(Press-News.org) Important new insights into how the brain compensates for temporary hearing loss during infancy, such as that commonly experienced by children with glue ear, are revealed in a research study in ferrets. The Wellcome Trust-funded study at the University of Oxford could point to new therapies for glue ear and has implications for the design of hearing aid devices.
Normally, the brain works out where sounds are coming from by relying on information from both ears located on opposite sides of the head, such as differences in volume and time delay in sounds reaching the two ears. The shape of the outer ear also helps us to interpret the location of sounds by filtering sounds from different directions, so-called spectral cues. This ability to identify where sounds are coming from not only helps us locate the path of moving objects, but also to separate different sound sources in noisy environments.
Glue ear, or otitis media, is a relatively common condition caused by a build-up of fluid in the middle ear that causes temporary hearing loss. By age 10, 8 out of 10 children will have experienced one or more episodes of glue ear. It usually resolves itself but more severe cases can require interventions such as the insertion of tubes, commonly known as grommets, to drain the fluid and restore hearing. If the loss of hearing is persistent, however, it can lead to impairments in later life even after normal hearing has returned, such as 'lazy ear', or amblyaudia, which leaves people struggling to locate sounds or pick out sounds in noisy environments such as classrooms or restaurants.
Researchers at the University of Oxford used removable earplugs to introduce intermittent, temporary hearing loss in one ear in young ferrets, mimicking the effects of glue ear in children. The team then tested their ability to localise sounds as adults and measured activity in the brain to see how the loss of hearing affected their development.
The results show that animals raised with temporary hearing loss were still able to localise sounds accurately while wearing an earplug in one ear. They achieved this by becoming more dependent on the unchanged spectral cues from the outer part of the unaffected ear. When the plug was removed and hearing returned to normal, the animals were just as good at localising sounds as those who had never experienced hearing loss.
Professor Andrew King, a Wellcome Trust Principal Research Fellow at the University of Oxford who led the study, explains: "Our results show that, with experience, the brain is able to shift the strategy it uses to localise sounds depending on the information that is available at the time. During periods of hearing loss in one ear - when the spatial cues provided by comparing the sounds at each ear are compromised - the brain becomes much more reliant on the intact spectral cues that arise from the way sounds are filtered by the outer ear. But when hearing is restored, the brain returns to using information from both ears to work out where sounds are coming from."
The results contrast with previous studies which looked at the effects of enduring hearing loss – rather than recurring hearing loss - on brain development. These earlier studies found that changes in the brain that result from loss of hearing persisted even when normal hearing returned.
The new findings suggest that intermittent experience of normal hearing is important for preserving sensitivity to those cues and could offer new strategies for rehabilitating people who have experienced hearing loss in childhood.
In addition, the finding that spectral cues from the outer ear are an important source of information during periods of hearing loss has important implications for the design of hearing aids, particularly those that sit behind the ear.
"Recurring periods of hearing loss are extremely common during childhood. These findings will help us to find better ways of rehabilitating those affected, which should limit the number who go on to develop more serious hearing problems in later life," adds Professor King.
The study is published today in the journal Current Biology.
###
Insights into how brain compensates for recurring hearing loss point to new glue ear therapies
2013-06-27
ELSE PRESS RELEASES FROM THIS DATE:
UCSF researchers discover species-recognition system in fruit flies
2013-06-27
A team led by UC San Francisco researchers has discovered a sensory system in the foreleg of the fruit fly that tells male flies whether a potential mate is from a different species. The work addresses a central problem in evolution that is poorly understood: how animals of one species know not to mate with animals of other species.
For the common fruit fly D. melanogaster, the answer lies in the chemoreceptor Gr32a, located on sensory neurons on the male fly's foreleg. "In nature, this sensory system would prevent the creation of hybrids that may not survive or cannot ...
Power for seaports may be the next job for hydrogen fuel cells
2013-06-27
LIVERMORE, Calif.— Providing auxiliary hydrogen power to docked or anchored ships may soon be added to the list of ways in which hydrogen fuel cells can provide efficient, emissions-free energy.
Hydrogen fuel cells are already powering mobile lighting systems, forklifts, emergency backup systems and light-duty trucks, among other applications. Now, researchers at Sandia National Laboratories have found that hydrogen fuel cells may be both technically feasible and commercially attractive as a clean, quiet and efficient power source for ships at berth, replacing on-board ...
