Stephan D. Brenowitz, Ph.D.

Acting Chief
Section on Synaptic Transmission

Dr. Brenowitz received a B.A. degree in Molecular Biology from the University of California–Berkeley and a Ph.D. in Neuroscience from the University of Wisconsin–Madison, where he studied plasticity at endbulb synapses of the cochlear nucleus in the laboratory of Laurence Trussell. During a postdoctoral fellowship with Wade Regehr at Harvard Medical School, he investigated mechanisms of endocannabinoid signaling and its modulatory effects on synaptic transmission in the cerebellum. Dr. Brenowitz joined the NIDCD as an Investigator in 2007. His laboratory explores mechanisms of synaptic transmission and plasticity in the auditory system using electrophysiology, two-photon imaging and molecular techniques.

Section on Synaptic Transmission

Research Statement

The Section on Synaptic Transmission investigates the synaptic and biophysical mechanisms that enable neurons to encode and process information. Specifically, we study mechanisms that enable computations in neural circuits of the auditory system. The general question we address is how local circuit interactions shape a neuron's response to physiologically realistic patterns of synaptic inputs. Our approach is to examine the behavior of specific types of auditory neurons in the context of the types of inputs they receive and the information they encode, and to determine the synaptic and biophysical mechanisms that enable these computations.

The auditory system, in particular the cochlear nucleus, is an excellent system to study how the brain performs complex computations. Acoustic information is initially represented in the auditory nerve, which encodes the frequency content of sounds reaching the ears. This system provides an excellent opportunity to investigate detailed mechanisms of synaptic plasticity, neuronal integration and network function in a well-defined circuit that can be preserved experimentally in slice preparations. Because the representation of sounds by the auditory nerve and many aspects of basic auditory circuitry are relatively well-described, the behavior and function of these neural circuits can be studied in a physiologically-relevant context.

Our experimental approach combines electrophysiology and optical techniques to study synaptic transmission and plasticity in the cochlear nucleus and auditory brainstem. These studies contribute to our understanding of how sensory stimuli are represented by neuronal activity and will enable improvements in treatment of hearing disorders. More generally, the auditory system provides an ideal system for linking mechanisms of synaptic plasticity and integration to functionally-relevant coding of neural information relevant for localization, identification and interpretation of sounds.

Selected Publications

• Brenowitz SD, Regehr WG. Reliability and heterogeneity of calcium signaling at single presynaptic boutons of cerebellar granule cells. Journal of Neuroscience 27:7888–7898, 2007.
• Brenowitz SD, Best AR, Regehr WG. Sustained elevation of dendritic calcium evokes widespread endocannabinoid release and suppression of synapses onto cerebellar Purkinje cells. Journal of Neuroscience 26:6481–6450, 2006.
• Brenowitz SD, Regehr WG. Associative short-term plasticity mediated by endocannabinoids. Neuron 45:419–431, 2005.
• Brenowitz SD, Regehr WG. Calcium dependence of retrograde inhibition at synapses onto Purkinje cells. Journal of Neuroscience 23:6373–6384, 2003.
• Brenowitz S, Trussell LO. Maturation of synaptic transmission at an endbulb synapse of the cochlear nucleus. Journal of Neuroscience 21:9487–9498, 2001.
• Brenowitz S, Trussell LO. Minimizing synaptic depression by control of release probability. Journal of Neuroscience 21:1857–1867, 2001.
• Brenowitz S, David J, Trussell L. Enhancement of synaptic efficacy by presynaptic GABA(B) receptors. Neuron 20:135–141, 1998.

Top