My lab is 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.