A study shows the critical roles of dopamine and serotonin in decision-making based on social contexts, showing how the chemicals influence the offers made in the end game. This understanding of neurotransmitter dynamics may provide new treatments for Parkinson’s and other psychiatric conditions. Credit: SciTechDaily.com
An international team describes a complex dance of dopamine and serotonin in the human brain, which sheds light on social decisions.
In a study published in Nature of human behaviorScientists have delved into the world of chemical neuromodulators in the human brain, particularly dopamine and serotonin, to uncover their role in social behavior.
The research, which involved brain surgery on people with Parkinson’s disease when they woke up, found parts of the brain involved in motor control and reward processing.
Led by Virginia Tech computational neuroscientist Montag, the international team has demonstrated a previously unknown neurochemical mechanism responsible for the human tendency to make decisions based on social context – people are more likely to accept offers from computers than the same offers from human players.
Scientists discuss their work to gain insights into the complexity of the brain and mind. The recent researchers include (from left) Dan Bang of Aarhus University in Denmark, Ken Kishida of Wake Forest University School of Medicine, Michael Friedland, executive director of Fralin Biomedical Research Institute; Peter Dayan, managing director of the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, and Read Montague, director of the Human Neuroscience Research Center at the Fralin Biomedical Research Institute, reflect on decades of success. Credit: Clayton Metz/Virginia Tech
Insights from the Ultimatum game
In the study, four patients undergoing deep brain stimulation surgery for Parkinson’s disease were immersed in a “take it or leave it” ultimatum game. For example, a player may propose to keep $16, while the patient gets the remaining $4. If the patient refuses to be divided, none of them will receive anything.
“You can teach people what to do with these kinds of games — to accept even small rewards as opposed to no rewards at all,” said Montag, a professor at Virginia Tech’s Carillion Mountcastle and the Fralin Biomedical Research Institute at VTC. Author of the study. “When people know they’re playing a computer, they play exactly like mathematical economists – they do what they’re supposed to do. But they can’t help themselves when they’re playing a human. They are often motivated to punish by rejecting the minimum bid.
Read Montag, who led the research team that documented the chemical underpinnings of social decision-making, talks about tapping into the fundamentals of what makes us human. Credit: Clayton Metz/Virginia Tech
Dopamine-serotonin dance
The idea that people make decisions based on social context is not new in neuroeconomic games. But now, for the first time, researchers have shown that the effects of social context may stem from the dynamic interactions between dopamine and serotonin.
Dopamine appears to be a continuous monitoring system that closely monitors when people make decisions and whether the current offer is better or worse than the previous one. Serotonin, on the other hand, seems to focus only on the current special offer, suggesting a more case-by-case evaluation.
This fast-paced dance takes place against a slow background, and dopamine is high when people play other people – in other words, when fairness comes into play. Together, these cues contribute to our brain’s assessment of value during social interactions.
“We’re shining a spotlight on different cognitive processes and ultimately getting answers to questions with better biological detail,” said first author Dan Bang, associate professor of clinical medicine and Lundbeck Foundation Fellow at Aarhus University in Denmark. at Fralin Biomedical Research Institute.
“Dopamine levels are higher when people interact with another person as opposed to a computer,” Bang said. “And here it was important that we measure serotonin so that we can be sure that the overall response to the social context is specific to dopamine.”
Seth Batten, a research associate at the Fralin Biomedical Research Institute, developed electrodes used to record the dopamine-serotonin dance. Credit: Clayton Metz/Virginia Tech
Seth Batten, a senior research associate in Montague’s lab and first author of the study, built the carbon-fiber electrodes implanted in patients undergoing deep brain stimulation surgery and helped collect the data at Mount Sinai Health System in New York.
“What’s unique about our method is that it allows us to measure more than one neurotransmitter at the same time – that effect shouldn’t be lost,” Batten said. “We’ve seen these signaling molecules before, but this is the first time we’ve seen them dance. No one has ever seen this dance of dopamine and serotonin in a social context.
