Thursday, April 1, 2010

Song Birds Give Insight to Human Language

An analysis of the zebra finch genome has identified more than 800 genes that have a role in the baby male chicks' ability to learn songs from their fathers.

The work carried out by a consortium of more than 20 international institutions could also help identify the genetic and molecular origins of speech disorders in humans. Researchers say it could lead to genetic clues related to autism, stroke, stuttering and Parkinson's Disease.
"The zebra finch genome will be a valuable tool for neuroscientists," says lead author Professor Wes Warren, of Washington University's Genome Centre, who also helped organize the genome sequencing project.

"They can now carry out studies to identify a core set of genes in the zebra finch brain involved in both hearing and producing song and then look to see if any of these genes are disrupted in people with speech disorders."
The male zebra finch (Taeniopygia guttata) was chosen by researchers for several reasons. The birds are easy to work with in captivity. Their quick growth allowed researchers to study whole generations in just three months. Mostly, the finch was chosen because of its ability to learn complex songs from its father, in a similar manner to how humans learn speech from parents. Young male fledglings at first seem to make random sounds, much like the babbling of human babies. With some practice, the young bird soon learns to imitate his father's song precisely. After the bird has mastered his family's song, he will sing it for the rest of his life and teach it to his offspring.

The analysis of the zebra finch genome showed that during the period when a young male finch is learning its family song, many genes in the brain get switched on or off. It was also found that many of the genes are an unusual type whose main function seems to be switching other genes on and off.
The system for singing has much more complexity than we imagined,” said co-author Erich Jarvis, Ph.D., Duke professor of neurobiology and a Howard Hughes Medical Institute Investigator.

“In the part of the brain that controls learning how to sing, about 5 per cent of the genes are regulated by the action of singing. I thought there might be 100 genes, but our laboratory found that there are at least 800 regulated genes turning off and on, and there may be many more.”
"The sophistication, the speed and the complexity is just amazing to me," [Prof. Wes] Warren says. And even though birds diverged from human ancestors more than 300 million years ago, both species seem to rely on many of the same genes for vocal communication, he says.
Scientists think this type of gene may be one of the keys to making vocal learning possible in a limited number of species, including bats, whales, elephants, birds and people. The research could help find genetic explanations for disorders that affect speech or communication. The findings could also have an impact on research into deafness and language learning after the critical learning period.

Zebra finches are just the second bird to have their genome sequenced. The first was the chicken.

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