Abstract
How do we know the reward value of a given food or fluid? The item must first be consumed and only then can its relative value be computed. Rodents consume fluids by emitting rhythmic trains of licks and reward value is likely encoded by neuronal activity entrained to the lick cycle. Here, we investigated the relationship between licking and reward signaling by the medial frontal cortex (MFC), a key cortical region for reward-guided learning and decision-making. Rats were tested in an incentive contrast procedure, in which they received alternating access to higher and lower value sucrose rewards. Neuronal activity in the MFC encoded the relative value of the ingested fluids, showing stronger entrainment to the lick cycle when animals ingested higher value rewards. The signals developed with experience, encoded the reward context, and depended on neuronal processing within the MFC. These findings suggest that consummatory behavior drives reward signaling in the MFC.
Footnotes
Abbreviated title: Value coding by the medial frontal cortex
Conflict of Interest: None
Financial Support: NSF grant 1121147, NIH grant DK099792-01A1, and the Klarman Family Foundation to ML and a NSF Graduate Research Fellowship to LMA.