Summary: For decades, dopamine has been cast as the brain’s “reward” chemical—the hit of pleasure when we get what we want. However, a new study reveals that dopamine also serves as a sophisticated guidance system.
By studying mice in visually cued environments, researchers discovered a second, distinct dopamine signal that acts like a GPS, calculating “trajectory errors” in real-time to tell the brain whether it is moving toward or away from a goal.
Key Facts
- The Trajectory Signal: Unlike the “value” signal (which fires based on how good a reward is), this new dopamine signal encodes whether current direction and speed are correct. It increases as you approach a goal and decreases if you veer off course.
- The Striatum Map: These guidance signals are located in the striatum (part of the basal ganglia). Researchers used new optical imaging to find that “value” and “guidance” signals occupy overlapping but distinct spatial gradients.
- Independence from Reward: This GPS-like function operates independently of the classic reward response, using different sensory and motor inputs to steer behavior.
- Speed Scaling: The signal scales with the animal’s movement speed, providing a high-fidelity “real-time” update—similar to how a driver uses landmarks to confirm they are on the right road home.
- Clinical Implications: Understanding this “guidance” role could revolutionize treatments for Parkinson’s, ADHD, and addiction, where the ability to steer behavior toward goals is often disrupted.
Source: Boston University
A Boston University-led research team has discovered a dopamine signal in the brain that helps determine whether you are moving toward or away from a goal potentially shedding new light on how the brain uses visual information to guide behavior.
The study recently published in Nature examined behavior in mice to show that when they encounter visual cues, dopamine in the striatum located in the basal ganglia, encodes “trajectory errors” or signals that indicate whether their current direction and speed are carrying it toward or away from its goal. These “guidance signals” operate independently from dopamine’s classic reward value responses and arise from different sensory and motor inputs.
The findings offer insight into how the brain uses environmental cues to steer behavior and could inform the development of more targeted therapies for conditions involving dopamine dysfunction, including Parkinson’s disease, addiction, OCD, and ADHD.
“This discovery reveals that dopamine isn’t just about how valuable something is,” said Mark Howe, Boston University College of Arts & Sciences assistant professor of psychological and brain sciences. “It’s also about whether you’re headed the right way. It’s a guidance signal, one that tells the brain to keep going or make a correction.”
A New View of Dopamine’s Role
For decades, dopamine has been widely understood as the brain’s “reward” chemical, firing when encountering cues associated with something positive. But this new research shows that visual cues also trigger a second, distinct dopamine signal, one that increases when you move toward a goal and decreases when you move away.
This trajectory error signal even scales with movement speed, making it ideal for real time course correction, like how humans might use familiar signs or landmarks while driving home.
Seeing the Brain in New Detail
The team developed a new method that allowed them to measure the dopamine signals optically across many regions throughout the entire striatum.
By mapping these signals, the researchers found the value and trajectory error signals appear in overlapping, but orthogonal spatial gradients within the striatum, and that they also occur at different moments in time. Together, this separation allows the brain to keep the two messages distinct: one for motivation, one for guidance.
Future Work
Howe and his collaborators are now working to manipulate these signals in specific ways to probe the causal impacts on learning and online control of decisions. They are also examining how the signals influence downstream components of the circuit.
“Dopamine is just the input to the striatum,” said Howe, who is also affiliated with Boston University Rajen Kilachand Center for Integrated Life Sciences & Engineering. “We want to understand how these signals shape the activity of downstream circuits to ultimately regulate behavior”
The team is also investigating broader questions: How do these signals translate into changes in movement? Are they essential for learning, online decision-making, or both? These remain key avenues for future research.
Funding: This work was supported by a Klingenstein-Simons Foundation fellowship, Whitehall Foundation Fellowship, National Institute of Mental Health and the NIH Jointly Sponsored Predoctoral Training Program in the Neurosciences award.
Complete information on authors, funders, methodology, limitations, and conflicts of interest is available in the published paper.
Key Questions Answered:
A: It still handles reward, but we now know it has a second job: Navigator. Think of the “reward” signal as the destination and the “trajectory” signal as the turn-by-turn directions. Without this second signal, you might be motivated to reach a goal but have no idea how to steer yourself there.
A: In these conditions, we know dopamine is out of balance. If the “guidance” signal is weak, a person might struggle to stay “on track” with a task, not because they aren’t motivated (reward), but because their brain isn’t providing the constant “keep going” feedback needed to finish the journey.
A: While this study used mice and advanced optical sensors, the striatum is an ancient part of the brain shared by all mammals. This suggests that when you are navigating a crowded room or driving a familiar route, your dopamine levels are likely fluctuating to keep you on the right path.
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: Jennifer Rosenberg
Source: Boston College
Contact: Jennifer Rosenberg – Boston College
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Striatum-wide dopamine encodes trajectory errors separated from value” by Eleanor H. Brown, Yihan Zi, Mai-Anh Vu, Safa Bouabid, Jack Lindsey, Chinyere Godfrey-Nwachukwu, Aaquib Attarwala, Ashok Litwin-Kumar, Brian DePasquale & Mark W. Howe. Nature
DOI:10.1038/s41586-025-10083-1
Abstract
Striatum-wide dopamine encodes trajectory errors separated from value
Goal-directed navigation requires animals to continuously evaluate their current direction and speed of travel relative to landmarks to discern whether they are approaching or deviating from their goal.
Striatal dopamine release signals the reward-predictive value of cues, probably contributing to motivation, but it is unclear how dopamine incorporates an animal’s ongoing trajectory for effective behavioural guidance.
Here we demonstrate that cue-evoked striatal dopamine release in mice encodes bidirectional trajectory errors reflecting the relationship between the speed and direction of ongoing movement relative to optimal goal trajectories.
Trajectory error signals could be computed from locomotion or visual flow, and were independent from simultaneous dopamine increases reflecting learned cue value.
Joint trajectory error and cue-value encoding were reproduced by the reward prediction error term in a standard reinforcement learning algorithm with mixed sensorimotor inputs. However, these two signals had distinct state space requirements, suggesting that they could arise from a common reinforcement learning algorithm with distinct neural inputs.
Striatum-wide multifibre array measurements resolved overlapping, yet temporally and anatomically separable, representations of trajectory error and cue value, indicating how functionally distinct dopamine signals for motivation and guidance are multiplexed across striatal regions to facilitate goal-directed behaviour.