Spiral galaxies like Milky Way bigger than thought, says CU-Boulder study
2013-06-27
Let's all fist bump: Spiral galaxies like our own Milky Way appear to be much larger and more massive than previously believed, according to a new University of Colorado Boulder study by researchers using the Hubble Space Telescope.
CU-Boulder Professor John Stocke, study leader, said new observations with Hubble's $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter. The current estimated diameter of the Milky Way, for example, ...
Spinning up antibacterial silver on glass
2013-06-27
The antibacterial effects of silver are well established. Now, researchers at Yonsei University in Seoul, Republic of Korea, have developed a technique to coat glass with a layer of silver ions that can prevent growth of pathogenic bacteria including Escherichia coli, Salmonella typhimurium and Campylobacter jejuni. The technology could be used to protect medical equipment and be particularly useful for applications in disaster recovery and the military environment.
Materials scientist Se-Young Choi and colleagues Cheol-Young Kim, Yu-Ri Choi and Kwang-Mahn Kim, explain ...
River deep, mountain high -- new study reveals clues to lifecycle of worlds iconic mountains
2013-06-27
Scientists have discovered the reasons behind the lifespan of some of the world's iconic mountain ranges.
The study conducted by the University of Melbourne, Australia, and Aarhus University, Denmark, has revealed that interactions between landslides and erosion, caused by rivers, explains why some mountain ranges exceed their expected lifespan.
Co-author Professor Mike Sandiford of the School of Earth Sciences at the University of Melbourne said the study had answered the quandary as to why there was fast erosion in active mountain ranges in the Himalayas and slow ...
No more leakage of explosive electrolytes in batteries
2013-06-27
Ulsan, South Korea-- A research team at Ulsan National Institute of Science and Technology (UNIST), S. Korea, found a new physical organogel electrolyte with two unique characteristics: an irreversible thermal gelation and a high value of the Li+ transference number.
A Recent fire on a Boeing 787 on the ground in Boston, US, was caused by a battery failure, it resulted in the release of flammable electrolytes, heat damage and smoke. If they had used a safer electrolyte, the risk would have been reduced.
Electrolytes are essential components of supercapacitors, batteries ...
Improving measurements by reducing quantum noise
2013-06-27
If you want to measure something very precisely, such as slight variations of a length, then you are very likely to use light waves. However, many effects, such as variations of gravity, or surface forces, can only be measured using particles that have a mass. Since, according to the rules of quantum mechanics, massive particles also behave like waves, interferometers can be built in which single atoms or even entire atomic clouds are used instead of light. A team from the Vienna University of Technology has now been able to develop a Mach-Zehnder interferometer for Bose-Einstein ...
Link shown between Crohn's disease and virus
2013-06-27
A new study reveals that all children with Crohn's disease that were examined had a commonly occurring virus – an enterovirus – in their intestines. This link has previously not been shown for this chronic inflammatory intestinal disorder. The findings are being published today in the latest issue of the international journal Clinical and Translational Gastroenterology.
These findings need to be confirmed in larger studies, but they are important, as this connection has never been pointed out before. This paves the way for a better understanding of what might be involved ...
Bioeconomy as a solution for South Australia's declining forest industry
2013-06-27
South Australia's forest industry is being significantly challenged as production levels fall due to declining export competitiveness and accordingly means for improving the industry's competitiveness are being sought. The South Australian State Government's Department for Manufacturing, Innovation, Trade, Resources and Energy (DMITRE) has invited VTT Technical Research Centre of Finland experts to undertake a study that identifies potential routes by which the increased competitiveness can be achieved.
Achieving world class productivity in existing business combined ...
Researchers track facial expressions to improve teaching software
2013-06-27
Research from North Carolina State University shows that software which tracks facial expressions can accurately assess the emotions of students engaged in interactive online learning and predict the effectiveness of online tutoring sessions.
"This work is part of a larger effort to develop artificial intelligence software to teach students computer science," says Dr. Kristy Boyer, an assistant professor of computer science at NC State and co-author of a paper on the work. "The program, JavaTutor, will not only respond to what a student knows, but to each student's feelings ...