May
20
For the love of dog!
Think about your favorite pet (maybe it belongs to you…or your roommate in my case). What does it look like? Where is its favorite spot to hang out? When was the last time you played with it? Now think about the same things, but about your best (human) friend. You might experience similar feelings of fondness or joy upon revisiting memories about your pet and your friend despite fundamental differences between spending time with a human and a non-human. Similarly, when you come home you might be just as happy to hug your dog/cat/snake as you would your loved one.
How do our brains and bodies deal with differences between affection for pets vs human loved ones? Could we simply replace human interaction with kitty cuddles to satisfy our social needs? We enjoy so many social benefits from spending time with pets and humans, and I’d like to know if our brains can tell the difference. Neuroscience research is scarce when it comes to how our brains process interactions with pets vs humans. We need to understand both what is similar and what is different in the brain when it comes to these interactions. Like why can I have just as much fun playing hide-and-go-seek with my baby cousin as I do with my sister’s cat? If I pretend enough, the cat can almost be human, but not quite.
Do you actually think a cat can be grumpy?
One contributing factor in how we view pets is whether we believe animals can experience different emotions like a human. If you think your pet can feel happy or sad, you are more likely to be empathetic and considerate towards the animal. For that reason, researchers predicted that animals viewed as pets, such as cats and dogs, would have more emotion attributed to them compared to animals viewed as food or pests, such as chickens and flies [1]. The researchers asked over 300 adult human subjects whether various types of animals could experience basic emotions (joy, sadness, anger, and fear) and more complex emotions (pride, guilt, and jealousy). The researchers were correct – the subjects attributed more basic and complex emotion to pets, specifically mammals, compared to flies and fish. Part of the reasoning was that mammals are closer to humans, according to people’s general knowledge of evolution, and so subjects were more likely to attribute human-like emotions to pet mammals. And it can be easier to feel emotions towards an animal when people believe animals can also feel emotions as well as express them in similar ways. They can’t talk, but mammals’ facial expressions can tell us a lot about what they are feeling.
PET Project: How does your dog make you feel?
Changes in your brain and body can affect those feelings of love and devotion towards our furry friends. Researchers can use brain imaging, heart rate and blood pressure monitors, and psychological assessments to quantify people’s reactions towards pets. One study in Japan tested the hypothesis that pet dogs would reduce stress – both psychological and bodily signs of stress [2]. (Think about the opposite of having a hangry pet lion.) Stress relief is a great reason to have a pet, and luckily there are lots of scientific tools to assess stress. The researchers measured brain activity using positron emission tomography (PET), a method which shows which brain regions are active by measuring how much energy they consume. Fourteen healthy adult pet owners received a PET scan, an electrocardiogram (heart monitor), and a stress response scale survey both with and without their dog present. It turned out that the dogs’ presence deactivated parts of the brain (pictured below) that are usually associated with stress responses.
Puppy power: These diagrams (left) and human PET brain images (right) show brain regions involved in stress were deactivated in the presence of the subject’s dog [2].
Bodily stress responses were not significantly different with or without the dog, as measured with the heart monitor. But that result makes sense given that the participant was generally relaxed both with and without the dog. Other studies looking at pet ownership and cardiovascular health also failed to find a significant association between having a pet and blood pressure or hypertension in older adults [3]. Even though the pet may not affect heart health, it could still improve a pet owner’s mood. Participant scores on the stress response scale survey were significantly reduced with the owner’s dog present, which suggests that the dog relieved psychological stress. Many people actually use the stress relieving effects in animal assisted therapies for a number of psychiatric disorders (see section below). Future PET (pet) studies could help us understand what other brain processes are involved in human-pet interactions.
fMRI Battles: Baby vs dog
Let’s get back to the question of how our brains can tell the difference between affection for a pet vs a human. Yes there are the obvious differences – how they look, smell, and sound. But how do they make you feel? Researchers in Boston posed this question towards mothers looking at images of their own child, their own dog, a stranger’s child, and an unfamiliar dog [4]. They wanted to understand the brain regions involved in the human-pet bond vs the mother-child bond, so they used fMRI to measure brain activity during each of those conditions. Participants also rated levels of excitement and pleasantness while viewing each image. Mothers apparently like their own children and dogs more than strangers; however, there was no difference between ratings for their own child and own dog. Meaning my mother doesn’t love me more than the dog? Possibly…
Baby on my mind: A mother’s own dog activated the fusiform gyrus, a brain region important for processing faces and social cognition. The dog also deactivated the NAcc/ventral striatum, which is involved in reward related behavior. These differences in activation can tell us how different brain processes are used when thinking of own pets vs own children [4].
