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 Stiffness matters
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>