The Avian Brain....

[Skyebirdsmom]

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NYTimes.com

Minds of Their Own: Birds Gain Respect
By SANDRA BLAKESLEE

Published: February 1, 2005

Birdbrain has long been a colloquial term of ridicule. The
common notion is that birds' brains are simple, or so
scientists thought and taught for many years. But that notion
has increasingly been called into question as crows and
parrots, among other birds, have shown what appears to be
behavior as intelligent as that of chimpanzees.

The clash of simple brain and complex behavior has led some
neuroscientists to create a new map of the avian brain.

Today, in the journal Nature Neuroscience Reviews, an
international group of avian experts is issuing what amounts
to a manifesto. Nearly everything written in anatomy textbooks
about the brains of birds is wrong, they say. The avian brain
is as complex, flexible and inventive as any mammalian brain,
they argue, and it is time to adopt a more accurate
nomenclature that reflects a new understanding of the
anatomies of bird and mammal brains.

"Names have a powerful influence on the experiments we do and
the way we think," said Dr. Erich D. Jarvis, a neuroscientist
at Duke University and a leader of the Avian Brain
Nomenclature Consortium. "Old terminology has hindered
scientific progress."

The consortium of 29 scientists from six countries met for
seven years to develop new, more accurate names for structures
in both avian and mammalian brains. For example, the bird's
seat of intelligence or its higher brain is now termed
the pallium.

"The correction of terms is a great advance," said Dr. Jon
Kaas, a leading expert in neuroanatomy at Vanderbilt
University in Nashville who did not participate in the
consortium. "It's hard to get scientists to agree
about anything."

Scientists have come to agree that birds are indeed smart, but
those who study avian intelligence differ on how birds got
that way. Experts, including those in the consortium, are
split into two warring camps. One holds that birds' brains
make the same kinds of internal connections as do mammalian
brains and that intelligence in both groups arises from these
connections. The other holds that bird intelligence evolved
through expanding an old part of the mammal brain and using it
in new ways, and it questions how developed that
intelligence is.

"There are still puzzles to be solved," said Dr. Peter Marler,
a leading authority on bird behavior at the University of
California, Davis, who is not part of the consortium. But the
realization that one can study mammal brains by using bird
brains, he said, "is a revolution."

"I think that birds are going to replace the white rat as the
favored subject for studying functional neuroanatomy,"
he added.

The reanalysis of avian brains gives new credibility to many
behaviors that seem odd coming from presumably dumb birds.
Crows not only make hooks and spears of small sticks to carry
on foraging expeditions, some have learned to put walnuts on
roads for cars to crack. African gray parrots not only talk,
they have a sense of humor and make up new words. Baby
songbirds babble like human infants, using the left sides of
their brains.

Avian brains got their bad reputation a century ago from the
German neurobiologist Ludwig Edinger, known as the father of
comparative anatomy. Edinger believed that evolution was
linear, Dr. Jarvis said. Brains evolved like geologic strata.
Layer upon layer, the brains evolved from old to new, from
fish to amphibians to reptiles to birds to mammals. By
Edinger's standards, fish were the least intelligent. Humans,
created in God's image, were the most intelligent. Edinger cut
up all kinds of vertebrate brains, noting similarities and
differences, Dr. Jarvis said.

In mammals, the bottom third of the brain contained neurons
organized in clusters. The top two-thirds of the brain, called
the neocortex, consisted of a flat sheet of cells with six
layers. This new brain, the seat of higher intelligence, lay
over the old brain, the seat of instinctual behaviors.

In humans, the neocortex grew so immense that it was forced to
assume folds and fissures, so as to fit inside the skull.

Birds' brains, in contrast, were composed entirely of
clusters. Edinger concluded that without a six-layered cortex,
birds could not possibly be intelligent. Rather, their brains
were fully dedicated to instinctual behaviors.

This view persisted through the 20th century and is still
found in most biology textbooks, said Dr. Harvey Karten, a
neuroscientist at the University of California, San Diego, and
a member of the consortium, whose research has long challenged
the classic view.

There is a bird way and a mammal way to create intelligence,
Dr. Karten said. One uses clusters. One uses flat sheet cells
in six layers. Each exploits the basic design of having a
lower brain and a higher brain with mutual connections.

