Hearing disorders of many types begin in the inner ear, but have long-term effects in the brain. The Hearing Research Focus Area 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.
Jeffrey Wenstrup. Ph.D., Director
Dr. Wenstrup’s team studies how emotional centers in the brain interact with the auditory system to establish the meaning of speech and other vocal communication sounds. The interpretation of social vocalizations depends on information about acoustic structure, other sensory stimuli, and internal state. The laboratory examines the mechanisms acting within the basolateral amygdala that integrate across these information sources. Dr. Wenstrup’s team seeks to relate these mechanisms to disorders that result in an altered emotional response to speech, such as schizophrenia, autism, and some forms of posttraumatic stress disorder.
Jianxin Bao, Ph.D.
Dr. Bao’s group focuses on developing new drug and gene therapies for hearing disorders such as hearing loss and tinnitus. The prevalence of age-related hearing loss is 63 percent for those 70 years of age and above. Approximately 15 percent of Americans between the ages of 20 and 69—or 26 million Americans—have noise-induced hearing loss. Tinnitus is highly associated with hearing loss. There are no medications against these disorders. The group conducts studies to prevent hearing loss and tinnitus through development of new technology platforms. In addition, the group is developing advanced hearing and molecular tests to better identify subtle cellular and synaptic changes in the cochlea that will provide a better time window for medical intervention.
Alexander Galazyuk, Ph.D.
Dr. Galazyuk’s laboratory studies tinnitus—the perception of sound in the ears or head when no external source is present. The American Tinnitus Association estimates that 50 million Americans experience tinnitus to some degree, with 16 million patients requiring tinnitus treatment. Tinnitus is the most prevalent disability among active military personnel and veterans. Dr. Galazyuk’s group is working to identify underlying brain mechanisms responsible for the development of tinnitus, as well as potential therapies for tinnitus.
Yong Lu, Ph.D.
Dr. Lu’s laboratory investigates the functions and cellular mechanisms of an important group of proteins (metabotropic glutamate receptors) in auditory processing under normal hearing and hearing loss conditions. The laboratory aims to provide a basic understanding of the role of these proteins in functionally well-established auditory circuits that analyze information for the localization of sound sources. Ultimately, this will provide the basis for therapeutic intervention in hearing disorders characterized by impaired sensitivity to precise temporal features in sounds.
Julia Huyck, Ph.D., Kent State University
Dr. Huyck’s group investigates why some people are better than others at perceiving and learning to perceive speech and other sounds. In particular, the research focuses on (1) changes in auditory perception and perceptual learning during adolescence and (2) the biological factors (e.g., sex, brain circuitry) and cognitive factors (e.g., attention, memory) affecting auditory perception and perceptual learning in adolescents and young adults. This research may identify strategies for the rehabilitation of adolescents and young adults with auditory processing disorder (~6 percent) or those with hearing loss (~20 percent) who are adjusting to new hearing aids or cochlear implants.
Jeffrey Mellott, Ph.D.
Dr. Mellott’s laboratory studies 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 defi cits, including impairment of the ability to detect fine differences in the timing of sounds. Dr. Mellott’s laboratory identifies the auditory circuits particularly susceptible to GABA loss during aging, using complex circuit tracing and imaging methods. Identifying these circuits will allow for improved therapeutic brain targets to ameliorate age-related hearing loss.
Bruna Mussoi, Au.D., Ph.D., Kent State University
Dr. Mussoi’s laboratory studies the factors that impact age-related changes in the auditory system, specifically as they relate to speech perception difficulties. The group uses electrophysiological and behavioral methods to address the relative contributions of peripheral, central and cognitive mechanisms to changes in speech perception in older adults. Ultimately, this knowledge can provide the basis for the development of auditory rehabilitation strategies that are better suited for the needs of the growing population of older adults.
Merri Rosen, Ph.D.
Dr. Rosen’s team studies developmental hearing loss, particularly the type that accompanies ear infections in children. Early hearing loss is a risk factor for later problems with speech processing due to changes in auditory brain regions. Dr. Rosen’s group investigates how early hearing loss affects the brain’s circuits and neural responses to sound, and how such altered circuits affect the perception of time-varying sounds such as speech. This research will identify which aspects of auditory processing are most at risk from early hearing loss, allowing the laboratory to develop strategies for intervention and remediation.
Brett Schofield, Ph.D.
Dr. Schofield’s group studies the neural circuits that underlie hearing. Acetylcholine and GABA are chemicals used for communication between nerve cells. These chemicals are important in many aspects of hearing, including selective attention, learning and understanding speech. They play a critical role in helping the brain adapt during normal development, during aging and in response to damage of the ear or brain. The long-term goal of this research is to understand how acetylcholine and GABA contribute to these tasks. Sophisticated imaging methods with light and electron microscopes are used to identify neural circuits in which acetylcholine and GABA modulate auditory processing.
Sharad Shanbhag, Ph.D.
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.
Bradley Winters, Ph.D.
Sound localization is critically important for selective attention which facilitates communication. Dr. Winters’ lab seeks to better understand the specialized cellular properties of brainstem neurons that support sound localization by comparing timing and intensity information between the two ears. Dr. Winters uses advanced electrophysiological and imaging approaches to study synaptic plasticity and dendritic physiology in these circuits. Understanding the biology of sound localization may underpin the development of more effective interventions for those with impairments.