An interesting story about the three-toed Brazilian sloth

Humans spend one-third of their time in sleep, often thinking about it day and night. Will animals have a colorful dream world like people? The scientist gave a positive answer.

Scientists have always been interested in whether animals dream. Three scientists from Brazil and the United States measured the EEG of the sloth with three toes, and found that this animal dreams. It dreams for about two hours. In the animal world, the sloth with three toes is not the champion of dreaming, because squirrels, porcupines, kangaroos, armadillos and other animals can dream for five or six hours every day.

Long-term research has proved that most reptiles do not dream, most birds only dream for a short time, and many mammals also dream.

Scientists observe the brain wave changes of animals during sleep through instruments. They found that different kinds of fish, insects, birds and mammals have different sleep patterns. Some animals sleep a lot every day, but each time they sleep for a short time; Some animals only sleep once a day. The rabbit only sleeps for 2 minutes every day, but it takes a nap three times a day for only a few seconds each time. Elephants sleep no more than two or three hours a day and can stay awake for two days in a row. Lions like to sleep. If they are full, they can sleep 18 hours. Horses only sleep for two hours a day, but they can doze off while walking.

Animals sleep in different positions. Elephants and giraffes sleep standing up; The horse sleeps standing or lying on its stomach; Bats sleep upside down; Fish floating in the water, sleeping motionless with eyes open; Dolphins sleep while swimming; Swift slept in a hurry even when flying; The fox dances before going to bed.

Different animals sleep in different ways, and the stories in dreams will be different. When a cat sleeps, it is always on high alert: its ears stand up, its tentacles keep vibrating, and even make a whirring sound, as if catching prey. Goats are the most difficult animals to sleep. In order to get enough sleep, it sleeps with the groundhog. When the situation is dangerous, the sound of the woodchuck screaming is the "signal" for the goat to escape. When a parrot sleeps, it often wraps its head under its wings and purrs like a cat. And orangutans sleep like people, apes sit against the wall and sleep, their heads hang down and monkeys wake up. If anything happens, they will wake up.

Are animal dreams like our human dreams a repeat of some scenes? According to Russian media reports, a new study shows that when a mouse enters a "dream", the scene it experienced on this day will pass before its eyes like a movie. Scientists believe that this phenomenon is very similar to the effect of human dreaming. This study confirms that the animal's brain will also recall the "past" and play it back in dreams.

Matt Wilson of the Massachusetts Institute of Technology said: "This study brings us closer to understanding the nature of animal dreams and enables us to grasp the role of dreams in dealing with past memories. "In previous similar research activities, Wilson has determined the movement of hippocampus (an area of the brain that participates in emotional formation and converts short-term memory into long-term memory) during sleep and nighttime activities. Studies have shown that rodents can indeed retain memories of past events. During the experiment, the various stimuli experienced by sleeping mice were "awakened" again. However, Wilson and others didn't understand how much these stimuli were related to the real scenes experienced by mice. What humans see in sleep is usually a very clear image, and its characteristics are like showing a movie. In order to determine whether there is a similar phenomenon in the brain activity of mice, scientists conducted a special experiment.

When mice were in different experimental mazes, the researchers measured the activity of hippocampus and visual center in their brains. When the maze changes, the activity of the above areas in the mouse brain will also change. Later, when the mice were asleep, scientists made repeated measurements of their brains. The results show that the "life scene" reflected in the mouse brain is exactly what you see when you run in the maze. Data of brain activity in mice show that they can also remember what they see.

In addition, scientists also recorded the activities of nerve cells in different areas of the mouse brain. The results show that these cells that are active in the maze are also very excited during sleep.