Functional architecture of neural circuits for leg proprioception in Drosophila

To effectively control their bodies, animals rely on feedback from proprioceptive mechanosensory neurons. In the Drosophila leg, different proprioceptor subtypes monitor joint position, movement direction, and vibration. Here, we investigate how these diverse sensory signals are integrated by central proprioceptive circuits. We find that signals for leg joint position and directional movement converge in second-order neurons, revealing pathways for local feedback control of leg posture. Distinct populations of second-order neurons integrate tibia vibration signals across pairs of legs, suggesting a role in detecting external substrate vibration. In each pathway, the flow of sensory information is dynamically gated and sculpted by inhibition. Overall, our results reveal parallel pathways for processing of internal and external mechanosensory signals, which we propose mediate feedback control of leg movement and vibration sensing, respectively. The existence of a functional connectivity map also provides a resource for interpreting connectomic reconstruction of neural circuits for leg proprioception.

Automated summary

In this study, different proprioceptor subtypes in the Drosophila leg are found to monitor joint position, movement direction, and vibration, with signals integrated and controlled by central proprioceptive circuits. The flow of sensory information is dynamically modulated by inhibition, revealing mechanisms for leg posture control and vibration sensing. The existence of parallel pathways for processing internal and external mechanosensory signals may play roles in feedback control of leg movement and vibration sensing, respectively, providing insights for interpreting connectomic reconstruction of neural circuits for leg proprioception.