Design for a binary synapse.
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.
Sterling
Peter
P
Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA.
Smith
Robert G
RG
D000818:Animals; D003624:Darkness; D004307:Dose-Response Relationship, Radiation; D005089:Exocytosis / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D051379:Mice; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D017785:Photons; D012160:Retina / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology
D016244:Guanosine 5'-O-(3-Thiotriphosphate)