Practice is for the birds

An article from scienceblog.net regarding "sleep and practice" with song birds is extremely interesting. It says something about "practice makes perfect."

According to a study published in Nature, sleep helps young birds master the art of song, and it does so in a surprising way. The study reveals that when zebra finches first wake up, the best of them are actually dramatically worse singers than they were the day before. It seems that individual birds that initially perform the worst during their "morning rehearsals" eventually become the best singers of all.

The study examined the effect of sleep on song learning in young
zebra finches. Individuals of this species are active in the
daytime, do not sing in darkness, and develop their song during a
critical window of "brain plasticity" between one and three months
after hatching.

In order to learn to sing, it's known that young birds must hear an
adult song, and through practice, develop their own version of the
tune by comparing their vocalizations to a memory template of the
song that they "hear in their heads."

Interestingly, researchers have previously found that zebra finch
brain neurons involved in vocal learning display patterns of
activity while the birds are asleep that are similar to the patterns
observed while awake birds are singing. Until now, however, there
has been no direct evidence that sleep affects song learning, and if
so, how.

To collect the data used in the study, City College New York
behavioral neuroscientists Ofer Tchernichovski and Sébastien
Derégnaucourt recorded every vocalization--approximately a million
syllables per bird--made by 12 young male zebra finches over several
months as the birds learned to imitate and perfect their own
renditions of recorded adult male zebra finch songs.

To assess the musical progress or lack thereof of the young birds,
Tchernichovski worked with Cold Spring Harbor Harbor Laboratory
theoretical neuroscientist Partha Mitra to develop algorithms that
became the basis of powerful software for analyzing the structure
and patterns of animal vocalizations (Sound Analysis Pro).

Surprisingly, instead of showing gradual improvement in which they
might wake up each day and "pick up where they left off" in their
vocal abilities, many of the birds displayed dramatic degradation in
the quality of their songs relative to how well they performed at
the end of the previous day. However, the quality of these birds'
songs improved after intense morning rehearsal to the point where by
the end of each new day, their singing was indeed better than the
day before.

The study yielded another counterintuitive result, namely, that
birds which ultimately learn to sing better than others--at the end
of their three months of rehearsal--actually awaken from sleep each
day as poorer singers than their ultimately less tuneful
counterparts (i.e. they have "stronger post-sleep deterioration" of
song development).

"We have more work to do to explain this 'one step back, two steps
forward' effect of sleep on the brain circuits that govern vocal
learning. But a useful analogy for now is the tempering of steel, in
which to gain its ultimate structure and strength, it is first
weakened," says Mitra.

Vocal learning in songbirds bears similarities to human speech
development: Novice birds go through a period of "screeching" before
learning to imitate songs accurately, much as babies babble before
grasping words. Therefore, the new research points to a need for a
quantitative study of the effects of sleep on learning in human
infants, says Mitra.

From Cold Springs Harbor Laboratory

Posted by Ed Reggi on March 24, 2005 01:45 PM in Articles
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