Botox Sheds Light on Alzheimer's

The injection introduces an error signal by making the bird sing a tune it really doesn't want to hear. The bird then struggles mightily to correct its song, and that — according to the theory — could stimulate all sorts of brain activity, including the regeneration of neurons. It's still too early to tell if that is happening but previous research suggests that it should.

Some of the birds in Kirn's lab have been deafened, and the time in their lives when the deafening occurred turns out to be crucial.

"If you deafen an adult bird, it's song will gradually degrade," he says, but if the bird is quite old, the degradation is much less than if the bird is younger. The older the bird is, the better its song, so the bird needs very little "auditory feedback" to maintain the right tune.

And that turns out to be very important because older birds produce fewer new neurons, and the decrease in production corresponds quite nicely with the decline in the bird's reliance on that auditory feedback.

The bird doesn't need to hear itself singing to maintain its song, so it doesn't need to keep fiddling with its "mental machinery," as Kirn puts it, and thus it grows fewer and fewer new neurons. In addition, fewer neurons die, so the bird has achieved a perfect balance, no longer needing to make adjustments in its level of neurons.

That would suggest — and at this point suggest is the right word — that the long effort to sing correctly is at the heart of the zebra finch's ability to grow new neurons."

Nobody in Kirn's lab is suggesting that Botox will cure Alzheimer's. But if it allows the researchers to pinpoint the precise way that the birds maintain their mental machinery as they age, that better understanding might lead to human applications further down the road. Strokes, Alzheimer's and paralysis result from, or cause, a reduction in neurons and a devastating loss of mental faculties."

So the hope here is that this kind of research will eventually help humans do what the tiny zebra finch does so easily. Just the thought of it is enough to make you want to sing.

Lee Dye’s column appears weekly on A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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