Electrical synapse Electrical synapse An electrical synapse is a mechanical and electrically conductive link between two neighboring neurons that is formed at a narrow gap between the pre- and postsynaptic neurons known as a gap junction. At gap junctions, such cells approach within about 3.8 nm of each other, a much shorter distance than the 20- to 40-nanometer distance that separates cells at chemical synapse. In many animals, electrical synapse-based systems co-exist with chemical synapses. Compared to chemical synapses, electrical synapses conduct nerve impulses faster, but, unlike chemical synapses, they lack gain—the signal in the postsynaptic neuron is the same or smaller
Intrinsically photosensitive retinal ganglion cells able to isomerize "all-trans-"retinal into "11-cis-"retinal when stimulated with light without help from additional cells. The two isoforms of melanopsin differ in their spectral sensitivity, for the "11-cis"-retinal isoform is more responsive to shorter wavelengths of light, while the "all-trans" isoform is more responsive to longer wavelengths of light. ipRGCs are both pre- and postsynaptic to dopaminergic amacrine cells (DA cells) via reciprocal synapses, with ipRGCs sending excitatory signals to the DA cells and the DA cells sending inhibitory signals to the ipRGCs. These inhibitory signals are mediated through GABA which is co-released from the DA cells along with dopamine.