The Shepherd-Willhite Laboratory

Yale School of Medicine

Department of Neurobiology

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.

3D reconstruction of the olfactory system. The rat brain atlas from Paxinos and Watson [Paxinos, G. & Watson, C. (2004) The Rat Brain in Stereotaxic Coordinates (Elsevier Academic, San Diego)] was used to trace the outlines of the olfactory structures in Reconstruct software. Each "rib" trace (tan) of the brain surface is 480 microns apart. anterior red solid - mitral cell layer; anterior purple trace - glomerular layer; green solid - lateral olfactory tract; purple solid - anterior olfactory cortex (or nucleus); yellow solid - tenia tecta; red solid - olfactory tubercle; blue solid - piriform cortex.