Source; Cedars Sinai
Researchers
from Cedars-Sinai’s Center for Neural Science and Medicine and
Department of Neurosurgery have uncovered how signals from a group of
neurons in the brain’s frontal lobe simultaneously give humans the
flexibility to learn new tasks—and the focus to develop highly specific
skills.
Their research, published today in the peer-reviewed journal Science, provides a fundamental understanding of performance monitoring, an executive function used to manage daily life.
The
study’s key finding is that the brain uses the same group of neurons
for performance feedback in many different situations—whether a person
is attempting a new task for the first time or working to perfect a
specific skill.
“Part
of the magic of the human brain is that it is so flexible,” said Ueli
Rutishauser, Ph.D., professor of Neurosurgery, Neurology, and Biomedical
Sciences, director of the Center for Neural Science and Medicine, the
Board of Governors Chair in Neurosciences and senior author of the
study. “We designed our study to decipher how the brain can generalize and specialize at the same time, both of which are critical for helping us pursue a goal.”
Performance
monitoring is an internal signal, a kind of self-generated feedback,
that lets a person know they have made a mistake. One example is the
person who realizes they drove 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 what they just said was inappropriate.
“That
‘Oh, shoot’ moment, that ‘Oops!’ moment, is performance monitoring
kicking in,” said Zhongzheng Fu, Ph.D., a postdoctoral researcher in the
Rutishauser Laboratory at Cedars-Sinai and first author of the study.
These
signals help improve performance on future attempts by passing
information to areas of the brain that regulate emotions, memory,
planning and problem-solving. Performance monitoring also helps the
brain adjust its focus by signaling how much conflict or difficulty was
encountered during the task.
“So
an ‘Oops!’ moment might prompt someone to pay closer attention the next
time they chat with a friend or plan to stop at the store on the way
home from work,” said Fu.
To
see performance monitoring in action, investigators recorded the
activity of individual neurons in the medial frontal cortex of study
participants. The participants were epilepsy patients who, as part of
their treatment, had electrodes implanted in their brains to help locate
the focus of their seizures. Specifically, these patients had
electrodes implanted in the medial frontal cortex, a brain region known
to play a central role in performance monitoring.
In
the Stroop task, which pits reading against color naming, participants
viewed the written name of a color, such as “red,” printed in ink of a
different color, such as green, and were asked to name the ink color
rather than the written word.
“This
creates conflict in the brain,” Rutishauser said. “You have decades of
training in reading, but now your goal is to suppress that habit of
reading and say the color of the ink that the word is written in
instead.”
In
the other task, the Multi-Source Interference Task (MSIT), which
involves recognizing numerals, participants saw three numerical digits
on screen, two the same and the other unique—for example, 1-2-2. The
subject’s task was to press the button associated with the unique
number—in this case, “1”—resisting their tendency to press “2” because
that number appears twice.
“These
two tasks serve as a strong test of how self-monitoring is engaged in
different scenarios involving different cognitive domains,” Fu said.
A structured response
As
the subjects performed these tasks, the investigators noted two
different types of neurons at work. “Error” neurons fired strongly after
an error was made, while “conflict” neurons fired in response to the
difficulty of the task the subject had just performed.
“When
we observed 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. This indicates that this brain area plays a role in
evaluating decisions after the fact, rather than making them.”
There
are two types of performance monitoring: domain general and domain
specific. Domain general performance monitoring tells us something went
wrong and can detect errors in any type of task—whether someone is
driving a car, navigating a social situation or playing Wordle for the
first time. This allows them to perform new tasks with little
instruction, something machines cannot do.
“Machines
can be trained to do one thing really well,” Fu said. “You can build a
robot to flip hamburgers, but it can’t adapt those skills to frying
dumplings. Humans, thanks to domain general performance monitoring,
can.”
Domain specific performance monitoring tells the person who made the error what went
wrong, detecting specific mistakes—that they missed a turn, said
something inappropriate or chose the wrong letter in a puzzle. This is
one way people perfect individual skills.
Surprisingly, neurons signaling domain general and domain specific information were intermingled in the medial frontal cortex.
“We
used to think there were portions of the brain dedicated to only domain
general performance monitoring and others to only domain specific,”
Rutishauser said.
“Our
study now shows that’s not the case. We’ve learned that the very same
group of neurons can do both domain general and domain specific
performance monitoring. When you’re listening to these neurons, you can
read out both types of information simultaneously.”
To
understand how these signals are interpreted by other areas of the
brain, it helps to think of the neurons as musicians in an orchestra,
Rutishauser said.
“If
they all play at random, the listeners—in this case the regions of the
brain receiving the signals—just hear a garbled set of notes,”
Rutishauser said.
“But
if they play an arranged composition, it’s possible to clearly hear the
various melodies and harmonies even with so many instruments—or
performance monitoring neurons—playing all at once.”
Too much or too little of this signaling, however, can cause problems, Rutishauser said.
Overactive
performance monitoring can manifest as obsessive-compulsive disorder,
causing a person to check obsessively for errors that don’t exist. At
the other extreme is schizophrenia, where performance monitoring can be
underactive to a degree that a person doesn’t perceive errors or the
inappropriateness of their words or actions.
“We
believe the mechanistic knowledge we have gained will be critical to
perfecting treatments for these devastating psychiatric disorders,”
Rutishauser said.
The
research team also included Jeffrey Chung, MD, director of the
Cedars-Sinai Epilepsy Program; Assistant Professor of Neurology Chrystal
Reed, MD, Ph.D.; Adam Mamelak, MD, professor of neurosurgery and
director of the Functional Neurosurgery Program; Ralph Adolphs, Ph.D.,
professor of Psychology, Neuroscience, and Biology at the California
Institute of Technology; and research associate Danielle Beam.
About this neuroscience research news
Author: Press Office
Source: Cedars Sinai
Contact: Press Office – Cedars Sinai
Image: The image is in the public domain
Original Research: Closed access.
“The geometry of domain-general performance monitoring in the human medial frontal cortex” by Zhongzheng Fu et al. Science
