Puppy Love: Mothers' brains show similar responses to images of their pet dogs and their own children

For the first time, researchers have used fMRI technology to compare the brain activity of women looking at images of their children and of their dogs.

Image: Marin/Flickr/CC BY-NC-ND 2.0

Image: Marin/Flickr/CC BY-NC-ND 2.0

The furry children of pet parents, also known as ‘dogs’ or ‘cats’, can strongly influence the emotional and physical well being of their owners. Owning a miniature carnivore such as a dog has various health benefits for the owner and the family, and the evidence only keeps amassing.

In the long term, owning a pet is associated with a longer lifespan and greater self-esteem for the owner.

Even spending a few minutes with a familiar dog can reduce an owner’s heart rate as well as their levels of insulin and cortisol (a stress hormone). For female dog owners, dog contact can also increase the levels of oxytocin (a bonding hormone) and….wait for it…prolactin – the hormone that elicits breast milk formation.

And don’t think this is a one way street; these same responses are detected in dogs too. Yes, even the prolactin.

Of course, all of these effects arise because we have deep emotional connections with our mammalian cousins. Humans have evolved complex emotions that tether us to other humans, and canines have evolved emotional repertoires to bond their packs, but how readily do these emotions jump species? And when owners affectionately refer to their pets as their ‘children’, just how far does this connection extend?

With science to the rescue, human mothers were placed in sophisticated brain blood-flow monitoring machines (functional MRIs) and exposed to images of their children, their dogs, as well as unfamiliar children and dogs.

All of the mothers had children of at least two years of age and dogs owned for at least two years. The control ‘stranger’ children shown to the mothers were matched to the ‘familiar’ children for age and gender. The mothers took part in a questionnaire at home and then a lab-based study two weeks later. Upon completing the lab-based component, the participants were also asked further questions to ensure they were attentive throughout the analyses.

The results of the fMRI were as follows: whether looking at images of their own children or of their own dogs, the mothers’ experienced similar ratings of ‘pleasantness’ and ‘excitement’. Areas of the mothers’ brains associated with reward, emotion, and affiliation were similarly activated when looking at their children and their furred-children alike.

Strangely, the region of the brain used in visual processing, facial cues, and social cognition was working harder when looking at their dog. The authors of the paper suggest “…facial cues may be a more central communication device for dog-human interaction…helping owners identify their dog, use gaze direction to communicate, and interpret emotional states.”

There were some fundamental differences though. Only children could elicit responses from the mothers’ midbrains – a neural region rich in vasopressin, dopamine, and oxytocin, all hormones involved in strong emotional bonding. The authors state that “…while [the midbrain] is also reported to have a critical function for other human-human relationships of evolutionary importance (romantic relationships), this does not appear to extend to the human-pet bond.”

As evidenced by these data, we feel strongly for mammals — humans and non-humans alike — but natural selection has saved the deepest bonds, lifetime bonds, for our partners and for our children.

Originally published on thinkinc.org.au

Story source: Science Daily

Quote source: Massachusetts General Hospital

Research paper: Luke E. Stoeckel, Lori S. Palley, Randy L. Gollub, Steven M. Niemi, Anne Eden Evins. Patterns of Brain Activation when Mothers View Their Own Child and Dog: An fMRI StudyPLOS ONE, 2014; 9 (10): e107205 DOI:10.1371/journal.pone.0107205