Animal dreaming

What animals dream -or even if they really dream-, has always been an unanswered question, resistant to scientific scrutiny. But now, two researchers studying memory produced evidence that during sleep, the brain of animals works similarly to sleep in humans.

The animals in question-four rats, seemed to be dreaming about something very specific: the maze they were learning to run. The study was conducted at the Massachusetts Institute of Technology (MIT), published in the latest issue of the journal Neuron, the Center for Learning and Memory at MIT.

The researchers found that patterns of brain activity identified when the rats ran through a circular maze, and they were rewarded with chocolate beans when they reached the three quarters of the way, was duplicated when the rats were sleeping.

The patterns were detected in clusters of neurons in the hippocampus, an area involved with the formation and memory storage. And were reproduced during phases of sleep that in humans are closely related to dreams. They were so precise, that the researchers could determine where in the maze the rat would find if you were awake, and if they would find still or moving.

"Surely the animal is evoking memories of those events that occurred when he was awake, and does the same while sleeping, dreaming," said Matthew Wilson, conductor of the MIT team.

He said the investigation is no exact proof that animals dream. But he noted that while the dream is essentially a subjective experience, the kind of evidence obtained in this type of study is the most they can achieve scientists. "Our ability to ask the animal to count the contents of these states is limited," Wilson quipped.

"Many philosophers and scientists tried to figure out if animals have some sort of awareness of their experiences, and this is strong evidence that they have similar experiences to ours," said Howard Eichenbaum, a professor of psychology at Boston University. Other experts believe that this finding, besides being a step to treat diseases like Alzheimer's and sleep disorders in humans-can support the idea that sleep plays a crucial role in encoding and storing memories.

The study demonstrates for the first time, that episodic memories are recreated or "remade" in the hippocampus during sleep, perhaps representing a process in which memory is consolidated and passed to other parts of the brain, a model championed by several researchers .

Previous studies indicate that when people learn new skills, their performance depends on the extent that we have two types of dream, dreamless slow-wave sleep or while sleeping at the beginning of the night, and the so-called rapid eye movement "REM (acronym in English), reached late at night. In humans, most dreams occur during REM.

Like humans, animals also go through different stages of sleep. Many mammals have REM periods characterized by intense activity in the brain and rapid eye movements. Wilson explained that the rat has a sleep cycle of 12 hours, usually has episodes of REM every 20 minutes, lasting about 2 minutes.

In the future, Wilson and his team hope to extend their work to other parts of the brain, for example, to examine the activity in areas responsible for sensory experience, like sight and smell.

The eventual result, guess the findings might be "a kind of animal correlate of Freudian psychoanalysis, a method to explain how conscious life influences the complexity and content of dreams, and how dreaming affects memory and performance during periods of full awareness.