Efferent Auditory Brainstem Circuits

Our laboratory has focused on auditory brainstem circuits that control the middle ear muscle reflexes, one of two major descending systems that provide feedback to the auditory periphery. Collaborating with M. Christian Brown, Ph.D., we are characterizing the anatomy and physiology of the middle ear muscle reflexes in a rat model using retrograde labeling studies as well as lesioning experiments of the cochlear nucleus. We also perform transneuronal tracing of these auditory brainstem pathways using pseudorabies virus (PRV), a powerful neurotropic viral tracer. Our group is using PRV to identify synaptically linked neurons in the CNS that are involved in both the medial olivocochlear and middle ear muscle reflex pathways.

Auditory Brainstem Implants

My clinical research interests in pediatric and adult cochlear implants have extended to work in the central auditory system as principal investigator and director of the Helene and Grant Wilson Auditory Brainstem Implant (ABI) Program, a multidisciplinary research and clinical effort with collaborators at Mass. Eye and Ear and Massachusetts General Hospital. Our goals are to 1) provide ABIs to patients who are deaf and are not candidates for cochlear implants due to injured or absent auditory nerves (patients with Neurofibromatosis Type 2, cochlear ossification / labyrinthitis ossificans, severe cochlear hypoplasia, or traumatic bilateral auditory nerve injury and 2) conduct basic and clinical research on how to improve the performance of ABIs.


Optical Stimulation of the Auditory System

Our recent work in the ABI lab has included the first efforts to optically stimulate neurons in the central auditory system using optogenetics. In contrast to electricity, light offers a theoretical advantage as it can be focused and may allow for the selective activation of hundreds of independent acoustic channels.