Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Training improves sound localization in ferrets

07.03.2006


Upon hearing the blare of a siren, you would quickly home in on the source and direction of the sound and take the necessary action, or precaution, such as pulling your car over or foregoing crossing the street until the ambulance has cleared. Mammals rely on sound localization skills to communicate, escape threats, and forage, among many other tasks. All through development the adult brain retains the capacity to rewire the networks that underlie these skills but it’s not clear which tasks benefit from plasticity or how the brain engenders this flexibility. In a study published in the open access journal PLoS Biology, Oliver Kacelnik, Andrew King, and colleagues showed by manipulating the hearing of adult ferrets that ferrets with obstructed hearing can quickly adapt to altered auditory cues when trained to do so in order to perform a necessary task. Their findings reveal that the frequency of the training was crucial in boosting the rate and extent of their improvement.


Measuring the accuracy with which ferrets can localize sound. (Photo: King et al.)



The brain processes spatial cues in the sound waves that enter each ear to localize sound and interprets sound on the horizontal plane by using disparities in how the sound reaches each ear, called interaural time differences and interaural level differences. Changes in level at different frequencies can reveal the source’s elevation.

To study adaptive hearing in an adult mammal, the authors blocked the left ears of ferrets with specially outfitted earplugs and measured their ability to localize sounds in the horizontal plane. They trained ferrets to approach a sound source to receive the reward. When the ferrets licked a waterspout, they triggered a burst of noise from one of twelve speakers. They were presented with sound bursts lasting either 1,000 or 40 milliseconds. Without earplugs, ferrets had no trouble localizing the sounds. They were slightly less adept at localizing the brief bursts. With earplugs, performance dropped considerably for both bursts. Ferrets had the most trouble with sounds coming for their left (obstructed) side, but errors increased significantly for all 12 sound sources. The authors retested one group of earplugged animals every six days to see if they could use the altered cues to recover their localization skills. By three weeks, the animals localized sound coming from the right side about as well as they had before the ear was plugged. The speed and accuracy with which the ferrets recovered their localization abilities depended on training, with more complete recovery when the animals received more frequent training.


To test the possibility that visual cues might help to boost auditory plasticity, the authors compared the earplugs’ behavioral effects on two groups of ferrets: one blind since infancy, and another with normal vision. Both groups could localize about the same without earplugs, made more errors after receiving the plug, and then steadily improved with the periodic retesting. These results show not only that the ferrets could be trained to reprocess abnormal localization cues but also that they could do so without visual cues. Then, by training another group of ferrets to localize both auditory and visual stimuli before inserting the earplug, the authors show that sound localization depends "exclusively on auditory training" and does not involve "a visual recalibration of auditory space." Furthermore, adaptation did not depend on error feedback, since rewards were not based on performance.

After removal of the earplugs, ferrets made errors reflecting a small bias toward the previously plugged ear: they initially processed the cues as if the ear was still plugged. This aftereffect, though transient, indicates that the adaptive response relies in part on reinterpreting the relationship between binaural cues and location. However, compensation for the earplug-disrupted binaural cues mainly involved the animals’ learning to make use of other cues that were less distorted by the earplug, including low-frequency interaural time differences, and spectral cues provided by the unobstructed ear.

Altogether, these results show that the adult auditory system can adapt to abnormal spatial cues and can do so rapidly with intensive training. By recording brain activity as animals perform the tasks described here, future studies can shed light on the brain regions responsible for this plasticity. Whatever the mechanism, the finding that plasticity follows targeted, intensive training suggests that patients with hearing disorders might benefit from a similar strategy--providing more evidence that an old brain can sometimes learn new tricks.

Paul Ocampo | EurekAlert!
Further information:
http://www.plosbiology.org

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

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...

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

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>