It’s not uncommon for people who have pets to refer to themselves as pet parents. But is that bond truly similar to the one a parent has with a child? To find out, a group of HMS researchers at Massachusetts General Hospital conducted a small study that used fMRI, a form of imaging, to capture the brain activity triggered when participants viewed images of their own children and dogs. The participant cohort? Women, specifically, mothers. The report was published in October 2014 in the online journal PLOS ONE.
In order to compare patterns of brain activation involved in the human-pet bond with those elicited by the maternal-child bond, the study enrolled 16 women, each of whom had at least one child aged 2 to 10 years and one pet dog that had been in the household for two years or longer.
Each participant was visited first at home, where she was asked to complete questionnaires regarding her relationships with her child and pet dog. While at the home, the researchers photographed the participant’s child and dog.
Each participant then visited the Athinoula A. Martinos Center for Biomedical Imaging at MGH for the fMRI screening. Functional magnetic resonance imaging produces a series of photographs that show changes in blood flow and oxygen levels in specific structures of the brain. Such changes indicate levels of activation in these structures. During the individual imaging sessions, each woman would view photos of her child and dog as well as photos of an unfamiliar child and a dog belonging to a different study participant. After imaging, each participant completed additional assessments and rated several images shown during the session on factors relating to pleasantness and excitement.
The imaging studies revealed both similarities and differences in the way key regions in a woman’s brain reacted to photographs of her child and her dog. Areas reported to be important for functions such as emotion, reward, affiliation, visual processing, and social interaction showed increased activity when a participant viewed images of either her child or her dog.
Images of a participant’s child, but not those of her dog, activated the substantia nigra/ventral tegmental area, a region important to bond formation. By contrast, images of a participant’s own dog sparked greater activity in the fusiform gyrus, a region involved in facial recognition and other visual processing functions, than did own-child images. The researchers think the greater response of the fusiform gyrus to own-dog images might reflect the increased reliance on visual, rather than verbal, cues in human-animal communications.
The results of this small study, say the researchers, hint not only that a common brain network important for pair-bond formation and maintenance activates when mothers view images of either their child or their dog but also that there may be brain-behavior differences that reflect the distinct evolutionary underpinnings of these relationships.
Image: Mattias Paludi