Which animals have dreams: Surprising facts

What do cats dream about?

Cats are among the first domestic animals whose dreams have been the subject of scientific study. In the 1960s, French scientist Michel Jouvet discovered that cats experience dreams. He observed how cats behaved during sleep and made some interesting discoveries.

In humans, during the rapid eye movement (REM) phase of sleep, muscles usually don't move, even though the brain is actively creating our dreams. This is called atonia, a state that protects us from involuntary movements while dreaming. Jouvet found that in cats, this state is controlled by a part of the brain known as the pons, which regulates the REM phase and causes partial muscle paralysis.

However, when Jouvet removed part of this brain structure, the cats' behavior changed. During REM sleep, they began to move as if they were awake: hunting, jumping, grooming, and even defending themselves from imaginary threats.

Jouvet called this state paradoxical sleep, where the cat's body remains still, but its brain is highly active. This allowed scientists to peek into the world of cats' dreams and understand that they may be reliving scenes from their everyday lives.

Researcher Peña-Guzmán notes that cats exhibit behavior that is very similar to the actions they perform when awake.

What cats see in their dreams (photo: Freepik)

Rats dream of mazes

Scientists have discovered that after rats navigate a maze during the day, they can replay the same route in their dreams. The hippocampus, a part of the brain responsible for forming and storing memories, encodes the neural map of the maze navigation while they are awake. Later, during sleep, their brains reactivate this map, suggesting that the rat is either recalling or rethinking the path it took.

This discovery, made in 2001, was one of the first to show that animals can have complex dreams. Neuroscientist Matthew Wilson from the Massachusetts Institute of Technology, one of the authors of the study, noted that this is just the beginning.

Wilson explains that other studies were conducted demonstrating that memories of past experiences manifesting during sleep may resemble what humans experience in their dreams.

Research has shown that when rats recall the maze during sleep, their brains also reactivate the visual images they saw while navigating the route. This includes sounds and emotional sensations that are revived when the rat travels through the maze during the REM phase of sleep.

What rats see in their dreams (photo: Freepik)

How zebra finches learn to sing in their sleep

Zebra finches are known for their melodic songs, but they are not born with this ability. Like humans, these birds must learn - listening, practicing, and perhaps even dreaming about singing.

In 2000, researchers discovered that neurons in the brains of zebra finches activate in a specific pattern while they sing. Scientists were able to reproduce this sequence note by note. Interestingly, while the birds sleep, their brains replay the same pattern, re-creating the songs they heard and sang during the day. This suggests they can remember and "practice" their songs while asleep.

Researchers propose that songbirds may dream about singing. Do they repeat the experience of being awake, or do these dreams resemble automated brain activity without consciousness? This question is still being explored.

Over the next two decades, it became evident that zebra finches have a sleep structure similar to humans, including REM sleep. Studies have also shown that the birds move their vocal muscles during sleep, synchronizing with the music in their heads.

Moreover, sleeping finches can improvise, creating variations of their songs. This indicates that they not only retain sensory information acquired during the day but also use it to create new versions of their songs, adapting and developing their skills even in their sleep.

Zebra finch (photo: Wikipedia)

Sources: National Geographic, Wikipedia