Main Connections of the Olfactory System
Odorant molecules bind to receptors on olfactory sensory neurons (OSNs) in the olfactory epithelium (OE), initiating an action potential. OSN populations that express a single receptor type (the segregated information represented as magenta, dark green, or orange cell somas) converge onto glomeruli (GL) in the olfactory bulb (OB). Periglomerular (PG) cells act in a mainly inhibitory manner at the glomerular level. Tufted cells (TC) and mitral cells (MC) innervate single glomeruli and project information to the pyramidal cells (PC) in the olfactory cortex. Granule cells (GC) inhibit MCs and TCs at synapses on their lateral dendrites and cell somas. PCs send centrifugal fibers to the GCs. Small arrows indicate the direction of postsynaptic potential and action potential propagation.