Cheep Dreams.

Have trouble remembering the lyrics to a favorite new song? Sleep on it!

That's what songbirds may do, a new study shows. Songbirds--lead vocalists of the animal world--appear to dream about the songs they sing during the day. Dreaming may be a form of "rehearsal" that improves their performance the next day.

To conduct their study, biologist Daniel Margoliash and colleagues at the University of Chicago compared the activity of neurons (nerve cells) in the brains of a dozen zebra finches, a type of songbird. They surgically attached a wire to a part of the bird brain called the robustus archistriatalis (roh-BUS-tuhs ark-is-tri-uh-TAL-is), or RA. The RA is connected to neurons that directly control muscles in the syrinx, or bird's song-producing organ located at the base of the throat.

Then researchers played recordings of bird songs to wakeful and sleeping birds. They wanted to see what, if any, effect the songs had on the birds' brain activity. Electrical signals from the birds' brains pulsed through the wires to an amplifier measuring brain activity.

To researchers' surprise, the music stimulated the birds' RA as they slept--as though the birds were "rehearsing" their own songs by silently dreaming about them. "It's possible that songs learned during the day affect the bursting patterns of the RA at night," says Margoliash. "They could serve to solidify the newly learned songs in the bird's mind."

By comparison, RA neurons in wide-awake birds showed no unusual response to the recordings --merely a normal, steady brain pattern. The biologists can't say for sure that birds perform better after a good night's rest. But their findings support another suspicion: sleep may help birds and other creatures fine-tune their memory through sleep rehearsal of daytime tasks.

Researchers plan to conduct similar tests in young zebra finches just learning to sing. Stay tuned.