Olfaction: Overview, Fig. 1

Schematic description of olfactory structures. The olfactory sensory neurons (OSN) expressing a common receptor converge onto the common olfactory glomeruli, where they make excitatory synapses with the mitral (Mi), periglomerular (PG) and external tufted (ET) cells. ET, PG, and SA cells interconnect in a local network of interneurons. The high convergence between the OSNs and glomerular cells can increase signal-to-noise ratio in the system (Linster and Cleland 2009). PG cells make inhibitory connections with Mi cell primary dendrites, allowing for contrast enhancement of the olfactory signal before the spike generation mechanism of the Mi cell (Cleland and Sethupathy 2006)