08 December 2008

Botox for the birds?

Researchers have found a new job for Botox: They've used it to paralyse the vocal cords of songbirds as part of an unusual study on how neurons are born.

Women of a certain age are addicted to it.

Now, researchers have found a new job for Botox, the famous facial wrinkle remover: They've used it to paralyse the vocal cords of songbirds as part of an unusual study on how neurons are born.

Replacing human brain cells
If the ongoing research is successful, scientists will get a better handle on how avian brains regenerate themselves over time. In the long term, the findings could contribute to ongoing efforts to find a way to replace human brain cells killed off by such disorders as Alzheimer's disease, says Dr James Grisolia, a neurologist at Scripps Mercy Hospital in San Diego.

Insights we learn about the birth of new nerve cells will help build a knowledge base that will let us do stem cell grafting and brain transplants in people some day, he says.

Why songbirds are being studied
What do songbird brains have to do with human brains? Not much, and that's the very reason neuroscientists are so fascinated by them.

The birds grow new brain cells throughout their lives, unlike other animals whose brains settle down after they've finished developing. (Some human brain cells appear to regenerate, but only in certain parts of the brain, such as those devoted to memory.)

Research in birds really challenges how we think we know the brain, says study leader John Kirn, an associate professor of neuroscience and behaviour at Wesleyan University in Connecticut, USA. Researchers like to think of the brain as a hard-wired computer, and it's hard to imagine how the brain continues to function when neurons are being replaced all the time, he says.

How the study was conducted
Kirn and his colleagues decided to study bird neurons by forcing songbird brains to kill off nerve cells and replace them with new ones. They did this by tinkering with the vocal cords of 18 zebra finches.

Birdsong itself is extremely unusual in the animal kingdom. Animals other than humans typically come preprogrammed with the ability to make sounds, such as meows or barks. They don't pick up new sounds. But birds learn how to sing over their lives and develop new ways of singing, Kirn explains.

They have a complex series of brain areas dedicated exclusively to the learning, production and perception of song, he says. These areas are completely absent from (for example) a chicken that does not learn its vocalisations.

Botox used to paralyse vocal cords
In their study, the researchers used Botox injections to paralyse the vocal cords of the 18 zebra finches. Botox, technically a neurotoxin, causes paralysis and, when injected into human faces, can smooth out wrinkles by preventing muscles from moving.

The researchers hoped the birds would realise their songs were distorted, kill off the relevant brain cells, and create new ones to fix the situation.

The researchers then anaesthetised the birds and studied their brains to see how they developed after the Botox injections. They indeed found new neurons had grown, and Kirn says the researchers hope to have final results available soon.

Grisolia cautions the findings won't lead to immediate treatments for humans suffering from brain disease. This is a small building block that will have to become a big edifice before it helps people, he says. - (HealthDayNews)

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