20 (Xinhuanet) -- When rats snuggle up for a nap, they replay "movies" of
their daily activities in what scientists suggest is the animal equivalent of
dreaming, a new study suggests.
When rats snuggle up for a nap, they
replay "movies" of their daily activities in what scientists suggest is
the animal equivalent of dreaming, a new study suggests. (File Photo)
The research supports the idea that memories are
cemented into the brain during sleep.
"This work brings us closer to an understanding of
the nature of animal dreams and gives us important clues as to the role of sleep
in processing memories of our past experiences," said co-researcher Matthew
Wilson at the Massachusetts Institute of Technology (MIT).
In a past study, Wilson measured activity in
rats' hippocampuses, the brain's memory center, while awake and sleeping. He found
that rats did form memories of events they experienced while awake, and that the
rodents replayed the memories while snoozing. But whether the rats replayed
actual images was unknown.
In human dreams, vivid images typically weave
together to form a memory movie. To find out if rats replay visuals, Wilson and
Daoyun Ji, also of MIT, measured brain activity in the hippocampus and visual
cortex while rats ran through mazes with different designs on the floors and
walls. The brain regions showed specific patterns as the animals sensed their
surroundings in the maze.
Also, the scientists recorded activity of individual
neurons in the rats' brains while the animals were awake and asleep. They found
that the same neurons spiked during wakeful play got reactivated during sleep.
From this the scientists infer that during sleep,
neurons in the visual region "talk" to those in the hippocampus in a sort of
"conversation," suggesting that rat naps help consolidate daily experiences and
make these memories stick.
For the first time, this work shows that the brain is
replaying memory events in two locations at once, in the visual and memory