Deciphering the interpretation of electrochemical signals recorded from patients during surgery has been a major challenge that has taken years to solve.
“The raw data we collect from patients is not limited to dopamine, serotonin, or norepinephrine — it’s a mix of those,” said Ken Kishida, a study co-author and associate professor of translational neuroscience. Neurosurgery, Wake Forest University School of Medicine. “We’re using machine-learning-type tools to identify what’s in the raw data, understand the signature, and identify what’s going on with dopamine and serotonin.”
in the Nature is the study of human behaviorResearchers have shown how the rise and fall of dopamine and serotonin are linked to human cognition and behavior.
“There’s a candy store full of wonderful techniques for asking biological questions in the model organism world, but it’s hard to ask questions about what makes you tick,” said Montague, who is also director of the Human Neuroscience Research Center and Fralin Biomedical Research Institute’s Human Neuroimaging Laboratory.
Addressing Parkinson’s
“At some point, after we’ve evaluated enough people, we’ll be able to unravel the pathology of Parkinson’s disease that gave us this opportunity,” said Montag, a professor at Virginia Tech’s College of Science.
Parkinson’s disease is characterized by a significant loss of dopamine-producing neurons in the brainstem, which often coincides with the onset of symptoms.
This loss affects the striatum, a region of the brain that is highly influenced by dopamine. As dopamine decreases, serotonin terminals begin to swell, indicating a complex interaction, as shown in rod models.
“There is preclinical evidence that disruption of the dopamine system tells the serotonin system, ‘Hey, we need to do something.’ But we’ve never seen the dynamics.” “That’s the first step we’re taking now, but hopefully once we get to hundreds of patients, we’ll be able to correlate this with symptomatology and provide some clinical clues about Parkinson’s pathology,” Montague said.
In this regard, researchers say, a window opens to learn about a wider range of brain disorders.
“The human mind is like a black box,” Kishida said. “We’ve developed one more way to look inside and understand how these systems work and how they’re affected by different clinical conditions.”
Michael Friedlander, executive director of the Fralin Biomedical Research Institute and a neuroscientist who was not involved in the study, said, “This work is revolutionizing the entire field of neuroscience and our ability to interrogate the human mind and brain – something that was not even possible with technology several years ago.
Psychiatry is an example of a medical field that could benefit from this approach, he said.
“We have a huge number of people in the world suffering from various mental illnesses, and in many cases, pharmacological solutions are not very good,” said Friedlander, vice president of health sciences and research at Virginia Tech. Technology. “Dopamine, serotonin and other neurotransmitters are closely involved in some of these disorders. This effort adds real precision and scale to understanding those problems. One thing we can be sure of is that this work is extremely important for developing future treatments. “
More than ten years in the making
The effort to measure neurotransmitters in the human brain in real time began 12 years ago when Montag assembled a group of experts who “think a lot about thinking.”
Scientists have published the first-of-its-kind observations of the human brain Neuron In the year In 2020, researchers reported that dopamine and serotonin work on a second-by-second basis to help people perceive the world and act based on their perceptions.
Recently, in a study published in October in the journal Current biologythe researchers used their method of recording chemical changes in active humans to gain insight into the brain’s noradrenaline system, which has long been a target for drugs to treat mental disorders.
And, in the magazine in December Advances in science, The team explained that the rapid changes in dopamine levels reflect a specific calculation of how people learn from rewards and punishments.
“We’ve made multiple activation measurements of neurotransmitters in different regions of the brain, and now we’re at the point where we’re tapping into critical things that make us human,” Montague said.
Reference: “Dopamine and serotonin in the substantia nigra monitor social context and value cues during economic exchange” by Seth R. Batten, Dan Bang, Brian H. Koppel, Ariana N. Davis, Matthew Heflin, Qixiu Fu, Ofer Perl, Kimia Ziafat, Alice Hashimi, Ignacio Saz, Leonardo S. Montag, 26 Feb 2024; Nature of human behavior.
DOI: 10.1038/s41562-024-01831-w