A new study finds dreams play a role in helping the brain sort through memories.
By Maggie Fox
The Associated Press
Oct. 14, 2000
A study involving people with amnesia, a popular computer game and sleep experts
may help explain why dreams are so weird and so important, experts said Thursday.
They said people with amnesia who played the popular computer game Tetris dreamed
about the images it invoked, but could not remember actually playing the game.
And, unlike people with normal memories, they never really got any better at the
game.
Subconscious Filing
This shows that when the brain is filing away the memories it needs to keep, it
has to go through a series of steps, and dreaming is a manifestation of one crucial
step, Dr. Robert Stickgold, a psychiatrist at Harvard Medical School in Boston,
who led the study, said.
Dreams are just the bodys way of clearing out the mental in-box,
Stickgold said.
The trick is to move it to the file cabinet and to file it in the right
place, Stickgold said in a telephone interview.
A lot of REM [rapid eye-movement] dreams, those really quirky, strange,
bizarre dreams that we have late at night, is the brain looking for ways to cross-index.
It is looking for cross references does this fit with this? Sometimes it
does and sometimes it doesnt, he said.
When it doesnt fit, the dream seems weird, he said. When the cross-reference
is a good one, the brain can reinforce the memory.
One way to test this is to look at people who are missing one of those vital memory
steps people with amnesia.
Tetris on the Brain
Stickgold had noticed that when he skied, he had vivid dreams about it.
When you go downhill skiing, when you go to sleep, you can feel the turns,
he said. This would make a good test, he said, but added he knew he would never
get the OK to take first-timers downhill skiing for a scientific experiment.
And then someone mentioned Tetris, a computer game that uses vivid images of falling
and rotating shapes that have to be manipulated by the player.
It, too, evokes dreams, Stickgold said. I play Tetris, that is all I see
going to sleep, he said.
Writing in todays issue of the journal Science, Stickgold and colleagues
said nearly two-thirds of the 27 volunteers they asked to play Tetris had dreams
about it.
Their group included five people with amnesia, caused by disease, stroke and other
accidents. Experts at the game and first-time players were also tested.
People in both groups reported that, as they fell asleep, they dreamed about images
of blocks falling and rotating, as they do on the computer screen when the game
is in progress. They did not actually dream about the game itself.
The amnesia patients did not remember playing the game and they did not ever improve,
unlike the volunteers with normal memory. Three of them did report the strange
dreams, however.
What You Did vs. What You Like
What these results, especially from the amnesics, tells us is that when
the brain puts dreams together, it does it without knowledge of and access to
memories of actual events in our life, Stickgold said.
We have two different memory systems. The hippocampal codes information
on events from our lives. So when I ask you what did you have for breakfast, you
go to the hippocampus for the answer, he added.
A second system is the neocortical, he said, referring to another
area of the brain.
So when I ask you when we go out for breakfast what do you like for
breakfast? that is a different type of question. When you go for that general
information you go to neocortex. An amnesic can tell you what they like for breakfast.
They cant tell you what they had for breakfast.
This is because their hippocampus is damaged. The findings suggest that the brain
does not go to the hippocampus to get images for dreams, but to the long-term,
neocortical system, the researchers said.
Copyright 2000 The Associated Press.
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