The Capita Foundation is proud to announce the following recipients of the 2011 Capita Foundation Auditory Research grant.
Adrian Fuente, Ph. D
The University of Queensland, Brisbane, Australia
Age-Related Changes in the Central Auditory Nervous System
and Hearing Aid Benefit in Older Adults
Age-related hearing impairment (ARHI), also referred to as presbycusis, is the most common sensory impairment observed in the elderly. ARHI can be defined as the age-related changes in peripheral and central auditory structures. The signs of age-related changes in the peripheral auditory structures are well known. The signs of age-related changes in the central auditory nervous system (CANS) are not fully understood, which drastically limits hearing rehabilitation programs in older adults. It is the aim of this research project to investigate age-related changes in the CANS and their effect on speech communication performance in older adults, and to determine to what extent age-related changes in the CANS affect hearing aid benefit in older adults. Three groups of subjects are being recruited: (1) normal-hearing younger adults; (2) normal-hearing older adults; and (3) older adult hearing aid users. All subjects are evaluated with electrophysiological and behavioral measures, investigating three aspects of the functioning of the CANS: (a) temporal resolution, (b) frequency resolution, and (c) binaural integration. Also, peripheral auditory function is evaluated with Pure-Tone Audiometry (PTA), and Distortion Product Otoacoustic Emissions (DPOAES). Cognitive function (attention and memory) is also evaluated. Speech communication is evaluated in all subjects with procedures such as the Hearing-in-Noise and Words-in-Noise tests. This study is expected to provide evidence on how declines in specific functions of the CANS adversely affect speech communication in older adults, and how these changes may affect hearing aid benefit in older adults. Therefore, new approaches to hearing rehabilitation programs in older adults may be developed, such as training programs focused on affected aspects of the CANS, in conjunction with hearing aids.
Carol De Filippo, Ph.D and Catherine Clark, Au.D
Improving Speech Perception in Prelingually Deaf Listeners:
Exploring a Novel Training Concept
For nearly a decade, cochlear implants have been an option for individuals with profound congenital hearing loss; however, the degree of auditory speech recognition benefit for this group can be disappointing. Age at onset and duration of deafness have been identified as significant factors that influence outcomes with a cochlear implant in this group; still, as much as 80% of the variance in individual performance remains unexplained. Factors that have yet to be explored include the nature of the training protocol and interactions between the visual and auditory modalities during training. The current research will lead to the development of a new training strategy that recognizes two premises: (a) the brain reorganizes in the presence of longstanding deafness, and (b) learning-dependent plasticity continues throughout life. The new procedure will attempt to demonstrate that, with appropriately devised experiences, the brain might be assisted to transition to a balanced bimodal percept. The goal of the current project is to simulate modulation of the visual component of a speech stimulus for use in audiovisual speech recognition training with congenitally deaf individuals who initiated auditory stimulation later in life.
Daniel J. Guillaume, M.D., M.Sc.
Department of Neurological Surgery
Oregon Health & Science University of Portland
Evaluation of Hearing Loss in Children
After Two Different Treatments for Hydrocephalus
The purpose of this study is to determine whether treatment for hydrocephalus is associated with hearing loss. Hydrocephalus occurs when brain fluid (cerebrospinal fluid, or CSF) that is continuously produced within brain cavities builds up because of blocked clearance pathways. It occurs in up to two of every 1000 births and is also acquired during life from a variety of causes. Hydrocephalus has traditionally been treated by tubes, or shunts, which allow the fluid to drain out of the brain compartment to another body fluid compartment, usually near the abdomen. A newer treatment, called "endoscopic third ventriculostomy" (ETV) can open blocks within the brain fluid spaces without a tube. Some researchers have shown evidence that placing a CSF shunt leads to significant hearing loss in patients, but this has not been properly studied. No researchers have studied hearing loss in patients treated with ETV. Hearing loss may occur in patients with shunts because the pressure within the brain compartment is lowered by the shunt, and this causes fluid shifts within the inner ear leading to hearing loss. The goal of this study is to compare hearing loss in children with hydrocephalus who have been treated with either a shunt or with ETV. The subject will receive a first hearing test just prior to treatment for hydrocephalus, a second test just after the treatment, and a third test about three months later. We will determine if there were any changes in the child’s hearing after treatment for hydrocephalus, compared to before. The child’s hydrocephalus treatment will not be changed by the study. This study will also use clinically obtained magnetic resonance imaging (MRI) to measure differences in the inner ears of patients, in an attempt to explain why some people lose hearing and others do not. Data will be analyzed to determine the incidence of hearing loss in patients undergoing treatment for hydrocephalus. Comparisons will be made based on which treatment was used.
