Olfactory tubercle

The olfactory tubercle (OT), also known as the tuberculum olfactorium, is a multi-sensory processing center that is contained within the olfactory cortex and ventral striatum and plays a role in reward cognition. The OT has also been shown to play a role in locomotor and attentional behaviors, particularly in relation to social and sensory responsiveness, and it may be necessary for behavioral flexibility. The OT is interconnected with numerous brain regions, especially the sensory, arousal, and reward centers, thus making it a potentially critical interface between processing of sensory information and the subsequent behavioral responses. The OT is a composite structure that receives direct input from the olfactory bulb and contains the morphological and histochemical characteristics of the ventral pallidum and the striatum of the forebrain. The dopaminergic neurons of the mesolimbic pathway project onto the GABAergic medium spiny neurons of the nucleus accumbens and olfactory tubercle (receptor D3 is abundant in these two areas ). In addition, the OT contains tightly packed cell clusters known as the islands of Calleja, which consist of granule cells. Even though it is part of the olfactory cortex and receives direct input from the olfactory bulb, it has not been shown to play a role in processing of odors. The olfactory tubercle differs in location and relative size between humans, other primates, rodents, birds, and other animals. In most cases, the olfactory tubercle is identified as a round bulge along the basal forebrain anterior to the optic chiasm and posterior to the olfactory peduncle. In humans and other primates, visual identification of the olfactory tubercle is not easy because the basal forebrain bulge is small in these animals. With regard to functional anatomy, the olfactory tubercle can be considered to be a part of three larger networks. First, it is considered to be part of the basal forebrain, the nucleus accumbens, and the amygdaloid nuclei because of its location along the rostral ventral region of the brain, that is, the front-bottom part.