Researchers from Cedars-Sinai''s Center for Neural Science and Medicineand the Department of Neurosurgery have discovered how signals from a group of neurons in the brain''s frontal lobe both allow humans to learn new tasks, while the focus is to develop highly specific abilities.Their study, published today in the peer-reviewed journalScience, provides a fundamental understanding of performance monitoring, an executive function used to manage daily life.
In many different situations, the brain uses the same group of neurons for performance feedback, whether it''s for the first time or in trying to improve a specific skill.
"The human body''s inherent charm is that it is so flexible," said a professor of neurosurgery, neurology, and biomedical sciences, who was the director of the Center for Neural Science and Medicine, and the Board of Governors Chair in Neurosciences. "We designed our research to decipher how the brain can generalize and specialize simultaneously, both of which are crucial for us to achieve a goal."
Performance monitoring is a personal emotional response that allows a person to know they have made a mistake. One example is the person who realizes they walked past an intersection where they should have turned. Another example is the person who says something in conversation and recognizes as soon as the words are out of their mouth that nothing.
"That ''Oh, shoot'' moment, that ''Oops!'' moment, is performance monitoring kicking in," said Zhongzheng Fu, PhD, a postdoctoral researcher in theRutishauser Laboratoryat Cedars-Sinai and the first author of the study.
These signals help improve performance in future attempts by delivering information to areas of the brain that regulate emotions, memory, planning, and problem-solving. Performance monitoring also assists the brain in adjusting its focus by demonstrating how much conflict or difficulty occurred during the task.
"So a ''Oops!'' moment might force someone to pay closer attention when they chat with a friend or intention to stop at the store on the way home from work," Fu said.
Investigators recorded the activity of individual neurons in the medial frontal cortex of study participants. Participants were epilepsy patients who, as part of their treatment, had electrodes implanted in their brains to assist locate the focus of their seizures. Specifically, these patients had electrodes implanted in the medial frontal cortex, a brain area known to play a central role in performance monitoring.
Participants were required to perform two commonly used cognitive tests, according to the team.
Participants viewed the written name of a color, such as "red," printed in an ink of a different color, such as green, and were asked to name the ink color rather than the written word.
"This is a blow in the brain," Rutishauser said. "You have decades of knowledge in reading, but now your goal is to suppress that habit of reading, and to say the color of the ink that the word is written in instead."
Participants saw three numerical numbers on screen, two the same and the other uniquefor example, 1-2-2. The subject''s task was to press the button associated with the unique number, "1"resisting their tendency to press "2." because that number appears twice.
"These two tasks serve as a powerful test of how self-monitoring is used in different situations, including several cognitive domains," Fu says.
A Structured Response
The researchers noted two different types of neurons at work as they performed these tasks. "Error" neurons were very successful after an error was made, while "conflict" neurons were fired as a result of the difficulties encountered by the subject.
"When we examined the activity of neurons in this brain area, it surprised us that most of them only become active after a decision or an action was completed," Rutishauser said. "This indicates that this brain area plays a role in assessing decisions after the fact rather than making them."
Domain general and domain specific are two types of performance monitoring; domain general sayssomethingwent wrong and can detect errors in any type of task, whether someone is driving a vehicle, navigating a social situation, or playing Wordle for the first time. This allows them to perform new tasks without much instruction, something machines cannot.
"Machines can be well trained to do one thing," Fu said. "You may build a robot to flip hamburgers, but it cant adapt those skills to frying dumplings. Humans, owing to domain general performance monitoring, are capable."
The person who made the errorwhat went wrong, detecting specific mistakes that they missed a turn, described something inappropriate, or chose the wrong letter in a puzzle is one way.
In the medial frontal cortex, neurons signaling domain general and domain specific information were infusions.
"We used to believe that there were sections of the brain dedicated to only domain general performance monitoring, but others to the domain specific," Rutishauser said. "Our research now shows that the exact same group of neurons has the ability to perform both domain general and domain specific performance monitoring. When you''re listening to these neurons, you''ll even read out both types of information simultaneously."
It''s helpful to think about neurons as musicians in an orchestra in order to understand how these signals are interpreted by other areas of the brain, according to Rutishauser.
"But if they play an organised composition, it''s possible to discern the diverse melodies and harmonies even with so many instrumentsor performance monitoring neurons playing all at once." Rutishauser claims.
According to Rutishauser, too much or too little of this signaling may jeopardize health.
Overactive performance monitoring can be a form of obsessive-compulsive disorder, causing a person to examine obsessively for shortcomings. At the other extreme is schizophrenia, where performance monitoring can be underactive to a degree that a person does not perceive errors or the inability of their words or actions.
"We believe that the mechanistic knowledge we have gained will be critical to the advancement of treatment for these terrible psychiatric ailments," says Rutishauser.
Jeffrey Chung, MD, the director of the Cedars-Sinai Epilepsy Program, an assistant professor of neurology Chrystal Reed, MD, PhD, Adam Mamelak, MD, a neurosurgery professor, and director of the Functional Neurosurgery Program, Ralph Adolphs, PhD, and a research associate Danielle Beam.