accessory olfactory bulb
Acronym: AOB
The term accessory olfactory bulb refers to one of two types of olfactory bulb; the other is the main olfactory bulb. Both are histologically and functionally defined structures of the olfactory system, The accessory bulb (AOB) receives input from the vomeronasal organ (VNO) via the vomeronasal-terminal nerve complex.(vntc). Unlike the main olfactory bulb (MOB), which provides input to several structures of the olfactory system, the AOB projects only to the amygdala, specifically to the cortical amygdalar nucleus and medial amygdalar nucleus ( Price-1990 Buck-2013 Keshavarzi-2015 ).
      The AOB is most prominent in the rat ( Swanson-2004 ) and the mouse ( AMBA-2024 ). In the human it is a vestigial structure ( Witt-2002 ) and, if it exists at all ( Francia-2014 ), in the macaque ( Zhang-2003 ). Evolutionary biologists attribute its vestigial status to primates' greater reliance on the visual and auditory systems for adaptation to the environment ( Witt-2002 ).
      Functionally the OLBa differs from the OLBm in that it belongs to the neural circuitry tor responding to pheromones, oderants emitted by social stimuli, as opposed to the main bulb's sensitivity to oderants emitted by physical stimuli, such as edible and inedible substances. Pheromones t trigger repoductive behaviors and physiological changes in others of the same species ( Zhang-2003 ). They influence hormonal systems via the amygdala to the hypothalamic-pituitary-gonadal axis ( Sonne-2023 ) and mating behavior via the medial amygdalar nucleus (MEA) to hypothalamus to periaqueductal gray (PAG) to extrapyramidal brainstem motor . Perhaps because the only pathway for signals from OLBa to forebrain evaluative and control structures is through the amygdala to hypothalamus and the extrapyramidal motor system ( Bowden-2021 ), pheromones can have instinctive emotional and behavioral effects in humans without being perceived consciously ( Grammer-2005 ). Updated 21 Jun 2024.

Also known as: No other name for this structure has appeared in PubMed.NeuroNames ID : 1565

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