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Published February 2007 | public
Journal Article

Reward Value Coding Distinct From Risk Attitude-Related Uncertainty Coding in Human Reward Systems


When deciding between different options, individuals are guided by the expected (mean) value of the different outcomes and by the associated degrees of uncertainty. We used functional magnetic resonance imaging to identify brain activations coding the key decision parameters of expected value (magnitude and probability) separately from uncertainty (statistical variance) of monetary rewards. Participants discriminated behaviorally between stimuli associated with different expected values and uncertainty. Stimuli associated with higher expected values elicited monotonically increasing activations in distinct regions of the striatum, irrespective of different combinations of magnitude and probability. Stimuli associated with higher uncertainty (variance) elicited increasing activations in the lateral orbitofrontal cortex. Uncertainty-related activations covaried with individual risk aversion in lateral orbitofrontal regions and risk-seeking in more medial areas. Furthermore, activations in expected value-coding regions in prefrontal cortex covaried differentially with uncertainty depending on risk attitudes of individual participants, suggesting that separate prefrontal regions are involved in risk aversion and seeking. These data demonstrate the distinct coding in key reward structures of the two basic and crucial decision parameters, expected value, and uncertainty.

Additional Information

© 2007 The American Physiological Society. Received 19 July 2006; Accepted 19 November 2006; Published online 1 February 2007; Published in print 1 February 2007. This study was supported by the Wellcome Trust, the Swiss National Science Foundation and the Roche Research Foundation. R. J. Dolan and W. Schultz are supported by Wellcome Trust Programme Grants, W. Schultz by a Wellcome Trust Principal Research Fellowship. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. We thank P. Bossaerts, Y. Christopoulos, L. Gregorios-Pippas, R. Henson, and K. Miyapuram for discussions and/or comments.

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