Summary: For decades, neuroscientists have struggled to explain how a single chemical—dopamine—can simultaneously manage two very different tasks: reinforcing reward-based learning and invigorating physical movement. A new study has finally uncovered the “switch.”
By studying brain activity in rats during decision-making tasks, researchers found that the timing of a second neurotransmitter, acetylcholine, acts as a gatekeeper. When dopamine is released while acetylcholine levels are dropping, the brain focuses on learning. However, if dopamine coincides with a burst of acetylcholine, it triggers movement vigor. This interaction happens in a matter of tens of milliseconds—literally the blink of an eye—and could offer a new map for treating Parkinson’s, schizophrenia, and depression.
Key Facts
- The “See-Saw” Dynamic: The relationship between these two chemicals works like a see-saw. Learning is promoted when dopamine rises as acetylcholine falls; movement is promoted when both rise together.
- Precision Timing: The difference between “learning a behavior” and “executing a movement” is determined by a window of just tens of milliseconds.
- Dual Roles Reconciled: This discovery addresses the “single-largest question” in dopamine research—how the same chemical can be responsible for both the cognitive process of reward and the physical process of motor control.
- Clinical Significance: Disorders like Parkinson’s (loss of motor control) and schizophrenia (altered learning/perception) are likely rooted in a breakdown of this specific timing mechanism.
Source: NYU
Scientists have long-studied the role of dopamine, a chemical in the brain that helps control learning and movement, in order to better understand Parkinson’s disease, schizophrenia, and depression—afflictions caused, in part, by a disruption or alteration of dopamine activity.
In a study of laboratory rats, New York University neuroscientists have uncovered a new dynamic in dopamine function: the timing of the interaction of two neurotransmitters—dopamine and acetylcholine—determines whether or not dopamine is effective in guiding learning or effective movement.
“This study addresses the single-largest question in the dopamine field, which is how to reconcile its dual roles in learning and motor control,” says Christine Constantinople, a professor in NYU’s Center for Neural Science and the senior author of the research, which appears in the journal Nature Neuroscience.
“Dopamine can both help learning by reinforcing behaviors that lead to rewarding outcomes or invigorate upcoming movements—depending on when acetylcholine is released.
“Our research shows that whether anything is learned from dopamine or whether dopamine promotes movement vigor comes down to the timing of acetylcholine release—a difference of a matter of tens of milliseconds, or about the blink of an eye.”
Dopamine is known to help with both learning and in controlling movement. With learning, dopamine reinforces behaviors that have been rewarding in the past by promoting synaptic plasticity—the ability of the brain to change in order to learn.
Notably, certain motor disorders, such as Parkinson’s disease, are due to the loss of certain dopamine neurons—though the specifics of what brings about this affliction are unclear. A major challenge for scientists, then, has been to better understand how a single neurotransmitter, dopamine, can support both reward-based learning and motor control.
In the Nature Neuroscience work, the researchers sought to better illuminate this dynamic by focusing on dopamine and another neurotransmitter, acetylcholine, which aids in muscle contraction, memory, and learning.
Their study of laboratory rats simultaneously measured dopamine and acetylcholine while the animals performed a decision-making task that involved both learning and moving: finding a reward (a source of water) after learning the significance of sound cues, which indicated the water’s amount and location.
The scientists hypothesized that varying acetylcholine-dopamine interactions would prompt either learning (the amount of future water rewards) or purposeful movement toward it.
The results showed that the timing of acetylcholine release determined whether dopamine promoted learning (i.e., predicted future behavior and changed neural dynamics) or moving (i.e., preceded and predicted the nature of movements). In many cases, the difference in timing was a matter of tens of milliseconds.
The scientists say the process is akin to a see-saw’s movement. When dopamine was concurrent with a reduction in acetylcholine release, it promoted learning; when it coincided with a burst of acetylcholine —or increase in acetylcholine release—it predicted the vigor of upcoming movements.
“When neurons such as dopamine and acetylcholine malfunction, they can contribute to Parkinson’s disease as well as schizophrenia and depression,” notes Constantinople.
“Therefore, a greater understanding of the mechanisms by which they coordinate different aspects of behavior holds promise for revealing novel therapeutic targets for these disorders.”
The paper’s other authors included NYU postdoctoral fellows Hee Jae Jang and Carla Golden and Royall McMahon Ward, an NYU research technician at the time of the study and now a doctoral student at Northwestern University.
Funding: This work was supported by grants from the National Institutes of Health (DP2MH126376, R01MH136272) and an Alfred P. Sloan Research Fellowship.
Key Questions Answered:
A: It’s efficient! Evolution repurposed dopamine to handle both. This study shows the brain doesn’t need two different chemicals; it just uses acetylcholine as a “traffic controller” to tell dopamine which job to do at any given millisecond.
A: That’s likely where diseases happen. If the timing is off, your brain might try to “learn” when it should be “moving,” or vice versa. This could explain the tremors and “freezing” seen in Parkinson’s or the disorganized thoughts in schizophrenia.
A: Yes. Most current drugs just try to raise or lower dopamine levels overall. By understanding this timing “switch,” scientists can look for ways to specifically target the interaction between dopamine and acetylcholine, potentially leading to much more precise treatments.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neuroscience research news
Author: James Devitt
Source: NYU
Contact: James Devitt – NYU
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Acetylcholine demixes heterogeneous dopamine signals for learning and moving” by Hee Jae Jang, Royall McMahon Ward, Carla E. M. Golden & Christine M. Constantinople. Nature Neuroscience
DOI:10.1038/s41593-026-02227-x
Abstract
Acetylcholine demixes heterogeneous dopamine signals for learning and moving
Midbrain dopamine neurons promote reinforcement learning and movement vigor. An outstanding question is how dopamine-recipient neurons in the striatum parse these heterogeneous signals.
Previous work suggests that cholinergic striatal interneurons may gate dopamine-dependent plasticity, but this has not been tested in behaving animals. Here we studied rats performing a decision-making task with reward-related and movement-related events.
Optical measurement of dopamine and acetylcholine release in the dorsomedial striatum (DMS) revealed that reward cues evoked cholinergic pauses with different phase relationships relative to dopamine.
When dopamine lagged cholinergic dips, dopamine predicted future behavior and DMS firing rates on subsequent trials. In contrast, when dopamine preceded cholinergic dips, there was no observable relationship between dopamine and learning.
Finally, when dopamine was coincident with cholinergic bursts, it preceded and predicted the vigor of contralateral orienting movements.
Our findings suggest that cholinergic dynamics determine whether dopamine promotes vigor or learning, depending on the instantaneous behavioral context.
