Editors' ChoiceNeurobiology

Neurons that Code for Uncertainty

Science's STKE  25 Mar 2003:
Vol. 2003, Issue 175, pp. tw123-TW123
DOI: 10.1126/stke.2003.175.tw123

In the classic Pavlovian experiment, dogs associate the ringing of a bell with subsequent presentation of food. It has since been shown that dopaminergic neurons in the ventral midbrain respond (by spiking) to stimuli that predict the subsequent arrival of rewards. In trials where the reward does not appear, there is a corresponding drop in the activity of these neurons. These findings led to the proposal that the information encoded by these neurons is the prediction error, or the difference between actual and predicted rewards. Fiorillo et al. (see the Perspective by Shizgal and Arvanitogiannis) now find a new population of dopaminergic neurons that appear to encode reward uncertainty; the activity of these neurons increases as the delivery of reward becomes less certain.

C. D. Fiorillo, P. N. Tobler, W. Schultz, Discrete coding of reward probability and uncertainty by dopamine neurons. Science 299, 1898-1902 (2003). [Abstract] [Full Text]

P. Shizgal, A. Arvanitogiannis, Gambling on dopamine. Science 299, 1856-1858 (2003). [Summary] [Full Text]