Abteilung I Hallermann » Techniken

To analyze neuronal function, we use a variety of cutting-edge methods:

Presynaptic patch-clamp recordings in acute brain slices

To directly investigate the presynaptic mechanisms of chemical synaptic transmission, we perform patch-clamp recordings from presynaptic nerve terminals in acute brain slices, e.g. from hippocampal mossy fiber boutons (Hallermann et al., PNAS, 2003) or cerebellar mossy fiber boutons (Figure showing a two-photon image of a cerebellar mossy fiber filled with a red dye during recording, scale bar 10 µm; Ritzau-Jost et al., Neuron, 2014).

 

Paired pre- and postsynaptic recordings

We established paired recordings from cerebellar mossy fiber boutons and postsynaptic granule cells to investigate synaptic transmission at sub-millisecond resolution (Figure showing a paired pre- and postsynaptic recording, magenta and green, respectively; scale bar 10 µm; Ritzau-Jost et al., Neuron, 2014).



 

High-resolution quantitative two-photon calcium imaging

Quantitative two-photon calcium imaging with various calcium indicators were established to better understand presynaptic high-frequency vesicular release (Figure showing presynaptic calcium concentration during 300 Hz transmission; Delvendahl et al., PNAS, 2015).



 

Presynaptic capacitance measurements

We showed that capacitance measurements can be used at central en-passant synaptic boutons (Hallermann et al., PNAS, 2003). To further increase the temporal resolution, we combined capacitance measurements and deconvolution methods (Figure showing the superposition of membrane capacitance and deconvolution-based cumulative vesicle fusion rate; Ritzau-Jost et al., Neuron, 2014).



 

Dendritic patch-clamp recordings

To understand dendritic integration, we use patch-clamp recordings from dendrites of cerebellar granule cells (see Figure; Delvendahl et al., Front Cell Neurosci, 2015) or cortical layer 5 pyramidal neurons (Hallermann et al., Nat Neurosci, 2012).



 

Modeling

We analyze calcium diffusion, calcium buffering, and vesicle fusion using the CalC simulation environment (web.njit.edu/~matveev; Figure illustrating a synaptic vesicle in grey and calcium channels in red; Delvendahl et al., PNAS, 2015). Channel gating and cellular excitability are simulated with Neuron (www.neuron.yale.edu; Hallermann et al., Nat Neurosci, 2012). Quantal short term plasticity is implemented in C++ (Hallermann et al., Neuron, 2010; Hallermann et al., J Neurosci, 2010).



 

Fluctuation analysis

Fluctuations of postsynaptic currents and of ionic currents are used to estimate parameters of synapses and of ion channels (Figure showing consecutive postsynaptic currents; Hallermann et al., Neuron, 2010).



 

Low-noise single channel recordings with quartz-glass pipettes

To resolve low-noise single channel currents, quartz-glass pipettes are used (Figure showing an opening of a nicotinic acetylcholine channel with a duration of 10 µs; Hallermann et al., J Physiol, 2005).