DAT1 polymorphism determines L-DOPA effects on learning about others' prosociality.

Despite that a wealth of evidence links striatal dopamine to individualś reward learning performance in non-social environments, the neurochemical underpinnings of such learning during social interaction are unknown. Here, we show that the administration of 300 mg of the dopamine precursor L-DOPA to 200 healthy male subjects influences learning about a partners' prosocial preferences in a novel social interaction task, which is akin to a repeated trust game. We found learning to be modulated by a well-established genetic marker of striatal dopamine levels, the 40-bp variable number tandem repeats polymorphism of the dopamine transporter (DAT1 polymorphism). In particular, we found that L-DOPA improves learning in 10/10R genoype subjects, who are assumed to have lower endogenous striatal dopamine levels and impairs learning in 9/10R genotype subjects, who are assumed to have higher endogenous dopamine levels. These findings provide first evidence for a critical role of dopamine in learning whether an interaction partner has a prosocial or a selfish personality. The applied pharmacogenetic approach may open doors to new ways of studying psychiatric disorders such as psychosis, which is characterized by distorted perceptions of others' prosocial attitudes.

Diminishing risk-taking behavior by modulating activity in the prefrontal cortex: a direct current stimulation study.

Studies have shown increased risk taking in healthy individuals after low-frequency repetitive transcranial magnetic stimulation, known to transiently suppress cortical excitability, over the right dorsolateral prefrontal cortex (DLPFC). It appears, therefore, plausible that differential modulation of DLPFC activity, increasing the right while decreasing the left, might lead to decreased risk taking, which could hold clinical relevance as excessively risky decision making is observed in clinical populations leading to deleterious consequences. The goal of the present study was to investigate whether risk-taking behaviors could be decreased using concurrent anodal transcranial direct current stimulation (tDCS) of the right DLPFC, which allows upregulation of brain activity, with cathodal tDCS of the left DLPCF, which downregulates activity. Thirty-six healthy volunteers performed the risk task while they received either anodal over the right with cathodal over the left DLPFC, anodal over the left with cathodal over the right DLPFC, or sham stimulation. We hypothesized that right anodal/left cathodal would decrease risk-taking behavior compared with left anodal/right cathodal or sham stimulation. As predicted, during right anodal/left cathodal stimulation over the DLPFC, participants chose more often the safe prospect compared with the other groups. Moreover, these participants appeared to be insensitive to the reward associated with the prospects. These findings support the notion that the interhemispheric balance of activity across the DLPFCs is critical in decision-making behaviors. Most importantly, the observed suppression of risky behaviors suggests that populations with boundless risk-taking behaviors leading to negative real-life consequences, such as individuals with addiction, might benefit from such neuromodulation-based approaches.

Anreizformen und Ausschöpfungsquoten bei postalischen Befragungen. Eine Prüfung der Reziprozitätshypothese

Mittels eines Methodenexperiments mit zwei randomisierten Versuchsgruppen (N jeweils 200) und einer Kontrollgruppe (N=200) wird untersucht, ob und in welchem Ausmaß Geschenke bei einer postalischen Befragung zur Erhöhung der Ausschöpfungsquote beitragen. Es zeigt sich, dass ein versprochenes Geschenk (Telefonkarte im Wert von 10 Schweizer Franken) die Ausschöpfungsquote nicht erhöht, während ein dem Fragebogen beigelegtes Geschenk zu einem Anstieg der Quote um zirka 10 Prozentpunkte führt. Die Befunde stehen in Einklang mit der Reziprozitätshypothese, derzufolge Vorleistungen von vielen Personen auch dann honoriert werden, wenn die reziproke Handlung nicht dem unmittelbaren Eigeninteresse eines Akteurs entspricht.

Neural correlates of wishful thinking.

