Neural Processing of Face Stimuli in Domesticated Dogs

    Many of our cognitive and physical abilities contribute to our survival. When looking into the face of the loved one, dopamine fills up our reward circuit. When looking a threatening stranger, amygdala releases stress hormones to activates the fight-or-flight response. Face stimuli is of significance to social cognition as it is helpful in understanding the environment. Facial recognition is extensively studied in humans, and more studies are also conducted on domestic animals in the recent years to investigate how animals can comprehend from observing faces. In the article, “Separate brain areas for processing human and dog faces as revealed by awake fMRI in dogs (Canis familiaris)”, by Thompkins et al., researchers explore the neural processing of domestic dogs when presented with face stimuli. 

    Since thousands of years ago, humans have started the domestication of pet. Dogs are undeniably one of the most domesticated animals, and this unique relationship humans and dogs share through interactions is fascinating. Dogs can adapt and respond to human’s speech and body gestures effectively while humans are able to deduce a meaning from observing a dog’s action or behavior. How can two different species understand and interact with each other by relying on face stimuli?  In 2013, researcher MacLean, Herrmann, Suchindran, and Hare studied canine cognition to gather furthermore evidence to collaborates on the evolutionary adaptations of interactions between different species. Many similar studies are conducted to understand the relationship between domesticated dogs and humans.

In the Thompkins et al. study, twelve dogs were included in the study to collect data of the neural activation through functional MRI (fMRI). The result has shown that different patches of the temporal cortex were more activated when presented with dog faces and when presented with human faces. Dog face area (DFA) refers to the area that were more responsive to the dog faces than to human faces; Human face area (HFA) refers to the area that were more responsive to the human faces than to dog faces. Part of the study also focuses on finding the functional analogues in the human brain for the DFA and the HFA to aid in comprehending the results and explore about how these regions play a role in the evolutionary aspects of dog domestication. Temporal cortex in human was extensively studied and has provided many supporting evidence for facial processing in that region of the brain; this is helpful in finding the analogues between dogs and human. Detecting an area with activation when presented with face stimuli in dog brain can be compared to the temporal lobe activation in human brain as functionally analogous.   

    Additionally, the study found that dog brain has two separate regions for processing human faces and dog faces. One of the factors that the researchers consider to be an explanation for the separation is neural plasticity. Neural plasticity evolves the dog brain to have a more polished processing for human faces and actions since their purpose/success is depended on the human. Although HFA is expected to be the region that is more fine-tuned, the fMRI data illustrates that HFA is more active as it is presented to social aspect pf dogs. Dogs are very responsive to the human cues, but it would be reasonable to have a brain area sensitive to social cognition within species.

   There are still many unanswered questions when it comes to canine cognition and how they can understand human facial expressions as well as human commands to successfully carry out their given tasks. Thompkins and a group of researchers compare the neural activation data of viewing the stimuli of dog and human faces to further collect data for the study of neural activation for face processing in canine. Evidence are still insufficient to draw conclusive connections of exactly how the dog brain works. Further research in this field of study to understand the connection between the neural activity and behaviors can play a significant role in influencing the training of dogs, especially in working roles.

References

•      Thompkins , Andie M., et al. “Separate Brain Areas for Processing Human and Dog Faces as Revealed by Awake Fmri in Dogs (Canis Familiaris).” Learning & Behavior, Springer US, 22 Oct. 2018, https://link.springer.com/article/10.3758/s13420-018-0352-z. 
•      MacLean, Evan L, et al. “(PDF) Individual Differences in Cooperative Communicative Skills Are More Similar between Dogs and Humans than Chimpanzees.” ResearchGate, 12 Dec. 2016, https://www.researchgate.net/publication/314007762_Individual_differences_in_cooperative_communicative_skills_are_more_similar_between_dogs_and_humans_than_chimpanzees.