main olfactory bulb
Acronym:
OLBm
The term main olfactory bulb refers, in the human and macaque, to a small oval white structure located in the cleft between the ventral surface of the frontal lobe and the floor of the cranial cavity ( Carpenter-1983 ). In the rat and mouse it is a much larger structure in comparison to the rest of the brain; there it occupies almost a quarter of the length of the cranial cavity ( Swanson-2004 ).
Though classically considered a separate structure from the cerebral cortex in primates ( Nomina-1983 ), it is classified on the basis of internal structure as a component of paleocortex in all species ( Stephan-1975 ). Also in all species it is connected rostrally with the olfactory nerve. Caudally in primates it connects topologically with the olfactory peduncle. Again, in all species it connects histologically and functionally with the olfactory cortex ( Swanson-2004 Buck-2013 )
It is a layered structure that contains cell bodies of the second-order neurons in the olfactory system. Each neuron in the bulb receives input from about 100 receptor neurons ( Wikipedia ). So, in information terms the amount of information transmitted from the receptor level (1 bit per receptor or ~25,000 bits) is recoded and compressed into about 250 bits per bulb neuron.
Functionally, the OLBm plays a roll in oderant feature detection. It is a key structure in the system that mediates the conscious sense of smell for odorants other than pheromones, which are sensed unconsciously through the accessory olfactory bulb. Updated 20 Jul 2024.
Also known as: olfactory bulb, Bulbus olfactoriusNeuroNames ID : 279
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