Research & Faculty

Hearing research group

Hearing disorders of many types begin in the inner ear, but have long-term effects in the brain. The Hearing Research Group at NEOMED seeks to deepen the understanding of how the central nervous system functions in association with hearing, communication and swallowing, how it is affected by hearing disorders, and how manipulation of the central nervous systems may improve these disorders.

Faculty Researchers

Professor and Chair of Anatomy and Neurobiology
Associate Dean of Research, College of Medicine
Phone: 330.325.6630
Email: jjw@neomed.edu

Our laboratory studies neural mechanisms underlying hearing and acoustically guided behaviors, particularly social communication. We have focused increasingly on interactions between hearing and emotions. Much of our current work examines three facets of these interactions: the link between vocal signals and an animal’s emotional state, the analysis of social vocalizations by emotional centers in the brain, and the manner in which emotional centers modify processing of sounds by the auditory system. We use a wide variety of approaches in our work—acoustic, behavioral, neurophysiological, pharmacological, and anatomical. We are particularly excited about technical developments that will allow us to analyze the activity of individual neurons during social interactions. Our work on the basic neural mechanisms forms the basis for future studies of disorders of acoustic communication that involve misinterpretations of the meaning of sounds.

We thank the National Institute for Deafness and other Communication Disorders for their support of this work.

Professor of Anatomy and Neurobiology
Director, Translational Research Center
Phone: 330.325.6445
Email: jbao@neomed.edu

Dr. Bao’s group focuses on understanding the molecular mechanisms underlying two of the most common forms of hearing loss in the United States. Age-related hearing loss, or hearing loss associated with the aging process, affects roughly half of Americans age 75 years and older, and noise-induced hearing loss, or hearing loss caused by excessive exposure to loud noise, impacts roughly 26 million adults between 20 and 69 years of age. One major cellular mechanism, cochlear synaptopathy, underlies both hearing disorders. Cochlear synaptopathy refers to the loss of synapses, or connections, between sensory cells in the cochlea (the inner ear) and the neurons that transmit sound signals to the brain. Because the sensory cells themselves aren’t damaged under certain conditions, cochlear synaptopathy can’t be detected in a typical hearing test, yet it is the probable reason that some people with reportedly normal hearing thresholds have difficulty understanding speech in environments with a high level of background noise. Dr. Bao’s group develops new functional and molecular technological platforms to study cochlear synaptopathy in both preclinical and clinical models. Because one hearing disorder, tinnitus, is closely associated with hearing loss, and that manifests as a perceived ringing, roaring, clicking, or buzzing in the ears in the absence of an external source of sound. Dr. Bao’s group is also developing tools to detect tinnitus in both rodent and primate models, and further to determine a possible link between tinnitus and synaptic changes, or plasticity, in a part of the brain known as the hippocampus. Currently, no medications have been found to treat any of the above three disorders. Through their research, Dr. Bao and his team are ultimately working to develop new therapies for the treatment and prevention of the most prevalent and debilitating hearing disorders affecting Americans today.

Associate Professor of Anatomy and Neurobiology
Phone: 330.325.6640
Email: agalaz@neomed.edu

The major focus of our research is tinnitus, the sensation of hearing a sound when no external sound is present. Almost all individuals experience this sensation for brief, unobtrusive periods. However, chronic sensation of tinnitus affects approximately 17% of the general US population. People with severe tinnitus may have trouble hearing, working and sleeping. Despite its ubiquity, the pathophysiology of tinnitus is poorly understood, and there is no FDA approved cure or treatment. Using the mouse tinnitus model which we have developed in our laboratory we study brain mechanisms responsible for tinnitus induction following an acoustic trauma. For our research we use a wide variety of techniques spanning from recording of electrical activity in single neurons extracellularly as well as intracellularly to behavioral approaches of tinnitus assessment using gap-induced inhibition of the acoustic startle reflex.

We thank the National Institute for Deafness and other Communication Disorders for their support of this work.

Assistant Professor of Audiology, Kent State University
Adjunct Assistant Professor of Anatomy and Neurobiology, NEOMED
Phone: 330.672.0249
Email: jhuyck@kent.edu

I was drawn to the field of audiology based on my experience as an individual with hearing loss. While studying for my B.S. in Communication Sciences and Disorders at Northwestern University, I became fascinated by the mechanisms underlying learning, particularly learning through listening. This caused me to pursue an M.A. in Learning Disabilities and a Ph.D. in Communication Sciences and Disorders from Northwestern. I am currently interested in the effects of maturation, aging, disability, and various aspects of cognition on the perceptual learning of speech and more basic auditory stimuli.

