Neuroscience Colloquium: Stefan Hallermann
Speaker: Stefan Hallermann (Carl-Ludwig-Institute for Physiology, University Leipzig, Leipzig, Germany)
Title: "Measuring presynaptic action potentials in cultured cortical neurons"
Date: Thursday, November 22nd 2018, 17:00 pm
Location: Paul-Ehrlich Lecturehall, Virchowweg 4, CCM
Abstract:
The shape of the presynaptic action potentials critically controls the strength of synaptic
transmission. However, knowledge about the properties and the plasticity of action
potentials in small nerve terminals is limited. Recently, recordings with voltage sensitive
indicators showed that potassium channels dynamically regulated the amplitude of
presynaptic action potentials in small nerve terminals of cultured neurons, conflicting direct
patch-clamp recordings from larger presynaptic terminals. Therefore, we have investigated
the shape and dynamics of presynaptic action potentials in cultured cortical neurons
by direct whole-cell patch-clamp recordings. Analyses using electrical circuits validated our
direct patch-clamp recordings with quartz glass electrodes and optimal current clamp
amplifiers. We found rapid and large action potentials (half-duration ~450 μs; amplitude
~120 mV; 36°C). Pharmacologically blocking potassium channels prolonged action
potentials but did not affect their amplitude. Thus, potassium channel activation regulates
the duration but not amplitude of action potentials at small nerve terminals.