Place fields of single spikes in hippocampus involve Kcnq3 channel-dependent entrainment of complex spike bursts

Abstract

Hippocampal pyramidal cells encode an animal’s location by single action potentials and complex spike bursts. These elementary signals are believed to play distinct roles in memory consolidation. The timing of single spikes and bursts is determined by intrinsic excitability and theta oscillations (5–10 Hz). Yet contributions of these dynamics to place fields remain elusive due to the lack of methods for specific modification of burst discharge. In mice lacking Kcnq3-containing M-type K+ channels, we find that pyramidal cell bursts are less coordinated by the theta rhythm than in controls during spatial navigation, but not alert immobility. Less modulated bursts are followed by an intact post-burst pause of single spike firing, resulting in a temporal discoordination of network oscillatory and intrinsic excitability. Place fields of single spikes in one- and two-dimensional environments are smaller in the mutant. Optogenetic manipulations of upstream signals reveal that neither medial septal GABA-ergic nor cholinergic inputs alone, but rather their joint activity, is required for entrainment of bursts. Our results suggest that altered representations by bursts and single spikes may contribute to deficits underlying cognitive disabilities associated with KCNQ3-mutations in humans.

Neuron-oligodendrocyte potassium shuttling at nodes of Ranvier protects against inflammatory demyelination

“…Kcnq3 -KO mouse strains were maintained at the animal facility of the UKM under specific pathogen–free conditions. Kcnq3 –/– mouse strains were generated in-house and have been previously described ( 67 , 68 ). All mice were maintained on a C57BL/6J background.…”

“…Kcnq3 KO mouse strains were maintained at the animal facility of University Hospital Münster under pathogen-free conditions. Kcnq3 -/mouse strains were obtained from Thomas Jentsch, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin and have been previously described (67,68). All mice were kept on a C57BL/6J background.…”

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