Sensory Signals of Load in Freely Walking Animals

Marshall University Research Corporation, Huntington WV

Investigators

Abstract

Every animal with legs has to generate forces by the legs to support the weight of the body when standing and walking. The effects of such loading are not constant, but vary on individual legs during the step cycle, on uneven terrain, when carrying objects, or when a leg loses its footing. To adapt to changing loads, the nervous system adjusts the contractions of the leg muscles. Receptors that specifically monitor forces in the limbs can potentially provide the central nervous system with detailed data about the direction, magnitude, and rate of change of loads to compensate by appropriate muscular control. This project utilizes electrophysiological recordings from individual receptors in the legs of freely walking insects. These recordings are used to analyze the sensory encoding of force information, including the forces from body weight loading and forces generated by limb muscles, the contribution of sensory receptors to compensatory reactions in walking under various conditions, and the integration of sensory signals of unloading into the timing and patterns of muscular activation during the swing phase of walking motion. Results will help develop a model for understanding how sensory inputs of loading signals are incorporated into the control of posture and locomotion, and will define functional connections of cellular circuits for sensorimotor integration. More broadly, there will be an impact on understanding vertebrate and invertebrate locomotion, on robotic locomotor control and development of 'smart' prostheses, and on opportunities for cross-disciplinary training.