Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

As autumn approaches, this chickadee’s brain begins to expand

12.09.2003


New nerve cells put fall foraging on fast track



The "senior moments" that herald old age, and the ability to forget where we put something we held in our hands just moments ago, give us humans much cause to envy a species like the black-capped chickadee.
Especially when fall is right around the corner.

Every autumn, the chickadee roams a territory covering tens of square miles, gathering seeds and storing them in hundreds of hiding places in trees and on the ground. Over the harsh winter that follows, the tireless songbird, which weighs about 12 grams and fits inside the typical human hand, faithfully re-visits its caches to feed.



The chickadee’s unerring spatial memory is remarkable enough, says Colin Saldanha, assistant professor of biological sciences at Lehigh University and an anatomist who has studied songbirds for six years.

But it is what happens inside the tiny songbird’s brain that Saldanha finds amazing. In the fall, as the chickadee is gathering and storing seeds, Saldanha says, its hippocampus, the part of the brain responsible for spatial organization and memory in many vertebrates, expands in volume by approximately 30 percent by adding new nerve cells. In songbirds, the hippocampus is located on the dorsal surface of the forebrain right beneath the skull. In mammals, the hippocampus is located beneath the cortex.

In the spring, when its feats of memory are needed less, the chickadee’s hippocampus shrinks back to its normal size, Saldanha says.

"To see this happen under natural conditions," says Saldanha, who began studying the black-capped chickadee in 2001, "is truly awe-inspiring.

"Our hypothesis is that this exaggerated growth occurs when the birds need it the most - and we’re interested in finding out what exactly triggers it."

Songbirds are the first species of vertebrate in which brain growth during adulthood has been found to occur, Saldanha says. By studying neurogenesis in the black-capped chickadee, Saldanha hopes to learn how hormones help guide the brain’s development and reorganization. He is particularly interested in the role played by the hormone estrogen in the growth of the hippocampus. Songbirds (like most vertebrates) make estrogen in their ovaries; scientists have determined that their brains also express aromatase, the enzyme that makes estrogen. Perhaps not surprisingly, the area of the songbird brain with the highest estrogen-making capability is the hippocampus.

"We know hormones affect the reorganization of the brain in ovo, in utero and during the early physical development of most vertebrates," Saldanha says. "We are trying to figure out whether the ability to make estrogen in the hippocampus is helping the dramatic reorganization of the [adult] brain."

Saldanha uses transmission electron microscopy (TEM) to examine neurons (nerve cells) and synapses (connections between nerve cells, where scientists think learning occurs) from the brain of the black-capped chickadee. His goal is to determine whether estrogen is being made in the cellular body or in the synapse, and whether the location of this estrogen-making ability changes seasonally.

"We’re looking at the ability of nerve cells and connections to make estrogen in the brain and asking if this ability is involved in brain reorganization," he says.

"We are the first lab, I think, to look at estrogen-synthesizing neurons in the songbird hippocampus at the electron-microscope level. We may, in fact, be the only lab using this technology to investigate songbird spatial memory."

Saldanha is licensed to catch and house birds by the U.S. Department of the Interior Bird Banding Laboratory and the Pennsylvania Game Commission. He has placed feeders in the woods around Lehigh’s Mountaintop Campus, and he keeps captive chickadees in an aviary outside his office in Iacocca Hall.

The behavior of the black-capped chickadee has been studied for a long time, he says, and much is known about its lifecycle and habits. Only recently have scientists begun to study its brain.

"It’s nice to have an ecological umbrella under which to ask biological questions. Because we know the birds’ natural behavior, I feel I can be more confident in the validity of my studies. It can be difficult sometimes to extend findings from the Petri dish to the real world."

Many neuro-degenerative diseases involve the hippocampus, Saldanha says. In humans, strokes can affect the hippocampus and cause a "profound deficit" in memory, especially in the ability to make new memories. In the brains of Alzheimer’s patients, the hippocampus shrinks.

But Saldanha stresses that his studies are new and that any applications lie far in the future.

"Maybe in the very long term, we can understand how to prevent and restore memory loss in patients with Alzheimer’s," he says. "Often times, the best way to fix something that’s broken is to figure how it works when it’s not broken."

Kurt Pfitzer | EurekAlert!
Further information:
http://www.lehigh.edu/

More articles from Life Sciences:

nachricht Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology

nachricht Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>