FIGURE 28.

Neuronal value coding incorporates reward cost and delay. A: construction of net utility from reward cost. Concave income utility (top) minus convex cost disutility (middle) results in nonmonotonic net utility (bottom). B: behavioral choice preferences reveal stronger reduction of subjective reward value by high compared with low effort cost (number of lever presses) in rats (income is identical). C: stronger reduction of cue response of single rat nucleus accumbens neuron by high (blue) compared with low (gray) effort cost. [B and C from Day et al. (116). Copyright 2010 John Wiley and Sons.] D: temporal discounting in monkey choice behavior (blue) and corresponding responses of dopamine neurons (red) across reward delays of 2–16 s (hyperbolic fittings; n = 33 neurons). [From Kobayashi and Schultz (285).]