The next time someone calls you a ``birdbrain,'' take it as a compliment. A University of Chicago researcher has learned that tiny Zebra finches are so smart that they silently practice their songs while they're asleep.

Daniel Margoliash, an associate professor in the department of organismal biology and anatomy, placed a tiny recording device attached to the skull of the small, gregarious birds. The device monitors the activity of brain cells called neurons, which send out and receive electrical impulses.

He found that his pint-size bird subjects showed a pattern of brain signals that was exactly the same as the one they displayed while singing their characteristic songs during the day. Although the birds didn't give voice to the songs at night, their brain waves proved they were rehearsing their musical repertoires while snoozing, Margoliash said.

Bird's Brain Reacts to Music

And he found even more evidence that the bird's brain reacted to the music when he played the song on tape as the bird slept. Again, the bird's neurons fired in tune to the familiar music, as the bird lay asleep and silent, said the researcher. Sleep was the common denominator.

``When the bird is awake the neurons fire vigorously. Otherwise, when he's awake and you play back songs, he doesn't respond. When he sleeps, the neurons burst and those patterns match his singing,'' he said. ``And when you play back songs when the animal is sleeping, the neurons respond.''

Margoliash's research is aimed at finding out more about how animals – and people – learn and remember. More specifically, he wants to know how the brain processes sounds, translating them into muscle activity that produces singing.

Sleeping Birds the Key

He turned to sleeping birds because animals that were awake showed no evidence of the rehearsal behavior. ``The way to think of it is a musician who struggles with some difficult passage during the day,'' Margoliash said. ``And he comes back in the next day and is doing remarkably better. There is certainly evidence that sleep helps in various tasks of humans. What's special here is we may be learning more about the actual mechanism of it.''

Young birds listen to adult singers to learn their tunes. The research suggests their brains store the complex musical information and practice it as a sort of dream, when other stimuli aren't there to interfere with learning.

Before he could move forward, Margoliash had to devise a device that was small enough to fit on the head of a Zebra finch and could measure the activity of neurons, brain cells that receive and send out electrical impulses.

Only the male of the Zebra finch sings, part of his seduction routine. The tiny birds, which weigh about 10 grams, are native to Australia and Timor, but are popular house pets worldwide. They are highly social with each other and reach sexual maturity after only about 90 days.

``It's a very nice, hardy little animal and makes for a very nice pet,'' said Margoliash, but he admitted he hadn't picked the bird for its musical prowess. The Zebra finch's song is ``a cross between a squeaky door and Bugs Bunny,'' he said.