Identification of interneurons that secure flexor-extensor alternation in the spinal cord

ZHANG, J.; GUILLERMO MARCOS LANUZA; WAN, Z.; ZHANG, Y.; VELASQUEZ, T.; FRANK, T.; GOULDING, M.

San Diego, CA, USA

Congreso; Annual Meeting Society for Neuroscience; 2010

Society for Neuroscience

Locomotion in terrestrial vertebrates is critically dependent on the reciprocating actions of flexor and extensor muscles around each limb joint. While efforts to genetically dissect the locomotor central pattern generator (CPG) in mice have identified interneuron cell types that regulate key aspects of the walking gait, the provenance of the interneurons that control the alternating limb flexor-extensor motor activity needed to articulate the limbs has remained elusive. We have identified and have begun to characterize a population of ventral inhibitory interneurons that contribute to securing alternating flexor-extensor activity in the hindlimb CPG. These interneurons cooperate with V1 interneurons to establish a reciprocating pattern of flexor and extensor motor activity and are necessary for limb movements. Current efforts are aimed at defining the cellular properties inputs and connectivity of these two classes of ventral interneuron. Our results identify the major components of the CPG network that secure flexor-extensor alternation, and they suggest a model for how the swimming CPG was modified during evolution to allow flexion-extension movements.