Featured Research

from universities, journals, and other organizations

Inner-ear disorders may cause hyperactivity

Date:
September 5, 2013
Source:
Albert Einstein College of Medicine
Summary:
Behavioral abnormalities are traditionally thought to originate in the brain. But a new study has found that inner-ear dysfunction can directly cause neurological changes that increase hyperactivity. The study, conducted in mice, also implicated two brain proteins in this process, providing potential targets for intervention.

Ear examination. For years, scientists have observed that many children and adolescents with severe inner-ear disorders -- particularly disorders affecting both hearing and balance -- also have behavioral problems, such as hyperactivity.
Credit: © corepics / Fotolia

Behavioral abnormalities are traditionally thought to originate in the brain. But a new study by researchers at Albert Einstein College of Medicine of Yeshiva University has found that inner-ear dysfunction can directly cause neurological changes that increase hyperactivity. The study, conducted in mice, also implicated two brain proteins in this process, providing potential targets for intervention.

Related Articles


The findings were published today in the online edition of Science.

For years, scientists have observed that many children and adolescents with severe inner-ear disorders -- particularly disorders affecting both hearing and balance -- also have behavioral problems, such as hyperactivity. Until now, no one has been able to determine whether the ear disorders and behavioral problems are actually linked.

"Our study provides the first evidence that a sensory impairment, such as inner-ear dysfunction, can induce specific molecular changes in the brain that cause maladaptive behaviors traditionally considered to originate exclusively in the brain," said study leader Jean M. Hébert, Ph.D., professor in the Dominick P. Purpura Department of Neuroscience and of genetics at Einstein.

The inner ear consists of two structures, the cochlea (responsible for hearing) and the vestibular system (responsible for balance). Inner-ear disorders are typically caused by genetic defects but can also result from infection or injury.

The idea for the study arose when Michelle W. Antoine, a Ph.D. student at Einstein at the time, noticed that some mice in Dr. Hébert's laboratory were unusually active -- in a state of near-continual movement, chasing their tails in a circular pattern. Further investigation revealed that the mice had severe cochlear and vestibular defects and were profoundly deaf. "We then realized that these mice provided a good opportunity to study the relationship between inner-ear dysfunction and behavior," said Dr. Hébert.

The researchers established that the animals' inner-ear problems were due to a mutation in a gene called Slc12a2, which mediates the transport of sodium, potassium, and chloride molecules in various tissues, including the inner ear and central nervous system (CNS). The gene is also found in humans.

To determine whether the gene mutation was linked to the animals' hyperactivity, the researchers took healthy mice and selectively deleted Slc12a2 from either the inner ear, various parts of the brain that control movement or the entire CNS. "To our surprise, it was only when we deleted the gene from the inner ear that we observed increased locomotor activity," said Dr. Hébert.

The researchers hypothesized that inner-ear defects cause abnormal functioning of the striatum, a central brain area that controls movement. Tests revealed increased levels of two proteins involved in a signaling pathway that controls the action of neurotransmitters: pERK (phosphorylated extracellular signal-regulated kinase) and pCREB (phospho-cAMP response-element binding protein), which is further down the signaling pathway from pERK. Increases in levels of the two proteins were seen only in the striatum and not in other forebrain regions.

To discover whether increased pERK levels caused the abnormal increase in locomotor activity, Slc12a2-deficient mice were given injections of SL327, a pERK inhibitor. Administering SL327 restored locomotor activity to normal, without affecting activity levels in controls. The SL327 injections did not affect grooming, suggesting that increased pERK in the striatum selectively elevates locomotor activity and not general activity. According to the researchers, the findings suggest that hyperactivity in children with inner-ear disorders might be controllable with medications that directly or indirectly inhibit the pERK pathway in the striatum.

"Our study also raises the intriguing possibility that other sensory impairments not associated with inner-ear defects could cause or contribute to psychiatric or motor disorders that are now considered exclusively of cerebral origin," said Dr. Hébert. "This is an area that has not been well studied."


Story Source:

The above story is based on materials provided by Albert Einstein College of Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. W. Antoine, C. A. Hubner, J. C. Arezzo, J. M. Hebert. A Causative Link Between Inner Ear Defects and Long-Term Striatal Dysfunction. Science, 2013; 341 (6150): 1120 DOI: 10.1126/science.1240405

Cite This Page:

Albert Einstein College of Medicine. "Inner-ear disorders may cause hyperactivity." ScienceDaily. ScienceDaily, 5 September 2013. <www.sciencedaily.com/releases/2013/09/130905142808.htm>.
Albert Einstein College of Medicine. (2013, September 5). Inner-ear disorders may cause hyperactivity. ScienceDaily. Retrieved January 28, 2015 from www.sciencedaily.com/releases/2013/09/130905142808.htm
Albert Einstein College of Medicine. "Inner-ear disorders may cause hyperactivity." ScienceDaily. www.sciencedaily.com/releases/2013/09/130905142808.htm (accessed January 28, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Wednesday, January 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Malnutrition on the Rise as Violence Flares in C. Africa

Malnutrition on the Rise as Violence Flares in C. Africa

AFP (Jan. 28, 2015) — Violence can flare up at any moment in Bambari with only a bridge separating Muslims and Christians. Malnutrition is on the rise and lack of water means simple cooking fires threaten to destroy makeshift camps where people are living. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Poultry Culled in Taiwan to Thwart Bird Flu

Poultry Culled in Taiwan to Thwart Bird Flu

Reuters - News Video Online (Jan. 28, 2015) — Taiwan culls over a million poultry in efforts to halt various strains of avian flu. Julie Noce reports. Video provided by Reuters
Powered by NewsLook.com
Media Criticizing Parents For Not Vaccinating Children

Media Criticizing Parents For Not Vaccinating Children

Newsy (Jan. 28, 2015) — As the Disneyland measles outbreak continues to spread, the media says parents who choose not to vaccinate their children are part of the cause. Video provided by Newsy
Powered by NewsLook.com
Shark Bite Victim Making Amazing Recovery

Shark Bite Victim Making Amazing Recovery

AP (Jan. 27, 2015) — A Texas woman who lost more than five pounds of flesh to a shark in the Bahamas earlier this month could be released from a Florida hospital soon. Experts believe she was bitten by a bull shark while snorkeling. (Jan. 27) 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