Keywords: Behavior Analysis | fMRI (Function Magnetic Resonance Imaging) | Anxiety
Presentation Type: Symposium
Background: Reward and punishment govern human behavior. Individuals seek to obtain rewards and to avoid punishment. By and large, studies have investigated the processes associated with reward and punishment separately. However, in daily life, obtaining rewards often comes with the likelihood of negative consequences (punishment). For behavior to be effective, humans need to resolve the conflict between these two determinants of behavior in most given situations. We have developed a novel paradigm that integrates reward and punishment to study the neurobiology of conflict in decision-making.
Methods:28 healthy volunteers completed and Aversion-Reward Conflict (ARC) paradigm during fMRI scanning. In the ARC paradigm participants chose between a safe option (pays $0.01) and a risky option (pays between $0.05-$1.00) at the risk of receiving uncomfortable electrical stimulation. Risk levels were varied between three categories (10%, 50%, 90% probability of shock). Thus, participants can avoid stimulation at the cost of foregoing reward. To predict the probability of each participant’s decision for each trial we utilized a Bayesian regression model that inferred a per-trial estimate of the probability of a subject’s decision (risky vs. safe option) conflict as a function of the risk, level of reward and reaction time. Choice was modeled as a logistic regression on risk and reward. Outputs from the behavioral analyses, in particular the distance-from-decision-boundary (point of maximum conflict), were used as parametric regressors in the fMRI analyses.
Results: fMRI analysis shows that activation in the dorsolateral prefrontal cortex (DLPFC) and the dorsal anterior cingulate cortex (dACC) increased as subjects approach their decision boundary (point of maximum conflict; p
Conclusions:While most previous work in decision-making has focused on studying reward and punishment separately, in this novel paradigm we integrate both risk of punishment as well as monetary reward to study the neural mechanisms underlying conflict processing during decision-making. The increased DLPFC and dACC activation during trials near the individual’s decision boundary suggests that DLPFC and dACC play a role in signaling and resolving the conflict that arises between choosing a reward coupled with electric stimulation or foregoing that reward to avoid an aversive experience.
Associate Professor of Psychology in the Department of Psychiatry
Massachusetts General Hospital
Saturday, November 18
10:15 AM – 11:45 AM
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