For each of the tests, similar brain regions were activated and associated with vision, emotion, and social interaction; however, there were also specific differences. For example, the amygdala, which is very important for emotion, was one brain region that was activated for both the mother’s own dog and own child. The amygdala activation for both can help explain why mothers gave similar pleasantness ratings for their dog and child because they experience similar levels of emotional ties to them. On the other hand, the fusiform gyrus, which is important for processing faces and social cognition, had more activity (pictured above) when a mother viewed an image of her own dog compared to her own child. Subject probably had more activity in this face processing brain region because communication and recognition between human and dog more heavily relies on the face and head direction. It makes sense that the human needs to use more facial processing power for a dog that cannot talk compared to a human child that can cry, move, and yell in order to communicate.
The midbrain, which is important for reward and affiliation, was more active while viewing images of her own child compared to her own dog. The midbrain was also more active for own child vs stranger, which tells us that maybe mothers feel closer to their child compared to their own dog since brain reward regions are more active. The midbrain is where a lot of brain chemistry takes place involving dopamine and oxytocin, which are needed in forming emotional bonds. So even though mothers gave similar ratings of excitement and pleasantness for their children and dogs, their brains showed distinct patterns of activity for their own child vs own pet that suggest mothers actually do feel emotionally closer to their children. The different activity patterns can reflect differences in the possibly stronger mother-child bond compared to the human-pet bond despite similarities in affection.
Therapy fluffies
As mentioned before, pets can offer really effective stress relief (in case your doubt about mother’s love is stressing you out). Animal assisted therapies have been around since the 1960s when Dr. Boris Levinson realized that a child patient would make more progress during sessions when he brought his dog, Jingles [5]. Dr. Levinson learned that many of his patients who were more quiet would be more open to talk with a dog present. Since then, animal assisted therapies have helped people suffering from post traumatic stress disorder, schizophrenia, depression, and other psychiatric illnesses [6-8]. These therapies involve interactions with dogs, cats, or horses to relieve stress and anxiety, creating a more welcome and safe environment for communication. As we saw with the fMRI study above, humans can form emotional bonds with animals, and those bonds can be helpful during therapy when a patient needs a trusted ally to talk to, which aids communication with the therapist. It is easier for some people to talk to a friendly furry face than an unfamiliar human.
Therefore positive human-animal interactions can be just as beneficial and meaningful as human-human interactions, and we should not underestimate the power of kitty cuddles, doggy snuggles, or any other expression of our love for animals.
References
[1] Wilkins, A. M., McCrae, L. S., & McBride, E. A. (2015). Factors affecting the Human Attribution of Emotions toward Animals. Anthrozoös, 28(3), 357-369.
[2] Sugawara, A., Masud, M. M., Yokoyama, A., Mizutani, W., Watanuki, S., Yanai, K., … & Tashiro, M. (2012). Effects of presence of a familiar pet dog on regional cerebral activity in healthy volunteers: A positron emission tomography study. Anthrozoös, 25(1), 25-34.
[3] Wright, J. D., Kritz-Silverstein, D., Morton, D. J., Wingard, D. L., & Barrett-Connor, E. (2007). Pet ownership and blood pressure in old age.Epidemiology, 18(5), 613-618.
[4] Stoeckel, L. E., Palley, L. S., Gollub, R. L., Niemi, S. M., & Evins, A. E. (2014). Patterns of brain activation when mothers view their own child and dog: an fMRI study. PloS one, 9(10), e107205.
[5] Levinson, B. M. (1969). Pet-oriented child psychotherapy. Charles C. Thomas, Springfield IL
[6] Hamama, L., Hamama-Raz, Y., Dagan, K., Greenfeld, H., Rubinstein, C., & Ben-Ezra, M. (2011). A preliminary study of group intervention along with basic canine training among traumatized teenagers: A 3-month longitudinal study. Children and Youth Services Review, 33(10), 1975-1980
[7] Lefkowitz, Carin, et al. “Animal-assisted prolonged exposure: A treatment for survivors of sexual assault suffering posttraumatic stress disorder.” Society & Animals 13.4 (2005): 275-296.
[8] Chu, C. I., Liu, C. Y., Sun, C. T., & Lin, J. (2009). The effect of animal-assisted activity on inpatients with schizophrenia. Journal of psychosocial nursing and mental health services, 47(12), 42-48.
Pet GIFs:
NeuWrite San Diego 
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