NIDCD researchers have led an effort to understand the genetic underpinnings of enlarged vestibular aqueducts (EVA), a condition associated with early hearing loss in children, and in some cases, thyroid problems in the teenage years. As the NIDCD scientists make great strides in understanding the causes of hearing loss in children with EVA, they are also contributing to our understanding of the molecules and mechanisms involved in healthy hearing. Read more.
Roughly 2.5 million people in the U.S. have severe speech impairments and rely upon the use of computerized voices. The lack of diversity in available synthetic voices means that many people may use the same generic voices. NIDCD grantee Rupal Patel, Ph.D., seeks to change this. Read more.
Recent Research and News
Hearing and Balance
Researchers from the NIDCD have found a strong association between hearing impairment and depression among U.S. adults of all ages, particularly in women. The findings were similar among whites, blacks, and Hispanics. The researchers used 2005-10 data from the National Health and Nutrition Examination Survey (NHANES). The findings are based on self-reports of hearing loss among adults ages 18 or older along with a standard questionnaire to assess depression based on the frequency and severity of symptoms. Adults 70 or older were also tested for hearing loss by trained examiners in an NHANES mobile examination center. Chuan-Ming Li, M.D., Ph.D., in the Epidemiology and Statistics Program at the NIDCD, was the lead author of the study.
Researchers supported by the NIDCD are launching a clinical trial to test a device that uses nervous system stimuli to rewire parts of the brain, in hopes of significantly reducing or removing tinnitus, a persistent buzzing or ringing sound in the ears in the absence of any real sound. The small clinical trial, which is recruiting volunteers, is being conducted at four centers in the United States. Contact information for the study is available on the study's website.
Expanding on earlier research, Johns Hopkins researchers report that people with balance disorders or dizziness traceable to an inner-ear disturbance show distinctive abnormal eye movements when the affected ear is exposed to the strong pull of an MRI’s magnetic field. The researchers first reported in 2011 that an MRI’s magnetic field pushes on the inner ear fluid responsible for maintaining balance, causing subjects undergoing MRI scans to have jerky eye movements and dizziness. Two new studies now suggest that these strong magnets could be used to diagnose, treat, and study inner ear disorders in the future, replacing more invasive and uncomfortable examinations.
A team of researchers, funded in part by the NIDCD, have discovered that using gene therapy may protect the inner ear nerve cells of humans with certain types of progressive hearing loss. The study used a mouse model with a mutated form of the connexin 26 gene, which produces the most prevalent form of hearing loss in humans. Some 30 percent of American children born deaf have this form of the gene. Mice with the mutated connexin 26 gene exhibit deterioration of the neurons that send a sound signal to the brain. The researchers found that a protein growth factor used to protect and maintain neurons, otherwise known as brain-derived neurotrophic factor (BDNF), could be used to block this degeneration. They then engineered a virus that could be tolerated by the body without causing disease, and inserted the growth factor into the virus. Finally, they surgically injected the virus into the ears of the mice. This factor was able to "rescue" the neurons in the inner ear by blocking their degeneration.
University of Florida researchers, funded in part by the NIDCD, have discovered that a dietary supplement shows promise for protecting against hearing loss related to gentamicin, a drug used to treat bacterial infections that are resistant to other antibiotics. In an animal model, the scientists tested the use of a dietary supplement containing the antioxidants beta carotene and vitamins C and E, as well as the mineral magnesium, for protection against gentamicin-induced hearing loss. The researchers found that animals that received the dietary supplement had maintained their hearing better than animals that did not take the supplement. The treatment is currently being tested in human clinical trials.
One of the major causes of hearing loss in mammals is damage to the sound-sensing hair cells in the inner ear. For years, scientists have thought that these cells are not replaced once they’re lost, but new NIDCD-funded research at Massachusetts Eye and Ear reveals that supporting cells in the ear can turn into hair cells in newborn mice. If the findings can be applied to older animals, they may lead to ways to help stimulate cell replacement in adults and to the design of new treatment strategies for people suffering from deafness due to hair cell loss.
