Synaptic integration of rhythmogenic neurons in the locomotor circuitry: The case of Hb9 interneurons

Lea Ziskind-Conhaim, George Z. Mentis, Eric P. Wiesner, David J. Titus

Research output: Chapter in Book/Report/Conference proceedingConference contribution

24 Scopus citations


Innovative molecular and genetic techniques have recently led to the identification of genetically defined populations of ipsilaterally projecting excitatory interneurons with probable functions in the rhythm-generating kernel of the central pattern generators (CPGs). The role of interneuronal populations in specific motor function is determined by their synaptic inputs, intrinsic properties, and target neurons. In this review we examine whether Hb9-expressing interneurons (Hb9 INs) fulfill a set of criteria that are the hallmarks of rhythm generators in the locomotor circuitry. Induced locomotor-like activity in this distinct population of ventral interneurons is in phase with bursts of motor activity, raising the possibility that they are part of the locomotor generator. To increase our understanding of the integrative function of Hb9 INs in the locomotor CPG, we investigated the cellular mechanisms underlying their rhythmic activity and examined the properties of synaptic inputs from low-threshold afferents and possible synaptic contacts with segmental motoneurons. Our findings suggest that the rhythmogenic Hb9 INs are integral components of the sensorimotor circuitry that regulate locomotor-like activity in the spinal cord.

Original languageEnglish (US)
Title of host publicationNeurons and Networks in the Spinal Cord
PublisherBlackwell Publishing Inc
Number of pages13
ISBN (Print)9781573317788
StatePublished - Jun 2010
Externally publishedYes

Publication series

NameAnnals of the New York Academy of Sciences
ISSN (Print)0077-8923
ISSN (Electronic)1749-6632


  • Hb9 interneurons
  • Hb9::eGFP transgenic mouse
  • locomotor central pattern generator
  • locomotor-like rhythms
  • rhythm-generating kernel
  • rhythmogenic interneurons


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