Binding of neurotransmitter by secondary neurons results in propagation of nerve signals through the various olfactory pathways. Sensory information reaches different regions of the brain including the (1) , which allows us to consciously perceive and identify the smell; (2) , which controls visceral reactions to smell, such as salivation, sneezing, or gagging; and (3) , which is a center for recognition of odors and often tying those odors to a particular emotion.