Research at the Center

Decisions under Uncertainty

“The distinction between neural mechanisms subserving different forms of uncertainty resolution provides an important constraint for neuroeconomic models of decision making.”

Read the JNeurosci paper (PDF)

Many decisions are made under uncertainty; that is, with limited information about their potential consequences. Uncertainty may be a static function of the decision stimuli, as when we know that a gamble carries some specific risk. Or, it may wax and wane as new information is accumulated. Previous neuroimaging studies of decision making have implicated regions of the medial frontal lobe in processes related to the resolution of uncertainty. However, a different set of regions in dorsal prefrontal and posterior parietal cortices has been reported to be critical for selection of actions to unexpected or unpredicted stimuli within a sequence. This second set of regions might be important as novel or predictable information is accumulated to reduce uncertainty.

To understand the neural basis of uncertainty, we used a novel task that required subjects to make decisions based upon a sequence of eight stimuli, in which uncertainty changed dynamically over time (from 20% to 50%) depending upon the stimuli presented. Activation within prefrontal, parietal, and insular cortices increased with increasing uncertainty. In contrast, within medial frontal regions, as well as motor and visual cortices, activation did not increase with increasing uncertainty. We conclude that the brain response to uncertainty depends upon the demands of the experimental task. When uncertainty depends on learned associations between stimuli and responses, as in previous studies, it modulates activation in the medial frontal lobes. But, when uncertainty develops over short time scales as information is accumulated toward a decision, dorsal prefrontal and posterior parietal contributions are critical for its resolution. The distinction between neural mechanisms subserving different forms of uncertainty resolution provides an important constraint for neuroeconomic models of decision making.