Dr. Ikaro Silva and Dr. Leo Celi
Harvard - MIT Division of Health Sciences and Technology
Hearing Loss Screening Through Cell Phones
It is estimated that roughly 3 out of 1000 children are born with a significant permanent hearing loss. Delayed and insufficient language development resulting from untreated hearing loss can negatively affect learning, social skills and future employment. Fortunately most of these deficits can be avoided by the use of relatively inexpensive hearing aids subsidized by governments. However, while standard methods for detecting hearing loss in a clinic are fast and relatively straightforward, for populations living in poor or distant rural areas, access to such clinics can be costly, difficult, or both. An inexpensive and mobile method for hearing loss detection can expand the reach of the current services provided by audiologists to these resource-constrained populations. Dr. Ikaro Silva’s project team will focus on using Sana’s Android platform, designed and managed by Dr. Leo Celi and the Sana team, in order to create a mobile hearing screening application capable of transmitting psychoacoutstical data to any clinic in the world for remote diagnosis by certified audiologists. Dr. Silva’s unique approach to the hearing screening process will leverage existing mobile networks in order to transmit the patients data, diagnosis, and hearing-aid fitting history collected on the mobile device for remote verification by audiologists. Moreover, because their ultimate goal is universal inexpensive hearing screening, both Dr. Silva and Dr. Celi, plan on making the software and de-identified pilot data open-source and free to the public.
John Ramcharitar, Ph.D
Department of Biology, St. Mary's College of Maryland
Physiological Assessment of Ototoxicity and Octoprotection
In New Zealand
The experimental approach proposed in this project has enormous potential for extending use of the zebrafish model in ototoxicity studies. After rapid screens involving larval assays, identified ototoxic and otoprotective agents may then be further assessed using a novel far-field recording technique in adult fish (see figure below). In this way, potential drug candidates can be further screened en route to testing in mammalian models, before potential clinical trials begin.
Martin Schwander, Ph.D
Rutgers University Department of Cell Biology and Neuroscience
Role of Gasdermins in Auditory Function and Hearing Loss
Deafness is the most common form of sensory impairment in humans and is frequently progressive in nature, but little is known about the molecular pathogenesis of the disease. Likewise, the mechanisms that control the differentiation of the inner ear sensory epithelia and neurons are poorly defined. Research in my laboratory is focused on deciphering how cellular and molecular factors work to regulate the development of sensory hair cells and neurons, which is essential to understanding disease mechanisms. Towards the end, we have employed a forward genetics screen and identified mutations in novel genes that progressive hearing loss in mice and humans. One mutation maps to the prejvakin gene, which is a founding member of a novel gene family, the gasdermins. Intriguingly. different mutations in pejvakin can lead either to hair cell dysfunction or defects in spiral ganglion neurons, indicative for the importance of gene function in both hair cells and neurons. Currently, we are using genetic and biochemical approaches to study the cellular function of gasdermin proteins, identify interacting proteins, and design strategies to analyze their in vivo function in the auditory system. Understanding the molecular function of gasdermins will ultimately aid in the design of new therapeutics that target these signaling pathways and that will be effective in preventing or treating progressive hearing loss.
Michelle Hastings, Ph.D
Cell Biology and Anatomy Chicago Medical School
Rosalind Franklin University of Health Sciences
Development of a Treatment for Usher Syndrome
Usher syndrome is the leading genetic cause of combined deafness and blindness. The Hastings lab is developing approaches to correct the deafness associated with the disease using antisense oligonucleotides that target the molecular defect caused by a gene mutation in the USH1C gene. The long-term goal of the project is to utilize this approach as a treatment for Usher syndrome and other causes of deafness. One hurdle to developing a treatment for Usher syndrome, as is the case for most diseases, is the diversity of genes and gene mutations that cause the disorder. One approach to targeting individual mutations for therapeutics is through the use of ASOs, which have a high degree of specificity and can be designed and manufactured relatively easily. Our initial work has focuses on one particular mutation that causes Usher syndrome, in order to develop the treatment approach and demonstrate the feasibility of therapy for the disease. Our results so far demonstrate that ASOs can target and correct the molecular defect caused by a mutation in the USH1C gene in mice that have been engineered to harbor a human USH1C mutation that causes Usher. These findings are an important step towards developing an ASO-based treatment for Usher syndrome that could be applied not only to the particular mutation targeted in this instance, but, in principle, to a large number of other mutations that cause Usher and deafness in general.
Yang Zhang, Ph.D
Speech-Language-Hearing Sciences (SLHS)
and Center for Neurobehavioral Development,
University of Minnesota
Investigating Neural Mechanisms for Listening
Through Cochlear Implant and Hearing Aid
This research project aims to investigate how the central auditory system codes speech sounds in cochlear implant users and hearing aid users and how listening experience adaptively alters the neural coding patterns. To perceive speech and other sounds, the listener must translate the continuous time-varying auditory signal into discrete meaningful categories. Different speech and auditory perception models account for how various acoustic features are decoded in relation to learning experience. However, our understanding of the underlying brain mechanisms for the adpative auditory learning experience in users of cochlear implant or hearing aid has been limited to the empirical methods available to researchers. Despite the rapid advancement of brain imaging techniques for hearing research, the presence of electronic devices such as hearing aid and cochlear implant prevents the proper use of many of the imaging techniques such as functional Magnetic Resonance Imaging (fMRI) and Magnetoencephalography. One viable neurophysiological approach is the use of electroencephalography (EEG). Auditory event-related potentials (ERPs), which are averaged EEG responses time-locked to specific stimuli of interest, have been widely adopted to study the neural processing of complex speech and nonspeech stimuli in the auditory system. To date, there have been very limited EEG/ERP studies on cochlear implant and hearing aid users due to difficulties in subject recruitment, signal contamination from the active electronic devices, and large inter-subject variability. The research project will develop experimental protocols and signal processing techniques to improve the quality of EEG data recording and analysis as well as to enhance our understanding of adaptive listening through the assistive hearing devices. The project pulls together hearing research scientists and collaborative resources at the University of Minnesota for frontier behavioral and neurophsiology work, which will have strong clinical implications.
San Diego 8th Grade Student
Music Through Multi-Frequency Tactile Sound
This experiment was conceived because of the author's discovery in a noisy classroom that by putting one's teeth on the neck of a guitar it was possible to hear the guitar's sounds no matter how loud the room became. After some research, it was deduced that this effect was happening because the guitar's vibrations were bypassing the eardrum, the middle ear, and entering directly into the cochlea. Tactile sound is the focus of this experiment. It hopes to identify a way to send audio signals to the brain without using the ears to "hear" the sound. It is based on the theory that generating vibrations in the same patterns as one would find in the diaphragm of a speaker, and placing those vibrations so they touch sensitive body parts, would enable individuals to perceive the vibration as sound. The specific goal of this experiment is to seek a way to enable hard-of-hearing people to perceive music. It uses existing technology and existing research as a foundation, from which a new device was created to make the experiment possible. By building a device that can translate electronic signals into vibrations, and then sending those vibrations through body parts of the human body, this may lead to a major change in the way millions of people who have significant hearing problems perceive sound. It may also affect the way non-hearing-impaired people hear music and enhance their perceptions of sound.