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“Birdbrain” No Longer Means “Stupid,” Asserts Scientific Consortium

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Duke Health News 919-660-1306

Note: An accompanying video interview with Erich Jarvis can be viewed here.

DURHAM, N.C. -- An international consortium of 29 neuroscientists has
proposed a drastic renaming of the structures of the bird brain to correctly
portray birds as more comparable to mammals in their cognitive ability. The
scientists assert that the century-old traditional nomenclature is outdated
and does not reflect new molecular, genetic and behavioral studies that
reveal the brainpower of birds.

For example, they identified behavioral studies demonstrating that
pigeons can discriminate cubist from impressionistic styles of painting;
that crows can make useful tools and pass on their skills to other birds,
and that parrots can not only learn human words but use them to communicate
with humans.

The researchers emphasize that the old view of evolution as progressive
and linear is outdated, pointing out that so-called "primitive" animals such
as birds evolved some 50 to 100 million years after mammals.

The Avian Brain Nomenclature Consortium published a report on the
rationale for the proposed revised nomenclature in the February 2005 issue
of Nature Reviews Neuroscience. A technical report detailing the revisions
was published in the May 2004 issue of the Journal of Comparative Neurology.
The consortium's efforts were supported by the National Institutes of Health
and the National Science Foundation, including the NSF's Waterman Award for
young researchers to the Nature Reviews Neuroscience paper's first author,
Duke University Medical Center neurobiologist Erich Jarvis.

"We believe that names have a powerful influence on the experiments we do
and the way in which we think," wrote the consortium members in their paper.
"For this reason, and in the light of new evidence about the function and
evolution of the vertebrate brain, the international consortium of
neuroscientists has reconsidered the traditional 100-year-old terminology
that is used to describe the avian cerebrum.

"Our current understanding of the avian brain -- in particular the
neocortex-like cognitive functions of the avian pallium -- requires a new
terminology that better reflects these functions and the homologies between
avian and mammalian brains."

The consortium members asserted that the old terminology -- which implied
that the avian brain was more primitive than the mammalian brain -- has
hindered scientific understanding. They concluded that "The inaccurate
evolution-based terminology for the vertebrate brain that was used
throughout the twentieth century became a severe impediment to the
communication of scientific discoveries and the generation of new
insights."

The consortium's revision of the nomenclature for avian brains is aimed
at replacing the century-old system developed in the 19th century by Ludwig
Edinger, considered the father of comparative neuroanatomy. Edinger's system
was based on the then-common practice of combining Darwin's recent theory of
evolution and Aristotle's old concept that there exists a natural "scale" of
creatures from lowest to highest. The result were the views that evolution
was progressive from organisms with "lower" intelligence to those with
"higher" intelligence and that evolution had a purpose -- the generation of
humans.

The resulting nomenclature used prefixes such as palaeo- ("oldest") and
archi- ("archaic") to designate structures in the avian brain and neo-
("new") to designate supposedly new structures, particularly in the
mammalian brain.

"According to this theory, the avian cerebrum is almost entirely composed
of basal ganglia, the basal ganglia is involved only in instinctive
behavior, and the malleable behavior that is thought to typify mammals
exclusively requires the so-called neocortex," wrote the researchers.

However, said Jarvis, "We have to get rid of the idea that mammals -- and
humans in particular -- are the pinnacle of evolution. We have to stop using
words like 'lower vertebrates' and 'higher vertebrates.' We also have to
understand that evolution is not linear, but an intricate branching process.
So, we can't automatically expect to track a structure in the human brain
back to other current vertebrate species."

According to Jarvis, new research "debunks the theory that the brain
evolved in stages, like the laying down of geological sediments layer by
layer. There is no evidence to show that there was a primordial brain
structure to which so-called higher brain structures were systematically
added."

In the Nature Reviews Neuroscience paper, the authors described studies
by other researchers and their own studies demonstrating that the so-called
"primitive" regions of avian brains were actually sophisticated processing
regions homologous to those in mammals.