In the 1960's, Dr. Karten carried out experiments using new
techniques to trace brain wiring and identify the paths taken
by various brain chemicals. In humans, a chemical called
dopamine is found mostly in lower brain areas, called basal
ganglia, which consist of clusters.

Using the same tracing techniques in birds, Dr. Karten found
that dopamine also projected primarily to lower clusters and
no higher. Later studies show numerous similarities between
clusters in the mammalian brain and lower clusters in the
avian brain. Experts now agree that the two regions are
evolutionarily older structures that lie underneath a
newer mantle.

Where the experts divide is on the question of the upper
clusters in a bird's brain. Agreed, they are not primitive
basal ganglia. But where did they come from? How did they
evolve? What is their function?
overy.com/fansites/petstar/videogallery/season
Dr. Karten and others in the consortium think these clusters
are directly analogous to layers in the mammalian brain. They
migrate from similar embryonic precursors and perform the
same functions. (Continued in part deaux)

[Skyebirdsmom]

For example, in mammals, sensory information - sights, sounds,
touch - flows through a lower brain region called the thalamus
and enters the cortex at the fourth layer in the
six-layered cortex.

In birds, sensory information flows through the thalamus and
enters specific clusters that are functionally equivalent to
the fourth layer. In this view, other clusters perform
functions done by different layers in the mammal brain.

A second group, including Dr. Georg Striedter of the
University of California, Irvine, a consortium member,
believes that upper clusters in the avian brain are an
elaboration of two mammalian structures - the claustrum and
the amygdala. In this view, these structures look alike in
bird and mammal embryos. But in birds they grow to enormous
proportions and have evolved entirely new ways to
support intelligence.

In mammals, the amygdala is involved in emotional systems, Dr.
Striedter said. "But birds use it for integrating
information," he said. "It's not emotional anymore."

Meanwhile, examples of brilliance in birds continue to flow
from fields and laboratories worldwide.

Dr. Nathan Emery and Dr. Nicola Clayton at the University of
Cambridge in England study comparisons between apes and
corvids - crows, jays, ravens and jackdaws. Relative to its
body size, the crow brain is the same size as the
chimpanzee brain.

Everyone knows apes use simple tools like twigs, Dr. Emery
said, selecting different ones for different purposes. But New
Caledonian crows create more complex tools with their beaks
and feet. They trim and sculpture twigs to fashion hooks for
fetching food. They make spears out of barbed leaves, probing
under leaf detritus for prey.

In a laboratory, when a crow named Betty was given metal wires
of various lengths and a four-inch vertical pipe with food at
the bottom, she chose a four-inch wire, made a hook and
retrieved the food.

Apes and corvids are highly social. One explanation for
intelligence is that it evolved to process and use social
information - who is allied with whom, who is related to whom
and how to use this information for deception. They
also remember.

Clark nutcrackers can hide up to 30,000 seeds and recover them
up to six months later.

Nutcrackers also hide and steal. If they see another bird
watching them as they cache food, they return later, alone, to
hide the food again. Some scientists believe this shows a
rudimentary theory of mind - understanding that another bird
has intentions and beliefs.

Magpies, at an earlier age than any other creature tested,
develop an understanding of the fact that when an object
disappears behind a curtain, it has not vanished.

At a university campus in Japan, carrion crows line up
patiently at the curb waiting for a traffic light to turn red.
When cars stop, they hop into the crosswalk, place walnuts
from nearby trees onto the road and hop back to the curb.
After the light changes and cars run over the nuts, the crows
wait until it is safe and hop back out for the food.

Pigeons can memorize up to 725 different visual patterns, and
are capable of what looks like deception. Pigeons will pretend
to have found a food source, lead other birds to it and then
sneak back to the true source.

Parrots, some researchers report, can converse with humans,
invent syntax and teach other parrots what they know.
Researchers have claimed that Alex, an African gray, can grasp
important aspects of number, color concepts, the difference
between presence and absence, and physical properties of
objects like their shapes and materials. He can sound out
letters the same way a child does.

Like mammals, some birds are naturally smarter than others,
Dr. Jarvis said. But given their range of behaviors, birds are
extraordinarily flexible in their intelligence quotients.
"They're right up there with hominids," he said.

Copyright 2005 The New York Times Company
http://www.nytimes.com/2005/02/01/sc...tml?oref=login

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Pet Star - Episode 309

Einstein, the brainy bird
Watch her winning moment!

http://media.animal.discovery.com/fa...09_winner.html