Limits...
Economy of the mind.

Powell K - PLoS Biol. (2003)

View Article: PubMed Central - PubMed

Affiliation: kendall2@nasw.org <kendall2@nasw.org>

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These variables, the neuroscientists hypothesized, might lie between environmental stimulus and action and be the link between sensory neurons and motor neurons in the brain. “We know that to make efficient decisions, you have to know the utility of the decision,” says Glimcher. “Economists had beautiful computational models to describe all of these processes” used to calculate utility... Dopamine neurons have long been implicated in reward-seeking behavior and are targets of highly addictive drugs like nicotine and cocaine... Because uncertainty and probability are inherently linked—that is, uncertainty is highest at a probability of 0.50 and lowest at 0 and 1—the researchers could then look for neuronal responses to both variables... What they found were two distinct ways in which the same dopamine neurons code for probability and uncertainty... In other words, this intervening activity was not seen when the probability equaled 0 or 1 and was greatest when the probability of getting a reward was 50/50, the highest level of uncertainty. “To make decisions about rewards or money, a person has to make predictions about the future, and in any prediction there is some uncertainty that is critical,” says Christopher Fiorillo, a neurophysiologist in Schultz' lab who led the study. “This is the first demonstration of a single neuron coding uncertainty. ” Fiorillo says there are probably many other types of neurons in the brain that can code uncertainty, but the fact that dopamine neurons do it adds another intriguing layer to decision-making behavior... After 100 trials, the probabilities were changed. “Basically, he's playing a two-armed slot machine whose payoff rates are constantly switched on him,” says Glimcher. “His behavior looks pretty erratic, but he's getting it about right... But game-theory work has shown that humans rarely think ahead in complex interactions far enough to arrive at the most rewarding decision... Glimcher, by applying the principles of the utility decision theory of maximal gain, has found neurons that may code the variables that go into such a decision... But, others say, since humans do not always act in a way that maximizes their gain, other computational models may give a better answer to how we make decisions in more complex contexts. “The difference is a question of perspective, since we're really all interested in the same issues,” says Joshua Gold, a neuroscientist at University of Pennsylvania in Philadelphia... It is at this point, Gold says, that other factors besides visual cues come into play as the monkey decides how to answer. “By getting the monkey to work in a regime where he's coming close to guessing, then we see much more influence by extraneous factors such as bias [i.e., the monkey's previous experiences] and size of reward,” says Gold... The subsequent experiment, where people played the Ultimatum Game inside a scanner that takes a functional magnetic resonance image (fMRI), showed that blood flow and, by proxy, neuronal activation increased in the frontal brain areas of cooperators... These areas included human homologs of the lateral intraparietal area that Glimcher had seen activated by reward size and probability and the anterior cingulate cortex that Schall found to send success or failure messages (Figure 3)... Camerer sees neuroeconomics as trying to “make a one-to-one mapping from economic theory to the brain... We have a head start, but it's very difficult to produce clear neuroscience that also has economic significance. ” In just a few decades, he envisions that economic theory may look very different, perhaps throwing out utility altogether and instead having a system of mechanisms found in the brain that interact to help a shopper decide, “What's for dinner?” And the knowledge coming out of the fledgling field—how the brain codes motivation and reward value—could be used to increase work output, promote more effective addictive drug rehab programs, and stabilize economies.

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Rewarding the BrainThe ventral midbrain is active when humans receive an unpredictable juice reward. Monetary rewards, although defined by cultural agreement, also engage the same subcortical reward processing structures. (fMRI image courtesy of P. Read Montague.)
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pbio.0000077-g003: Rewarding the BrainThe ventral midbrain is active when humans receive an unpredictable juice reward. Monetary rewards, although defined by cultural agreement, also engage the same subcortical reward processing structures. (fMRI image courtesy of P. Read Montague.)

Mentions: “We wanted to design an imaging experiment to demonstrate that when people reciprocate, brain processing is different than when they are not cooperating,” says McCabe. The subsequent experiment, where people played the Ultimatum Game inside a scanner that takes a functional magnetic resonance image (fMRI), showed that blood flow and, by proxy, neuronal activation increased in the frontal brain areas of cooperators. These areas included human homologs of the lateral intraparietal area that Glimcher had seen activated by reward size and probability and the anterior cingulate cortex that Schall found to send success or failure messages (Figure 3).


