Dogs’ brains sync with ours when we gaze into their eyes, study finds

If you’ve ever felt like your dog knows exactly what you’re thinking, you might just be right.

That’s according a new study, which has revealed that dogs’ brains sync with ours when they gaze into our eyes.

Scientists from the Chinese Academy of Sciences found that neurons in parts of the brain associated with attention synchronised more strongly as pairs of dogs and humans became more familiar.

However, dogs with a gene that causes autism-like symptoms showed much lower synchronisation.

It has long been known that humans brains sync up as we interact but this marks the first time that brain synchrony has ever been observed across species. 

Whenever humans interact in social situations, the patterns of activity in our brains and bodies begin to fall into synchronised patterns.

Subconsciously, our heart rates, breathing, and the activation of neurons in the brain become the same as those of the people around us.

In their paper, published in Advanced Science, the researchers explain: ‘During social interactions, interacting individuals are not isolated, but are embedded in a multibrain system.’

Scientists have recently observed that mice, bats, and monkeys also experience a similar kind of synchronisation when engaging with members of their own species.

But, until now, scientists have never observed brain synchronisation between members of two different species.

To try to understand if this was possible, the researchers fitted pairs of humans and dogs with EEG monitors to record their levels of brain activity.

Dogs were chosen as the experimental animal of choice since research has proven that dogs have a remarkably deep connection with humans. 

Previously unfamiliar pairs had their brain activity recorded while in separate rooms, in the same room but not interacting, and while petting and looking into each other’s eyes.

The researchers found that the pairs’ brains became much more synchronised while they were engaging than when they were just in the same room.

The researchers write: ‘We demonstrated for the first time that directed interbrain neural coupling occurs between humans and dogs, particularly in the frontal and parietal regions, both of which are associated with joint attention.’

The level of synchronisation also dramatically increased over five days of testing as the pairs became more familiar.

In a second experiment, the participants were either asked to pet the dog without making eye contact or just making eye contact without touching.

Both forms of interaction raised the level of brain synchronisation, but eye gazing was associated with more activity in the brain’s frontal region while petting produced activation in the parietal region.

Importantly, the synchronisation created by touch and eye gazing together was more than the sum of these interactions separately.

This suggests that interactions which use more than one form of communication create a much stronger connection at the neural level.

The researchers also used these findings to deepen our understanding of autism spectrum disorders (ASD).

Using the CRISPR gene editing technique, the researchers created dogs with a mutation on the SHANK3 gene – one of the most common risk factors for ASD.

Dogs with this mutation showed clear autism-like behaviours and displayed significantly reduced brain synchrony when interacting with humans.

Co-author Dr Yong Zhang, of the Chinese Academy of Sciences, says: ‘Disrupted inter-brain synchronization might be used as a biomarker for autism.’

However, in an unusual development, the researchers also found that a single dose of the psychedelic LSD was able to almost completely reverse these effects.

The dogs were given a dose of 7.5 micrograms of LSD per kilogram of weight – the equivalent of a 600 microgram dose for an 80kg human.

For reference, a 2021 study found that a 200 microgram dose in humans was sufficient to produce ‘ego dissolution’ and ‘oceanic boundlessness’.

24 hours after administering the drug the researchers performed the test again and found that synchronisation significantly increased in the parietal and frontal regions.

The researchers say these findings could pave the way for treating or managing some of the disruptive symptoms of autism spectrum disorders in humans.

Dr Zhang says: ‘LSD or its derivatives might ameliorate the social symptoms of autism.’