Comparing Apples and Oranges: Using Reward-Specific and Reward-General Subjective Value Representation in the Brain

Abstract

The ability of human subjects to choose between disparate kinds of rewards suggests that the neural circuits for valuing different reward types must converge. Economic theory suggests that these convergence points represent the subjective values (SVs) of different reward types on a common scale for comparison. To examine these hypotheses and to map the neural circuits for reward valuation we had food and water-deprived subjects make risky choices for money, food, and water both in and out of a brain scanner. We found that risk preferences across reward types were highly correlated; the level of risk aversion an individual showed when choosing among monetary lotteries predicted their risk aversion toward food and water. We also found that partially distinct neural networks represent the SVs of monetary and food rewards and that these distinct networks showed specific convergence points. The hypothalamic region mainly represented the SV for food, and the posterior cingulate cortex mainly represented the SV for money. In both the ventromedial prefrontal cortex (vmPFC) and striatum there was a common area representing the SV of both reward types, but only the vmPFC significantly represented the SVs of money and food on a common scale appropriate for choice in our data set. A correlation analysis demonstrated interactions across money and food valuation areas and the common areas in the vmPFC and striatum. This may suggest that partially distinct valuation networks for different reward types converge on a unified valuation network, which enables a direct comparison between different reward types and hence guides valuation and choice.

Connectivity reveals relationship of brain areas for reward-guided learning and decision making in human and monkey frontal cortex

“…However, there is also evidence the vmPFC tracks values of items even in the absence of any decision or when watching somebody else choosing (24,25). Some studies have suggested that these value representations are independent of reward type (money, food) (26) and reflect the impact of other Fig. 1.…”

Extending the Study of Decision Values to Cases Where Options Are Presented Using Different Sensory Modalities

“…As Levy and Glimcher (2011) point out, this demonstrates a spatial overlap, but it does not follow that the neural decision value signal for different reward types is also on the same scale. The method of using mixed-type trials to estimate exchange rates (scaling factors) across different reward types allows the authors to test this common scale property.…”

“…Regions in which activity correlates with all reward types are deemed candidates for common currency calculation. Levy and Glimcher (2011) proceeded in a similar fashion. Participants were exposed to choice situations in which they were asked to choose between options from three different reward types: water, food, and money.…”

“…While previous work has shown that decision values for several different reward types are encoded in spatially overlapping brain regions (Chib et al, 2009), this by itself did not permit the conclusion that they are also encoded on the same scale, which is essential to the concept of common cur-rency. This gap is filled by the work of Levy and Glimcher (2011).…”

Altered reward anticipation: Potential explanation for weight gain in schizophrenia?

“…Recent meta-analyses indicate that, for a broad range of stimuli (monetary, erotic and food rewards), the ventral striatum is engaged in reward anticipation (Bartra et al, 2013;Sescousse et al, 2013). Even within individuals the striatum, as well as ventromedial prefrontal cortex, encode the value of various types of reward, for example, money and food, although reward-type-specific representations arise in other regions (Howard et al, 2015;Levy and Glimcher, 2011). However, in paradigms using primary rewards, food is typically not given directly.…”