Aditi Kaveti ’23
Dopamine is a notorious molecule, with effects ranging from heightened sense of happiness and increased energy, to anxiety and difficulty sleeping. It is involved in cognitive processing related to reward and pleasure. Research into this molecule offers a wide range of study as scientists attempt to understand the dynamics and neuromodulation that occurs in the brain.
Conrad Foo, a graduate student at UC San Diego, worked with a team of researchers to further investigate the role of dopamine in the human body, specifically, the related spontaneous impulses of this well-known neurotransmitter molecule. Foo led this research project after discovering that dopamine is not only present in the face of pleasurable or reward-based expectations, but is also seen as random impulses in the neocortex of mice. The research was performed by a team of researchers from the Department of Physics and Section of Neurobiology at UC San Diego and the Icahn School of Medicine in Mount Sinai, New York. The goal of the research was to investigate whether the mice were aware of these random impulses.
The team documented the impulses in the lab through molecular and optical imaging techniques and used a reward feedback system to reveal the brain’s inner workings. The spontaneous impulses were found to occur at a rate of around 0.01 per second. The mice were placed on a treadmill and received a reward if they were able to control the dopamine impulses. They were trained to change the amplitude and rate of the dopamine impulses by altering their brain dynamics. By the second day of training, the mice had increased both the rate and amplitude of their impulses. The researchers found that the mice were able to control these impulses and could even trigger the dopamine impulse themselves. Upon these findings, the team concluded that these dopamine impulses are actually a strategic method used to motivate behavioral planning processes such as foraging, finding a mate, and other social behaviors. The mice are able to manipulate the levels of chemical messengers in their brain in order to set up a reward-predictive stimulus that induces necessary survival behaviors. This discovery in the study of dopamine and brain dynamics may allow researchers to learn more about how animals can motivate themselves to perform actions that do not have known reward stimuli.
1. Conrad Foo, et al., Reinforcement learning links spontaneous cortical dopamine impulses to reward, Current Biology, ISSN 0960-9822, 2021, https://doi.org/10.1016/j.cub.2021.06.069
2. Image retrieved from: https://commons.wikimedia.org/wiki/File:Dopamine_3D_ball.png