BEHAVIORAL PERTURBATIONS OF TUNING DYNAMICS IN RAT ORBITOFRONTAL CORTEX

Environmental and internal information must be processed into a form that is relevant for decision-making. Single neurons in the orbitofrontal cortex (OFC) encode and combine that information to compute expected value. However, it is unclear whether their encoding is stable across time (days) and contexts (behavioral tasks). To evaluate the stability, we used chronic Neuropixels implants to record from OFC neurons over consecutive sessions. In each session, the rat performed one of two tasks investigating distinct notions of value in decision-making, reward amount and temporal uncertainty. In both decision tasks, rats discriminated the number of clicks in binaural click streams and received a water reward for correct choices (left or right). In the first task, reward sizes were varied in blocks of trials to probe the integration of sensory and spatial value information. In the second task, reward delays were varied, such that rats invested time to collect rewards, providing a behavioral report of temporal value. Neuronal firing-rate dynamics during both decision tasks were mostly peaked and tiled the trial duration. Additionally, the firing-rate amplitudes covaried with task variables defined by a parsimonious model reproducing key aspects of the decision-making behavior. We tracked identical single units across behavioral sessions and found that, for the common part of the tasks, neurons maintained their dynamical profile and encoding. For the task-specific epochs, neurons roughly maintained the peak timing, but the shape of their dynamics and the encoded information reflected the changing value computation, giving insight into the OFC algorithm underlying value-based decision-making.