Proprioceptive Detection of Joint Limits and Its Role in Limb Sensorimotor Control

Project Summary Many animals have specialized proprioceptors that fire when a limb reaches the limit of its range. In mammals, including humans, the extremes of joint position are detected by low-threshold Ruffini endings and Pacinian corpuscles embedded within joint capsules. Like other proprioceptors, joint receptors are distributed throughout the body, which has made it challenging to understand if and how they are specialized for sensing and controlling specific movements. This project will leverage tools only available in the fruit fly, Drosophila, to provide new insight into basic neural mechanisms of limb sensorimotor control by specialized proprioceptive organs called hair plates. Hair plates are tightly- packed arrays of sensory hairs positioned close to joints in the insect cuticle. Our preliminary data suggests that hair plate proprioceptors fire at the limits of the joint range, in a manner analogous to mammalian joint receptors. In this project, we will combine experimental and computational approaches to test the hypothesis that hair plates function as proprioceptive limit detectors to stabilize limb posture and guide movement. A deeper understanding of proprioceptive limit detection and its contributions to motor control has the potential to transform the way in which we understand and treat sensorimotor disorders.