NIDCD-supported scientists at Stanford University and St. Jude’s Children’s Hospital have shown that spontaneous hair cell regeneration does in fact occur in the immature mammalian cochlea. Until now, although it has been possible to coax postnatal mammalian inner ear cells in the lab to differentiate into hair cells, it was not believed that this process occurred spontaneously in the body. The next step will be to better understand factors that can enhance hair cell survival, in addition to those that initiate this spontaneous regeneration. Understanding the pieces of this puzzle may eventually help restore lost hearing in humans.
Researchers funded largely by the NIDCD at Massachusetts Eye and Ear, Harvard Medical School, Massachusetts Institute of Technology, and Massachusetts General Hospital have, for the first time, linked aspirin to a halt in the growth of vestibular schwannomas (also known as acoustic neuromas), a sometimes lethal intracranial tumor that typically causes hearing loss and tinnitus. The researchers performed a retrospective analysis of more than 600 people diagnosed with vestibular schwannoma at Mass. Eye and Ear. Their research suggests a potential therapeutic role for aspirin in inhibiting tumor growth and is leading to a clinical prospective study to assess efficacy of this well-tolerated anti-inflammatory medication in preventing growth of these intracranial tumors.
Although the brain becomes smaller with age, shrinkage seems to be fast-tracked in older adults with hearing loss, according to researchers from Johns Hopkins University and the National Institute on Aging. The study, which was partly funded by the NIDCD, adds to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall.
Taste and Smell
Scientists at the University of Colorado School of Medicine, supported by the NIDCD, have shed light on one of the most common of ailments—the runny nose. The team, team led by Marco Tizzano, Ph.D., and Thomas Finger, Ph.D, found cells lining the noses of mice that may be key. These cells—called solitary chemosensory cells (SCCs)—detect potential irritants and pass along the alert to pain-sensing nerve terminals. The nerves then release a substance, called an inflammatory response, that triggers the body's defenses. Understanding how this works could help researchers find ways to prevent the response and offer relief to many.
Findings from NIDCD-supported researchers at NYU Langone Medical Center have found that memory of specific odors depends on the ability of the brain to learn, process, and recall accurately and effectively during slow-wave sleep—a deep sleep characterized by slow brain waves. Using animal models, the scientists show that odor memory was strengthened when odors sensed the previous day were replayed during sleep. Memories deepened more when odor reinforcement occurred during sleep than when the animals were awake. These findings on odor perception and processing could open pathways to a greater understanding of neurodegenerative disorders, such as Parkinson’s and Alzheimer’s diseases, which feature early loss of smell.
University of Florida researchers supported by the NIDCD say that they have identified the neurons involved in locating a specific scent—call it “lobster radar”—and that the discovery may help to develop improved electronic “noses” to detect landmines and other explosives. For many years, scientists have worked to create sensors that can detect everything from contamination in food products to harmful bacteria to land mines and explosives. The researchers have discovered a type of olfactory neuron in lobsters that constantly discharges small bursts of electrical pulses, much like radar uses pulses of radio energy to detect airplanes or thunderstorms. UF researchers speculate that these so-called “bursting” neurons might cue the crustaceans in on an odor’s location—especially important when they are searching for food or trying to avoid danger.
NIH-supported scientists from the Monell Chemical Senses Center have found that children who most prefer high levels of sweet tastes also prefer high levels of salty taste and that, in general, children prefer sweeter and saltier tastes than do adults. These preferences relate not only to food intake but also to measures of growth and can have important implications for efforts to change children’s diets. Many illnesses of modern society are related to poor food choices. Because children consume far more sugar and salt than recommended, which contributes to poor health, understanding the biology behind children’s preferences for these tastes could help in efforts to reduce their intake.
