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Interneuronal gap junctions increase synchrony and robustness of hippocampal ripple oscillations
Author(s) -
Holzbecher André,
Kempter Richard
Publication year - 2018
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.14267
Subject(s) - ripple , neuroscience , physics , hippocampal formation , gap junction , biophysics , biology , intracellular , quantum mechanics , voltage , microbiology and biotechnology
Sharp wave–ripples ( SWR s) are important for memory consolidation. Their signature in the hippocampal extracellular field potential can be decomposed into a ≈100 ms long sharp wave superimposed by ≈200 Hz ripple oscillations. How ripple oscillations are generated is currently not well understood. A promising model for the genesis of ripple oscillations is based on recurrent interneuronal networks ( INT ‐ INT ). According to this hypothesis, the INT ‐ INT network in CA 1 receives a burst of excitation from CA 3 that generates the sharp wave, and recurrent inhibition leads to an ultrafast synchronization of the CA 1 network causing the ripple oscillations; fast‐spiking parvalbumin‐positive basket cells ( PV + BC s) may constitute the ripple‐generating interneuronal network. PV + BC s are also coupled by gap junctions ( GJ s) but the function of GJ s for ripple oscillations has not been quantified. Using simulations of CA 1 hippocampal networks of PV + BC s, we show that GJ s promote synchrony beyond a level that could be obtained by only inhibition. GJ s also increase the neuronal firing rate of the interneuronal ensemble, while they affect the ripple frequency only mildly. The promoting effect of GJ s on ripple oscillations depends on fast GJ transmission ( ≲ 0.5 ms), which requires proximal GJ coupling ( ≲ 100 μm from soma), but is robust to variability in the delay and the amplitude of GJ coupling.