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Neuron. 2014 Apr 2;82(1):138-50. doi: 10.1016/j.neuron.2014.02.013.

V1 and v2b interneurons secure the alternating flexor-extensor motor activity mice require for limbed locomotion.

Author information

1
Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
2
Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires 1405, Argentina.
3
Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, MA 02111, USA.
4
Department of Neurosciences, Cell Biology, and Physiology, Wright State University, Dayton, OH 45435, USA.
5
Department of Neurosciences, Cell Biology, and Physiology, Wright State University, Dayton, OH 45435, USA; Department of Physiology, Emory University, Atlanta, GA 30322, USA.
6
Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA. Electronic address: goulding@salk.edu.

Abstract

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.

PMID:
24698273
PMCID:
PMC4096991
DOI:
10.1016/j.neuron.2014.02.013
[Indexed for MEDLINE]
Free PMC Article

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