Summary: The dopamine system helps the brain anticipate when and for how long unpleasant events will occur, but it does so without encoding prediction errors for those aversive events.
Source: Netherlands Institute for Neuroscience
A new study at the Netherlands Institute for Neuroscience clarifies how dopamine responds to unpleasant, aversive events.
Dopamine is widely known for its central role in motivation, learning and movement. A key function of the dopamine system is to signal unexpected rewards and to encode differences between expected and received rewards—so-called reward prediction errors. When a reward is larger or more surprising than expected, dopamine neurons increase their activity; when rewards fall short of expectations, activity is suppressed. Those error signals are essential for learning from experience and for adapting behavior to obtain desirable outcomes.
Rewarding versus aversive stimuli
While many studies have mapped dopamine’s relationship with rewarding stimuli, far fewer have systematically investigated how dopamine responds to unpleasant or aversive stimuli. Prior experiments in this area have produced mixed results, leaving open key questions: Do dopamine neurons respond to aversive events? Can they predict aversive events? And do they encode an aversive prediction error akin to reward prediction errors?
New findings on dopamine and aversive events
In work now published in eLife, researchers at the Netherlands Institute for Neuroscience led by Ph.D. student Jessica Goedhoop and group leader Ingo Willuhn examined these questions by measuring dopamine release in rats exposed to an aversive auditory stimulus—white noise—and to cues that predicted that noise. White noise is a reliable, aversive sound for rats and allowed the team to probe dopamine signals under controlled conditions.
The researchers observed that dopamine levels in the nucleus accumbens core declined gradually during exposure to white noise, producing a sustained negative ramp while the aversive stimulus persisted. With repeated pairings, cues that predicted the forthcoming white noise began to evoke a similar decrease in dopamine, indicating that the system learned to anticipate the aversive event and its timing. Crucially, however, these dopamine changes did not reflect an aversive prediction error in the same way dopamine encodes rewarding prediction errors.
Unlike reward-driven signals, the dopamine response to white noise was not sensitive to the intensity or “value” of the aversive stimulus, nor was it modulated by the broader context or by probabilistic contingencies. The response shifted only partially from the aversive outcome toward the predictive cue, and although unpredicted white noise did produce a different recovery profile—slower signal recovery after unpredicted than predicted noise—this pattern did not match the hallmarks of a classical prediction-error signal.
Taken together, these results indicate that nucleus accumbens dopamine primarily signals when an aversive event will occur and how long it will last, rather than encoding a negative prediction error that scales with aversive value. The signal therefore appears to track prediction and duration, not value or prediction error, for aversive auditory stimuli in this experimental setting.
Group leader Ingo Willuhn commented, “This is a very thorough and systematic study that takes a lot of variables into account. The results give us a better understanding of the role of dopamine release in processing aversive events. There is a growing interest into the role of dopamine in aversion. We used a novel aversive stimulus that enabled to conduct a more thorough analysis of dopamine than previously possible.”
These findings are relevant beyond basic neuroscience because addictive drugs can hijack and amplify dopamine signals, producing exaggerated effects on neuronal plasticity. A clearer picture of how dopamine normally represents aversive events helps to refine our understanding of how pathological states may arise when dopamine signaling becomes dysregulated.
About this dopamine research news
Author: Press Office
Source: Netherlands Institute for Neuroscience
Contact: Press Office – Netherlands Institute for Neuroscience
Image: The image is in the public domain
Original Research: Open access. “Nucleus accumbens dopamine tracks aversive stimulus duration and prediction but not value or prediction error” by Jessica N Goedhoop et al., published in eLife.
Abstract
Nucleus accumbens dopamine tracks aversive stimulus duration and prediction but not value or prediction error
There is active debate on the role of dopamine in processing aversive stimuli, with proposed roles ranging from no involvement to signaling an aversive prediction error (APE).
In this study, dopamine release in the nucleus accumbens core (NAC)—a region closely linked to reward prediction errors—was measured in rats exposed to white noise (WN), an effective aversive stimulus, and to cues that predicted the noise.
Both white noise and its predictive cues induced a negative dopamine ramp, followed by slow recovery when the stimulus ended. Unlike reward conditioning, the dopamine signal during aversive stimulation was invariant to WN intensity, context valence, and probabilistic contingencies, and the response shifted only partially toward the predictive cue.
Unpredicted WN produced slower post-stimulus recovery than predicted WN. When rewarding and aversive stimuli were presented together, dopamine responses were additive, despite differing signal qualities.
Overall, these results demonstrate that NAC dopamine primarily tracks the prediction and duration of aversive events rather than encoding an aversive prediction error.