FROM THE TWITCHING WHISKERS OF BABES, NAP TIME BEHAVIOR SHAPES THE BRAIN
The whiskers of
newborn rats twitch as they sleep, and that could open the door to new
understandings about the intimate connections between brain and body. The
discovery reinforces the notion that such involuntary movements are a vital
contributor to the development of sensorimotor systems, say researchers who
report their findings along with video of those whisker twitches on Oct. 18 in Current Biology, a Cell Press publication
"We found that
even whiskers twitch during sleep -- and they do so in infant rats long before
they move their whiskers in the coordinated fashion known as whisking,"
said Mark Blumberg of The University of Iowa. "This discovery opens up new
avenues for investigating how we develop critical connections between the
sensors in our body and the parts of the brain that interpret and organize
sensory information."
In fact, the baby
rats' whiskers don't just twitch, they twitch very rapidly and in complex ways.
Those twitches during sleep are tied to bursts of activity in the brain, which
aren't often observed when rats are awake.
Other parts of the
body twitch spontaneously during sleep, too, including the eyes (think
"rapid eye movements") and the limbs. "Spontaneous motor
activity can play many different roles in early development and even throughout
life," Blumberg explains. "It can be a source of brain activity in
general as well as a source of highly specific, patterned activity that can
help shape specific neural circuits."
But no one had given
much thought to this activity in the very special case of whiskers, which are
as important to rats as eyes are to humans. Each individual whisker maps to
discrete regions of the brain that process information from that individual whisker
alone. The whisker-specific brain regions form arrangements that map
beautifully to the physical arrangements of whiskers on the snout.
That precise
organization has made the study of whiskers very popular amongst
neuroscientists seeking a basic understanding of the developmental mechanisms
linking peripheral sensors and brain, and that's what makes this new discovery
all the more intriguing. It might also give us a new appreciation for the
important work infants are doing even as they sleep.
"One of the jobs
of the infant is to learn how all the parts of the body function even as those
parts are growing in size and proportion," Blumberg says. "It is a
difficult job."
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