Summary: New research reveals dopamine has a previously unknown role: reshaping our memories of rewarding experiences. In a study using mice, scientists found dopamine helps reduce the perceived value of memories linked to rewards, altering future behavior toward those rewards.
When mice recalled memories of sweet food while feeling unwell, dopamine actively devalued these memories, causing the animals to avoid the food later—even though the food itself never made them sick. This discovery expands our understanding of dopamine beyond traditional views, suggesting novel approaches for treating addiction, depression, and other disorders driven by unwanted reward-related memories.
Key Facts:
- Novel Role: Dopamine actively reduces the value of reward-associated memories, influencing future behaviors.
- Behavioral Shift: Devaluing memories alone was sufficient to change future eating behavior in mice, even without direct negative experiences.
- Therapeutic Potential: These findings could lead to treatments targeting harmful memories underlying addiction and psychiatric conditions.
Source: Michigan State University
New research out of Michigan State University expands on current understanding of the brain chemical dopamine, finding that it plays a role in reducing the value of memories associated with rewards.
The study — published in the open access journal Communications Biology — opens new avenues for understanding dopamine’s role in the brain.
The research team discovered that dopamine is involved in reshaping memories of past rewarding events — an unexpected function that challenges established theories of dopamine function.
“We discovered that dopamine plays a role in modifying how a reward-related memory is perceived over time,” said Alexander Johnson, associate professor in MSU’s Department of Psychology and lead researcher of the study.
In the study, mice were presented with an auditory cue that had previously been associated with a sweet-tasting food. This led to a retrieval of the memory associated with consuming the food. At this time, mice were made to feel temporarily unwell, similar to how you feel if you’ve eaten something that has upset your stomach.
When the mice had fully recovered, they displayed behavior as if the sweet-tasting food had made them unwell. This occurred despite the fact that when mice were made to feel unwell, they had only retrieved the memory of the food, not the food itself. This initial finding suggests that devaluing the memory of food is sufficient to disrupt future eating of that food.
The research team next turned their attention to the brain mechanisms that could be controlling this phenomenon. Using an approach by which they could label and reactivate brain cells that were engaged when the food memory was retrieved, the researchers identified that cells producing the chemical dopamine appeared to play a particularly important role. This was confirmed through actions that manipulated and recorded dopamine neuron activity during the exercise.
“Our findings were surprising based on our prior understanding of dopamine’s function. We typically don’t tend to think of dopamine being involved in the level of detailed informational and memory processing that our study showed,” Johnson explained.
“It’s a violation of what we expected, revealing that dopamine’s role is more complex than previously thought.”
The team also used computational modeling and were able to capture how dopamine signals would go about playing this role in reshaping reward memories.
“Understanding dopamine’s broader functions in the brain could provide new insights into how we approach conditions like addiction, depression and other neuropsychiatric disorders,” said Johnson.
“Since dopamine is implicated in so many aspects of brain function, these insights have wide-ranging implications. In the future, we may be able to use these approaches to reduce the value of problematic memories and, as such, diminish their capacity to control unwanted behaviors.”
About this dopamine and memory research news
Author: Jack Harrison
Source: Michigan State University
Contact: Jack Harrison – Michigan State University
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Devaluing memories of reward: a case for dopamine” by Alexander Johnson et al. Communications Biology
Abstract
Devaluing memories of reward: a case for dopamine
Midbrain dopamine cells encode differences in predictive and expected value to support learning through reward prediction error.
Recent findings have questioned whether reward prediction error can fully account for dopamine function and suggest a more complex role for dopamine in encoding detailed features of the reward environment.
In this series of studies, we describe a novel role for dopamine in devaluing sensory features of reward.
Mesencephalic dopamine cells activated during a mediated devaluation phase were later chemogenetically reactivated. This retrieval of the devalued reward memory elicited a reduction in the hedonic evaluation of sucrose reward.
Through optogenetic and chemogenetic manipulations, we confirm dopamine cells are both sufficient and necessary for mediated devaluation, and retrieval of these memories reflected dopamine release in the nucleus accumbens.
Consistent with our computational modeling data, our findings indicate a critical role for dopamine in encoding predictive representations of the sensory features of reinforcement.
Overall, we elucidate a novel role for dopamine function in mediated devaluation and illuminate a more elaborate framework through which dopamine encodes reinforcement signals.