Wishful thinking (WT) implies the overestimation of the likelihood of desirable events. It occurs for outcomes of personal interest, but also for events of interest to others we like. We investigated whether WT is grounded on low-level selective attention or on higher level cognitive processes including differential weighting of evidence or response formation. Participants in our MRI study predicted the likelihood that their favorite or least favorite team would win a football game. Consistent with expectations, favorite team trials were characterized by higher winning odds. Our data demonstrated activity in a cluster comprising parts of the left inferior occipital and fusiform gyri to distinguish between favorite and least favorite team trials. More importantly, functional connectivities of this cluster with the human reward system were specifically involved in the type of WT investigated in our study, thus supporting the idea of an attention bias generating WT. Prefrontal cortex activity also distinguished between the two teams. However, activity in this region and its functional connectivities with the human reward system were altogether unrelated to the degree of WT reflected in the participants' behavior and may rather be related to social identification, ensuring the affective context necessary for WT to arise.

A common mechanism underlying food choice and social decisions

People make numerous decisions every day including perceptual decisions such as walking through a crowd, decisions over primary rewards such as what to eat, and social decisions that require balancing own and others’ benefits. The unifying principles behind choices in various domains are, however, still not well understood. Mathematical models that describe choice behavior in specific contexts have provided important insights into the computations that may underlie decision making in the brain. However, a critical and largely unanswered question is whether these models generalize from one choice context to another. Here we show that a model adapted from the perceptual decision-making domain and estimated on choices over food rewards accurately predicts choices and reaction times in four independent sets of subjects making social decisions. The robustness of the model across domains provides behavioral evidence for a common decision-making process in perceptual, primary reward, and social decision making.

Analysis of hand kinematics reveals inter-individual differences in intertemporal decision dynamics

During intertemporal decisions, the preference for smaller, sooner reward over larger-delayed rewards (temporal discounting, TD) exhibits substantial inter-subject variability; however, it is currently unclear what are the mechanisms underlying this apparently idiosyncratic behavior. To answer this question, here we recorded and analyzed mouse movement kinematics during intertemporal choices in a large sample of participants (N = 86). Results revealed a specific pattern of decision dynamics associated with the selection of “immediate” versus “delayed” response alternatives, which well discriminated between a “discounter” versus a “farsighted” behavior—thus representing a reliable behavioral marker of TD preferences. By fitting the Drift Diffusion Model to the data, we showed that differences between discounter and farsighted subjects could be explained in terms of different model parameterizations, corresponding to the use of different choice mechanisms in the two groups. While farsighted subjects were biased toward the “delayed” option, discounter subjects were not correspondingly biased toward the “immediate” option. Rather, as shown by the dynamics of evidence accumulation over time, their behavior was characterized by high choice uncertainty.

Effects of stereotypic behaviour and chronic mild stress on judgement bias in laboratory mice

Cognitive processes are influenced by underlying affective states, and tests of cognitive bias have recently been developed to assess the valence of affective states in animals. These tests are based on the fact that individuals in a negative affective state interpret ambiguous stimuli more pessimistically than individuals in a more positive state. Using two strains of mice we explored whether unpredictable chronic mild stress (UCMS) can induce a negative judgement bias and whether variation in the expression of stereotypic behaviour is associated with variation in judgement bias. Sixteen female CD-1 and 16 female C57BL/6 mice were trained on a tactile conditional discrimination test with grade of sandpaper as a cue for differential food rewards. Once they had learned the discrimination, half of the mice were subjected to UCMS for three weeks to induce a negative affective state. Although UCMS induced a reduced preference for the higher value reward in the judgement bias test, it did not affect saccharine preference or hypothalamic–pituitary–adrenal (HPA) activity. However, UCMS affected responses to ambiguous (intermediate) cues in the judgement bias test. While control mice showed a graded response to ambiguous cues, UCMS mice of both strains did not discriminate between ambiguous cues and tended to show shorter latencies to the ambiguous cues and the negative reference cue. UCMS also increased bar-mouthing in CD-1, but not in C57BL/6 mice. Furthermore, mice with higher levels of stereotypic behaviour made more optimistic choices in the judgement bias test. However, no such relationship was found for stereotypic bar-mouthing, highlighting the importance of investigating different types of stereotypic behaviour separately.

