NOSE-SENSE! Pt 2 - What part does the brain play?
The dog’s brain differs in size and ability compared for instance to the human brain. The olfactory bulb responsible for analyzing and processing scents is much larger in dogs than humans. Responsible for processing scents that are detected by cells in
the dog’s nasal cavity, it is approximately 40 times larger in dogs than humans. The human brain is dominated by a large visual cortex whilst the dog’s is dominated by the olfactory cortex. In fact, the olfactory bulb makes up around one eight of the dog’s brain! (Balance Behavior, n.d.)
In order for a dog to identify and differential various odors the entire process starts not in the brain but in the nasal passageways. With over 300 million olfactory receptors in the nose alone compared to humans’ 6 million, our canine friends are powerfully equipped. (Hao Jia, 2014)
The part of the dog’s brain that is devoted to analyzing the smells is the olfactory bulb. The Royal Society published in 2009 a paper emphasizing how important fluid dynamics of odorant transportation during sniffing in canines. (Brent A. Craven, 2009)
“Traditional explanations for canine olfactory acuity, which include large sensory organ size and receptor gene repertoire, overlook the fluid dynamics of odorant transport during sniffing. But odorant transport to the sensory part of the nose is the first critical step in olfaction.” (Brent A. Craven, 2009)
Their study included different species varied in size and volume to the canine. They compared the nasal anatomical cavities of each and the deducted that this was essential in olfactory sharpness and keenness of thought. This could also account for the dog’s ability to differential and categorize different smells even though their brain size is smaller. In 1958 Negus commented in his book,
“The olfactory recess ‘is seen at its height of perfection in the dog” (Negus, 1958)
Next time: A summary of the dog's sense of smell!