In an article published last week in the influential journal Neuron, the researchers report the concentration of dopamine governs decisions so precisely that measuring the level right before allows accurate prediction of the outcome. Additionally, the scientists found that changing the dopamine level is sufficient to alter an upcoming choice.
The work may open new avenues for treating disorders like Parkinson’s disease where a person cannot select a movement to initiate, as well as obsessive-compulsive disorder and drug addiction.
“Because we cannot do more than one thing at a time, the brain is constantly making decisions about what to do next,” said Xin Jin, an assistant professor in Salk’s Molecular Neurobiology Laboratory and the paper’s senior author. “In most cases our brain controls these decisions at a higher level than talking directly to particular muscles, and that is what my lab mostly wants to understand better.”
Jin’s team designed a study in which mice chose between pressing one of two levers to get a sugary treat. The levers were on the right and left side of a custom-built chamber, with the treat dispenser in the middle.
“This particular design allows us to ask a unique question about what happens in the brain during this mental and physical switch from one choice to another,” said Hao Li, a Salk research associate and the paper’s co-first author.
As the mice performed the trials, the researchers measured the dopamine concentration in the animals’ brains via embedded electrodes much finer than a human hair. The scientists were able to accurately predict the animal’s upcoming choice of lever based on dopamine concentration alone.
“We think that if we could restore the appropriate dopamine dynamics—in Parkinson’s disease, OCD and drug addiction—people might have better control of their behavior,” said Jin. “This is an important step in understanding how to accomplish that.”
The work was funded by the National Institutes of Health, The Dana Foundation, the Ellison Medical Foundation and the Whitehall Foundation.
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