An excess of the signalling molecule dopamine in the brain can have a negative influence on our ability to make decisions. This occurs during drug use, in the manic phase of bipolar disorder and as a side effect of dopamine replacement therapy in Parkinson’s disease. In these situations, people often display overly optimistic, reckless and self-destructive behaviour. Neurobiologists Jeroen Verharen, Roger Adan and Louk Vanderschuren from the Faculty of Veterinary Medicine and UMC Utrecht describe a mechanism behind this phenomenon in a publication in the influential journal Nature Communications.
Dopamine is a signalling molecule in the brain that plays an important role in emotional and cognitive processes. One of the most important functions of dopamine is its role in our capacity to learn from positive and negative experiences.
Verharen: “When something nice happens, like when you’re being served a tasty dessert, your brain releases dopamine. That teaches you to repeat the actions that preceded that pleasant experience. But if your behaviour leads to something unpleasant, such as hurting yourself, then the release of dopamine is inhibited. You learn that the action in question is not something to be repeated. Until recently, however, we did not know exactly where dopamine mediates these learning processes in the brain.”