Even-Skipped(+) Interneurons Are Core Components of a Sensorimotor Circuit that Maintains Left-Right Symmetric Muscle Contraction Amplitude

Neuron. 2015 Oct 21;88(2):314-29. doi: 10.1016/j.neuron.2015.09.009. Epub 2015 Oct 1.

Abstract

Bilaterally symmetric motor patterns--those in which left-right pairs of muscles contract synchronously and with equal amplitude (such as breathing, smiling, whisking, and locomotion)--are widespread throughout the animal kingdom. Yet, surprisingly little is known about the underlying neural circuits. We performed a thermogenetic screen to identify neurons required for bilaterally symmetric locomotion in Drosophila larvae and identified the evolutionarily conserved Even-skipped(+) interneurons (Eve/Evx). Activation or ablation of Eve(+) interneurons disrupted bilaterally symmetric muscle contraction amplitude, without affecting the timing of motor output. Eve(+) interneurons are not rhythmically active and thus function independently of the locomotor CPG. GCaMP6 calcium imaging of Eve(+) interneurons in freely moving larvae showed left-right asymmetric activation that correlated with larval behavior. TEM reconstruction of Eve(+) interneuron inputs and outputs showed that the Eve(+) interneurons are at the core of a sensorimotor circuit capable of detecting and modifying body wall muscle contraction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Drosophila Proteins / physiology*
  • Functional Laterality / physiology*
  • Homeodomain Proteins / physiology*
  • Interneurons / chemistry
  • Interneurons / physiology*
  • Muscle Contraction / physiology*
  • Nerve Net / chemistry
  • Nerve Net / physiology*
  • Psychomotor Performance / physiology*
  • Transcription Factors / physiology*

Substances

  • Drosophila Proteins
  • GAL4 protein, Drosophila
  • Homeodomain Proteins
  • Transcription Factors
  • eve protein, Drosophila