PT  - JOURNAL ARTICLE
AU  - Esther van Duuren
AU  - Geoffrey van der Plasse
AU  - Jan Lankelma
AU  - Ruud N. J. M. A. Joosten
AU  - Matthijs G. P. Feenstra
AU  - Cyriel M. A. Pennartz
TI  - Single-Cell and Population Coding of Expected Reward Probability in the Orbitofrontal Cortex of the Rat
AID  - 10.1523/JNEUROSCI.0005-09.2009
DP  - 2009 Jul 15
TA  - The Journal of Neuroscience
PG  - 8965--8976
VI  - 29
IP  - 28
4099  - http://www.jneurosci.org/content/29/28/8965.short
4100  - http://www.jneurosci.org/content/29/28/8965.full
SO  - J. Neurosci.2009 Jul 15; 29
AB  - The orbitofrontal cortex (OFC) has been implicated in decision-making under uncertainty, but it is unknown how information about the probability or uncertainty of future reward is coded by single orbitofrontal neurons and ensembles. We recorded neuronal ensembles in rat OFC during an olfactory discrimination task in which different odor stimuli predicted different reward probabilities. Single-unit firing patterns correlated to the expected reward probability primarily within an immobile waiting period before reward delivery but also when the rat executed movements toward the reward site. During these pre-reward periods, a subset of OFC neurons was sensitive to differences in probability but only very rarely discriminated on the basis of reward uncertainty. In the reward period, neurons responded during presentation or omission of reward or during both types of outcome. At the population level, neurons were characterized by a wide divergence in firing-rate variability attributable to expected probability. A population analysis using template matching as reconstruction method indicated that OFC generates a distributed representation of reward probability with a weak dependence on neuronal group size. The analysis furthermore confirmed that predictive information coded by OFC populations was quantitatively related to reward probability, but not to uncertainty.