In a first-of-its-kind observation in the human brain, an international team of researchers found that two well-known neurochemicals ̵
The findings show that researchers can continuously and simultaneously measure the activity of both dopamine and serotonin – whose receptor and host sites are therapeutic targets for disorders ranging from depression to Parkinson’s disease – in the human brain.
In addition, neurochemicals appear to integrate people’s perceptions of the world with their actions, indicating that dopamine and serotonin have much more expansive roles in the human nervous system than previously known.
Known as neuromodulators, dopamine and serotonin have traditionally been associated with reward processing – how good or bad people perceive the result after taking action.
The survey online today in the magazine Neuron opens the door to a deeper understanding of the expanded role of these systems and their roles in human health.
“A huge number of people around the world are taking pharmaceutical compounds to disrupt the dopamine and serotonin delivery systems to change their behavior and mental health,” said P. Reed Montague, senior author of the study and professor and director of the Center for human neurology and the Human Neuroimaging Laboratory at the Fralin Institute for Biomedical Research in Virginia Tech Carilion. “For the first time, moment-to-moment activity in these systems has been measured and determined to be involved in perception and cognitive abilities. These neurotransmitters act simultaneously and integrate activity at significantly different time and space scales than anyone expected.”
A better understanding of the basic actions of dopamine and serotonin during perception and decision making can provide an important picture of psychiatric and neurological disorders, the researchers said.
“Every choice someone makes involves taking information, interpreting that information, and making decisions about what they have made,” said Kenneth Kishida, a research correspondent and assistant professor of physiology and pharmacology and neurosurgery at Wake Forest School of Medicine. . “There is a whole range of psychiatric illnesses and neurological disorders in which this process changes in patients, and dopamine and serotonin are the main suspects.”
The lack of chemically specific methods for studying neuromodulation in humans on a rapid scale hinders the understanding of these systems, according to Montague, an honorary professor at the Wellcome Center for Human Neuroimaging at University College London and a professor of physics at Virginia Tech College of Science.
But now, in the first measurements, scientists have used an electrochemical method called “fast-scan cyclic voltammetry,” which uses a small carbon-fiber microelectrode that has low voltage amplified through it to detect real-time dopamine and serotonin activity.
In the study, researchers recorded fluctuations in dopamine and serotonin using specially designed electrodes in five patients undergoing deep brain stimulation by implanting electrodes to treat essential tremor or Parkinson’s disease. Patients were awake during surgery, playing a computer game designed to quantify aspects of thinking and behavior while taking measurements.
In each round of the game, patients looked briefly at a point cloud and were asked to judge the direction in which they were moving. The method, developed by co-author Dan Bang, a postdoctoral fellow of Sir Henry Welcome, and Steve Fleming, a Sir Henry Dale / Royal Society Fellow, both at the Center for Human Neuroimaging at University College London, helped show that dopamine and participates in simple perceptual decisions, outside the traditional context of rewards and losses.
“These neuromodulators play a much broader role in supporting human behavior and thinking, and in particular they are involved in the way we handle the outside world,” Bang said. “For example, if you move through a room and the lights are off, you move differently because you are not sure where the objects are. Our work suggests that these neuromodulators – especially serotonin – play a role in signaling how insecure we are about the external environment. “
Montagu and Kishida, along with Terry Lorenz, an assistant, and Jason White, a senior research fellow, both at the Fralin Institute for Biomedical Research, began work on a new statistical approach to identifying dopamine and serotonin signals while they were still at Baylor Medical. college in Houston, Texas.
“Ken has tackled the challenge of doing rapid neurochemistry in humans during active cognition,” Montague said. “Many other good groups of scientists have not been able to do this. In addition to calculating huge amounts of data, there are complex problems to solve, including large, basic algorithmic problems.”
Until recently, only slow methodologies such as PET scans could measure the effects of neurotransmitters, but they were not close to the frequency or volume of second-to-second measurements of fast-scan cyclic voltammetry.
The measurements in the new study were made at Wake Forest Baptist Medical Center and involved neurosurgical teams led by Adrian W. Laxton and Stephen B. Tatter.
“The enthusiasm that neurosurgeons feel for this study stems from the same reasons they were doctors – first and foremost, they want to do the best for their patients and have a real passion for understanding how the brain works to improve patients’ outcomes.” “Both are collaborative scientists, along with Charles Branch, chairman of the neurosurgery department at Wake Forest, who is an incredible advocate for this work.”
In the same way, Montague said, “You can’t do this without surgeons being real partners side by side, and certainly not without people allowing you to record their brains while implanting electrodes to relieve the symptoms of neurological problems.” disorder. “
Montague had read a study in Notices of the National Academy of Sciences this prompted him to turn to colleagues Bang and Fleming of University College London to adapt a task for patients to perform during surgery that would reveal seconds of dopamine and serotonin signaling in real-time output to the outside world. apart from their often acclaimed roles in award-related processes.
“I said I have this new method for measuring dopamine and serotonin, but I need you to help with the task,” Montague said. “They got into the study. The study really took a lot of work and an integrated constellation of people to get those results.”
The study was funded by grants for various researchers from the Trust Trust, National Institutes of Health, including the National Institute on Drug Abuse, the National Institute of Mental Health, the National Institute of Neurological Disorders and Stroke.
Scientists report the role of dopamine and serotonin in human perception and decision making
Neuron (2020). DOI: 10.1016 / j.neuron.2020.09.015
Provided by Virginia Tech
Quote: Scientists find that neurochemicals have unexpectedly deep roles in the human brain (2020, October 12), extracted on October 12, 2020 from https://medicalxpress.com/news/2020-10-scientists-neurochemicals-unexpectedly- profound-roles.html
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