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 Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>