One of the sensory systems important for postural control is the vestibular system, part of the inner ear in the head. The semicircular canal organs are the fluid-filled tubes and associated sensory structures in this system that detect rotational motion. There are three canals on each side of the head, and on each side they are oriented in almost perpendicular planes; this general structure is conserved in all bony vertebrates. It is curious that the canal arcs are apparently never exactly in flat planes, and that they also always are slightly skewed from being mutually perpendicular. It is not yet clear how the detailed fluid dynamics within these curved tiny tubes are encoded into neural responses that signal particular directions of head rotation. This collaborative project uses a combination of electrophysiological recording of neural activity and computerized modeling of the detailed dimensions and physical properties of the fluid flow in the canal of the ears in a well-studied model system with very accessible canals, the toadfish. In a novel approach, the canals are not modeled in isolation, but each canal is modeled in the context of the fluid movement in the adjoining canals. The results will provide fundamental advances in our understanding of these sensory parts of a sophisticated control system for posture and locomotor control. The potential impact will extend beyond simply basic otolaryngology, because it will lead to understanding evolutionary as well as biological considerations of mechanisms for postural function and sensorimotor control.
