Summary: A new study reveals a new role for dopamine: helping to deal with disappointment.
Traditionally associated with the reinforcement of rewards, this research shows that dopamine levels in rats rise after disappointing outcomes, increasing motivation. The newly discovered neurons, called “anti-RPE,” signal increased levels of dopamine after a lack of reward and reduced response to unexpected rewards, suggesting a unique mechanism for maintaining motivation despite setbacks.
This new understanding may provide insight into potential treatments for a variety of psychiatric and neurological disorders.
Key facts:
- Cutting-edge techniques were used to precisely measure the activity of dopamine neurons in rats.
- The activity of anti-RPE dopamine neurons decreases when rats are unexpectedly rewarded.
- These insights can influence learning and personal development strategies.
source: Kyoto University
Dopamine is known to increase when outcomes are promising and decrease when expectations are not met. However, this role does not explain the ability to overcome disappointment.
Now researchers at Kyoto University Graduate School of Medicine have found neurons in rats that increase dopamine immediately after disappointment as a coping mechanism. The study was published in the journal Scientific progress.
“Every day we strive to achieve goals, but we often face failure and disappointment. Fortunately, thanks to dopamine, our brain can cope with such setbacks,” says corresponding author Masaaki Ogawa of Kyoto University.
Midbrain dopamine neurons may influence learning and motivation, indicators in the study of psychiatric disorders. Credit: Neuroscience News“Conventionally, we associate dopamine with self-reward, but our results show that its other function is self-motivation.”
This neural mechanism that helps deal with frustration could lead to new treatments for psychiatric and neurological disorders, including depression, addiction and Parkinson’s disease.
“It will also provide insight into activities aimed at higher goals such as independent learning and self-development.”
In animals other than humans, on the other hand, failure and frustration are intertwined with their survival, especially in foraging and mating.
Ogawa’s team trained rats to keep looking for fresh water. Then, even when rats fail to obtain their reward, they can switch their behavior to subsequently receive a reward afterward.
Neuronal activity in the rats during this behavior—measured with millisecond-to-second time precision using opto-electrophysiology and calcium imaging—confirmed that the cells observed were indeed dopamine neurons.
The researchers manipulated the rats’ behavior by artificially stimulating the neural circuit at the moment of perceived disappointment as a result of not receiving their expected rewards.
“It was surprising that the activity of dopamine neurons, which showed increased activity after disappointment, decreased after the rats received unexpected rewards,” explains Ogawa.
Midbrain dopamine neurons may influence learning and motivation, indicators in the study of psychiatric disorders. In addition, these neurons provide a reward signal called reward prediction error, or RPE, which is the difference between received rewards minus expected rewards. RPE neurons—critical for learning based on reward value—do not directly support the behavioral switch to pursue a reward after the moment of unexpected nonreward, but instead support negative learning.
However, Ogawa’s team suggests a new type of dopamine neuron—the anti-RPE type—that shows an increased response to the absence of reward and a decreased response to unexpected rewards.
“This bidirectional response fundamentally changes our understanding of how dopamine works in motivating behavior,” says Ogawa.
About this dopamine research news
Author: Masaaki Ogawa
source: Kyoto University
Contact: Masaaki Ogawa – Kyoto University
Image: Image credited to Neuroscience News
Original Research: Free access.
“Dopamine error signal for active coping with lack of expected reward” by Masaaki Ogawa et al. Scientific progress
Summary
Dopamine error signal for active coping with lack of expected reward
To get more of a certain uncertain reward, animals must learn to actively overcome the lack of reward and adjust their behavior to get it again. The neural mechanisms underlying such reward omission coping remain unclear.
Here, we developed a task in rats to monitor active behavioral switching to the next reward following absence of reward. We found that some dopamine neurons in the ventral tegmental area showed increased responses to unexpected reward omission and decreased responses to unexpected reward, following the opposite responses of well-known reward prediction error (RPE) signaling dopamine neurons.
Increases in dopamine reflected in the nucleus accumbens correlate with behavioral adjustments to actively cope with unexpected lack of reward. We propose that these responses signal an error to actively cope with the lack of expected reward.
Thus, the dopamine error signal cooperates with the RPE signal, enabling adaptive and robust pursuit of an uncertain reward to ultimately obtain more reward.