Transfer Pricing in the Decentralized Multinational Corporation

This paper considers how the multinational corporation's transfer price responds to changes in international corporate effective tax rates. It extends the decentralized decision-making analysis of transfer pricing in the context of different tax rates. It adopts and extends Bond's (1980) model of the decentralized multinational corporation that assumes centralized transfer pricing. The direction of transfer price change is as expected, while the magnitude of change is likely to be less than predicted by the Horst (1971), centralized decision-making model. The paper extends the model further by assuming negotiated transfer pricing, where the analysis is partitioned into perfect and imperfect information cases. The negotiated transfer pricing result reverts to the Horst (1971), or centralized decision-making, result, under perfect information. Under imperfect information, the centralized decision-making result obtains when top management successfully informs division general managers or it successfully implements a non-monetary reward scheme to encourage division general managers to cooperate. Under simplifying assumptions, centralized decision-making dominates decentralized decision-making, while negotiated transfer pricing weakly dominates centralized transfer pricing.

Predicting State Allocation of Funds: The Case of John Rowland and his Hometown of Waterbury, Connecticut.

This study attempts to analyze the underlying factors and motives influencing the allocation of discretionary state expenditures. The fact that some cities receive more money than other cities begs the question of what accounts for this variation. After framing the provision of state money within the theoretical framework of political patronage, a case study of Governor Rowland’s tenure in office and the accompanying expenditures to Connecticut’s 17 largest cities from 1995 to 2004 was conducted to evaluate whether a disproportionate amount of money was given to Rowland’s hometown of Waterbury, Connecticut. Besides employing a statistical analysis that determined that cities with similar characteristics received different amounts of money, interviewing was conducted to identify reasons for such variation. The results indicate that Waterbury received a greater amount of money than was predicted based on the city’s economic and demographic characteristics, and that non-objective and biased factors such as favoritism, the need to reward political support, or the desire to increase political loyalty sometimes take precedence over more objective factors.

Salvaging Historic Shipwrecks

The salvage of historic shipwrecks involves a debate between profit-oriented salvagers, who wish to maximize profit, and archeologists, who wish to maximize historical value. We use a principal-agent model to derive the optimal reward scheme for salvagers, including a minimum duty of care in conducting the salvage operation. A review of U.S. and international law suggests that, while there is an emerging recognition of the need to devote greater care to salvaging those wrecks that are located, current doctrines provide inadequate incentives to locate historic wrecks in the first place.

Murky Waters: The Law and Economics of Salvaging Historic Shipwrecks

The salvage of historic shipwrecks involves a debate between salvors, who wish to maximize profit, and archeologists, who wish to preserve historical value. Traditionally, salvage of shipwrecks has been governed by admiralty law, but the Abandoned Shipwreck Act of 1987 transferred title of historically important wrecks in U.S. waters to the state in whose waters the wreck is found, thereby abrogating admiralty law. This paper examines incentives to locate and salvage historic wrecks under traditional admiralty law and proposes an efficient reward scheme. It then re-considers current U.S. and international law in light of the results.

The Adjunct Life

The author describes her experiences as a librarian and an adjunct professor at the Graduate School of Library and Information Science at Simmons College in South Hadley, Massachusetts. She enjoys teaching students about library science, and loves her job. She says it can be difficult balancing two jobs, but that the reward of helping create new librarians makes it worth it. It also helps her keep her own skills current.

The opioid antagonist naltrexone and its pharmacological role in treating alcohol dependence: A literature review

Naltrexone, an opioid antagonist, was the second drug approved for treatment of alcohol dependence in the U.S. Its approval followed two landmark studies published in the U.S. in 1992. [1, 2] These studies showed that a combined treatment of naltrexone and behavioral therapy reduced alcohol consumption in alcoholics. Opioid antagonists decrease craving for alcohol and help to reduce drinking by blocking opioid peptide receptors in the body that are active in a dopamine chemical reward system. ^ Despite their usefulness, opioid antagonists have been underutilized. Health providers not educated in the use of opioid antagonists hold the view that opioid antagonist therapy is ineffective. However, it is apparent from the relevant literature that this therapy, when properly understood and targeted, has the potential to make a positive contribution in treating alcohol dependent patients. ^ This thesis will review the scientific literature and the present body of knowledge regarding opioid antagonists (naltrexone) and their pharmacological role in treating alcohol dependence.^