Associate Professor of Anatomy and Neurobiology
Phone: 330.325.6656
Email: ylu@neomed.edu

We investigate the cellular mechanisms of auditory processing, with a focus on neuromodulation under normal hearing and hearing-impaired conditions. Electrophysiological (e.g. whole-cell recordings) and optical imaging (e.g. calcium imaging) approaches, combined with pharmacological immunohistochemistry tools, are employed. We aim to provide a basic understanding of neuromodulation in functionally well-established auditory circuits that analyze information for sound localization. Ultimately, this will provide the basis for therapeutic intervention in hearing disorders characterized by impaired sensitivity to precise temporal features in sounds.

Assistant Professor of Anatomy and Neurobiology
Phone: 330.325.6625
Email: jmellott@neomed.edu

We study how the neural circuits in hearing change as we age. Age-related hearing loss is associated with a reduction in the level of GABA, a key neurochemical used to communicate among neurons throughout the auditory system. The loss of GABA leads to a variety of hearing deficits, including impairment of the ability to detect fine differences in the timing of sounds.

My laboratory identifies the auditory circuits particularly susceptible to GABA loss during aging, using complex circuit-tracing, immunohistological and imaging methods.

Assistant Professor of Anatomy and Neurobiology
Phone: 330.325.6516
Email: mrosen@neomed.edu

Early hearing loss is a risk factor for later problems with speech processing due to changes in auditory brain regions, and early stress exacerbates these deficits. Our laboratory studies how early hearing loss and stress can change auditory perception related to speech, and its underlying neural circuits. We use behavioral, neurophysiological, neurochemical, anatomical, and computational techniques to measure how neural activity and circuitry are altered by these developmental disorders, and how neural changes correlate with deficits in learning and perception. We measure neural responses to vocal communication and to natural and artificial sounds in the Mongolian gerbil, using implanted electrode arrays or intracellular recordings, where we can manipulate neurochemicals to assess circuit contributions to neural responses. We test animal perception using a variety of behavioral tasks, including operant conditioning and acoustic startle. This work lets us identify interventions that remediate perceptual deficits arising from these early experiences, in addition to understanding their underlying causes.

Research Assistant Professor of Anatomy and Neurobiology
Phone: 330.325.6407
Email: psalehi@neomed.edu

Platinum-based chemotherapy, such as cisplatin, provides an effective treatment for a variety of malignancies; however, its cytotoxic effects also lead to doselimiting side effects including ototoxicity, nephrotoxicity, and neurotoxicity. Approximately 60% to 80% of the patients treated with cisplatin develop hearing loss, which is usually permanent, bilateral and progressive.

A major focus of our studies is to identify the underlying genetic factors associated with cisplatin-induced ototoxicity. Our experiments result in a better understanding of the biological rules that make inner ear hair cells resistant to cisplatin damage based on the genetic background. Identification of the genetic factors contributing to cisplatin-induced ototoxicity in rodents can lead to novel prophylactic or therapeutic strategies against cisplatin-induced ototoxicity.

We use CBA/CaJ mice for Auditory Brainstem Response (ABR), Distortion Product Otoacoustic Emissions (DPOAEs), morphological assessments (Immunohistochemistry), and investigation of the biological pathways at cellular and subcellular levels.

In parallel to genetic assays, we investigate the effect of the calcium channel blockers on tumor growth in cisplatin mice. The effect of the cisplatin and calcium channel blocker combination treatment on tumor growth will be assessed by IVIS imaging which is a non-invasive technique for longitudinal monitoring of tumor progression, cell trafficking and gene expression patterns in primates.

Professor of Anatomy and Neurobiology
Phone: 330.325.6655
Email: bschofie@neomed.edu

We study brain circuits that modulate how we hear. Such modulation allows us to maximize sensitivity when we need to hear a faint sound (Was that your phone?), filter out noise when we want to hear a friend’s voice in a noisy restaurant, or ignore irrelevant sounds (but not important ones!) when we’re trying to sleep. Acetylcholine is a neurotransmitter that plays a role in these and many other aspects of hearing, helping the brain adapt during normal development, during aging and in response to damage of the ear or brain. A goal of our research is to understand modulation of hearing and how acetylcholine circuits contribute to these tasks.

We study hearing circuits in guinea pigs, rats and mice. We combine the latest techniques using replication-deficient viruses and transgenic animals with classical anatomical tracing and immunohistochemistry to label specific neural pathways. We examine these pathways with light and electron microscopes to identify the cell types and their synaptic connections and thus characterize the brain circuits that allow us to hear.

Research Assistant Professor of Anatomy and Neurobiology
Phone: 330.325.6549
Email: sshanbhag@neomed.edu

What are the mechanisms by which information is encoded in the brain and how is this information used? These two questions form the basis of my research. I am currently exploring the representation of social vocalizations by neurons in the amygdala using optogenetic and neurophysiological techniques. I also have a long-standing interest in the coding of spatial information by the auditory system.

Questions?

Jeffrey Wenstrup, Ph.D.
Professor and Chair of Anatomy and Neurobiology
Phone: 330.325.6630
Email: jjw@neomed.edu

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