It helps people refrain from actions good and bad, experts say
THURSDAY, Aug. 23 (HealthDay News) -- If you've ever been of "two minds" about doing something, a new study may explain why.
Scientists say one part of the brain is responsible for initiating action, while a totally separate area is in charge of not taking that action.
This newly identified region, involved in an aspect of self-control, may change conceptions of human free will, the researchers said. It could also explain the basis of impulsive as well as reluctant behavior, they added.
"The central issue is quite simple. If we want to do something, and we decide not to, how does that brain wire that?" said Rajesh Miranda, associate professor of neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine. "They showed the region in the brain that can act as a gate to suppress a plan to do something," said Miranda, who was not involved in the research.
"The big search in neuroscience is, are there general inhibiting or specific inhibiting circuits?" added another outside expert, Dr. John Hart, a spokesman for the American Academy of Neurology and a behavioral neurologist and cognitive neuroscientist at the University of Texas at Dallas. "This is another piece of the puzzle. . . . but does it generalize beyond that task to all life decisions? That has yet to be shown," he said.
This study and others like it are really in their infancy, Miranda pointed out. That's important to remember, since the findings could one day have legal and other implications.
"This kind of data could have implications for legal definitions of 'diminished capacity,' " he explained. "There's a potential for informing legal definitions of mental illness and things like that."
The study, which was published in the Aug. 22 issue of The Journal of Neuroscience, was conducted by researchers from University College London, in the United Kingdom, the Max Planck Institute in Leipzig, Germany, and Ghent University, Belgium.
Using functional magnetic resonance imaging (fMRI), the researchers studied the brain activity of participants in two situations -- when they acted out as they had planned, or when they decided not to follow their original intention.
Fifteen right-handed individuals (seven males and eight females, average age 26) participated in a "go-no-go" exercise. They were asked to press a button on a keyboard but first to indicate what time they were going to perform this action. They were also asked to choose instances in which they stopped before actually pressing the button.
When participants decided not to press the button, a specific area of the frontal lobe region of the brain lit up. When participants followed through, however, the area did not light up.
The executive-function frontal lobes, which have previously been identified with inhibition, are part of what makes humans human, neurologists say.
"These areas are the most expanded in humans as compared to animals," explained Dr. Kimford Meador, spokesman for the American Academy of Neurology and professor of neurology at the University of Florida, Gainesville. "The frontal lobe is important for initiation, for planning, personality, creativity."
"The frontal lobes distinguish us from lower-order creatures," added David Masur, director of neuropsychology in the department of neurology at Montefiore Medical Center and clinical professor of neurology at Albert Einstein College of Medicine, both in New York City. "We have larger frontal lobes, and these are what really are responsible for much of what we define as human behavior, social interaction, ability to plan, organize, some language ability, abstract reasoning or thinking."
For now, the implications of the research are esoteric but, down the line, who knows?
"Much of our society is based on the concept of not only free will but also 'free won't,' the inhibition of response," Masur explained. "The difference between us as intelligent ordered social creatures and the society that would run amok is the ability to inhibit our responses, the ability to take control if a situation calls for it, to stop acting in a particular way . . . Maybe down the line somebody can develop a drug or hormone or transmitter system that targets that particular area of brain which strengthens the ability to negate responses which are too impulsive."
"It's a fascinating mind-brain question about where does our free will begin and end," added Meador.
There's more on how the brain is structured at Brainexplorer.org.
SOURCES: Kimford Meador, M.D., professor, neurology, University of Florida, Gainesville, and spokesman, American Academy of Neurology; Rajesh Miranda, Ph.D., associate professor, neuroscience and experimental therapeutics, Texas A&M Health Science Center College of Medicine; David Masur, Ph.D., director, neuropsychology, department of neurology, Montefiore Medical Center and clinical professor of neurology, Albert Einstein College of Medicine, New York City; John Hart, M.D., behavioral neurologist and cognitive neuroscientist, University of Texas at Dallas, and spokesman, American Academy of Neurology; Aug. 22, 2007, The Journal of Neuroscience
All rights reserved