Fig. 1: Synaptic and volume transmission.
Schematic comparison of key features of the organization of synaptic (A) and volume (B) transmission. Tight apposition is a hallmark of synapses. Volume transmission lacks this organization and release-receptor distances are often much larger than at synapses. While synaptic transmission is typically mediated by ionotropic receptors, volume transmission usually operates through G protein-coupled receptors (GPCRs). Estimated transmission distances and speeds are indicated at the bottom and discussed in the text.
