Summary: Dopamine may not control the strength or speed of movements as long believed. Instead, it appears to function as a fundamental chemical that allows movement in the first place. The experiments showed that altering rapid bursts of dopamine had no impact on how strongly the animals moved, while raising baseline dopamine levels restored normal movement.
This rethinking of dopamine’s role could reshape the way movement disorders are treated, including conditions characterized by slow or impaired motor function. The findings highlight a simpler therapeutic goal: stabilizing basal dopamine rather than recreating rapid signaling spikes.
Key facts:
Rethink dopamine: Fast bursts of dopamine did not change the speed or strength of movement in the experiments. Baseline matters: Restoring baseline dopamine (not momentary spikes) improved movement. Treatment information: Findings suggest that targeting stable dopamine levels can refine approaches to treating movement disorders.
Source: McGill University
A McGill-led study is challenging a popular theory about how dopamine drives movement, a discovery that could change the way scientists think about Parkinson’s disease treatments.
Published in Nature Neuroscience, the research found that dopamine does not determine the speed or strength of each movement, as previously thought. Rather, it appears to act as the underlying support system that makes movement possible.
“Our findings suggest that we should rethink the role of dopamine in movement,” said senior author Nicolas Tritsch, an assistant professor in the Department of Psychiatry at McGill and a researcher at the Douglas Research Centre.
“Restoring dopamine to a normal level may be enough to improve movement. That could simplify the way we think about treating Parkinson’s.”
Dopamine is known to be important for motor stamina, which is the ability to move with force and speed. In Parkinson’s patients, dopamine-producing neurons deteriorate, causing slower movements, tremors, and balance problems.
The standard treatment for Parkinson’s, levodopa, helps restore movement, but why it works is not well understood. In recent years, advanced tools have detected rapid spikes in dopamine during movement, leading many to believe that these spikes control stamina.
The new study points in the opposite direction.
“Rather than acting as an accelerator that sets the speed of movement, dopamine appears to function more like motor oil. It is essential for the system to function, but not the signal that determines how fast each action is executed,” Tritsch said.
Measuring dopamine in real time
The researchers measured brain activity in mice while they pressed a weighted lever, turning dopamine cells “on” or “off” using a light-based technique.
If quick bursts of dopamine controlled vigor, the change in dopamine at that time should have made the movements faster or slower. To his surprise, it had no effect. In tests with levodopa, they found that the drug worked by increasing the basal level of dopamine in the brain, not by restoring fast bursts.
A more precise treatment target
More than 110,000 Canadians are living with Parkinson’s disease, a number expected to double by 2050 as the population ages.
The authors note that a clearer explanation of why levodopa is effective opens the door to new therapies designed to maintain baseline dopamine levels.
It also encourages a new look at older therapies. Dopamine receptor agonists have shown promise, but caused side effects because they acted too broadly in the brain. The new finding gives scientists insight into how to design safer versions.
Funds
The study was funded by Canada’s First Research Excellence Fund, awarded through the Healthy Brains, Healthy Lives initiative of McGill University and the Fonds de Recherche du Québec.
Key questions answered:
A: No. The study shows that dopamine enables movement but does not dictate its speed or strength.
A: Increases baseline dopamine levels, restoring the general chemical environment that movement requires.
A: Therapies can focus on keeping dopamine stable rather than mimicking rapid bursts, supporting safer and more targeted approaches.
Editorial notes:
This article was edited by a Neuroscience News editor. Magazine article reviewed in its entirety. Additional context added by our staff.
About this research news on dopamine and neuroscience
Author: Keila DePape
Source: McGill University
Contact: Keila DePape – McGill University
Image: Image is credited to Neuroscience News.
Original research: Open access.
“Dopamine fluctuations of less than a second do not specify the vigor of ongoing actions” by Nicolas Tritsch et al. Nature Neuroscience
Abstract
Dopamine fluctuations of less than a second do not specify the vigor of ongoing actions.
Dopamine (DA) is essential for the production of vigorous actions, but it is still unclear how DA modifies the elicitation of motor commands.
Here we show that sub-second DA transients in the mouse striatum are neither necessary nor sufficient to specify the vigor of continuous forelimb movements.
Our findings have important implications for our understanding of how DA contributes to motor control under physiological conditions and in Parkinson’s disease.
