Henrique von Gersdorff, Ph.D.
Background
Henrique von Gersdorff earned a Ph.D. in Physics from the University of Minnesota and a Ph.D. in Neurobiology from Stony Brook University in New York. He received his B.S. in Physics from the Federal University of Rio de Janeiro, Brazil. He was a research scientist in high-energy physics at Brookhaven National Laboratory, and had postdoctoral fellowships at Stony Brook University and the Max-Planck Institute for Biophysical Chemistry, Department of Membrane Biophysics, Göttingen. In 1998 he was appointed assistant scientist in the Vollum Institute and was promoted to scientist in 2004. He also holds an associate professorship in the Cell and Developmental Biology department of OHSU.
Summary of Current Research
Sensory information is conveyed by neurons specialized to faithfully transmit large amounts of information at high rates. A key event in synaptic transmission is the release of neurotransmitter via vesicle fusion at synaptic terminals. Direct studies of synaptic terminals have been hampered by technical constraints. However, using high time resolution patch-clamp and membrane capacitance measurements, von Gersdorff and his associates have studied the kinetics of vesicle fusion (exocytosis) and subsequent membrane retrieval (endocytosis) in single, live synaptic terminals from bipolar cells of the goldfish retina and from hair cells of the frog amphibian papilla. These cells have compact ribbon-type active zones that contain a large pool of releasable vesicles suitable for the transfer of high bandwidths of information. Following short depolarizations, a fast form of endocytosis can be observed, indicating that synaptic vesicle membrane is quickly re-internalized after vesicle fusion. Von Gersdorff and his colleagues are presently investigating mechanisms for short-term synaptic plasticity at reciprocal synapses in retinal slices, and multivesicular release at the hair cell synapse using capacitance measurements together with paired recordings of hair cells and their afferent fibers.
To study conventional active zone synapses, the lab has been examining the calyx of Held nerve terminal, a pivotal element in the auditory brainstem circuitry that computes sound source localization. Precise timing of action potential discharges is essential for accomplishing this task. Nevertheless, the mechanisms that modulate and preserve the timing of spikes are poorly understood. Von Gersdorff and his coworkers are studying these mechanisms and short-term forms of plasticity at this synapse. The large size of the calyx terminal allows them to patch-clamp the terminal and the postsynaptic cell simultaneously, and thus to measure Ca2+ currents, presynaptic capacitance changes, and glutamate release. This direct access to the terminal allows the lab to study the kinetics of synaptic vesicle exocytosis and endocytosis, neurotransmitter reuptake, and the modulation of neuronal output patterns by presynaptic receptors and the Na+/K+-ATPase pump. Presently, the lab is focused on developmental changes that fine-tune auditory synapses for high frequency firing, and developing techniques for imaging the fast dynamics of Ca2+ and Na+ ions in the nerve terminal and axonal afferent fibers.
Selected Publications
Li, G.L., Keen, E., Andor-Ardó, D., Hudspeth, A.J., and von Gersdorff, H. (2009) The unitary event underlying multiquantal EPSCs at a hair cell's ribbon synapse. J. Neurosci. 29:7558-7568.
Srinivasan, G., Kim, J.H., and von Gersdorff, H. (2008) The pool of fast releasing vesicles is augmented by myosin light chain kinase inhibition at the calyx of Held synapse. J. Neurophysiol. 99:1810-1824.
Kim, J.H., Sizov, I., Dobretsov, M., and von Gersdorff, H. (2007) Presynaptic Ca2+ buffers control the strength of a fast post-tetanic hyperpolarization mediated by the α3 Na+/K+-ATPase. Nature Neurosci. 10:196-205.
Renden, R. and von Gersdorff, H. (2007) Synaptic vesicle endocytosis at a CNS nerve terminal: faster kinetics at physiological temperatures and increased endocytotic capacity during maturation. J. Neurophysiol. 98:3349-3359.
Li, G.-L., Vigh, J., and von Gersdorff, H. (2007) Short-term depression at the reciprocal synapses between a retinal bipolar cell terminal and amacrine cells. J. Neurosci. 27:7377-7385.
Kushmerick, C., Renden, R., and von Gersdorff, H. (2006) Physiological temperatures reduce the rate of vesicle pool depletion and short-term depression via an acceleration of vesicle recruitment. J. Neurosci. 26:1366-1377.
Hull, C., Studholme, K., Yazulla, S., and von Gersdorff, H. (2006) Diurnal changes in exocytosis and the number of synaptic ribbons at active zones of an ON-type bipolar cell terminal. J. Neurophysiol. 96:2025-2033.
Vigh, J., Li, G.-L., Hull, C., and von Gersdorff, H. (2005) Long-term plasticity mediated by mGluR1 at a retinal reciprocal synapses. Neuron 46:469-482.
Leão, R.M., Kushmerick, C., Pinaud, R., Renden, R., Li, G.-L., Taschenberger, H., Spirou, G., Levinson, S.R., and von Gersdorff, H. (2005) Presynaptic Na+ channels: locus, development, and recovery from inactivation at a high-fidelity synapse. J. Neurosci. 25:3724-3738.
