Mouse Study Sheds New Light on How Memories Are Stored10/08/12
MONDAY, Oct. 8 (HealthDay News) -- During sleep, and even under
anesthesia, part of the brain behaves as if it's remembering
something, new animal research suggests.
The finding about the entorhinal cortex -- which is involved in
learning, memory and Alzheimer's disease in humans -- challenges
conventional theories about memory consolidation during sleep, the
University of California, Los Angeles researchers said.
For the study, which was performed on mice, the researchers
measured the activity of single neurons from three parts of the
brain involved in memory formation in order to identify which brain
region was activating other areas of the brain and how this
activation was spreading.
The investigators discovered that the entorhinal cortex has what
is called persistent activity, which is believed to be involved in
working memory when people are awake, such as remembering a phone
number or following directions.
"The big surprise here is that this kind of persistent activity is happening during sleep, pretty much all the time," study senior author Mayank Mehta, a professor of neurophysics, said in a UCLA news release. "These results are entirely novel and surprising. In fact, this working memory-like persistent activity occurred in the entorhinal cortex even under anesthesia."
Persistent activity in the entorhinal cortex during sleep may be
a way to unclutter memories and delete information that was
processed during the day but not needed, which results in important
memories becoming prominent and readily accessible, Mehta
The findings are important because people spend one-third of
their lives sleeping, and a lack of sleep causes various health
problems, including learning and memory problems, Mehta said. The
researcher also noted that Alzheimer's disease starts in the
entorhinal cortex and these patients are known to have sleep
However, experts point out that results from animal research are
not necessarily applicable to humans.
The study was published online Oct. 7 in the journal
The U.S. Centers for Disease Control and Prevention has more
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