November 13, 2008

Songbirds Sing From Internal Song Books

A new study shows that songbirds learn to sing from a hymn sheet in their head.

Researchers found a region of the Zebra Finch brain had what they believe to be an internal recording of how the birds ought to be singing.

The Swiss research team wrote in the journal Nature that a separate region of the brain seems to enable birds to identify mistakes in their songs.

According to scientists from Zurich University this research could shed light on how humans learn to speak.

The electrical activity of cells in the zebra finches brains were monitored as the birds were singing and listening to recordings of other zebra finches.

Some neurons were constantly active, as if the finches were listening to a recording in their brain.

When the birds made a mistake, or when they heard recordings of songs which featured disturbances or disruptions, other cells became active.

These cells are the ones that enable the birds to learn from their errors, according to lead author Professor Richard Hahnloser of the University of Zurich.

"This is a proof of concept that birds do actually listen to their own songs, and they do seem to be comparing it to something that they expect, or would like to hear," he said.

"So these neurons could give us a clue of how the birds learn their songs, with reference to some song that they've previously stored in their brain".

It has been assumed that humans learn to use complex vocal patterns by first listening to their speech and then comparing it to patterns stored in the brain, like songbirds.

The closest relative to humans are the great apes, who do not speak, so songbirds may provide a better model to observe how speech develops.

Scientist used zebra finches to identify the "clock" that controls the timing of complex vocal behavior in songbirds.

Both birdsong and human speech require precisely timed execution.  However, the specific brain circuits involved in the timing were unknown.

Michael Long and Michale Fee, both researchers, attempted to identify these "clocks" by cooling down the cells in different areas of the finches' brain.

A region known as the high vocal center slowed the finches' songs down by 45% when cooling the temperature of that region.

This cooling did not affect the sequences of the notes sung.  This suggests the "clock" that regulates the timing of birdsong lies in the HVC.

The team from Massachusetts Institute of Technology suggests that its technique could help identify the "clocks" for other complex behavior.

Image Courtesy Adrian Pingstone - Wikipedia


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