1-infused mice which received no morphine treatment (CONR), whereas vehicle-infused mice preceded the morphine injection (MIC) showed increased BDNF expression in hippocampus and prefrontal cortex, as compared to vehicle-infused mice which received no morphine treatment (CONC). Intracerebroventricular shRACK1 treatment reversed these, and in fact, ShRACK1-infused mice preceded the morphine injection (MIR) showed reduced BDNF expression in hippocampus and prefrontal cortex, as compared to MIC. In the conditioned place preference (CPP) test, inactivating RACK1 markedly reduces morphine-induced conditioned place preference. Non-specific changes in CPP could not account for these effects since general CPP of shRACK1- and vehicle-infused animals was not different. Combined behavioral and molecular approaches have support the possibility that the RACK1-BDNF system plays an important role in the response to morphine-induced reward.

  17. Deciphering causal and statistical relations of molecular aberrations and gene expressions in NCI-60 cell lines

    Directory of Open Access Journals (Sweden)

    Li Shyh-Dar

    2011-11-01

    Full Text Available Abstract Background Cancer cells harbor a large number of molecular alterations such as mutations, amplifications and deletions on DNA sequences and epigenetic changes on DNA methylations. These aberrations may dysregulate gene expressions, which in turn drive the malignancy of tumors. Deciphering the causal and statistical relations of molecular aberrations and gene expressions is critical for understanding the molecular mechanisms of clinical phenotypes. Results In this work, we proposed a computational method to reconstruct association modules containing driver aberrations, passenger mRNA or microRNA expressions, and putative regulators that mediate the effects from drivers to passengers. By applying the module-finding algorithm to the integrated datasets of NCI-60 cancer cell lines, we found that gene expressions were driven by diverse molecular aberrations including chromosomal segments' copy number variations, gene mutations and DNA methylations, microRNA expressions, and the expressions of transcription factors. In-silico validation indicated that passenger genes were enriched with the regulator binding motifs, functional categories or pathways where the drivers were involved, and co-citations with the driver/regulator genes. Moreover, 6 of 11 predicted MYB targets were down-regulated in an MYB-siRNA treated leukemia cell line. In addition, microRNA expressions were driven by distinct mechanisms from mRNA expressions. Conclusions The results provide rich mechanistic information regarding molecular aberrations and gene expressions in cancer genomes. This kind of integrative analysis will become an important tool for the diagnosis and treatment of cancer in the era of personalized medicine.

  18. Effect of chromatic aberration on atomic-resolved spherical aberration corrected STEM images.

    Science.gov (United States)

    Kuramochi, Koji; Yamazaki, Takashi; Kotaka, Yasutoshi; Ohtsuka, Masahiro; Hashimoto, Iwao; Watanabe, Kazuto

    2009-12-01

    The effect of the chromatic aberration (C(c)) coefficient in a spherical aberration (C(s))- corrected electromagnetic lens on high-resolution high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) images is explored in detail. A new method for precise determination of the C(c) coefficient is demonstrated, requiring measurement of an atomic-resolution one-frame through-focal HAADF STEM image. This method is robust with respect to instrumental drift, sample thickness, all lens parameters except C(c), and experimental noise. It is also demonstrated that semi-quantitative structural analysis on the nanometer scale can be achieved by comparing experimental C(s)- corrected HAADF STEM images with their corresponding simulated images when the effects of the C(c) coefficient and spatial incoherence are included.

  19. Putting the brakes on the "drive to eat": Pilot effects of naltrexone and reward based eating on food cravings among obese women

    Science.gov (United States)

    Mason, Ashley E.; Laraia, Barbara; Daubenmier, Jennifer; Hecht, Frederick M.; Lustig, Robert H.; Puterman, Eli; Adler, Nancy; Dallman, Mary; Kiernan, Michaela; Gearhardt, Ashley N.; Epel, Elissa S.

    2015-01-01

    Purpose Obese individuals vary in their experience of food cravings and tendency to engage in reward-driven eating, both of which can be modulated by the neural reward system rather than physiological hunger. We examined two predictions in a sample of obese women: (1) whether opioidergic blockade reduced food-craving intensity, and (2) whether opioidergic blockade reduced an association between food-craving intensity and reward-driven eating, which is a trait-like index of three factors (lack of control over eating, lack of satiation, preoccupation with food). Methods Forty-four obese, pre-menopausal women completed the Reward-based Eating Drive (RED) scale at study start and daily food-craving intensity on 5 days on which they ingested either a pill-placebo (2 days), a 25mg naltrexone dose (1 day), or a standard 50mg naltrexone dose (2 days). Results Craving intensity was similar under naltrexone and placebo doses. The association between food-craving intensity and reward-driven eating significantly differed between placebo and 50mg naltrexone doses. Reward-driven eating and craving intensity were significantly positively associated under both placebo doses. As predicted, opioidergic blockade (for both doses 25mg and 50mg naltrexone) reduced this positive association between reward-driven eating and craving intensity to non-significance. Conclusions Opioidergic blockade did not reduce craving intensity; however, blockade reduced an association between trait-like reward-driven eating and daily food-craving intensity, and may help identify an important endophenotype within obesity. PMID:26164674

  20. Design of an aberration corrected low-voltage SEM

    NARCIS (Netherlands)

    Aken, R.H. van; Maas, D.J.; Hagen, C.W.; Barth, J.E.; Kruit, P.

    2010-01-01

    The low-voltage foil corrector is a novel type of foil aberration corrector that can correct for both the spherical and chromatic aberration simultaneously. In order to give a realistic example of the capabilities of this corrector, a design for a low-voltage scanning electron microscope with the lo