Sniffing Your Way to Better Hospital Experiences – Materials

4 - Designed to Sniff - Olfactory Bulbs

Designed to Sniff – Olfactory Bulbs

While the total size of a dog’s brain is approximately one tenth the size of the human brain… the portion devoted to smell is about 40 times larger than ours. A human’s brain is dominated by a large visual cortex while a dog’s brain is dominated by the olfactory cortex. In her book, Inside of a Dog, cognitive scientist Dr. Alexandra Horowitz describes it this way,

“As we see the world, the dog smells it. The world of scents is at least as rich as the world of sight.” (Horowitz, 2009)

The nose is the fastest, most direct route by which information can get to the brain. While visual or auditory data goes through an intermediate staging ground on the way to the cortex, the highest level of processing, the receptors in the nose connect directly to nerves in specialized olfactory “bulbs” in the brain. The olfactory receptor cells in a dog’s nose extend throughout the entire layer of specialized olfactory epithelium found on the ethmo-turbinate bones of the nasal cavity. The olfactory bulbs account for one eighth of the dog’s brain. It is located in the fore-brain and is responsible for processing scents detected by cells in the nasal cavity.

The olfactory bulb is extremely important to the dog due to its function of processing scent. Scent information travels from the olfactory bulb to the limbic system which is the most primitive part of the brain (dealing with emotions, memory and behavior). It also travels to the cortex, the outer part of the brain that has to do with conscious thought. In addition to these two areas, information also travels to the taste sensory cortex to create the sense of flavor. Because olfactory information goes to both the primitive and complex part of the brain it effects dogs’ actions in more ways than we may readily observe.

(Horowitz, 2009) Horowitz, A. 2009. Inside of a Dog: What Dogs See, Smell, and Know. Scribner.