Humans love our dogs, but do dogs love us back? Or is their apparent enthusiasm just an evolved form of acting? Two teams have used MRI machines to provide answers.

We cannot, of course, know what dogs are thinking. But we can see the parts of the brains they are using in different situations, and this can be very revealing.

When humans are studied in this way researcher show them photos or videos to see what response it will elicit. But Gregory Berns of Emory University, Atlanta points out that “Olfaction is believed to be dogs’ most powerful and perhaps important sense.” Consequently, he allowed twelve dogs from ten breeds to smell scents from strangers and people they knew and from other dogs while lying in an MRI machine. 

The study, published in March in Behavioral Processes, used only dogs that could be persuaded to lie still in the machine, so the sample may be a little skewed. Nevertheless, these good dogs responded more intensively to the smell of familiar humans than anything else, with scans showing the region of the brain known as the caudate nucleus was more active for this smell than even familiar dogs. 

The caudate has multiple functions but in humans one is to react to visual beauty. It is known to be intensely active in the early stages of romantic love.

In irrelevant -- but too cute to leave out -- detail from the study, Berns and his co-authors reported the dogs “were all highly proficient at remaining in the chin rest [and] wearing ear muffs.”

^{Berns et al. The 12 dogs whose brains got more excited by smelling humans they knew than other familiar dogs.}

In the same month, Attila Andics of Eotvos Lorand University in Budapest reported in Current Biology that dogs' brains respond to the emotional tone in our voices very much as humans do. “This is the first comparative neuroimaging study of a nonprimate species and humans,” Andics and his colleagues write. “Functional analogies were found between dog and human nonprimary auditory cortex.”

"It's very interesting to understand the tool kit that helps such successful vocal communication between two species," Andics told Brain.mic. 

Andics says the MRI work confirms what those who live with canines have noticed for generations. Dogs behave like babies when scared, running to humans they have formed a bond with, unlike animals like horses which are more likely to flee than seek support.

An even more startling observation of the extent to which dogs have bonded with humans is their tendency to look people in the eyes. Andic was part of a study that attempted to train wolves to do the same thing. Even when the wolves were raised by humans from pups they would not initiate eye contact with those that cared for them. Andics claims the only other animals inclined to make eye contact with humans are our primate relatives. 

"Bonding with owners is much more important for dogs than other pets," Andics said.

So far the brain scans have not been extended to cats. Possibly because everyone is afraid of what the results may reveal.