Relationship between parental feeding practices and weight status in a lower socioeconomic pre-school population

High prevalence of overweight and obesity among preschool children in the low income population is consistently documented in research with one of every seven low-income, preschool-aged children classified as obese. Parental feeding practices have the potential to be contributing factors to the obesity epidemic. However, the impact of parental feeding practices on obesity in preschool age children has not been well explored. The purpose of this study was to determine relationships between the parental feeding practices of using dessert, sweets or candy as a reward for finishing foods, restricting dessert if the child does not finish their plate at dinner, asking the child to consume everything on their plate at dinner, and having family dinners to obesity in low income, preschool age children.^ A cross-sectional secondary data analysis was completed using the STATA 11 statistical software. Descriptive statistics were completed to summarize demographic and BMI data of participants, as well as parental feeding behavior variables. Pearson’s correlation was implemented to determine a correlation between parental feeding behavior variables and BMI z scores. Predictive relationships between the variables were explored through multivariable linear regression analysis. Regression analyses were also completed factoring in the confounders of gender, age, and ethnicity.^ Results revealed (1) no significant correlations or predictive trends between the use of rewards, forced consumption, or family dinner and BMI in low income preschool age children, and (2) a significant negative correlation and predictive trend between restriction of desserts and BMI in low income preschool age children. Since the analysis supported the null hypothesis for the practices of reward use, forced consumption, and family dinner, these practices are not considered risk factors for obese level BMIs. The inverse association found for practice of restriction and BMI suggests it is unnecessary to discourage parents from using restriction. Limitations of the study included the sample size, reliability of the answers provided on the Healthy Home Survey by participant guardians, and generalizability of the sample to the larger population.^

Relationships of impulsivity and physical fighting history to alcohol -induced aggression in women

Research suggests women respond to the aggression-inducing effects of alcohol in a manner similar to men. Highly aggressive men are more prone to alcohol-induced aggression, but this relationship is less clear for women. This study examined whether alcohol consumption would differentially affect laboratory-measured aggression in a sample of aggressive and non-aggressive women and how those differences might be related to components of impulsive behavior. In 39 women recruited from the community (two groups: with and without histories of physical fighting) ages 21–40, laboratory aggressive behavior was assessed following placebo and 0.80 g/kg alcohol consumption (all women experienced both conditions). Baseline laboratory impulsive behavior of three impulsivity models was later assessed in the same women. In the aggression model (PSAP), participants were provoked by periodic subtractions of money, which were blamed on a fictitious partner. Aggression was operationalized as the responses the participant made to subtract money from that partner. The three components of impulsivity that were tested included: (1) response initiation (IMT/DMT), premature responses made prior to the completion of stimulus processing, (2) response inhibition (GoStop), a failure to inhibit an already initiated response, and (3) consequence sensitivity (SKIP and TCIP), the choice for a smaller-sooner reward over a larger-later reward. I hypothesized that, compared to women with no history of physical fighting, women with a history of physical fighting would exhibit higher rates of alcohol-induced laboratory aggression and higher rates of baseline impulsive responding (particularly for the IMT/DMT), which would also be related to the alcohol-induced increases aggression. Consistent with studies in men, the aggressive women showed strong associations between laboratory aggression and self-report measures, while the non-aggressive women did not. However, unlike men, following alcohol consumption it was the non-aggressive women's laboratory aggression that was related to their self-reports of aggression and impulsivity. Additionally, response initiation measures of impulsivity distinguished the two groups, while response inhibition and consequence sensitivity measures did not; commission error rates on the IMT/DMT were higher in the aggressive women compared to the non-aggressive women. Regression analyses of the behavioral measures showed no relationship between the aggression and impulsivity performance of the two groups. These results suggest that the behavioral (and potentially biological) mechanism underlying aggressive behavior of women is different than that of men. ^