The term olfactory tubercle refers to a histologically defined, predominantly cellular structure. It is located on the ventral surface of the basal forebrain, caudal to the anterior olfactory nucleus, medial to the olfactory tract, rostral to the piriform cortex and ventral to the nucleus accumbens and substantia innominata. It contains some islands of Calleja. In the rat ( Swanson-2004 ) and the mouse ( Hof-2000 ) it protrudes on the rostroventral surface of the basal forebrain and is clearly stratified. In primates, however, it does not protrude from surrounding areas and is penetrated by numerous small blood vessels. These give it an appearance on dissection that accounts for the name 'anterior perforated substance' in human neuroanatomy ( Crosby-1962 ). In the macaque it is somewhat more prominent than in the human and bounded medially by the tenia tecta ( Price-2004 ). Functionally it is part of the olfactory system, which mediates the sense of smell ( Buck-2013 ). A connection to the periaqueductal gray suggests a behavioral role in eating (Zhou-2024). Inasmuch as OTB is part of the ventral striatum ( Heimer-1995 ), shares a pattern of connectivity with neighboring nucleus accumbens (ACB), is densely innervated by dopaminergic fibers and supports electrical self-stimulation, it is believed to be involved in motivation and reward-supported learning ( Wesson-2020 ). The observation that its olfactory input is solely from the main olfactory bulb (OLBm) ( Buck-2013 ) would suggest that its primary behavioral functions might be approach and avoidance responses to positive and negative oderants from potentially edible substances. Updated 20 Jun 2024.