NIH awards $1.8 million for sound research

	Michael Burger's research explores how the auditory system processes sound information.

Michael Burger, assistant professor of neuroscience in the biological sciences department, has been awarded a $1.8 million grant from the National Institutes of Health’s (NIH) National Institute on Deafness and other Communication Disorders for his research entitled “Efferent Inhibitory Mechanisms in Binaural Processing.”
The five-year grant will allow Burger to build upon the preliminary data he first collected under a grant he received from the Deafness Research Foundation for his work on “Efferent Function in Sound Localization Processing.”
“I’m very excited about this grant because it provides the funds to ensure the long-term viability of my lab and gives me the resources I need to attack my research agenda,” Burger says. “It’s very validating to have people in my field appreciate my work and my approach to auditory neuroscience.”
Burger is interested in how the auditory system processes sound information. The ear and the brain work in tandem to determine the location of sound, relying on a specialized neural circuit in the brain devoted to the process. The brain is able to compute where sound comes from by determining when a sound wave strikes each ear. Auditory neurons can detect the tiny microsecond differences in arrival time of a sound between the two ears. This system also has to function over a wide range of sound intensities, making this computation particularly challenging.
“I am extremely impressed with the way Mike investigates fundamental cell-to-cell processes in deciphering how the brain detects the location of sounds,” says Murray Itzkowitz, professor and chair of the biological sciences department. “While the hearing health implications of his research are clear, I see his program as providing a model to explore many complex aspects of brain function and that, too, explains why the NIH is so interested in his program.”
Implications for clinical applications

	This image shows axons (in green) making synapses on the neurons (in red) that are responsible for computing sound location in the bird auditory system. The white traces show electrical activity from another class of neuron, which provides inhibitory input to the neurons shown in red.

The research centers on the question of how cellular, synaptic, and systems level properties are integrated to allow sensory neurons to extract and represent features of the acoustic environment. The grant will enable Burger to further explore how the inhibitory components of the circuit influence processing in each brain area involved in computing sound source location.
Burger and the other members of his lab work with chickens, which have brain circuitry similar to human brain structures. Chickens also serve as good developmental models because researchers are able to study hearing at any stage. Over the long term, Burger hopes to use the findings gleaned from his work with chickens to build a mechanistic understanding of sound localization circuitry in vertebrate systems.
Burger first began studying hearing at a bat auditory neuroscience lab while a Ph.D. student at the University of Texas at Austin and later started working with birds as a senior postdoctoral fellow at the Department of Otolaryngology-Head and Neck Surgery at the University of Washington. In 2005, he was awarded a prestigious Alexander von Humboldt Research Fellowship at the University of Munich. Burger joined the Lehigh faculty in 2006.
While this research may be fundamental in nature, its contributions could play a significant role in clinical applications. Understanding how normal brain circuits function can help develop or improve prosthetic devices, such as cochlear implants. These electronic devices substitute for damaged structures in the ear that may not function properly, and can restore hearing to deaf patients.
Although a lot is known about the process of how information moves from the ear to the brain, less is understood about efferent feedback—the information that travels from the higher regions of the brain back to lower processing centers. Burger says that current prosthetic devices don’t take into account any such feedback.
“We’re investigating basic principles of brain physiology—how synapses and neural circuits function as well as how they are regulated,” Burger says. “But without a long history of this kind of research, devices like cochlear implants would never have been developed.”
--Tricia Long