- WASHINGTON (Reuters) - It's
a tough life being a laboratory rat -- being made to run maze after maze,
for hours on end, with only a few chocolate sprinkles as pay.
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- In fact, it's such a demanding job that the rats actually
dream about it, researchers said on Wednesday.
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- ``We know that they are in fact dreaming and their dreams
are connected to actual experiences,'' Matthew Wilson of the Center for
Learning and Memory at the Massachusetts Institute of Technology, who led
the study, said in a statement.
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- Writing in the journal Neuron, they said their findings
were not only fascinating but could shed light on what dreams do for humans.
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- Wilson and graduate student Kenway Louie taught the rats
to run around a circular track in exchange for treats.
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- ``We give them little chocolate sprinkles -- little decorator
sprinkles. They like that,'' Wilson said in a telephone interview.
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- They implanted tiny electrodes in the rats' brains --
a procedure that scientists say is painless and allows them to monitor
the activity of individual neurons.
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- They focused on the hippocampus, which is the part of
the brain where, in humans, memories of experiences are formed.
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- They monitored the rats' brain activity while they ran
the maze, and then monitored what the brains did when the animals slept.
Like all mammals, including humans, rats go through phases of rapid eye
movement (REM) sleep, which in humans correlates with dreaming.
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- The patterns were so similar that the researchers could
tell where on the maze the rats were in their dreams and how fast they
were dreaming they were running.
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- ``We could identify what segment and what the pattern
of the running activity was during this REM sleep -- literally what they
were doing -- how they were running, where they were running,'' Wilson
said.
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- ``Remarkable And Amazing''
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- ``It's remarkable and amazing to us. I can tell you the
first time I saw this it was the most amazing thing I had ever seen --
the pattern of firing of cells in the brain,'' he said.
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- Wilson believes the rat dreams have a purpose. Research
has shown that humans and other animals learn -- even tasks -- better when
they literally sleep on it.
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- The rat work suggests dreams may be a literal rehearsal.
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- ``We believe the reactivation of memory during sleep
has some importance in the formation of memories,'' he said.
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- ``We are trying to learn from experiences, trying to
take in things while awake. We are finding the rules and regulations, trying
to figure out how the world works.''
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- It also shows that the brains of rats are more complex
than had been believed. The dream sequences lasted for minutes at a time.
Scientists had not known whether lower animals such as rodents could recall
such long sequences of events.
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- ``I think it does force us to think about animal cognition,''
Wilson said.
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- And that brings up the question of how ``dumb animals''
are treated.
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- ``I am an animal researcher. You might think my staunchest
enemies might be those involved in animal rights. But we are concerned
about animal welfare,'' Wilson said.
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- Next, Wilson and Louie plan to see if the neural activity
correlates with the movements the rats make in their sleep. ''Their legs
twitch, their whiskers move. They are expressing certain suppressed motor
patterns that might relate to what they are actually dreaming about,''
Wilson said.
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- Wilson's work reinforces a study last year in which a
team at the University of Chicago found that songbirds dream about their
singing. Daniel Margoliash and colleagues also used implanted wires to
monitor the brain activity of birds while they sang and while they slept.
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