Executive control signals in orbitofrontal cortex during response inhibition

Abstract

Orbitofrontal cortex (OFC) lesions produce deficits in response inhibition and imaging studies suggest that activity in OFC isstronger on trials that require suppressionofbehavior, yet few studies have examined neural correlatesatthe single-unit levelinabehavioral task that probes response inhibition without varying other factors, suchas anticipated outcomes. Here we recorded from single neurons inlateral OFC in a task that required animals in the minority of trials to STOP or inhibit an ongoing movement and respond in the opposite direction.Wefound that populationandsingle-unit firing was modulated primarilybyresponsedirection and movementspeed, and that very few OFC neurons exhibited a response independent inhibition signal. Remarkably, the strength of the directional signal was not diminished on STOP trials and was actually strongeronSTOP trials during conflict adaptation. Finally, directional signals were stronger during sessions in which rats had the most difficulty inhibiting behavior. These results suggest that “inhibition” deficits observed with OFC interference studies reflect deficits unrelatedtosignaling the needtoinhibit behavior, but instead supporta role for OFCinexecutive functions related to dissociating between two perceptually similar actions during response conflict.