Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers find how brain hears the sound of silence

11.02.2010
University of Oregon team discovers that separate brain pathways process the start and end of what we hear

A team of University of Oregon researchers have isolated an independent processing channel of synapses inside the brain's auditory cortex that deals specifically with shutting off sound processing at appropriate times. Such regulation is vital for hearing and for understanding speech.

The discovery, detailed in the Feb. 11 issue of the journal Neuron, goes against a long-held assumption that the signaling of a sound's appearance and its subsequent disappearance are both handled by the same pathway. The new finding, which supports an emerging theory that a separate set of synapses is responsible, could lead to new, distinctly targeted therapies such as improved hearing devices, said Michael Wehr, a professor of psychology and member of the UO Institute of Neuroscience.

"It looks like there is a whole separate channel that goes all the way from the ear up to the brain that is specialized to process sound offsets," Wehr said. The two channels finally come together in a brain region called the auditory cortex, situated in the temporal lobe.

To do the research, Wehr and two UO undergraduate students -- lead author Ben Scholl, now a graduate student at the Oregon Health and Science University in Portland, and Xiang Gao -- monitored the activity of neurons and their connecting synapses as rats were exposed to millisecond bursts of tones, looking at the responses to both the start and end of a sound. They tested varying lengths and frequencies of sounds in a series of experiments.

It became clear, the researchers found, that one set of synapses responded "very strongly at the onset of sounds," but a different set of synapses responded to the sudden disappearance of sounds. There was no overlap of the two responding sets, the researchers noted. The end of one sound did not affect the response to a new sound, thus reinforcing the idea of separate processing channels.

The UO team also noted that responses to the end of a sound involved different frequency tuning, duration and amplitude than those involved in processing the start of a sound, findings that agree with a trend cited in at least three other studies in the last decade.

"Being able to perceive when sound stops is very important for speech processing," Wehr said. "One of the really hard problems in speech is finding the boundaries between the different parts of words. It is really not well understood how the brain does that."

As an example, he noted the difficulty some people have when they are at a noisy cocktail party and are trying to follow one conversation amid competing background noises. "We think that we've discovered brain mechanisms that are important in finding the necessary boundaries between words that help to allow for successful speech recognition and hearing," he said.

The research -- funded in part by the UO's Robert and Beverly Lewis Center for Neuroimaging Fund -- aims to provide a general understanding of how areas of the brain function. The new findings, Wehr said, could also prove useful in working with children who have deficits in speech and learning, as well as in the design of hearing aids and cochlear implants. He also noted that people with dyslexia have problems defining the boundaries of sounds in speech, and tapping these processing areas in therapy could boost reading skills.

About the University of Oregon

The University of Oregon is a world-class teaching and research institution and Oregon's flagship public university. The UO is a member of the Association of American Universities (AAU), an organization made up of the 62 leading public and private research institutions in the United States and Canada. The UO is one of only two AAU members in the Pacific Northwest.

Source: Michael Wehr, assistant professor of psychology, 541- 346-5866, wehr@uoregon.edu

Links:

Wehr faculty page: http://psychweb.uoregon.edu/people/wehr-michael
Wehr lab: http://www.neuro.uoregon.edu/wehr/index.html
UO psychology department: http://psychweb.uoregon.edu/
Institute of Neuroscience: http://www.neuro.uoregon.edu/

Jim Barlow | EurekAlert!
Further information:
http://www.uoregon.edu

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>