Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Overactive nerves in head and neck may account for 'ringing in the ears'

14.01.2008
Results in animals suggest that acupuncture and trigger point therapy may be effective treatments for people plagued by tinnitus

Do your ears ring after a loud concert" Nerves that sense touch in your face and neck may be behind the racket in your brain, University of Michigan researchers say.

Touch-sensing nerve cells step up their activity in the brain after hearing cells are damaged, a study by U-M Kresge Hearing Research Institute scientists shows. Hyperactivity of these touch-sensing neurons likely plays an important role in tinnitus, often called “ringing in the ears.” The study, now online in the European Journal of Neuroscience, will appear in the journal’s first January issue.

The research findings were made in animals, but they suggest that available treatments such as acupuncture, if used to target nerves in the head and neck, may provide relief for some people plagued by tinnitus, says Susan E. Shore, Ph.D., lead author of the study and research professor in the Department of Otolaryngology and the Kresge Hearing Research Institute at the U-M Medical School.

People with tinnitus sense ringing or other sounds in their ears or head when there is no outside source. Whether it’s mild and intermittent or chronic and severe, tinnitus affects about one in 10 people. An estimated 13 million people in Western Europe and the United States seek medical advice for it. It is a growing problem for war veterans. Since 2000, the number of veterans receiving service-connected disability for tinnitus has increased by at least 18 percent each year, according to the American Tinnitus Association.

Increasing numbers of baby boomers are also finding that when they can’t hear as well as they used to, tinnitus seems to move in. The condition commonly occurs with hearing loss, but also after head or neck trauma such as whiplash or dental work.

Tinnitus varies in individuals from a faint, high-pitched tone to whooshing ocean waves to annoying cricket-like chirping or screeching brakes. For some, it is constant and debilitating.

Some people, oddly enough, find that if they clench the jaw or press on the face or neck, they can temporarily stop tinnitus, or in some cases bring it on. To understand tinnitus and its strange link to touch sensations, Shore and her research team have conducted a series of studies in guinea pigs, measuring nerve activity in a part of the brain called the dorsal cochlear nucleus that processes auditory and other signals.

In normal hearing, the dorsal cochlear nucleus is the first stop in the brain for sound signals arriving from the ear via the auditory nerve. It’s also a hub where “multitasking” neurons process sensory signals from other parts of the brain.

“In this study, we showed that when there is a hearing loss, other parts of the brain that normally convey signals to the cochlear nucleus have an enhanced effect,” says Shore, who is also an associate professor in the Department of Molecular and Integrative Physiology at the U-M Medical School.

“When you take one source of excitation away, another source comes in to make up for it. The somatosensory system is coming in, but may overcompensate and help cause tinnitis,” she says.

The somatosensory system is a nerve network in the body that provides information to the brain about touch, vibration, skin temperature and pain. The part of the system that provides sensations from the face and head, called the trigeminal system, brings signals to the cochlear nucleus that help us hear and speak.

But when people experience hearing loss or some other event, such as having a cavity filled or a tooth implanted, these neurons from the face and head can respond like overly helpful relatives in a family crisis. The resulting neuron firings in the cochlear nucleus, like too many phone calls, create the din of tinnitus, a “phantom sound” produced in the brain.

In the study, Shore and the paper’s second author Seth Koehler, a U-M Ph.D. student in the U-M departments of Otolaryngology and Biomedical Engineering measured the patterns of activity of neurons in the brains of normal and deafened guinea pigs. They used a 16-electrode array to measure signals from the trigeminal nerve and multisensory neurons in the dorsal cochlear nucleus. When they compared results in the two groups, they found clear differences in trigeminal nerve activity.

“The study shows that in deafened animals, the somatosensory response is much stronger than in animals with normal hearing,” Shore says.

Shore’s research team knew from earlier research that some neurons in the cochlear nucleus become hyperactive after hearing damage, and this hyperactivity has been linked to tinnitus in animals.

“This study shows that it is only those neurons that receive somatosensory input that become hyperactive,” she says, which should make the search for treatments for tinnitus in some people more straightforward.

Many people with temporomandibular joint syndrome (TMJ), a condition that causes frequent pain in the jaw, experience tinnitus. Shore’s research could lead to a better understanding of this link. In people with TMJ, the somatosensory system is disrupted and inflamed. Shore says that it’s possible that in this situation, as in hearing loss, somatosensory neurons stir excessive neuron activity in the cochlear nucleus.

Anne Rueter | EurekAlert!
Further information:
http://www.umich.edu
http://www.blackwell-synergy.com/doi/full/10.1111/j.1460-9568.2007.05983.x
http://www.tinnitusresearch.org/

More articles from Health and Medicine:

nachricht Nitric oxide-scavenging hydrogel developed for rheumatoid arthritis treatment
06.06.2019 | Pohang University of Science & Technology (POSTECH)

nachricht Infants later diagnosed with autism follow adults’ gaze, but seldom initiate joint attention
24.05.2019 | Schwedischer Forschungsrat - The Swedish Research Council

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

Im Focus: Cost-effective and individualized advanced electronic packaging in small batches now available

Fraunhofer IZM is joining the EUROPRACTICE IC Service platform. Together, the partners are making fan-out wafer level packaging (FOWLP) for electronic devices available and affordable even in small batches – and thus of interest to research institutes, universities, and SMEs. Costs can be significantly reduced by up to ten customers implementing individual fan-out wafer level packaging for their ICs or other components on a multi-project wafer. The target group includes any organization that does not produce in large quantities, but requires prototypes.

Research always means trying things out and daring to do new things. Research institutes, universities, and SMEs do not produce in large batches, but rather...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Concert of magnetic moments

14.06.2019 | Information Technology

Materials informatics reveals new class of super-hard alloys

14.06.2019 | Materials Sciences

New imaging modality targets cholesterol in arterial plaque

14.06.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>