ljh at ljh at
Sat Aug 5 11:36:34 EST 1995

There was an interesting article in Scientific American (November 1990)
that suggests that sleep is important to memory formation. The article is
"The Meaning of Dreams," by Jonathan Winson. He remarks on p. 92 that
"In 1989 Pavlides and I located two CA1 neurons in the rat hippocampus that
had different place fields. We recorded from both cells simultaneously.
After determining the normal firing rates in awake and asleep animals, we
positioned the rat in the place field of one of the neurons. The neuron
fired vigorously, mspping that location. The second cell fired only
sporadically because it was not coding space. We continued recording from
the two pairs of neurons as the rat moved about and then entered several
sleep cycles. Six pairs of neurons were studied in this manner.
"We found that neurons that had coded space fired at a normal rate as the
animal moved about prior to sleep. In sleep, however, they fired at a
significantly higher rate than their previous sleeping baseline. There was
no such increase in firing rate during sleep in neurons that had not
mapped space. This experiment suggested that the reprocessing or strengthening
of information encoded when the animal was awake occurred in sleep at the
level of individual neurons."

Don't know if it's been replicated, but it sure is interesting.

Lisa J. Harris

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