Top-down and bottom-up signals for flexible orofacial behaviors

Abstract Project 5: Top-down and bottom-up signals for flexible orofacial behaviors (O’Connor as lead) Orofacial behaviors involve sequences of individual motor actions — such as chewing, licking, swallowing, breathing, and so forth — that must be tightly coordinated given the essential function they play in sustaining life and the dire consequences of errors in coordination such as choking or aspirating foodstuffs. In mammals, orofacial behaviors are also highly flexible and can be altered in real-time based on sensory feedback and behavioral context, for instance during vocal social communication, biting, and sniffing. How the brain satisfies the competing demands of tight coordination and high flexibility remains an important unresolved problem. Its solution will require a quantitative understanding of how high-level cortical circuits interact with the mid- and low- level hindbrain circuits that mediate orofacial behavior, and how high-level signals for planning and control interact with low-level sensory feedback signals. The goals of Project 5 are: (1) to develop a set of licking-based behavioral tasks for mice that have varying sensorimotor requirements; (2) to quantify descending task-related signals that populations of neurons in orofacial areas of the cortex send to mid- and hindbrain circuits that control orofacial behaviors; and (3) quantify ascending feedback signals that may impact high-level control. Project 5 will provide crucial insight into the dynamics of the circuits for descending control that are studied anatomically in Project 4 and provide constraints on the models developed in Projects 1 and 2. Results will also establish functional roles of the descending inputs to the brainstem oscillators studied in Project 3 and the integrative midbrain hubs studied in Project 1.