| Glomerulus (olfaction) |
Article Index for Glomerulus |
Information AboutGlomerulus (olfaction) |
The glomerulus (plural '''glomeruli''') in Olfaction is a structure in the Olfactory Bulb . It is made up of a globular tangle of Axon s from the Olfactory Receptor Neuron s in the Olfactory Epithelium and Dendrite s from the Mitral Cell s, Tufted Cell s, and other cell types. Glomeruli are important waystations in the pathway from the Nose to the Olfactory Cortex . Each glomerulus receives input from olfactory receptor neurons expressing only one type of olfactory receptor. There are tens of millions of olfactory receptor cells, but only about two thousand glomeruli. In a remarkable example of convergence, glomeruli receive input from between five thousand and ten thousand olfactory receptor cells but only output onto ten to twenty five mitral cells. By combining so much input, the Olfactory System is able to detect even very faint Odor s. Besides the mitral cell dendrites, the dendrites of other cell types, known collectively as ''juxtaglomerular cells'' also synapse at the glomerulus. These juxtaglomerular cells, which include so-called ''short axon cells'' and ''periglomerular cells'' are mainly GABA -ergic. They may be involved in Feedback or Lateral Inhibition . The glomerulus is the basic unit in the odor map of the olfactory bulb. Each odor activates a different pattern of glomeruli, such that simply by analyzing the different sets of activated glomeruli, one could theorectically decode the identity of the odor. This odor map, however, is modified by the circuitry within the ofactory bulb so that the spiking pattern of the second-order Mitral Cells is likely different from what is observed by looking at glomerular activation (which with most techniques represents mostly pre-synaptic action potentials in Olfactory Sensory Neuron Axons }. |
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