Research shows brain synchronization between humans and dogs

Research shows brain synchronization between humans and dogs

Study shows how looking at and stroking each other synchronizes human and dog brains, while autism-related gene mutations in dogs reduce this connection.

In a recent study published inAdvanced scienceResearchers examined cross-species brain connections between dogs and humans. They also examined whether autism-related genetic abnormalities in dogs hinder social interaction between human-dog pairs.

background

The bond between humans and dogs has evolved over time, with dogs being domesticated for their protective and hunting abilities. They have become valuable household members, providing companionship and emotional support. Interspecies partnerships bring mutual benefits but rarely reach the level of communication between humans and dogs. Dogs can read, understand, and respond to various human emotions and linguistic cues through facial expressions, behaviors, and vocal tones. However, the brain mechanisms underlying social communication between species remain unknown.

About the study

In the present study, researchers examined the brain processes that enable communication between humans and dogs. They examined the influence of autism-related gene changes in dogs on social interactions between the two species.

Non-invasive wireless electroencephalograms (EEG) simultaneously recorded brain activity in beagles (research dogs) and humans during social interactions. To validate the results, the researchers assessed brain correlations between different areas of the brain in three situations. The situations included no social interaction in separate rooms, with social interaction in one room, and without social interaction in one room. Social interactions included petting and looking at each other.

The researchers compared interbrain coupling during full social interactions (mutual gaze + stroking) with partial social interaction (mutual gaze or stroking alone) to evaluate the synergistic effects of mutual gaze and stroking on interbrain coupling. They also examined brain activity connections between dog and human participants in various studies and recorded the two species' brain activity during social interactions for five days to assess the influence of social familiarity on neural coupling between brains.

The anatomy of the human brain

The researchers then conducted an additional five-day study to assess the durability or changes in interactions between the brains over longer periods of time. Linear regressions examined the relationship between the duration of social interactions and cross-brain activity. Generalized Partially Directed Coherence (GPDC) algorithms assessed the directionality of activity coupling between brains.

Researchers developed an autism spectrum disorder (ASD) model for dogs with SH3 and multiple ankyrin repeat domain 3 (Shank3) mutations using clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) genome editing.

Behavioral studies such as the three-chamber test and human-dog interaction experiments showed autism-like symptoms in the mutants. For five days, researchers explored the neural brain connection between mutant dogs and humans. Theta/beta wave ratios (TBR) suggested attention problems in the mutants during social interactions between humans and dogs.

Researchers also examined the effects of lysergic acid diethylamide (LSD), a psychedelic, on brain function. They administered a single dose of 7.5 μg/kg body weight of LSD intramuscularly and observed the effect after 24 hours.

Results

Stroking and mutual staring led to interbrain synchronization in the parietal and frontal areas of the brain during human-dog interactions. These brain areas are involved in joint attention. The interbrain association in these brain areas of dogs and humans caused by mutual looking or petting alone was much lower than combined social interactions, including petting and mutual staring.

Over five days, the intensity of synchronization increased as the human-dog dyad became more familiar. Linear regression analyzes revealed a strong positive association between time of social contact, correlations between brain activities and GPDC values. After a week of social contact, logistic growth curve regressions showed that interbrain correlation in the frontal and parietal areas had plateaued.

Interbrain correlations between humans and dogs were much lower in different sessions than in the same interaction sessions. The results show that mutual engagement between dogs and humans is crucial to the neural connections between brains. During human-dog social interaction, the human takes the lead and the dog follows. The mutated canines showed reduced alertness and eliminated connections between brains. A single dose of LSD solved the problems.

Conclusions

The study found that the neural synchronizations between brains between family dogs and humans are identical to those seen in human-human interactions. The frontoparietal network is essential for coordinating activity between brains and paying attention to sensory information. Dogs with Shank3 mutations showed poor brain circuitry and attention comparable to those with ASD. A single dose of LSD restored reduced brain connectivity and joint attention in the mutant dogs, suggesting that LSD may improve social impairment in ASD patients.

The results suggest possible biological markers of interbrain neuronal activity for the diagnosis of autism spectrum disorders and the development of specific non-hallucinogenic LSD analogues to treat social deficits. Further research into brain coupling could improve knowledge of the neurological mechanisms underlying social interactions between typically developing people and people with mental illnesses such as ASD.

Sources: