To learn what is happening in the brain and nervous system when hyperacusis is present, we used sound-evoked, functional magnetic resonance imaging (fMRI) to locate regions of abnormal activity in the central nervous system of rats with behavioral evidence of hyperacusis induced with an ototoxic drug (sodium salicylate). We observed enhanced central auditory gain and were able to confirm this electrophysiologically.
‘Chemical earmuffs’ could prevent hearing loss
Once you start to lose your hearing, you can’t get it back. But what if you could prevent hearing loss by blocking in advance the effects of loud noises? That’s a route a team of biologists at the University of Iowa and Washington University, St. Louis, says may be possible.
HHF Connects with Researchers at the World’s Largest Conference on Hearing & Balance Science
Nearly 1,800 hearing and balance researchers and related experts gathered Jan. 25–29, 2020, in San Jose, CA for the 43rd annual Midwinter Meeting of the Association for Research in Otolaryngology (ARO), the largest academic association in the field. This included a number of Hearing Health Foundation (HHF)-affiliated researchers, members of the HHF Board of Directors and scientific advisory bodies, and HHF staff.
HHF Board Chair John Dillard Participates in Congressional Hearing Research Program
The Congressionally Directed Medical Research Programs’ (CDMRP), Hearing Restoration Research Program (HRRP) consumer advocate John Dillard participated in January the evaluation of research applications submitted to the HRRP in January.
A Key Molecule Required for the Regeneration of Auditory Hair Cells in the Avian Inner Ear
Hair cells in the cochlea are the only cells in our body specialized to encode the energy in sound waves. As a result, we lose our hearing when hair cells die, which occurs during aging and after exposure to excessive noise or ototoxic drugs. Research indicates that no adult mammals replace their auditory hair cells once they are lost.
First-Generation College Students and More Highlights From Meet the Researcher
Each year Hearing Health Foundation’s (HHF) Emerging Research Grants (ERG) program funds innovative hearing and balance projects from promising early-career scientists. A program created by Collette Ramsey Baker, in 1958 when HHF was founded, ERG continues to be a cornerstone of our mission. We eagerly look forward to applications from potential grantees, due this year on Feb. 10, 2020, and publicizing their projects and careers.
Changes in the Tiny Vessels of the Inner Ear’s Balance Organ Reveal Links to Ménière’s Disease
By Gail Ishiyama, M.D.
The integrity and permeability of the blood labyrinthine barrier (BLB) in the inner ear is important to maintain an adequate blood supply and to control the passage of fluids, molecules, and ions. Identifying the cellular and structural components of the BLB is critical to understanding inner ear microvasculature (micro vessels) and designing the efficient delivery of therapeutics across the BLB, potentially to treat hearing and balance disorders such as Ménière’s disease.
(A) Uniformly thick vessels (red) in a vestibular schwannoma utricle with arrows pointing to a wrapping pericyte cell. (B) In a thick vessel from a Ménière’s patient, there is disorganization of the pericyte processes (white arrows) and evidence of degeneration of the vascular endothelial cells and thin areas of the vessel wall (green). (C) This zoomed-out image shows constriction in the blood vessels (left arrow).
My team and I used fluorescence microscopy to study the microvasculature in the utricular macula, which detects the body’s linear movement, of patients who had undergone surgery for Ménière’s disease or vestibular schwannoma. As published in Frontiers in Cellular Neuroscience on Oct. 4, 2019, we found a significantly decreased number of junctions, total vessel length, and average vessel length in the microvasculature in Ménière’s disease specimens compared with vestibular schwannoma and control specimens.
The vessels in Ménière’s specimens appeared disorganized with abnormal, uneven, or constricted shapes, atypical branching, and decreased coverage and thinning, leaving vascular endothelial cells (VECs) exposed and unprotected. Our prior research had shown that in Ménière’s disease, VECs are damaged and that they contain oxidative stress markers. Our new study underscores possible mechanisms behind BLB disruption in Ménière’s and the subsequent signs of edema (excess fluid), which disrupts the homeostasis of the hearing and balance structures.
The report indicates that interventions aimed at preventing damage to the microvasculature may help stop the progression of damage to the vestibular system, restoring balance and preventing vertigo spells. It could be that decreasing vessel constriction and BLB leakage will help prevent chronic damage to balance structures; this may help explain how steroids administered to Ménière’s patients provide temporary relief from dizziness symptoms.
The paper also shows that human inner ear tissue can be used to compare and contrast findings in animal models to design better therapies for vestibular and auditory disorders. We hope that the deeper understanding of the anatomy of the BLB and its changes during disease will enable the development of noninvasive delivery strategies for treating hearing and balance disorders.
Gail Ishiyama, M.D., a 2016 and 2018 Emerging Research Grants recipient, is a clinician-scientist who is a neurology associate professor at UCLA’s David Geffen School of Medicine.
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Filling in the Gaps
The annual meeting of Hearing Health Foundation’s (HHF) Hearing Restoration Project (HRP) was held in Seattle Dec. 12–14, 2019. As always, we use this extended in-person meeting to discuss in detail the progress of the consortium over the past year and to develop our plan for the upcoming year.
Looking to Other Sensory Organs to Better Understand Hair Cell Regeneration
In a Sept. 25, 2019, article published in the Annual Review of Cell and Developmental Biology, Hearing Restoration Project (HRP) consortium member Tatjana Piotrowski, Ph.D., and colleagues at the Stowers Institute for Medical Research in Missouri summarize the existing literature on hair cell regeneration in the context of sensory cell regeneration more broadly.
Watch This New Captioned Video from Our Hearing Restoration Project (HRP)
In October, the Scientific Director of Hearing Health Foundation (HHF)’s Hearing Restoration Project (HRP), Peter Barr-Gillespie, Ph.D., was the keynote speaker of The New York Academy of Sciences (NYAS)’s “Hearing Restoration and Hair Cell Regeneration,” a symposium to connect internationally recognized hearing loss experts from academia, industry, government, and nonprofit organizations.