Our research centers on the role of neural plasticity in the etiology of hearing disorders, of which tinnitus is our best working example. Tinnitus is a problem that plagues over 30 million Americans and is perceived as a persistent and annoying sound that has no external acoustic source. Approximately 2-3 million Americans experience tinnitus in a severe, chronic and debilitating form that interferes with sleep, concentration and the ability to perform effectively in the workplace.
Past work from our group has examined the role of injury to the inner ear and, in particular, to a certain subgroup of sensory hair cells called outer hair cells as triggers of tinnitus. Agents that damage outer hair cells, such as intense noise and ototoxic drugs, were found to trigger plastic readjustments in the cochlear nucleus, a brain center that receives input from the auditory nerve. Both within and beyond the cochlear nucleus these readjustments were found to tip the normal balance of excitatory and inhibitory inputs to neurons toward the side of excitation. A byproduct of this readjustment is an increase in resting (or what is usually referred to as spontaneous) neural activity. This condition of ‘hyperactivity’ is now widely believed to represent an important physiological hallmark of tinnitus.
We are presently studying the mechanisms underlying the emergence of this tinnitus-related hyperactivity. An understanding of these mechanisms is key for identifying treatment targets. To this end, we seek to identify the cell populations that are hyperactive and determine the role of changes in specific neurotransmitter receptors in the induction of the hyperactive state of neurons. To bring this work to the translational level, we are currently using our research model to test potential drug therapies for their ability to reduce tinnitus-related hyperactivity. The goal of this work is to identify molecules that will eliminate the hyperactive state of auditory neurons without changing sensitivity to normal sounds in the external world.
The laboratory recently expanded its scope to include collaborative research with Dr. Daniel Alam of the Head and Neck Institute. This work focuses on the effects of pharmacotherapies on facial nerve regeneration and tumor suppression following nerve trauma and facial transplant.
