Physiology and Function of Sensory Feedback Loops

Animal locomotion results from the intricate interplay between connections within the nervous system and sense organs that monitor the execution of commands from the central nervous system. For animals that swim by undulating the whole body, sensory receptors detect body bending and transmit that information to the central nervous system, where the 'commanded' and realized movements are compared and compensatory actions are orchestrated. Much is already known about the neuronal wiring diagrams for some behaviors and about relevant sensory structures, but the nature of the connections between the two is largely unknown. The experiments funded by this grant are designed to advance the understanding of interactions between stretch receptors in the body wall, their connections with the central nervous system, and the importance of these interactions in generating an optimal body shape during locomotion.

Experiments are conducted on animal preparations and on isolated central nervous systems with two approaches. One approach is electrophysiological, with the aim of describing stretch-sensitive receptors in greater detail and to map their interactions with neurons in the central nervous system. The other is a 'systems' approach, with experiments designed to test the functional importance of the stretch receptors for swimming movements. Electrophysiological experiments to map neuronal interactions are conducted with standard extracellular and intracellular recording techniques. Systems experiments, employing similar techniques, include tests of whether stretch receptors form oscillatory circuits with the central nervous system and of the nature of intersegmental mechanical interactions. Because there is significant functional similarity between swimming and related locomotory movements in all animals, insights gained from this research will be widely applicable throughout the animal kingdom.