New study reveals its role in reversal learning

New study reveals its role in reversal learning


Have you ever wondered how your brain manages to switch gears when life suddenly changes the rules of the game? Researchers have now shed light on this very process, revealing that a key brain chemical plays a pivotal role in helping us adapt to new situations. By combining brain imaging techniques with a specially designed task, they found that dopamine, a brain chemical often associated with pleasure and reward, is also crucial in helping us learn from our mistakes and adjust our decisions accordingly.

The findings have been published in the scientific journal Nature Communications.

Dopamine is a name that often pops up in conversations about happiness, motivation, and addiction. This brain chemical is a sort of messenger that transmits signals within the brain, affecting our mood, sleep, learning, concentration, and even our movement. But its role is far more complex than just making us feel good.

Dopamine is intricately involved in how we make decisions, especially in situations that require us to learn, unlearn, and relearn based on new information. The researchers embarked on this study to dive deeper into the mysteries of dopamine, motivated by the desire to understand how it influences our ability to adapt our decisions when circumstances change.

“I have a general interest in understanding what dopamine does in the human brain and what sorts of cognitive processes it supports,” said lead author Filip Grill, a postdoctoral researcher at the Donders Centre for Cognitive Neuroimaging. “Dopamine is a mysterious molecule since it seems to be related to several behavioral domains including processing of motivational, cognitive, and motor functions.”

“The vast majority of research on how dopamine relates to behavior is done in rodents and non-human primates, since it is difficult to measure dopamine and especially dopamine-release in humans while we are actively engaged in some behavior. This kind of translation from animal to human is also something I am very interested in.

The study brought together 26 volunteers from the community, ensuring none had a history of neurological or psychiatric illness, drug or alcohol dependence, or any condition that would interfere with the brain imaging used in the research.

Participants engaged in a computer-based task while undergoing brain scans using two advanced techniques: positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). This task was a reversal learning paradigm, a method used to explore how individuals adjust their decisions based on changing rewards.

The task was a game of guessing whether a hidden number was above or below five, with correct guesses rewarded and incorrect ones not. Unbeknownst to the participants, the rules for rewards changed during the task, creating periods of stability and volatility that mimicked real-life situations where the ‘right’ choice can suddenly become ‘wrong.’

The PET scans were used to detect changes in dopamine levels in the brain by measuring the binding of a radioactive compound that competes with dopamine for the same brain receptors. The fMRI scans, on the other hand, provided insight into brain activity by detecting changes in blood flow, offering a glimpse into which parts of the brain were working harder during different phases of the task.

The researchers observed significant findings through the PET scans, particularly in the striatum, a brain region known for its role in reward processing. They found that dopamine release increased in this area when participants faced the switch from stable to volatile rules, suggesting dopamine’s key role in signaling the need for a strategy change. This dopamine release correlated with the participants’ ability to adapt their decisions based on new information, with higher dopamine levels linked to quicker adjustment and better performance on the task.

“I think the general view of dopamine is that it is a kind of reward molecule but here we show that dopamine is also released when we learn from errors,” Grill told PsyPost. “Individuals that were very sensitive to their errors released more dopamine. However, these individuals were not necessarily best at the task. Instead, individuals that released a medium amount of dopamine had best performance.”

The fMRI data complemented these findings by showing increased brain activity in areas associated with attention and decision-making, especially after the rule change. This activity pattern suggests that the brain engages a network of regions to process unexpected outcomes and to adapt decisions accordingly.

“Seeing a rather strong brain–behavior correlation is quite surprising,” Grill remarked. “I hope I will get surprised again in the future.”

While the study’s results are compelling, they come with their share of limitations. For instance, the design of the brain imaging study meant that researchers could not compare their findings against a baseline of brain activity without the task, potentially overlooking how individual differences in dopamine levels might influence adaptability. Furthermore, the complexity of human behavior and brain chemistry means that dopamine is not the only player in this adaptive process. Future research could benefit from exploring how other neurotransmitters interact with dopamine and contribute to our ability to learn and adjust to new information.

The journey to fully understand the human brain’s adaptability is far from over. Future studies could explore how different levels of dopamine affect decision-making in various contexts, perhaps by incorporating tasks that simulate more complex real-life scenarios or by using pharmacological methods to alter dopamine levels directly. Another promising direction is to examine the role of dopamine in populations with neurological conditions that affect decision-making and learning, providing insights that could inform new therapeutic approaches.

“The study was conducted with healthy young adults,” Grill noted. “The long-term goal is to adapt the paradigm to investigate dopamine release during different behaviors in neurological and psychiatric disorders with abnormal dopamine signaling such as Parkinson’s disease and schizophrenia.”

The study, “Dopamine release in human associative striatum during reversal learning,” was authored by Filip Grill, Marc Guitart-Masip, Jarkko Johansson, Lars Stiernman, Jan Axelsson, Lars Nyberg, and Anna Rieckmann.


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