Trust, Competition and Cooperation in Autism Spectrum Disorder

Objective: Impaired social interactions and repetitive behavior are key features of autism spectrum disorder (ASD). In the present study we compared social decision-making in subjects with and without ASD. Subjects performed five social decision-making games in order to assess trust, fairness, cooperation & competition behavior and social value orientation. Methods: 19 adults with autism spectrum disorder and 17 controls, matched for age and education, participated in the study. Each subject performed five social decision-making tasks. In the trust game, subjects could maximize their gain by sharing some of their money with another person. In the punishment game, subjects played two versions of the Dictator’s Dilemma. In the dictator condition they could share an amount of 0-100 points with another person. In the punishment condition, the opponent was able to punish the subject if he/she was not satisfied with the amount of points received. In the cooperation game, subjects played with a small group of 3 people. Each of them could (anonymously) select an amount of 5, 7.5 or 10 Swiss francs. The goal of the game was to achieve a high group minimum. In the competition game, subjects performed a dexterity task. Before performing the task, they were asked whether they wanted to compete (winner takes it all) or cooperation (sharing the joint achieved amount of points) with a randomly selected person. Lastly, subjects performed a social value orientation task where they were playing for themselves and for another person. Results: There was no overall difference between healthy controls an ASD subjects in investment in the trust game. However, healthy controls increased their investment over number of trials whereas ASD subjects did not. A similar pattern was found for the punishment game. Furthermore, ASD subjects revealed a decreased investment in the dictator condition of the punishment game. There were no mean differences in competition behavior and social value orientation. Conclusions: The results provide evidence for differences between ASD subjects and healthy controls in social decision-making. Subjects with ASD showed a more consistent behavior than healthy controls in the trust game and the dictator dilemma. The present findings provide evidence for impaired social learning in ASD.

Disruption of right prefrontal cortex by low-frequency repetitive transcranial magnetic stimulation induces risk-taking behavior

Decisions require careful weighing of the risks and benefits associated with a choice. Some people need to be offered large rewards to balance even minimal risks, whereas others take great risks in the hope for an only minimal benefit. We show here that risk-taking is a modifiable behavior that depends on right hemisphere prefrontal activity. We used low-frequency, repetitive transcranial magnetic stimulation to transiently disrupt left or right dorsolateral prefrontal cortex (DLPFC) function before applying a well known gambling paradigm that provides a measure of decision-making under risk. Individuals displayed significantly riskier decision-making after disruption of the right, but not the left, DLPFC. Our findings suggest that the right DLPFC plays a crucial role in the suppression of superficially seductive options. This confirms the asymmetric role of the prefrontal cortex in decision-making and reveals that this fundamental human capacity can be manipulated in normal subjects through cortical stimulation. The ability to modify risk-taking behavior may be translated into therapeutic interventions for disorders such as drug abuse or pathological gambling.

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.