Selective presynaptic inhibition of leg proprioception in behaving Drosophila

Controlling arms and legs requires feedback from the proprioceptive sensory neurons that detect joint position and movement1,2. Proprioceptive feedback must be tuned for different behavioural contexts3–6, but the underlying circuit mechanisms remain poorly understood. Here, using calcium imaging in behaving Drosophila, we find that the axons of position-encoding leg proprioceptors are active across a range of behaviours, whereas the axons of movement-encoding leg proprioceptors are suppressed during walking and grooming. Using connectomics7–9, we identify a specific class of interneurons that provide GABAergic presynaptic inhibition to the axons of movement-encoding proprioceptors. These interneurons receive input from parallel excitatory and inhibitory descending pathways that are positioned to drive the interneurons in a context-specific and leg-specific manner. Calcium imaging from both the interneurons and their descending inputs confirms that their activity is correlated with self-generated but not passive leg movements. Taken together, our findings reveal a neural circuit that suppresses specific proprioceptive feedback signals during self-generated movements. A study in Drosophila has identified a neural circuit that selectively suppress movement-encoding proprioceptors during self-generated movements such as walking and grooming.