The Ingestive Response Reflects Neural Dynamics in Gustatory Cortex

Upon delivery of a taste onto the tongue, the neural gustatory circuit must decide whether to ingest or reject the stimulus. While there has been much work in rodents investigating the neural activity leading to the rejection decision and its associated orofacial movements, characterization of behaviors related to ingestion have received much sparser attention. To address this, here we simultaneously measured electromyographic (EMG) activity of the jaw opener muscle and single-neuron activity from gustatory cortex (GC) so that we could characterize ingestion-related behaviors and their association with neural dynamics. We developed a machine-learning classifier to accurately identify distinct orofacial movements from EMG signals, thereby revealing multiple novel subtypes of ingestion-related behaviors. The frequency of occurrence of each shifts significantly around the time of the consumption decision, a change in behavior that is tightly coupled with the transition in GC's neural firing patterns into the state reflecting the tastant's palatability. These findings demonstrate a direct link between neural dynamics in GC and the orchestration of the physical movements that define ingestive behavior, highlighting GC's general role not just in taste perception and decision making, but also in the control of motor actions.