accessory olfactory bulb
Acronym:
OLBa
The term accessory olfactory bulb (OLBa) refers to one of two types of olfactory bulb; the other is the main olfactory bulb (OLBm). Both are histologically and functionally defined structures of the olfactory system (OLS), The OLBa receives input from the vomeronasal organ (VNO) via the vomeronasal-terminal nerve complex.(vntc). Unlike the OLBm, which provides input to several structures of the OS, the OLBa projects only to the amygdala (AMG), specifically to the cortical amygdalar nucleus (COA) and medial amygdalar nucleus (MEA) ( Price-1990 Buck-2013 Keshavarzi-2015 ).
The OLBa is most prominent in the rat ( Swanson-2004 ) and the mouse ( AMBA-2024 ). In the human it clearly exists ( Barrall-2009 ) but is quite small compared to that of the rodent ( Witt-2002 ). In the macaque, it is even less prominent, if it exists at all ( Francia-2014 Zhang-2003 ), Evolutionary biologists attribute its lesser status in primates to their greater reliance on the visual and auditory systems for adaptation to social stimuli ( Witt-2002 ).
Functionally the OLBa differs from the OLBm in that it belongs to the neural circuitry tor responding to pheromones, odorants emitted by social stimuli, as opposed to the main bulb's sensitivity to odorants emitted by physical stimuli, such as edible and inedible substances. Pheromones t trigger reproductive behaviors and physiological changes in others of the same species ( Zhang-2003 ). They influence hormonal systems via the AMG to the hypothalamic-pituitary-gonadal axis ( Sonne-2023 ) and mating behavior via the MEA to hypothalamus (HYP) to periaqueductal gray (PAG) to extrapyramidal brainstem motor nuclei. Perhaps because the only pathway for signals from OLBa to forebrain evaluative and control structures is through the AMG to HYP and the extrapyramidal motor system ( Bowden-2021 ). Pheromones can have instinctive emotional and behavioral effects in humans without being perceived consciously ( Grammer-2005 ). Updated 6 Sep 2024.
Also known as: No other name for this structure has appeared in PubMed.NeuroNames ID : 1565
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