No matter how deeply asleep your four-legged friend seems, the moment you cough, laugh or yawn, he secretly notices it.
Dogs are social and communicative animals. When they notice something striking in their environment, they often react strongly. For example, they prick up their ears when they hear someone barking or start wagging their tails when people speak to them in a high-pitched voice. Of course, this all happens when dogs are awake. But a new study now suggests that they also process sounds while napping.
Emotions
Over the years of domestication, dogs have integrated seamlessly into our human society. They communicate regularly with both other dogs and people. Meanwhile, we know that dogs, just like people, react differently depending on the emotions (positive or negative) they hear. In addition, they can link the sounds of both other dogs and people to matching facial expressions. Furthermore, research has shown that sleep – in both dogs and humans – is important for processing emotions and strengthening memory.
Study
In a new study, the researchers went a step further. They wanted to know whether dogs also show different responses to stimuli with different emotional charges and from different sources (humans and other dogs) while they sleep. Why this is important? “One of the reasons we conducted this study was simply out of curiosity,” says researcher Huba Eleőd in an interview with Scientias.nl. “We wanted to better understand the way the dog brain works because dogs provide an interesting new animal model for research in non-invasive comparative neuroscience.”
Sounds
A total of thirteen dogs participated in the study, which were tested separately. Just before the experiment began, the dogs settled down for their daily nap, with their owners by their side. While the dogs were napping, the researchers played different sounds. These included both positive and neutral sounds, coming from dogs and people. This includes growling, panting and whining (dog sounds) and coughing, sighing and yawning (human sounds). The researchers avoided sounds with extremely negative emotions to avoid waking the dogs. Each sound clip lasted one second and was played at a constant volume.
Electrodes
The research team then measured the neural response using electrodes placed on the head. During the measurements, small electrical currents running through the brain were detected and recorded. This is a non-invasive, painless and relatively simple way to obtain information about the brain’s electrical activity.
A dog takes a nice afternoon nap while researchers measure brain activity using electrodes placed on its head. Image: Scientific Reports (2023)
Neural response
The study leads to an interesting discovery. It turns out that even when dogs sleep, they pick up and process sounds from their environment. “The different sounds even led to significantly different patterns of brain activity,” Eleőd explains. “This shows that the dogs’ brains respond differently when they hear a human, for example, compared to the sound of another dog.”
Significant
Basically, dogs respond to sounds even when they are in a deep sleep state. And that is actually quite remarkable. Not only can they recognize different sounds while sleeping, they can even distinguish who is making this sound and whether it is a positive or neutral sound. “This is similar to how the human brain can process sounds while someone is sleeping,” says Eleőd. According to him, the findings are significant. “This discovery is important because it is the first time we have found evidence that dogs engage in complex sound processing during sleep,” Eleőd said.
Ears on sticks
A pressing question is of course why sleeping dogs seem to have ‘ears on sticks’. What is the purpose of this? “The ability to process signals during sleep is actually a very useful property,” Eleőd explains when asked. “It allows animals to remain alert to possible dangers, even while they sleep.” And that is certainly important in the case of mammals. Mammals spend a significant part of their lives sleeping. The ability to process stimuli from their environment, not only when awake but also during sleep, is essential for survival. “Although many animals likely possess this trait, it has not yet been extensively studied due to technical challenges,” Eleőd continues. “We do know that people are able to process emotional sounds, even when we are deeply asleep. In fact, certain parts of the brain involved in emotions are even more active during sleep than when a person is awake.”
The results of the research, published in the prestigious journal Scientific Reports, increase our understanding of how dogs process information in their brains and lay a foundation for future research in this area. “These findings open the door to many possible research directions,” notes Eleőd. “For example, we could measure the brain responses of dogs when they listen to different types of barks recorded in various social situations.” But as mentioned, that is subject to further research. For now, the researchers have shown that even when your dog seems completely lost, he is still secretly watching you. This suggests that their obedient and sensory systems remain somewhat active, even when they are curled up in their basket and dozing.
2023-09-21 06:30:39
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