Featured Research

from universities, journals, and other organizations

Deafening affects vocal nerve cells within hours

Date:
March 7, 2012
Source:
Duke University Medical Center
Summary:
Portions of a songbird's brain that control how it sings have been shown to decay within 24 hours of the animal losing its hearing.

Neurons (nerve cells) are labeled with green fluorescent protein, and other neurons in the brain are labeled in the background with either red or blue tracers. The small bulbs (i.e., dendritic spines) on the spidery dendrites show places where nerve cells connect and communicate, called synapses, and when these spines shrank over time, this predicted vocal degradation in the songbirds.
Credit: Image courtesy of Duke University Medical Center

Portions of a songbird's brain that control how it sings have been shown to decay within 24 hours of the animal losing its hearing.

The findings, by researchers at Duke University Medical Center, show that deafness penetrates much more rapidly and deeply into the brain than previously thought. As the size and strength of nerve cell connections visibly changed under a microscope, researchers could even predict which songbirds would have worse songs in coming days.

"When hearing was lost, we saw rapid changes in motor areas in that control song, the bird's equivalent of speech," said senior author Richard Mooney, PhD, professor of neurobiology at Duke. "This study provided a laser-like focus on what happens in the living songbird brain, narrowed down to the particular cell type involved."

The study was published in Neuron journal online on March 7, 2012.

Like humans, songbirds depend on hearing to learn their mating songs -- males that sing poorly don't attract mates, so hearing a song, learning it, and singing correctly are all critical for songbird survival. Songbirds also resemble humans and differ from most other animals in that their songs fall apart when they lose their hearing, and this feature makes them an ideal organism to study how hearing loss may affect the parts of the brain that control vocalization, Mooney said.

"I will go out on a limb and say that I think similar changes also occur in human brains after hearing loss, specifically in Broca's area, a part of the human brain that plays an important role in generating speech and that also receives inputs from the auditory system," Mooney said.

About 30 million Americans are hard of hearing or deaf. This study could shed light on why and how some people's speech changes as their hearing starts to decline, Mooney said.

"Our vocal system depends on the auditory system to create intelligible speech. When people suffer profound hearing loss, their speech often becomes hoarse, garbled, and harder to understand, so not only do they have trouble hearing, they often can't speak fluently any more," Mooney said.

The nerve cells that showed changes after deafening send signals to the basal ganglia, a part of the brain that plays a role in learning and initiating motor sequences, including the complex vocal sequences that make up birdsong and speech.

Although other studies had looked at the effects of deafening on neurons in auditory brain areas, this is the first time that scientists have been able to watch how deafening affects connections between nerve cells in a vocal motor area of the brain in a living animal, said Katie Tschida, PhD, a postdoctoral research associate in the Mooney laboratory who led the study.

Using a protein isolated from jellyfish that can make songbird nerve cells glow bright green when viewed under a laser-powered microscope, they were able to determine that deafening triggered rapid changes to the tiny connections between nerve cells, called synapses, which are only one thousandth of a millimeter across.

"I was very surprised that the weakening of connections between nerve cells was visible and emerged so rapidly -- over the course of days these changes allowed us to predict which birds' songs would fall apart most dramatically," Tschida said. "Considering that we were only tracking a handful of neurons in each bird, I never thought we'd get information specific enough to predict such a thing."

The research was supported by the National Science Foundation and the National Institute on Deafness and Other Communication Disorders.


Story Source:

The above story is based on materials provided by Duke University Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Katherine A. Tschida, Richard Mooney. Deafening Drives Cell-Type-Specific Changes to Dendritic Spines in a Sensorimotor Nucleus Important to Learned Vocalizations. Neuron, 8 March 2012; 73(5) pp. 1028 - 1039 DOI: 10.1016/j.neuron.2011.12.038

Cite This Page:

Duke University Medical Center. "Deafening affects vocal nerve cells within hours." ScienceDaily. ScienceDaily, 7 March 2012. <www.sciencedaily.com/releases/2012/03/120307132204.htm>.
Duke University Medical Center. (2012, March 7). Deafening affects vocal nerve cells within hours. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2012/03/120307132204.htm
Duke University Medical Center. "Deafening affects vocal nerve cells within hours." ScienceDaily. www.sciencedaily.com/releases/2012/03/120307132204.htm (accessed October 20, 2014).

Share This



More Mind & Brain News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Court Ruling Means Kids' Online Activity Could Be On Parents

Court Ruling Means Kids' Online Activity Could Be On Parents

Newsy (Oct. 17, 2014) In a ruling attorneys for both sides agreed was a first of its kind, a Georgia appeals court said parents can be held liable for what kids put online. Video provided by Newsy
Powered by NewsLook.com
The Best Foods To Boost Your Mood

The Best Foods To Boost Your Mood

Buzz60 (Oct. 17, 2014) Feeling down? Reach for the refrigerator, not the medicine cabinet! TC Newman (@PurpleTCNewman) shares some of the best foods to boost your mood. Video provided by Buzz60
Powered by NewsLook.com
You Can Get Addicted To Google Glass, Apparently

You Can Get Addicted To Google Glass, Apparently

Newsy (Oct. 15, 2014) Researchers claim they’ve diagnosed the first example of the disorder in a 31-year-old U.S. Navy serviceman. Video provided by Newsy
Powered by NewsLook.com
First Confirmed Case Of Google Glass Addiction

First Confirmed Case Of Google Glass Addiction

Buzz60 (Oct. 15, 2014) A Google Glass user was treated for Internet Addiction Disorder caused from overuse of the device. Morgan Manousos (@MorganManousos) has the details on how many hours he spent wearing the glasses, and what his symptoms were. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins