May 24, 2001 Scientists at Massachusetts General Hospital (MGH) and two other institutions have found that discrete parts of the human brain respond in an ordered fashion to the anticipation and reward of money. The study, published in this week’s Neuron, demonstrates the first linkage of human brain events to ideas from behavioral economics. The research reveals that monetary rewards tap into a generalized system in the human brain that also processes other categories of reward such as drugs and food.
“This work argues that we can begin to dissect the systems that process reward and organize behavior in humans,” says lead author Hans Breiter, MD, co-director of the Motivation and Emotion Neuroscience Center in the Department of Radiology at MGH. “This is also the first demonstration that a monetary reward in a gambling-like experiment produces brain activation very similar to that observed in a cocaine addict receiving an infusion of cocaine.” In other words, he says the results may give credence to the theory that gambling behavior may be similar to drug addiction.
The study was conducted by MGH scientists in collaboration with colleagues Peter Shizgal, PhD, director of the Center for Studies in Behavioral Neurobiology at Concordia University in Montreal, and Daniel Kahneman, PhD, professor of Psychology at Princeton University. Their work incorporates a concept developed by Kahneman and colleagues in the late 1970s called “prospect theory.” This theory, which is based upon the notion that certain biases influence people’s choices, has profoundly influenced the field of behavioral economics.
Breiter and his colleagues have demonstrated that multiple areas of the brain are involved in assessing the potential of receiving a gain or loss. Many of these same regions also respond when the individual wins or loses money.
The researchers measured their findings from the brains of volunteers who participated in a game of chance. Brain activity was monitored through a neuroimaging process called high-field functional magnetic resonance imaging (fMRI). The volunteers were given $50 and were told that during the game, they might lose some or all of it, retain it, or increase it. Each subject was shown a sequence of spinners that were divided into three sectors – each with a different monetary value. These spinners included good spinners ($10, $2.50, $0), intermediate spinners ($2.50, $0, -$1.50), or bad spinners ($0, -$1.50, -$6).
Subjects watched an arrow spin on each spinner for six seconds, and then stop on one of the sectors to deliver a gain or loss. Under this scenario, the scientists measured brain signals during the anticipation state (before the spinner stopped) and during the outcome phase (after the spinner stopped).
The brain images recorded by fMRI displayed distinct patterns. Subjects demonstrated high, medium and low signals from some brain regions that mirrored the observation of the good, intermediate and bad spinners. “The results showed that an incentive unique to humans – money – produced patterns of brain activity that closely resembled patterns seen previously in response to other types of rewards. This similarity suggests that common brain circuitry is used for various types of rewards,” notes Breiter. One implication of this study is that scientists may be able use brain scans in the future to measure what people like and don’t like.
Further research to determine the roles played by the different components of this brain circuitry may help scientists understand the development of impulse disorders such as drug abuse and compulsive gambling.
Funding for the study was provided by the National Institute of Drug Abuse, the Office of National Drug Control Policy, the Canadian Institutes of Health Research, the National Science Foundation, the National Center for Responsible Gaming, the National Foundation for Functional Brain Imaging, the National Institute of Health, and the Human Brain Project.
The Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $300 million and major research centers in AIDS, the neurosciences, cardiovascular research, cancer, cutaneous biology, transplantation biology and photo-medicine. In 1994, the MGH joined with Brigham and Women’s Hospital to form Partners HealthCare System, an integrated health care delivery system comprising the two academic medical centers, specialty and community hospitals, a network of physician groups and nonacute and home health services.
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