Economy of the mind.

Powell K - PLoS Biol. (2003)

Rewarding the BrainThe ventral midbrain is active when humans receive an unpredictable juice reward. Monetary rewards, although defined by cultural agreement, also engage the same subcortical reward processing structures. (fMRI image courtesy of P. Read Montague.)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC300687&req=5

pbio.0000077-g003: Rewarding the BrainThe ventral midbrain is active when humans receive an unpredictable juice reward. Monetary rewards, although defined by cultural agreement, also engage the same subcortical reward processing structures. (fMRI image courtesy of P. Read Montague.)
Mentions: “We wanted to design an imaging experiment to demonstrate that when people reciprocate, brain processing is different than when they are not cooperating,” says McCabe. The subsequent experiment, where people played the Ultimatum Game inside a scanner that takes a functional magnetic resonance image (fMRI), showed that blood flow and, by proxy, neuronal activation increased in the frontal brain areas of cooperators. These areas included human homologs of the lateral intraparietal area that Glimcher had seen activated by reward size and probability and the anterior cingulate cortex that Schall found to send success or failure messages (Figure 3).

View Article: PubMed Central - PubMed

Affiliation: kendall2@nasw.org <kendall2@nasw.org>

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

These variables, the neuroscientists hypothesized, might lie between environmental stimulus and action and be the link between sensory neurons and motor neurons in the brain. “We know that to make efficient decisions, you have to know the utility of the decision,” says Glimcher. “Economists had beautiful computational models to describe all of these processes” used to calculate utility... Dopamine neurons have long been implicated in reward-seeking behavior and are targets of highly addictive drugs like nicotine and cocaine... Because uncertainty and probability are inherently linked—that is, uncertainty is highest at a probability of 0.50 and lowest at 0 and 1—the researchers could then look for neuronal responses to both variables... What they found were two distinct ways in which the same dopamine neurons code for probability and uncertainty... In other words, this intervening activity was not seen when the probability equaled 0 or 1 and was greatest when the probability of getting a reward was 50/50, the highest level of uncertainty. “To make decisions about rewards or money, a person has to make predictions about the future, and in any prediction there is some uncertainty that is critical,” says Christopher Fiorillo, a neurophysiologist in Schultz' lab who led the study. “This is the first demonstration of a single neuron coding uncertainty. ” Fiorillo says there are probably many other types of neurons in the brain that can code uncertainty, but the fact that dopamine neurons do it adds another intriguing layer to decision-making behavior... After 100 trials, the probabilities were changed. “Basically, he's playing a two-armed slot machine whose payoff rates are constantly switched on him,” says Glimcher. “His behavior looks pretty erratic, but he's getting it about right... But game-theory work has shown that humans rarely think ahead in complex interactions far enough to arrive at the most rewarding decision... Glimcher, by applying the principles of the utility decision theory of maximal gain, has found neurons that may code the variables that go into such a decision... But, others say, since humans do not always act in a way that maximizes their gain, other computational models may give a better answer to how we make decisions in more complex contexts. “The difference is a question of perspective, since we're really all interested in the same issues,” says Joshua Gold, a neuroscientist at University of Pennsylvania in Philadelphia... It is at this point, Gold says, that other factors besides visual cues come into play as the monkey decides how to answer. “By getting the monkey to work in a regime where he's coming close to guessing, then we see much more influence by extraneous factors such as bias [i.e., the monkey's previous experiences] and size of reward,” says Gold... The subsequent experiment, where people played the Ultimatum Game inside a scanner that takes a functional magnetic resonance image (fMRI), showed that blood flow and, by proxy, neuronal activation increased in the frontal brain areas of cooperators... These areas included human homologs of the lateral intraparietal area that Glimcher had seen activated by reward size and probability and the anterior cingulate cortex that Schall found to send success or failure messages (Figure 3)... Camerer sees neuroeconomics as trying to “make a one-to-one mapping from economic theory to the brain... We have a head start, but it's very difficult to produce clear neuroscience that also has economic significance. ” In just a few decades, he envisions that economic theory may look very different, perhaps throwing out utility altogether and instead having a system of mechanisms found in the brain that interact to help a shopper decide, “What's for dinner?” And the knowledge coming out of the fledgling field—how the brain codes motivation and reward value—could be used to increase work output, promote more effective addictive drug rehab programs, and stabilize economies.

Show MeSH