Regeneration of a central synapse restores nonassociative learning

Barbara K. Modney, Christie L. Sahley, Kenneth J. Muller

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Sensitization is a form of nonassociative learning in which a strong or noxious stimulus persistently enhances the response produced by a weaker stimulus. In the leech Hirudo medicinalis, the S-interneuron is required for sensitization of the shortening response. A single S-cell axon was surgically separated from its sole synaptic partner, the neighboring S-cell. This consistently eliminated sensitization without impairing reflexive shortening itself, as measured in semi-intact specimens. Sensitization of the shortening reflex returned after 3 weeks when the severed axon grew and regenerated its specific electrical synapse within the nerve cord, as shown by restored conduction of impulses between S-cells. This confirms the essential role of one neuron, the S-cell, in sensitization, and it demonstrates that regeneration of the synapse between S-cells restores this example of nonassociative learning.

Original languageEnglish (US)
Pages (from-to)6478-6482
Number of pages5
JournalJournal of Neuroscience
Issue number16
StatePublished - Aug 15 1997


  • Axotomy
  • Hirudo medicinalis
  • Invertebrate learning
  • Leech
  • Nerve repair
  • Nonassociative conditioning
  • Plasticity
  • Regeneration
  • S-cell
  • Synapse regeneration

ASJC Scopus subject areas

  • Neuroscience(all)


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