kenny
11-30-2006, 12:32 PM
hi all
Bird's secret hovers in brain
Scientists find larger visual-movement detectors in hummingbirds
UNNATI GANDHI
From Wednesday's Globe and Mail
For something that weighs as little as three grams, the hummingbird has long captured some big minds with its unique ability to hover over flowers while remaining perfectly still.
But its secret has finally fluttered out.
A pair of researchers from the University of Alberta have pinpointed a section of the tiny bird's brain that may be responsible for its unique ability to stay motionless midair, ending decades of guesswork by researchers fascinated by the world's smallest bird.
"From a pure science perspective, it's just amazing that they can do this because they're staying perfectly stationary in space for long periods of time, despite the fact that their wings are beating at like 75 times per second, which really must be jerking them around," said Dr. Doug Wong-Wylie, who holds the Canada Research Chair in Behavioural and Systems Neuroscience and who co-wrote the study with a colleague from the University of Alberta, Dr. Andrew Iwaniuk.
Previous research into how the hummingbird is able to maintain a stable position in space, despite gusts of wind that could throw it off, has looked at physiological explanations ranging from its enlarged heart, to its unique bony shoulder blade structure, to its high metabolic rate.
But no researchers had looked at the hummingbird's brain to identify how it can hover.
Dr. Wong-Wylie and Dr. Iwaniuk found that a specific nucleus -- one that detects any movement of the entire visual world -- was two to five times bigger in the hummingbird than in any other species, relative to brain size. The hummingbird's brain is about the size of a grain of rice.
"If you want to make sure you stay stationary, you just have to make sure nothing on the retina moves. That's what this nucleus does," said Dr. Wong-Wylie, who has been studying the lentiformis mesencephali nucleus in different species for about 20 years.
He gave the example of standing still while balanced on one foot.
"If you close your eyes, it won't be as easy, and the reason for this is that you can't use visual information to help you stay stationary."
Part of the reason this type of research hasn't been conducted before is because it's difficult to have access to hummingbird specimens.
They're extremely uncommon in Canada, because hummingbirds come from exotic locales and they are difficult to catch, Dr. Iwaniuk said.
The researchers, whose study will be published in the January issue of the Journal of Comparative Neurology, were able to get the birds from the National Museum of Natural History, the Field Museum of Natural History, and the Louisiana State University Museum of Natural Science.
"It's really cool," said Dr. Wong-Wylie, who has been fascinated with hummingbirds for as long as he can remember, not only because they hover but because they're the only bird that can fly backwards.
"We're always talking about wanting to design autonomous robots that can do this, that can maintain their stability. Well, they're going to have to look at the hummingbird to design one."
ken
Bird's secret hovers in brain
Scientists find larger visual-movement detectors in hummingbirds
UNNATI GANDHI
From Wednesday's Globe and Mail
For something that weighs as little as three grams, the hummingbird has long captured some big minds with its unique ability to hover over flowers while remaining perfectly still.
But its secret has finally fluttered out.
A pair of researchers from the University of Alberta have pinpointed a section of the tiny bird's brain that may be responsible for its unique ability to stay motionless midair, ending decades of guesswork by researchers fascinated by the world's smallest bird.
"From a pure science perspective, it's just amazing that they can do this because they're staying perfectly stationary in space for long periods of time, despite the fact that their wings are beating at like 75 times per second, which really must be jerking them around," said Dr. Doug Wong-Wylie, who holds the Canada Research Chair in Behavioural and Systems Neuroscience and who co-wrote the study with a colleague from the University of Alberta, Dr. Andrew Iwaniuk.
Previous research into how the hummingbird is able to maintain a stable position in space, despite gusts of wind that could throw it off, has looked at physiological explanations ranging from its enlarged heart, to its unique bony shoulder blade structure, to its high metabolic rate.
But no researchers had looked at the hummingbird's brain to identify how it can hover.
Dr. Wong-Wylie and Dr. Iwaniuk found that a specific nucleus -- one that detects any movement of the entire visual world -- was two to five times bigger in the hummingbird than in any other species, relative to brain size. The hummingbird's brain is about the size of a grain of rice.
"If you want to make sure you stay stationary, you just have to make sure nothing on the retina moves. That's what this nucleus does," said Dr. Wong-Wylie, who has been studying the lentiformis mesencephali nucleus in different species for about 20 years.
He gave the example of standing still while balanced on one foot.
"If you close your eyes, it won't be as easy, and the reason for this is that you can't use visual information to help you stay stationary."
Part of the reason this type of research hasn't been conducted before is because it's difficult to have access to hummingbird specimens.
They're extremely uncommon in Canada, because hummingbirds come from exotic locales and they are difficult to catch, Dr. Iwaniuk said.
The researchers, whose study will be published in the January issue of the Journal of Comparative Neurology, were able to get the birds from the National Museum of Natural History, the Field Museum of Natural History, and the Louisiana State University Museum of Natural Science.
"It's really cool," said Dr. Wong-Wylie, who has been fascinated with hummingbirds for as long as he can remember, not only because they hover but because they're the only bird that can fly backwards.
"We're always talking about wanting to design autonomous robots that can do this, that can maintain their stability. Well, they're going to have to look at the hummingbird to design one."
ken