M. Christian Brown
Associate Professor of Otology and Laryngology, Harvard Medical School
Dr. Brown's research investigates the descending neural systems in the auditory pathway. Although their functions are poorly understood, these systems allow higher centers in the brain to control the activity of lower centers. Studies are focused on the olivocochlear system, which consists of several groups of brainstem neurons that control activity in the cochlea and the cochlear nucleus. The laboratory also studies motoneurons that innervate the middle-ear muscles and whose action regulates sound transmission through the middle ear. Both of these descending systems are organized into reflexes that respond to sound and we are working on the “wiring diagram” of the reflex pathways.
A second major research area is on improving the auditory brainstem implant (ABI). The ABI is a neural prosthesis that restores hearing in deaf individuals that are not eligible for the cochlear implant. However, the ABI is not as successful as the cochlear implant because users do not understand speech as well. Research in this area is developing metrics for identifying which neural populations are stimulated by the ABI, and to identify whether particular populations are most important for carrying information about speech. The laboratory is also working on ways to improve the type of stimulation provided by the ABI.
1. Brown, MC, de Venecia, RK, Guinan, JJ, Jr. (2003) Responses of MOC neurons: Specifying the interneurons of the reflex pathway. Exp. Brain Res. 153:491-498.
2. de Venecia RK, Liberman MC, Guinan JJ, Jr. and Brown MC (2005) Medial olivocochlear reflex interneurons are located in the posteroventral cochlear nucleus. J. Comp. Neurol. 487:345-360.
3. Benson, T, and Brown, MC (2006) Ultrastructure of synaptic input to medial olivocochlear neurons. J. Comp. Neurol. 499: 244-257.
4. Brown MC and Levine JL (2008) Dendrites of Medial Olivocochlear (MOC) Neurons in Mouse. Neurosci. 154: 147-159.
5. Lee DJ, Benson TE and Brown MC (2008) Diverse synaptic terminals on rat stapedius motoneurons. J. Assoc. Res. Otolaryngol. 9:321-333.
6. Brown MC Vetter DE. (2008) Olivocochlear neuron central anatomy is normal in α9 knockout mice. J. Assoc. Res. Otolaryngol. In Press.