Featured Research

from universities, journals, and other organizations

Built-in amps: How subtle head motions, quiet sounds are reported to the brain

Date:
February 15, 2010
Source:
Marine Biological Laboratory
Summary:
Subtle head motions are amplified by inner-ear hair cells before the signal is reported to the brain, report scientists. In both the auditory and the vestibular systems, hair cell response is nonlinear: the lower the strength of the stimulus, the more the hair cell amplifies the signal.

A single hair cell from a frog ear magnified by a scanning electron microscope. Hair cells are essential sound and balance detectors in the inner ear. The study of these cells, which are a limited commodity and easily damaged in humans, is key to understanding hearing and balance loss.
Credit: Image by Jason Meyers, Assistant Professor of Biology, Colgate University

The phrase "perk up your ears" made more sense last year after scientists discovered how the quietest sounds are amplified in the cochlea before being transmitted to the brain.

When a sound is barely audible, extremely sensitive inner-ear "hair cells" -- which are neurons equipped with tiny, sensory hairs on their surface -- pump up the sound by their very motion and mechanically amplify it. Richard Rabbitt of the University of Utah, a faculty member in the MBL's Biology of the Inner Ear course, reported last spring on the magnification powers of the hair cell's hairs.

Now, Rabbitt and MBL senior scientist Stephen Highstein have evidence that hair cells perform similarly in another context -- in the vestibular system, which sends information about balance and spatial orientation to the brain.

"The bottom line is we have 'accelerometers' in the head that report on the direction of gravity and the motion of the head to the brain," says Highstein. "What we found is they respond with a greater magnitude than expected for very small motions of the head. This brought to mind a similar amplification of very small signals by the human inner-ear cochlea. And, in fact, the vestibular system and the cochlea have a sensory element in common: the hair cells." Rabbitt and Highstein found that, in both the auditory and the vestibular systems, the hair cell response exhibits "compressional nonlinearity": The lower the strength of the stimulus, the more the hair cells "tune themselves up to amplify the stimulus," Highstein says.

The toadfish was used for this study. "What's interesting is the boney fishes evolved some 3 to 4 million years ago; subsequently this feature of its hair cells was apparently co-opted by the mammalian cochlea. Evolution conserved this feature, and the mammal later used it to improve hearing sensitivity," Highstein says.


Story Source:

The above story is based on materials provided by Marine Biological Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rabbitt et al. Mechanical amplification by hair cells in the semicircular canals. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.0906765107

Cite This Page:

Marine Biological Laboratory. "Built-in amps: How subtle head motions, quiet sounds are reported to the brain." ScienceDaily. ScienceDaily, 15 February 2010. <www.sciencedaily.com/releases/2010/02/100209091842.htm>.
Marine Biological Laboratory. (2010, February 15). Built-in amps: How subtle head motions, quiet sounds are reported to the brain. ScienceDaily. Retrieved October 1, 2014 from www.sciencedaily.com/releases/2010/02/100209091842.htm
Marine Biological Laboratory. "Built-in amps: How subtle head motions, quiet sounds are reported to the brain." ScienceDaily. www.sciencedaily.com/releases/2010/02/100209091842.htm (accessed October 1, 2014).

Share This



More Mind & Brain News

Wednesday, October 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Do Video Games Trump Brain Training For Cognitive Boosts?

Do Video Games Trump Brain Training For Cognitive Boosts?

Newsy (Sep. 29, 2014) More and more studies are showing positive benefits to playing video games, but the jury is still out on brain training programs. Video provided by Newsy
Powered by NewsLook.com
Your Spouse's Personality May Influence Your Earnings

Your Spouse's Personality May Influence Your Earnings

Newsy (Sep. 26, 2014) Research from Washington University suggest people with conscientious spouses have greater career success. Video provided by Newsy
Powered by NewsLook.com
Can A Blood Test Predict Psychosis Risk?

Can A Blood Test Predict Psychosis Risk?

Newsy (Sep. 26, 2014) Researchers say certain markers in the blood can predict risk of psychosis later in the life. The test can aid in early treatment for the condition. Video provided by Newsy
Powered by NewsLook.com
Harpist Soothes Gorillas, Orangutans With Music

Harpist Soothes Gorillas, Orangutans With Music

AP (Sep. 25, 2014) Teri Tacheny, a harpist, has a loyal following of fans who appreciate her soothing music. Every month, gorillas, orangutans and monkeys amble down to hear her play at the Como Park Zoo in Minnesota. (Sept. 25) Video provided by AP
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