Dino Levy Ph.D.
Head of Department of
Neuroeconomics & Neuromarketing
Coller School of Management
Tel Aviv University
“The neural correlates of value representations and economic inconsistency”
It is well established that the ventromedial prefrontal cortex (vmPFC) represents value using a common currency across categories of rewards. First, I will present a study in which we examined how common are the neural value representations in the vmPFC. That is, we examined if the vmPFC represents value irrespective of the sensory modality in which alternatives are presented. On each trial, subjects chose between a safe alternative and a lottery, which was presented visually or aurally while inside the fMRI scanner. We found that the anterior portion of the vmPFC tracks subjective value irrespective of the sensory modality, strengthening the notion that the vmPFC encodes value on a common scale. In addition, we found that the visual and auditory sensory cortices, are also sensitive to the value of stimuli, albeit in a modality-specific manner. This demonstrates that there are value representations in sensory areas. Second, I will present a study, in which we examined the neural correlates of economic inconsistency using fMRI. Consistency in choices (rationality) is a prerequisite for any normative economic choice theory, but its neural origins are unknown. Revealed preference theory provides analytic tools to test the inconsistency level of a decision maker. However, all current inconsistency indices measure an aggregate-level of inconsistency, which prevent a thorough examination of its neural correlates. Therefore, we developed a novel index that measures a trial-level inconsistency score. We then use the trial-level index to measure the severity of each choice inconsistency, and directly trace its neural correlates. We found that activity in the vmPFC and dACC correlated with the trial-specific index. Importantly, these same regions represented subjective value. These findings suggest that deviation from rational choice occurs in the same regions responsible for value representation. Lastly, I will discuss possible mechanisms that could account for these findings.