Neuron
Volume 82, Issue 1, 2 April 2014, Pages 138-150
Journal home page for Neuron

Article
V1 and V2b Interneurons Secure the Alternating Flexor-Extensor Motor Activity Mice Require for Limbed Locomotion

https://doi.org/10.1016/j.neuron.2014.02.013Get rights and content
Under an Elsevier user license
open archive

Highlights

  • Functional identification of the neurons controlling flexor-extensor CPG activity

  • V1 and V2b neurons cooperatively control reciprocal flexor-extensor motor behaviors

  • Ia inhibitory INs are derived from two genetic sources: V1 and V2b interneurons

  • Evolutionary conservation of the neurons used to control flexor-extensor alternation

Summary

Reciprocal activation of flexor and extensor muscles constitutes the fundamental mechanism that tetrapod vertebrates use for locomotion and limb-driven reflex behaviors. This aspect of motor coordination is controlled by inhibitory neurons in the spinal cord; however, the identity of the spinal interneurons that serve this function is not known. Here, we show that the production of an alternating flexor-extensor motor rhythm depends on the composite activities of two classes of ventrally located inhibitory neurons, V1 and V2b interneurons (INs). Abrogating V1 and V2b IN-derived neurotransmission in the isolated spinal cord results in a synchronous pattern of L2 flexor-related and L5 extensor-related locomotor activity. Mice lacking V1 and V2b inhibition are unable to articulate their limb joints and display marked deficits in limb-driven reflex movements. Taken together, these findings identify V1- and V2b-derived neurons as the core interneuronal components of the limb central pattern generator (CPG) that coordinate flexor-extensor motor activity.

Cited by (0)

6

Co-first author

7

Present address: Department of Anatomy and Neurobiology, Dalhousie University, Halifax, NS B3H 4R2, Canada