Rats 'can dream just like humans'
Scientists have peered into the dreams of rats and discovered they
can be as complex as those of humans.
Researchers were able to pinpoint when rats were dreaming about running
around a circular maze in search of a food reward.
By monitoring their brain activity, they were able tell where the animals
would be in the maze had they been awake, and whether they were dreaming
of running or standing still.
While dogs and cats often seem to dream, and studies have shown that
mammalian brains follow the same series of sleeping states, this is the
first research to indicate what animals are dreaming about.
Dr Matthew Wilson, from the Centre for Learning and Memory at the Massachusetts
Institute of Technology, Boston, said: "No one knew for certain that animals
dreamed the way we do, which can involve replaying events, or at least
components of events, that occurred while we were awake.
"We looked at the firing patterns of a collection of individual cells
to determine the content of rats' dreams. We know that they are in fact
dreaming and their dreams are connected to actual experiences."
Dr Wilson told the annual meeting of the American Association for the
Advancement of Science how his team first trained rats to run along a circular
maze for a food reward.
They monitored the animals' brain activity during the task and when
they were asleep. As each rat ran, its brain produced a distinctive pattern
of neurons firing in the hippocampus, a brain region known to be involved
The rats' brain activity was again recorded during REM (rapid eye movement)
sleep - a sleep phase which in humans is when most dreaming occurs.
In about half of more than 40 episodes of REM sleep examined, researchers
found a repeat of the unique signature of brain activity created as the
rats ran in the maze. The correlation was so close that it was possible,
as an animal dreamed, to reconstruct where it would be in the maze if it
was awake and how it would be moving.
Story filed: 13:27 Tuesday 19th February 2002