Dopamine helps us learn from positive and negative experiences

Researchers at the Wake Forest University School of Medicine have revealed new insights into the role of dopamine, a key neurotransmitter, in human behavior. 

The experts investigated dopamine’s role in learning from both positive and negative experiences. This research marks a significant advancement in understanding how dopamine influences decision-making and behavioral adaptation.

Reward and punishment 

Dopamine, a neurotransmitter produced in the brain, has long been associated with positive emotions and functions like movement, cognition, and learning. 

However, this study sheds light on its comprehensive role, emphasizing its crucial involvement in processing both reward and punishment prediction errors. 

This suggests that dopamine’s function extends beyond the realm of positive emotions, playing a pivotal role in learning from negative experiences as well.

The role of dopamine

“Previously, research has shown that dopamine plays an important role in how animals learn from ‘rewarding’ (and possibly ‘punishing’) experiences. But, little work has been done to directly assess what dopamine does on fast timescales in the human brain,” said lead author Dr. Kenneth Kishida. 

“This is the first study in humans to examine how dopamine encodes rewards and punishments and whether dopamine reflects an ‘optimal’ teaching signal that is used in today’s most advanced artificial intelligence research.”

How the research was conducted

For the investigation, Dr. Kishida’s team used a combination of fast-scan cyclic voltammetry and machine learning to measure dopamine levels at an impressive rate of 10 measurements per second. This technique, however, is limited to invasive procedures like deep-brain stimulation (DBS) surgeries, commonly used to treat Parkinson’s disease, essential tremor, obsessive-compulsive disorder, and epilepsy.

In collaboration with neurosurgeons Dr. Stephen B. Tatter and Dr. Adrian W. Laxton from Atrium Health Wake Forest Baptist Medical Center, the researchers inserted a carbon fiber microelectrode deep into the brains of participants undergoing DBS for essential tremor. 

While awake in the operating room, these participants engaged in a computer game that involved making choices with monetary consequences, allowing the researchers to monitor dopamine responses to rewards and punishments.

Dopamine levels were measured continuously, once every 100 milliseconds, throughout each of the three stages of the game.

Critical new insights 

The study revealed that dopamine signals both positive and negative experiences in an optimal manner for learning outcomes. 

“We found that dopamine not only plays a role in signaling both positive and negative experiences in the brain, but it seems to do so in a way that is optimal when trying to learn from those outcomes. What was also interesting, is that it seems like there may be independent pathways in the brain that separately engage the dopamine system for rewarding versus punishing experiences,” said Dr. Kishida.

“Our results reveal a surprising result that these two pathways may encode rewarding and punishing experiences on slightly shifted timescales separated by only 200 to 400 milliseconds in time.”

Study implications 

Dr. Kishida believes that this research may lead to a better understanding of how the dopamine system is affected in humans with psychiatric and neurological disorders. He noted that additional research is needed to understand how this signaling is altered in psychiatric and neurological disorders.

“Traditionally, dopamine is often referred to as ‘the pleasure neurotransmitter,”‘ said Dr. Kishida. “However, our work provides evidence that this is not the way to think about dopamine. Instead, dopamine is a crucial part of a sophisticated system that teaches our brain and guides our behavior.” 

“That dopamine is also involved in teaching our brain about punishing experiences is an important discovery and may provide new directions in research to help us better understand the mechanisms underlying depression, addiction, and related psychiatric and neurological disorders.”

The study is published in the journal Science Advances. 

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