Dogs and humans have a long and close history of contact. Fellow Psychology Today writer Mark Derr's essays continually offer close, critical, and current views about this unique, closely reciprocal, and enduring association. But, what does the dog's nose tell the dog's brain and us about this close relationship? Quite a bit, it turns out.

It's well known that the nose of dog is a super sensitive organ and dogs rely on olfactory input in important ways, even from "yellow snow", to provide information about their sense of self ("Hidden tales of yellow snow: What a dog's nose knows - Making sense of scents"). And now we've learned, based on neuroimaging studies conducted by Emory University's Dr. Gregory Berns who also writes for Psychology Today and his colleagues, that the dog's brain responds differently to familiar and unfamiliar odors of humans and dogs.

In an essay published this week in Behavioural Processes called "Scent of the Familiar: An fMRI Study of Canine Brain Responses to Familiar and Unfamiliar Human and Dog Odors" that is available online, Professor Berns, Andrew M. Brooks, and Mark Spivak discovered, using fMRI imaging, that "the caudate [nucleus of dogs] was activated maximally to the familiar human. Importantly, the scent of the familiar human was not the handler, meaning that the caudate response differentiated the scent in the absence of the person being present." In addition, the response was most activated to the scent of the familiar human. 

What this all means is that "while the olfactory bulb/peduncle was activated to a similar degree by all the scents, the caudate was activated maximally to the familiar human. Importantly, the scent of the familiar human was not the handler, meaning that the caudate response differentiated the scent in the absence of the person being present. The caudate activation suggested that not only did the dogs discriminate that scent from the others, they had a positive association with it. This speaks to the power of the dog's sense of smell, and it provides clues about the importance of humans in dogs’ lives."

As time goes on we will learn more and more from neuroimaging studies not only about the power of a dog's nose but also about the strong, reciprocal, and enduring relationship that has formed between ourselves and "our best friends".

Marc Bekoff's latest books are Jasper's story: Saving moon bears (with Jill Robinson; see also), Ignoring nature no more: The case for compassionate conservation (see also)and Why dogs hump and bees get depressed (see also).

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