Neural coding of upshifted, downshifted, and blocked outcomes in the rat (lateral) orbitofrontal cortex

There is much debate over what information about outcomes the orbitofrontal cortex encodes in order to support outcome-guided behavior. One model is that the primary job of neurons there is to distill information down to a single common value currency. By another model, orbitofrontal neurons signal more specific information about outcomes. Such information would be relevant to determining value, particularly relative to other similar and dissimilar outcomes, but it is not fundamentally a value signal. Consistent with the latter, we have reported in rats that the orbitofrontal cortex 1) is critical to a number of behaviors that do not require value per se and 2) not critical when value is required. Here we use one such manipulation - blocking and unblocking - to ask directly how this involvement is reflected in neural activity. We use blocking as a control manipulation to isolate what associative information about the outcome is available to enter into an association with a conditioned stimulus, then we unblock learning by manipulating the value or other features of the outcome. We report that orbitofrontal neurons fire to cues that predict changes in outcomes largely without regard to whether those changes alter value or are largely valueless. These results suggest that neurons in rat (lateral) orbitofrontal cortex are at least as interested in signaling outcome features as the are in signaling value in any sort of simple way, and further suggest that value itself may be best conceived as just one of these features.