Willfully Controlling Dopamine in the Brain
Isabelle Wilson, Biological Sciences, Summer 2021
Figure: Depiction of the dopaminergic system for reward processing in the brain. Research at the University of California San Diego demonstrated that mice can anticipate dopamine impulses in the neocortex (including the nucleus accumbens and prefrontal cortex) to manipulate their corresponding motor response (Source: Wikimedia Commons).
Dopamine is considered the brain’s “feel good” chemical messenger; it motivates us to seek out rewards such as food, sex, and social engagement. Historically, researchers assumed that dopamine was subconsciously released when the brain expects a reward. Furthermore, they thought that this mechanism enabled neurons in the brain to communicate and control movement in response to the anticipated reward (Marsden, 2006). However, Conrad Foo from the University of California San Diego recently found that mice can learn to manipulate the brain’s random dopamine impulses for rewards (University of California – San Diego, 2021). This finding contradicts the longstanding perception of the function of neurotransmitters and provides evidence that our brains can learn to control seemingly subconscious neurological processes.
The neocortex is the part of the cerebral cortex that consists of grey matter and is where higher cognitive functioning originates from. In mice, the neocortex is flooded with unpredictable dopamine impulses at a rate of about 0.01 times per second. Foo wanted to determine whether mice are aware that these impulses are occurring. He placed mice on a treadmill and gave them a reward if they proved they were able to control their random dopamine signals. Not only did the mice prove that they were aware of the spontaneous impulses through this reward feedback mechanism, but they also anticipated and acted upon the dopamine bursts. When the reward was expected, mice intentionally elicited their dopamine impulses according to neural activity in their neocortex. When the reward was removed, mice no longer were able to evoke the impulses (University of California – San Diego, 2021). Foo concluded that dopamine is likely a prominent stimulus that enables mice to plan their motor response to an incoming reward (Foo, 2021).
This research is groundbreaking in establishing a new connection between dopamine and the salience of rewards. Moving forward, Foo will investigate how these unpredictable dopamine impulses motivate foraging, mating, and social behavior (Foo, 2021). The ability to potentially control our response to rewards through intentional manipulation of dopamine impulses has vast implications and prompts further research into the exact mechanism of neurotransmitters in the brain.
References
Foo, C. (2021, July 23). Reinforcement learning links spontaneous cortical dopamine impulses to reward. Science Direct. https://www-sciencedirect-com.dartmouth.idm.oclc.org/science/article/pii/S0960982221008988? via%3Dihub.
Marsden C. A. (2006). Dopamine: the rewarding years. British journal of pharmacology, 147 Suppl 1(Suppl 1), S136–S144. https://doi.org/10.1038/sj.bjp.0706473
University of California – San Diego. (2021, July 23). ‘Feel good’ brain messenger can be willfully controlled, new study reveals: Neuroscientists show that mice can learn to manipulate random dopamine impulses for reward. ScienceDaily. Retrieved August 1, 2021 from www.sciencedaily.com/releases/2021/07/210723121512.htm