Our behavior is often guided by the desire to obtain positive outcomes and avoid negative consequences, and neuroscientists have put a great deal of effort into looking for reward and punishment "centers" in the brain. Now, new research published by Cell Press in the October 6 issue of the journal Neuron reveals that neural signals related to reinforcement and punishment are far more broadly distributed throughout the entire human brain than was previously thought.
Understanding the neural basis of reinforcement and punishment processing is of paramount importance to cognitive neuroscience," explains primary study author Dr. Timothy Vickery from the Department of Psychology at Yale University. "Most perceptual and cognitive functions are served by discrete brain structures, and thus the focus in the reward literature has been on understanding specialized circuits that process reward, such as the basal ganglia. In our study, we tested whether signals related to decision outcomes, encompassing both reinforcement and punishment, may be represented more extensively beyond the traditional reward- and penalty-processing areas that have been described."
Dr. Vickery and colleagues imaged the brains of human subjects as they engaged in either matching-pennies or rock-paper-scissors games and used a sophisticated pattern analysis to analyze brain responses. The researchers were surprised to discover that both reinforcement and punishment representations were pervasive throughout the entire cortex. This suggests that reward and punishment may influence a much more widespread range of cognitive and perceptual processes than was previously imagined. Interestingly, the findings also indicated that the distribution of punishment signals and reinforcement signals are largely similar. This is in contrast to previous studies suggesting that there are limited regions encoding punishment and far more regions associated with reward.
Taken together, the findings provide evidence that both positive and negative outcomes can directly influence neural processing throughout the entire brain. "While it is likely that the basal ganglia and its projections are responsible for the core functions of reward-related processing, many other brain regions are at least provided with this information," concludes Dr. Vickery. "This suggests an imperative to study the effects of reinforcement and punishment in domains where they are not usually considered as important factors—from low-level sensory systems to high-level social reasoning. Such distributed representations would have adaptive value for optimizing many types of cognitive processes and behavior in the natural world."