Activity Regulates the Incidence of Heteronymous Sensory-Motor Connections

Neuron. 2015 Jul 1;87(1):111-23. doi: 10.1016/j.neuron.2015.05.045. Epub 2015 Jun 18.


The construction of spinal sensory-motor circuits involves the selection of appropriate synaptic partners and the allocation of precise synaptic input densities. Many aspects of spinal sensory-motor selectivity appear to be preserved when peripheral sensory activation is blocked, which has led to a view that sensory-motor circuits are assembled in an activity-independent manner. Yet it remains unclear whether activity-dependent refinement has a role in the establishment of connections between sensory afferents and those motor pools that have synergistic biomechanical functions. We show here that genetically abolishing central sensory-motor neurotransmission leads to a selective enhancement in the number and density of such "heteronymous" connections, whereas other aspects of sensory-motor connectivity are preserved. Spike-timing-dependent synaptic refinement represents one possible mechanism for the changes in connectivity observed after activity blockade. Our findings therefore reveal that sensory activity does have a limited and selective role in the establishment of patterned monosynaptic sensory-motor connections.

Publication types

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

MeSH terms

  • Animals
  • Metalloendopeptidases / pharmacology
  • Mice
  • Motor Neurons / drug effects
  • Motor Neurons / physiology*
  • Muscle, Skeletal / innervation*
  • Muscle, Skeletal / physiology
  • Neuromuscular Blocking Agents / pharmacology
  • Neurons, Afferent / drug effects
  • Neurons, Afferent / physiology*
  • Proprioception / drug effects
  • Proprioception / physiology*
  • Spinal Cord / drug effects
  • Spinal Cord / physiology*
  • Synapses / drug effects
  • Synapses / physiology
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology
  • Tetanus Toxin / pharmacology


  • Neuromuscular Blocking Agents
  • Tetanus Toxin
  • Metalloendopeptidases
  • zinc-endopeptidase, tetanus neurotoxin