Those studies, which included tracing of neural pathways and behavioral
studies, showed that such avian brain regions carried out sensory
processing, motor control and sensorimotor learning just as did the
mammalian neocortex. Also, wrote the scientists, molecular studies have
shown that the avian and mammalian brain regions are comparable in their
genetic and biochemical machinery. The neocortex and related areas in the
mammalian brain are derived from a region in the embryonic cerebrum called
the pallium, which means mantle or covering. Edinger thought, however, that
most of this region in the bird cerebrum was part of the basal ganglia.
Accordingly, he gave them names that ended in the basal ganglia term
"-striatum", a practice he also employed in naming the parts of the
mammalian basal ganglia.

As a result of the recent studies, the consortium has recommended such
changes as renaming the avian brain region called the "archistriatum" as the
"arcopallium," (arched pallium); and renaming the region that includes part
of the true basal ganglia in birds, the "palaeostriatum primitivum" and the
"ventral palaeostriatum" which sits below the pallium as the "pallidum"
(pallidal or pale domain).

The consortium's work began in 1997 and was organized by Jarvis, Anton
Reiner of the University of Tennessee Health Science Center in Memphis,
Martin Wild of the University of Auckland in New Zealand, and other
neurobiologists, dubbing themselves the ThinkTank. Jarvis recalled that
"there were people in the field of avian neurobiology who knew the real
structures behind these names and knew the names were wrong. And as a member
of the younger generation of neurobiologists, I just felt that it was
against my conscience to continue to use terminology that I knew was wrong
and would mislead scientists."

For example, said Jarvis, researchers not familiar with the growing body
of scientific literature demonstrating the sophistication of the avian brain
could not understand how birds could exhibit sophisticated cognitive
abilities with brains that held only what the nomenclature designated as the
equivalent of the human basal ganglia.

The result of the scientists' objections led to a seven-year effort,
which steadily recruited new participants. This effort culminated in an
intensive international scientific forum at Duke in 2002, in which the new
nomenclature was developed.

"We knew that we were doing something that may have an impact, not only
on the immediate conduct of research in neuroscience, but on neuroscience
for the next hundred years," said Jarvis. "And, this nomenclature will help
people understand that evolution has created more than one way to generate
complex behavior -- the mammal way and the bird way. And they're comparable
to one another. In fact, some birds have evolved cognitive abilities that
are far more complex than in many mammals."

Besides Jarvis, other co-authors of the paper were
-- Onur Güntürkün, Ruhr-Universität Bochum, Germany,
-- Laura Bruce, Creighton University School of Medicine,
-- András Csillag, Semmelweis University, Hungary,
-- Harvey Karten, University of California San Diego,
-- Wayne Kuenzel, University of Arkansas
-- Loreta Medina, University of Murcia, Spain,
-- George Paxinos, Prince of Wales Medical Research Institute,
Australia,
-- David J. Perkel, University of Washington,
-- Toru Shimizu, University of South Florida,
-- Georg Striedter, University of California at Irvine,
-- Martin Wild, University of Auckland, New Zealand,
-- Gregory F. Ball, Johns Hopkins University,
-- Jennifer Dugas-Ford, University of Chicago,
-- Sarah Durand, CUNY-LaGuardia,
-- Gerald Hough, Rowan University,
-- Scott Husband, University of South Florida,
-- Lubica Kubikova, Duke University Medical Center,
-- Diane Lee, California State University Long Beach,
-- Claudio Mello, Oregon Health & Science University,
-- Alice Powers, St. John's University,
-- Connie Siang, Duke University Medical Center,
-- Tom Smulders, University of Newcastle, United Kingdom,
-- Kazuhiro Wada, Duke University Medical Center,
-- Stephanie White, University of California, Los Angeles,
-- Keiko Yamamoto, University of Tennessee Health Science Center,
-- Jing Yu, Duke University Medical Center,
-- Anton Reiner, University of Tennessee Health Science Center,
-- Ann Butler, George Mason University.

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