New research shows "dopamine levels increase in response to stressful stimuli, and not just pleasurable ones, potentially rewriting facts about the 'feel-good' hormone -- a critical mediator of many psychiatric diseases."
"In the press, dopamine is often referred to as a 'pleasure molecule' or a 'reward molecule. In the scientific community, research has helped us understand that dopamine's role in learning and memory is more complex than that, but we did not have a complete and accurate theory that could explain what dopamine actually does in the brain."
"The prevailing model, called the reward prediction error theory, is based on the idea that dopamine signals predictions about when rewards will occur. This theory suggests that dopamine is a tracker of every error we make when we try to achieve rewards. The authors show that reward prediction error theory is only accurate in a subset of learning scenarios by proving that 'while rewards increase dopamine, so do stressful stimuli.'" "We then go on to show that dopamine is not a reward molecule at all. It instead helps encode information about all types of important and relevant events and drive adaptive behavior -- regardless of whether it is positive or negative."
This work was done by fitting a machine learning model to the behavior of dopamine as measured by optogenetics in mice brains.
