Scientists at Wake Forest University School of Medicine have conducted a groundbreaking study to uncover the role of dopamine in encoding reward and punishment prediction errors in the human brain. Dopamine, a neurotransmitter that facilitates communication between nerve cells, has long been associated with positive emotions. However, this research reveals that it also plays a crucial role in processing negative experiences.
The study, published in Science Advances, utilized fast-scan cyclic voltammetry, an electrochemical technique, combined with machine learning, to measure dopamine levels in real-time. This method, performed during invasive procedures like deep-brain stimulation surgery, allowed researchers to monitor dopamine fluctuations at a rate of 10 measurements per second.
Working in collaboration with neurosurgeons from Atrium Health Wake Forest Baptist, the researchers inserted a carbon fiber microelectrode into the brains of three participants scheduled to undergo deep-brain stimulation treatment for essential tremor. While the participants played a simple computer game, dopamine measurements were continuously taken in the striatum, a brain region associated with decision-making and cognition.
Throughout the game, the participants’ choices were either rewarded or punished with real monetary gains or losses. The study revealed that dopamine signaling not only conveyed positive and negative experiences but also optimized learning from these outcomes. The researchers discovered distinct pathways in the brain that separately engaged the dopamine system for rewarding and punishing experiences, with each pathway encoding these experiences on slightly shifted timescales.
Lead researcher Kenneth T. Kishida, Ph.D., emphasized the significance of these findings for understanding the impact of the dopamine system on psychiatric and neurological disorders. He stressed the need for further research to explore how dopamine signaling is altered in conditions such as depression, addiction, and related disorders.
Contrary to the traditional view of dopamine as the “pleasure neurotransmitter,” this study highlights its role as a vital component in a sophisticated system that teaches our brain and guides behavior. The involvement of dopamine in learning from punishing experiences provides valuable insights that could lead to new directions in research and a deeper understanding of various disorders.