Friday, October 10, 2014

Love for a dog just as deep

MATERNAL BONDS: MGH study suggests neurobiological basis of human-pet relationship.

It has become common for people who have pets to refer to themselves as “pet parents,” but how closely does the relationship between people and their non-human companions mirror the parent-child relationship? A small study from a group of MGH researchers makes a contribution to answering this complex question by investigating differences in how important brain structures are activated when women view images of their children and of their own dogs. Their report recently was published in the open-access journal PLOS ONE.

“Pets hold a special place in many people’s hearts and lives, and there is compelling evidence from clinical and laboratory studies that interacting with pets can be beneficial to the physical, social and emotional well-being of humans,” says Lori Palley, DVM, of the MGH Center for Comparative Medicine, co-lead author of the report. “Several previous studies have found that levels of neurohormones like oxytocin – which is involved in pair-bonding and maternal attachment – rise after interaction with pets, and new brain imaging technologies are helping us begin to understand the neurobiological basis of the relationship, which is exciting.”

In order to compare patterns of brain activation involved with the human-pet bond with those elicited by the maternal-child bond, the study enrolled a group of women with at least one child aged 2 to 10 years old and one pet dog that had been in the household for two years or longer. Participation consisted of two sessions, the first being a home visit during which participants completed several questionnaires, including ones regarding their relationships with both their child and dog.

The second session took place at the MGH Martinos Center for Biomedical Imaging, where functional magnetic resonance imaging (fMRI) – which indicates levels of activation in specific brain structures by detecting changes in blood flow and oxygen levels – was performed as participants lay in a scanner and viewed a series of photographs. The photos included images of each participant’s own child and own dog alternating with those of an unfamiliar child and dog. After the scanning session, each participant completed additional assessments, including an image recognition test, and rated several images from each category shown during the session on factors relating to pleasantness and excitement.

Of 16 women originally enrolled, complete information and MR data was available for 14 participants. The imaging studies revealed both similarities and differences in the way important brain regions reacted to images of a woman’s own child and own dog. Areas previously reported as important for functions such as emotion, reward, affiliation, visual processing and social interaction all showed increased activity when participants viewed either their own child or their own dog. A region known to be important to bond formation – the substantia nigra/ventral tegmental area (SNi/VTA) – was activated only in response to images of a participant’s own child. The fusiform gyrus, which is involved in facial recognition and other visual processing functions, actually showed greater response to own-dog images than own-child images.

“Although this is a small study that may not apply to other individuals, the results suggest there is a common brain network important for pair-bond formation and maintenance that is affected when mothers view images of either their child or their dog,” says Luke Stoeckel, PhD, MGH Department of Psychiatry and co-lead author of the PLOS One report. “We also observed differences in activation of some regions that may reflect variance in the evolutionary course and function of these relationships.”

Co-author Randy Gollub, MD, PhD, of MGH Psychiatry adds, “Since fMRI is an indirect measure of neural activity and can only correlate brain activity with an individual’s experience, it will be interesting to see if future studies can directly test whether these patterns of brain activity are explained by the specific cognitive and emotional functions in human-animal relationships.”
The investigators note that further research is needed to replicate these findings in a larger sample and to see if they are seen in other populations and in relationships with other animal species.



Read more articles from the 10/10/14 Hotline issue.

 

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