Human-Dog Brain Synchronisation Reveals a Deeper Bond

If you have ever looked into a dog’s large, soulful eyes and felt connected, you may have experienced a brief instance of brain synchronisation.

Chinese researchers have, for the first time, detected neural activity becoming synchronised across two species: people and dogs. Their results indicate that the bond we form with pets may operate at a deeper neurological level.

Earlier research has shown that activity in important brain areas can become aligned when people speak or collaborate with each other. This is, however, the first set of experiments to describe a comparable effect between humans and another species.

Human-dog brain synchronisation during interaction

The scientists recorded brain activity from people and dogs using electrodes placed on the skull. For the study, 10 young beagles were paired with humans they did not know, with each pair becoming acquainted over five days.

During the tests, each human-dog pair communicated without words, including by looking at one another or through a traditional pat. As a control condition, the person and dog remained in the same room without engaging with each other.

“We observed that inter-brain correlations in frontal and parietal regions dramatically increased… during mutual gaze,” write the study authors, whose team was led by Chinese Academy of Sciences biologist Wei Ren.

The researchers saw comparable synchronisation when participants simply stroked the dogs, although the alignment was stronger in the parietal brain area in that situation.

In people, activity in the frontal and parietal regions is linked with shared attention. Previous research has established that petting a dog increases activity in the human frontal lobe, suggesting that people are closely attentive to, and emotionally involved with, their animal. Until now, though, it was uncertain whether the dog’s brain reflected this activity.

Mutual gaze and petting strengthen the connection

When participants were instructed to both stroke the dogs and look into their eyes, the brain activity shared between them was more strongly connected than when they were only patting or only gazing at the animals.

To determine whether the human or canine brain was guiding this rhythmic neural interaction, the researchers used a specialised mathematical algorithm.

After entering data from every human-dog encounter, the team established that the human brains initiated the linked neural activity. Synchronisation between the brains of the human-dog pairs increased as the study progressed, suggesting that they were forming a bond.

ASD-like characteristics and LSD treatment in dogs

Some scientists propose that the reduced brain synchronisation seen with other people may underlie social-cognition deficits in autism spectrum disorder (ASD).

The researchers explored this idea by repeating the experiments with nine dogs displaying traits similar to those associated with human ASD. These human-dog pairings showed lower inter-brain synchronisation, pointing to less shared attention.

Earlier studies have shown that LSD can improve social behaviour in mice. The team therefore gave the dogs with ASD-like characteristics one dose of the psychedelic, which ultimately enhanced the dogs’ synchronisation with their paired humans.

Although the study was small and requires further investigation, the researchers say these dogs could offer a useful model for examining the neural mechanisms behind the social deficits linked to ASD.

“Our findings suggest potential inter-brain activity biomarkers for ASD diagnosis and development of engineered non-hallucinogenic analogs of LSD to correct social deficits,” the authors conclude.

The study appeared in Advanced Science.