Sub-populations of spinal V3 interneurons form layered microcircuits and play different roles in locomotor control

Coordinated motor control relies on the appropriate recruitment of distinct interneuron populations within the spinal cord. The cardinal class of excitatory V3 spinal interneurons are crucial for generating robust and stable locomotion, yet their molecular heterogeneity, circuit organization, and functional outputs have remained elusive. In our recent studies, we have identified multiple V3 subpopulations that have specific molecular profiles and distinct anatomical and physiological properties. These subpopulations were recruited differently in different locomotor activities. We then further demonstrated that the ventral V3 subpopulations formed layered microcircuits, which could function to ensure flexible yet accurate movements.