Scientists funded in part by the NIDCD at the Monell Chemical Senses Center have identified the presence of odor-producing chemical compounds in human earwax, and they note that these compounds differ between individuals of East Asian origin and Caucasians. The findings suggest that human earwax, an easily obtained bodily secretion, could be an overlooked source for diagnostic information.
Scientists at Washington University in St. Louis and the University of Iowa, funded in part by the NIDCD, have discovered a new class of cells expressing olfactory receptors in the human lung, which they are calling pulmonary neuroendocrine cells, or PNECs. Unlike the receptors found in the nose, which are located in the membranes of nerve cells, the ones in the lungs are in the membranes of neuroendocrine cells and trigger the release of hormones that make the airway constrict.
Voice, Speech, and Language
In the first known study of its kind, researchers funded by the National Institutes of Health (NIH) and the National Science Foundation have shown that the language we learn as a child affects brain structure, as does hearing status. While previous research had shown that people who are deaf and those who have healthy, or normal, hearing differ in brain anatomy, these studies were limited to individuals who are deaf and use American Sign Language (ASL) from birth. The new study found differences in brain structure between those who grew up using ASL and those who grew up using English. Differences were also seen between hearing and deaf volunteers, regardless of whether they used English or ASL. Since both language and hearing are housed in nearby locations in the brain, understanding which differences are attributed to hearing and which to language is critical in understanding the mechanisms by which experience shapes the brain.
Researchers at the University of California San Francisco, funded in part by the NIDCD, have reported that the brain doesn’t respond to the individual sound segments known as phonemes—such as the b sound in “boy”—but is instead tuned to detect simpler elements, which are known to linguists as “features.” This organization may give listeners an important advantage in interpreting speech, the researchers said, since the articulation of phonemes varies considerably across speakers, and even in individual speakers over time. The work may add to our understanding of reading disorders, in which printed words are imperfectly mapped onto speech sounds.
Researchers at New York University and NYU Langone Medical Center, funded in part by the NIDCD, have found that we use both sides of our brain for speech. This finding alters previous conceptions about neurological activity. The results offer insights into how to potentially treat speech-related inhibitions caused by stroke or injury and lay the groundwork for better rehabilitation methods.
According to NIDCD-funded researchers at Vanderbilt University, children with autism spectrum disorders (ASD) have trouble integrating simultaneous information from their eyes and their ears. The study is the first to illustrate the link and strongly suggests that deficits in the sensory building blocks for language and communication can ultimately hamper social and communication skills in children with autism. The researchers suggest that if this deficit in early sensory function can be successfully treated, children with autism might see benefits in language and in communication and social interactions.
Scientists, industry and advocacy leaders, and members of Congress celebrated the dedication of one of the world’s largest neuroscience facilities—the John Edward Porter Neuroscience Research Center—on the National Institutes of Health campus. The new building, a state-of-the-art laboratory structure, will be home to 85 principal investigators from 10 NIH institutes and centers and will house some 800 scientists. Read more.
On March 25, the NIDCD partnered with the National Eye Institute (NEI) to host a Twitter chat to discuss Usher syndrome, a disorder that causes progressive loss of hearing and vision. Read more.
The American Academy of Audiology recently presented NIDCD scientist Carmen Brewer, Ph.D., with a Distinguished Achievement Award. Read more.
NIDCD’s Noisy Planet Campaign
The NIDCD’s Noisy Planet campaign brought engaging information and fun educational activities to the 3rd USA Science & Engineering Festival in Washington D.C. The biannual festival is a national grassroots effort to advance STEM (science, technology, engineering, and math) education and to inspire the next generation of scientists and engineers. Read more.
A group of middle school students from Virginia recently contacted the Noisy Planet team to ask for materials about noise-induced hearing loss. The students are members of a team that participated in this year’s eCybermission competition, for which they created a computer program called Decibel mApp. Read more.