Large, Stable Spikes Exhibit Differential Broadening in Excitatory and Inhibitory Neocortical Boutons

Andreas Ritzau-Jost, Timur Tsintsadze, Martin Krueger, Jonas Ader, Ingo Bechmann, Jens Eilers, Boris Barbour, Stephen M. Smith, Stefan Hallermann

Research output: Contribution to journalArticlepeer-review

Abstract

Presynaptic action potential spikes control neurotransmitter release and thus interneuronal communication. However, the properties and the dynamics of presynaptic spikes in the neocortex remain enigmatic because boutons in the neocortex are small and direct patch-clamp recordings have not been performed. Here, we report direct recordings from boutons of neocortical pyramidal neurons and interneurons. Our data reveal rapid and large presynaptic action potentials in layer 5 neurons and fast-spiking interneurons reliably propagating into axon collaterals. For in-depth analyses, we establish boutons of mature cultured neurons as models for excitatory neocortical boutons, demonstrating that the presynaptic spike amplitude is unaffected by potassium channels, homeostatic long-term plasticity, and high-frequency firing. In contrast to the stable amplitude, presynaptic spikes profoundly broaden during high-frequency firing in layer 5 pyramidal neurons, but not in fast-spiking interneurons. Thus, our data demonstrate large presynaptic spikes and fundamental differences between excitatory and inhibitory boutons in the neocortex.

Original languageEnglish (US)
Article number108612
JournalCell Reports
Volume34
Issue number2
DOIs
StatePublished - Jan 12 2021

Keywords

  • action potential
  • en passant bouton
  • interneuron
  • layer 5 pyramidal neuron
  • long-term plasticity
  • neocortex
  • presynapse
  • short-term plasticity

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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