Optogenetic analysis of synaptic function

Nat Methods. 2008 Oct;5(10):895-902. doi: 10.1038/nmeth.1252. Epub 2008 Sep 14.


We introduce optogenetic investigation of neurotransmission (OptIoN) for time-resolved and quantitative assessment of synaptic function via behavioral and electrophysiological analyses. We photo-triggered release of acetylcholine or gamma-aminobutyric acid at Caenorhabditis elegans neuromuscular junctions using targeted expression of Chlamydomonas reinhardtii Channelrhodopsin-2. In intact Channelrhodopsin-2 transgenic worms, photostimulation instantly induced body elongation (for gamma-aminobutyric acid) or contraction (for acetylcholine), which we analyzed acutely, or during sustained activation with automated image analysis, to assess synaptic efficacy. In dissected worms, photostimulation evoked neurotransmitter-specific postsynaptic currents that could be triggered repeatedly and at various frequencies. Light-evoked behaviors and postsynaptic currents were significantly (P <or= 0.05) altered in mutants with pre- or postsynaptic defects, although the behavioral phenotypes did not unambiguously report on synaptic function in all cases tested. OptIoN facilitates the analysis of neurotransmission with high temporal precision, in a neurotransmitter-selective manner, possibly allowing future investigation of synaptic plasticity in C. elegans.

Publication types

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

MeSH terms

  • Acetylcholine / physiology
  • Animals
  • Animals, Genetically Modified
  • Caenorhabditis elegans / physiology
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology
  • Light*
  • Motor Neurons / physiology
  • Muscle Contraction
  • Muscle Relaxation
  • Synapses / physiology*
  • Synaptic Transmission
  • gamma-Aminobutyric Acid / physiology


  • Carrier Proteins
  • channelopsin-2, Chlamydomonas reinhardtii
  • gamma-Aminobutyric Acid
  • Acetylcholine