brain remembers things better, but why? In a recent study,
psychiatrist Giulio Tononi at the University of
Wisconsin—Madison and his colleagues found evidence that sleep
actively cements the connections between brain cells that allow
us to learn new skills.
the study, 11 volunteers learned to play a simple game that
required them to move a cursor between different locations on a
computer screen. Prior research had shown that playing this game
activates an area called the right posterior
parietal cortex, which lies behind and above the
A week later, the
participants in the study played the same game just before going
to sleep. Unknown to them, the scientists made the task more
difficult by slightly skewing the location of the target area.
The players were able to compensate for the change and learn how
to reach the target accurately.
As the gamers slept, the scientists used
electroencephalogram (EEG) recordings to tune in on a
distinctive type of electrical rhythm that occurs in the brain
during sleep. Called slow wave activity (SWA), it represents the
synchronized firing of large numbers of brain cells. The EEGs
showed increased SWA in right posterior parietal cortex. People
who showed the greatest increase in SWA demonstrated the most
skill in later rounds of the game.
The study is
exciting because it essentially catches the brain in the act of
learning. It suggests that as we sleep, SWA helps to strengthen
connections made between individual brain cells during our
waking hours. This provides insight into the role that sleep
plays in transforming experience (in this case, playing the
computer game) into a form of
long-term memory (greater skill at manipulating the
"Local Sleep And Learning,"
by Reto Huber, PhD, and others. (Nature, July 1, 2004, Volume
430, pp. 78-81.)