Fig. 3.

Schematics of the known input-output connections of three ipsilaterally projecting inhibitory INs. The three populations project directly to ipsilateral MNs. A: a fraction (~20%) of V1 INs includes Renshaw cells (RC) and reciprocal inhibitory interneurons Ia (Ia INs). Ia INs synapse primarily onto flexor-related MNs. B: a fraction (~20%) of V2b INs includes Ia INs. The interneurons synapse primarily onto extensor-related MNs. Together, V1 and V2b INs account for the entire population of Ia INs and control flexor-extensor alternating locomotor activity. C: GAD65-expressing INs project to ipsilateral MNs, other GABAergic INs, and dorsal spinocerebellar tract (DSCT) neurons.