Dr. Whitlon and Dr. Lie investigated several enzymes to determine their effect on the regrowth of SGNs. She found that inhibiting an enzyme called Rho kinase led to accelerated growth of SGN nerve fibers. Whitlon used a novel technique she developed to culture SGNs taken from mice. Whitlon then applied the Rho kinase inhibitor to the cells. “This was the first time in our field that we have seen that the direct inhibition of an enzyme increased nerve fiber growth of auditory neurons,” she said.

Mouse spiral ganglion neurons. Blue=nuclei of all cell types. Red=neurons.

Since then, Whitlon has used her cell culture technique to prescreen other compounds for effects on cochlear neuron survival and regeneration. “In fields like cancer research, there are vast chemical “libraries” made up of drugs and other pharmacologic agents that are tested for their effects on tumor and other cells,” says Whitlon. “I wanted to take advantage of all those available libraries and use them for hearing drug discovery.”

Using the spiral ganglion cell culture technique that she developed, Whitlon took advantage of a technique that lets her screen hundreds of chemicals to determine their effects on SGN growth. Different groups of SGN cell cultures are exposed to different chemical compounds. The cultures are stained, automatically imaged and the nerve fibers are measured with a specialized computer program. Automated imaging and measurements let Whitlon measure nerve fiber growth under hundreds of chemical conditions and zero in on potential compounds that have promise. In effect, it lets her perform hundreds of experiments at once, saving vast amounts of labor and time and animals.
“The AHRF grant helped me investigate an idea that hadn’t been looked at before in the auditory system,” Whitlon says. “Since then, I have been able to leverage the results of my AHRF grant to secure larger federal funding and take the idea further.”

Whitlon hopes that her rapid screening of chemical compounds will help identify a pharmacological intervention that can be used to regrow SGNs in the inner ear and serve as a fundamental building block of hearing restoration.

Sound is composed of many distinct temporal and frequency information. Figure 1(A) shows the waveform for a vowel “/A/” from a word “ABA”. This sound can be broken into two components: temporal envelope plotted in Figure 1(B), and temporal fine structure plotted in Figure 1(C). In Figure 1(A), the temporal envelope is plotted as a red line. As shown in Figure1 (B) and (C), temporal envelope is a slowly changing component over time, whereas temporal fine structure is a fast changing component. A major problem with current cochlear implants is that they do a poor job of translating the temporal fine structure of sound. This makes it difficult for implant users to follow conversations in some places, like in a busy restaurant. Music also loses much of the detail for cochlear implant users, because musical pitch information is encoded in the temporal fine structure.

Figure 1. (A) Time-domain display of a spoken word /A/ of “ABA”. (B) The envelope component of this speech is shown. (C) The temporal fine structure of this speech is shown.

Dr. Won’s research focuses on measuring and describing how normal listeners encode acoustic cues. He studies listeners’ perception abilities as well as the brain response (called frequency following response). To do this, he will measure the brain responses from individual listeners with normal hearing as they are presented with various sounds containing only temporal envelope, or only temporal fine structure, or both (“natural sound”). He will measure the brain response from electrodes placed on his subjects’ head vertex, forehead and earlobes. Dr. Won will then look at how the neural response correlates to the different sound conditions.

“The frequency following responses measured from normal listeners should closely reflect the properties of sound,” says Dr. Won. “By studying this in normal listeners, and really understanding exactly what is at work in sound perception, we should be able to provide guidance to cochlear implant engineers on what they need to add to future devices to better represent the finer details of sound.”Dr. Won’s research is timely important because there is increasing awareness of the importance of cortical processes involved when using a cochlear implant. “I am very grateful to American Hearing Research Foundation for supporting my research. I hope my efforts may contribute to restore hearing and improve the quality of life of those who suffer from hearing loss”, says Dr. Won.

The striated organelle is a structural, filament-like component of cochlear and vestibular hair cells. It is located directly underneath the stereocilia, the “hair part” of hair cells. Because this structure may affect the tension on the “hairs” and may also provide a means for the brain to control this tension, Lysakowski believes the striated organelle plays an important role in modulating how they respond to sound and head motion.

Lysakowski will study the structure of the striated organelle furtherusing high-voltage electron microscopy and will use mass spectrometry to determine its protein composition. She will also look at how hair cells behave when the striated organelle is disrupted.

His research, funded by the AHRF for 2012, focuses on the role of a gene called En1. This gene plays a role in the development of a region of the brain called the superior olivary complex (SOC). The SOC processes information from the cochlea and uses it to locate sounds in space. Maricich will look at how the selective deletion of En1in mouse models affects the developing auditory system and how it might influence how the SOC connects to other auditory neurons.

Previously, researchers used surgical ablation techniques to study how cutting out various auditory neurons affected hearing. Genetic deletion is much more specific and eliminatescollateral damage caused by cutting, which can influence results. In earlier research, Maricich found that En1 appeared to play an important role during embryonic development of the SOC.In his current research, he will further investigate the role of En1 and hearing.

“Describing how En1 works in the developing auditory system and how it influences connectivity of hearing neurons between the brain and inner ear will help lay a foundation for understanding how abnormalities in this gene may contribute to hearing loss,” says Maricich.

Mr. Muench is currently Founder and President of Campion Corporation, a venture capital provider. Previously, he was involved in investment banking, commercial bank operations, and the investment department at a major insurance group.

Mr. Muench has provided leadership and guidance to Chicago Associates, an investment club from Northwestern University Graduate School.

Dr. Micco is currently Assistant Professor of Otolaryngology and Head and Neck Surgery at Northwestern Medical School. He is a member of several professional organizations, including the Chicago Medical Society, the Chicago Laryngology and Otological Society, and the American College of Surgeons (Associate Fellow).

Dr. Micco holds an M.D. from Northwestern University. He has published many articles in scientific journals and has received numerous awards, including Outstanding Scientific Presentation from the International Politzer Society.

Dhar received his bachelor’s degree in audiology and speech language therapy in 1992 from the National Institute for the Hearing Handicapped, University of Mumbai, India. He also served as a clinical audiologist and clinical coordinator at the Speech and Hearing Institute Research Center in India, where he oversaw audiology clinics and schools for the deaf.

Dhar earned his master’s degree in audiology in 1995 from Utah State University in Logan, and earned his Ph.D. from Purdue University, West Lafayette, Indiana. After graduating from Purdue, Dhar joined the faculty at Indiana University, Bloomington, as an assistant professor. He is now at the Roxelyn and Richard Pepper Department of Communication Sciences and Disorders at Northwestern University. His research focuses on otoacoustic emissions as they relate to cochlear mechanics.