http://www.eurekalert.org/pub_releases/2006-11/uoa-uoa112906.php
Public release date: 29-Nov-2006
University of Alberta researchers discover hummingbird secret
Scientists identify part of the hummingbird's tiny bird brain that
helps it hover
Hummingbird genera Doryfera
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University of Alberta researchers have pinpointed a section in the tiny
hummingbird's brain that may be responsible for its unique ability to
stay stationary mid-air and hover.
"This was a very exciting moment for us," said Dr. Doug Wong-Wylie,
Canada Research Chair in Behavioural and Systems Neuroscience and
psychology professor at the U of A. "As soon as we looked at these
specimens it was obvious that something was different in the
hummingbirds' brains than other species."
Wong-Wylie and Dr. Andrew Iwaniuk, also from the Department of
Psychology in the Faculty of Science, compared hummingbird brains to 28
other bird species, obtained from the National Museum of Natural
History, the Field Museum of Natural History, and the Louisiana State
University Museum of Natural Science. Hummingbirds are well known for
their wing speed and ability to hover and fly forward and backward with
more precision than a helicopter. It is critical that the hummingbird
remain perfectly still as it feeds itself while darting in and out of
flower blossoms with pinpoint accuracy. The bird must be able to
maintain a stable position space, despite the fact that their wings are
beating 75 times per second and that disruptive effects such as wind
gusts could throw them off.
Much work has been done on the hummingbirds' physiological make up—such
as its enlarged heart, high metabolic rate and specialized wing
kinematics--but nothing has been done on the neural specializations of
the bird.
"Part of the reason this type of work hasn't been done before is
because of access to the birds," said Iwaniuk. "In Canada especially
they tend to be uncommon, they come from exotic locales and they are
not easy to catch, so we were very fortunate to be able to study the
specimens we did."
The scientists found that a specific nuclei—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 smaller than a fingertip. "We reasoned that this
nucleus helps the hummingbird stay stationary in space, even while
they're flying," said Wong-Wylie. "These birds must have a good
optomotor response considering they are stationary 90 per cent of the
time. This specific nuclei is likely responsible for that."
Wong-Wylie and Iwaniuk plan to continue this line of research and have
hummingbirds track visual motion while watching the nucleus to see how
it reacts.
###
This research is published early online in "The Journal of Comparative
Neurology" and will come out in its print edition in January.
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