Phasic dopamine signals: from subjective reward value to formal economic utility

- Dopamine neurons code subjective value of different rewards according to behavioral choices.
- Dopamine neuronal and voltammetry responses follow individual risk preferences.
- Dopamine neuronal and voltammetry responses follow temporal reward discounting.
- Dopamine voltammetry responses are sensitive to effort cost.
- Dopamine neuronal responses code formal economic utility.

Although rewards are physical stimuli and objects, their value for survival and reproduction is subjective. The phasic, neurophysiological and voltammetric dopamine reward prediction error response signals subjective reward value. The signal incorporates crucial reward aspects such as amount, probability, type, risk, delay and effort. Differences of dopamine release dynamics with temporal delay and effort in rodents may derive from methodological issues and require further study. Recent designs using concepts and behavioral tools from experimental economics allow to formally characterize the subjective value signal as economic utility and thus to establish a neuronal value function. With these properties, the dopamine response constitutes a utility prediction error signal.