Olfaction is dependent on a large network of multiple primary and secondary processing centers connected in parallel and serial manners. Some of these centers are linked with non-olfactory regions. Olfactory receptor neurons project into the olfactory bulb which projects to the olfactory cortex. The olfactory cortex is a three layered cortex with several distinct sub-regions, the largest being the pyriform cortex. The other main components of the olfactory cortex are the olfactory tubercle and the anterior olfactory cortex. Olfactory tubercle differs in relative size and location between rodents, humans, non-humans and other animals. Olfactory tubercle is identifiable as a round bulge along …show more content…
Instead, it is a trilaminar structure in the anterior-most aspects, which, in the more ventral areas becomes a grating structure. Further, unlike other olfactory cortical areas, the olfactory tubercle does not possess an association fiber system. The olfactory tubercle receives monosynaptic olfactory input from the pyriform cortex and the olfactory bulb. Axons of the olfactory bulb second order neurons fasciculate to form the lateral olfactory tract that travels along the ventral-lateral aspect of the brain. Axons enter the molecular layer of the olfactory tubercle where they synapse onto olfactory tubercle neurons in the dense cell layer. Mitral cells innervate the pyriform cortex. Tufted cells of the ventral portion send a large dominant projection into the olfactory tubercle. Thus, these are the two sources of output from the olfactory …show more content…
Pyriform cortex represents the valence of smells but not the source. Olfactory tubercle responds to intended smells. Thus, olfactory tubercle is involved in attention modulation of the early olfactory code. Like the olfactory bulb and pyriform cortex, the olfactory tubercle has several features that link it to the role of processing smells. Olfactory processing regions from the nose are integral in the multimodal processing of sensory data. These regions include the orbitofrontal cortex, pyriform cortex and the endopiriform nucleus. The olfactory tubercle functions as a multi-sensory processing center. The olfactory tubercle changes social, sensory and attention responsiveness and locomotive behavior. Thus, olfactory tubercle plays a role in