Design for a binary synapse

Neuron. 2004 Feb 5;41(3):313-5. doi: 10.1016/s0896-6273(04)00044-3.


The mammalian rod transfers a binary signal, the capture of 0 or 1 photon. In this issue of Neuron, Sampath and Rieke show in mouse that the rod's tonic exocytosis in darkness completely saturates a G protein cascade to close nearly all postsynaptic channels. A full-sized photon event supresses exocytosis sufficiently to allow approximately 30 postsynaptic channels to open simultaneously. Thus, the synapse behaves like a digital gate, whose hallmark is reliability and resistance to noise.

Publication types

  • Comment

MeSH terms

  • Animals
  • Darkness
  • Dose-Response Relationship, Radiation
  • Exocytosis / physiology
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Humans
  • Mice
  • Models, Neurological
  • Neurons / physiology
  • Photons
  • Retina / physiology
  • Retinal Rod Photoreceptor Cells / physiology*
  • Synapses / physiology*
  • Synaptic Transmission / physiology*
  • Vision, Ocular / physiology


  • Guanosine 5'-O-(3-Thiotriphosphate)