Dendritic excitability of mouse frontal cortex pyramidal neurons is shaped by the interaction among HCN, Kir2, and Kleak channels

Michelle Day, David B. Carr, Sasha Ulrich, Ema Ilijic, Tatiana Tkatch, D. James Surmeier*

*Corresponding author for this work

Research output: Contribution to journalArticle

126 Scopus citations

Abstract

Dendritically placed, voltage-sensitive ion channels are key regulators of neuronal synaptic integration. In several cell types, hyperpolarization/cyclic nucleotide gated (HCN) cation channels figure prominently in dendritic mechanisms controlling the temporal summation of excitatory synaptic events. In prefrontal cortex, the sustained activity of pyramidal neurons in working memory tasks is thought to depend on the temporal summation of dendritic excitatory inputs. Yet we know little about how this is accomplished in these neurons and whether HCN channels play a role. To gain a better understanding of this process, layer V-VI pyramidal neurons in slices of mouse prelimbic and infralimbic cortex were studied. Somatic voltage-clamp experiments revealed the presence of rapidly activating and deactivating cationic currents attributable to HCN1/HCN2 channels. These channels were open at the resting membrane potential and had an apparent half-activation voltage near -90 mV. In the same voltage range, K+ currents attributable to Kir2.2/2.3 and K +-selective leak (Kleak) channels were prominent. Computer simulations grounded in the biophysical measurements suggested a dynamic interaction among Kir2, Kleak, and HCN channel currents in shaping membrane potential and the temporal integration of synaptic potentials. This inference was corroborated by experiment. Blockade of Kir2/Kleak channels caused neurons to depolarize, leading to the deactivation of HCN channels, the initiation of regular spiking (4-5 Hz), and enhanced temporal summation of EPSPs. These studies show that HCN channels are key regulators of synaptic integration in prefrontal pyramidal neurons but that their functional contribution is dependent on a partnership with Kir2 and Kleak channels.

Original languageEnglish (US)
Pages (from-to)8776-8787
Number of pages12
JournalJournal of Neuroscience
Volume25
Issue number38
DOIs
StatePublished - Sep 21 2005

Keywords

  • Hyperpolarization-activated cation current
  • Inward rectifier
  • KCNK
  • Prefrontal cortex
  • Single-cell RT-PCR
  • Voltage clamp
  • Whole-cell recording

ASJC Scopus subject areas

  • Neuroscience(all)

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