Intro | Olfactory Nerve Axons | Olfactory Bulb | Olfactory Cilia | Olfactory Nerve
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
Each Olfactory Bulb is located on either side of the nasal passage at the base of the brain. They lie on a perforated, thin layer of bone that separates the nasal cavity from the brain. Impulses carried away from the olfactory cilia synapse in the bulbs before traveling to the cortex for processing.
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The synaptic connection between the receptor and mitral cells within the olfactory bulb occurs in a complex clump or ball of axonal and dendritic branches called the olfactory glomeruli. There are approximately 10,000 of these glomeruli; each one receiving input from approximately 2,000 receptor cells. The arrangement by which information is collected could provide the anatomical basis for selective responses to odors. How then might 1,000 different receptor types result in the discrimination of 10,000 different odors ? Indeed, it was recently discovered that receptors synapsing in the same glomerulus contain the same type of protein receptor molecule. Odor molecules bind to more than one receptor type, however. Therefore, although each glomerulus represents the activity from only one type of receptor, the spatial pattern of activity across the glomeruli of the bulbs will differ for each odor.