THE POWER OF MONEY AND HOW WE USE IT
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THE POWER OF MONEY AND HOW WE USE IT
ATLANTA, October 17, 2006 - Brain mechanisms that govern decision making are linked fundamentally to the ways we learn, according to new reports. And the lure of money is a powerful tool for learning about the way we make decisions, how fear and value affect those decisions, and what goes wrong -- as in cases of drug abuse and anxiety disorders -- when healthy responses to reward and loss go awry.
Using the power of money, researchers are defining answers to intriguing questions about learning and choosing: Is a socially reinforced fear as powerful as a biologically based one? Can brain activity predict our decisions about what to buy? What part of the brain anticipates reward? And do gamblers choose slots over poker due to a biological difference?
"Some of the leading work in this area shows that our sensibilities about money spring forth from our need to make economical choices for survival," says Read Montague, PhD, of Baylor College of Medicine.
"Neuroscience and economics have long been cousin disciplines for the mere fact that organisms run on batteries," Montague says. "Their every move is a choice taken and choices foregone. Consequently, the economic realities of existence forced on organisms the need to value the world around them quickly and accurately. These biological needs left humans with complex and subtle capacities to value the future and judge potential outcomes, and recent work in a new area called neuroeconomics now forms a 'fusion field' where neuroscience realities meet economic theories."
In experiments exploring the role of fear in decision making, researchers found that money can influence conditioning and brain mechanisms associated with fear. Mauricio Delgado, PhD, and colleagues at Rutgers University and New York University compared the impact of biologically based and socially defined negative reinforcement.
"Animal studies have traditionally used rewards, such as food, or punishments, such as electric shock, to modulate learning," says Delgado. "In human culture, however, common reinforcers that influence behavior are usually socially defined."
With that in mind, the Rutgers team had participants play a gambling game in which they were guaranteed to win $59. In two subsequent sessions, they learned to associate one of two colored squares with a mild shock to the wrist and the other with none, and one of another pair of colors with a loss of $6. The scientists measured the participants' stress response throughout.
Paired with functional magnetic resonance imaging, the results showed a similar physiological fear response in anticipation of shock and of losing money. Regions in the striatum, involved in learning about rewards and punishments, were activated in both sessions, while other areas, such as the insula -- involved in intense feelings, including disgust -- were more active during the sessions using shock.
"This suggests that money, a secondary reinforcement that acquires its properties through social and cultural means, can influence the conditioning and underlying mechanisms in the brain that lead to learning about fear, similar to how a biologically based reinforcement would," says Delgado.
New results show clear differences in brain activity underlying simple anticipation as compared to preparation to maximize an anticipated outcome.
In their experiments, Elliot Stein, PhD, and colleagues at the National Institute on Drug Abuse used functional magnetic resonance imaging (fMRI) to examine brain activity in 14 normal, healthy adults while they were performing a certain task. In the task, participants win money by responding as fast as they can to a target symbol that appears on a screen. Before seeing the symbol -- a plus sign -- participants see two other stimuli: a symbol and the word win or lose, telling them whether they are going to win or lose money on the trial, and a figure (a stack of dollar bills, for example) indicating the potential magnitude of the win or loss. On each win, trial participants will get at least $1.00, but will win the amount of money they see in the second stimulus if they are fast enough to respond to the target. On loss trials, they will always lose at least $0.75, but will lose the amount they see in the second stimulus if they are too slow to respond to the target.
The brain response to the first type of stimulus is believed to be associated with the anticipation of losses or gains. The response to the second stimulus is linked to one's preparation to maximize outcomes, i.e., to maximize winning or minimize losing. The researchers found that a number of brain regions, including the caudate, were activated in response to the first stimulus, but not to the second stimulus. In addition, there was a difference in the magnitude of brain activity in the caudate, an area associated with reward processing, in response to win vs. loss stimuli for the first stimulus. Researchers say that this suggests that this area is more responsive to an anticipated gain, compared to an upcoming loss. The results support previous findings using the task.
In experiments aimed at clarifying the neurobiological factors underlying pathological gambling, Arne Møller, MD, and colleagues at the Aarhus University Hospitals in Denmark used PET scans of 20 men given the classic Iowa gambling task. Based on their gambling behavior, the subjects were divided into three groups -- risk seeking, advantageous strategy, and loss averse -- and the scientists measured the extent to which a marker bound to the dopamine receptors in the subjects' brains.
The results, while preliminary, suggest an interaction between gambling behavior and brain response, which is linked to the Sensation Seeking personality trait, they report. The findings may have implications for differentiating subtypes of pathological gamblers based on their gambling behavior and dopamine response. Specifically, high-sensations seeking pathological gamblers may be more likely to seek stimulation from certain types of games, such as poker or blackjack, and certain types of gambling behavior, which may mediate a dopamine-based addiction. Medium- and low-sensation seeking pathological gamblers may be more likely to seek stimulation from other types of games, such as slot machines, which are more punishment or loss averse.
"This is consistent with the notion, that introverts (low-sensation seeking) need relatively less stimulation to reach optimal arousal, while extroverts (high-sensation seeking) need relatively more stimulation to reach this state," says Møller. "We claim that response to gambling in terms of dopamine increase or decrease is a state superimposed on a trait that defines general gambling strategy."