A1 Journal article (refereed)
Hippocampal responses to electrical stimulation of the major input pathways are modulated by dentate spikes (2022)

Lehtonen, S., Waselius, T., Penttonen, M., & Nokia, M. S. (2022). Hippocampal responses to electrical stimulation of the major input pathways are modulated by dentate spikes. Hippocampus, 32(11-12), 808-817. https://doi.org/10.1002/hipo.23470

JYU authors or editors

Publication details

All authors or editors: Lehtonen, Suvi‐Maaria; Waselius, Tomi; Penttonen, Markku; Nokia, Miriam S.

Journal or series: Hippocampus

ISSN: 1050-9631

eISSN: 1098-1063

Publication year: 2022

Publication date: 16/09/2022

Volume: 32

Issue number: 11-12

Pages range: 808-817

Publisher: John Wiley & Sons

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1002/hipo.23470

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/83278

Abstract

Dentate gyrus (DG) is important for pattern separation and spatial memory, and it is thought to gate information flow to the downstream hippocampal subregions. Dentate spikes (DSs) are high-amplitude, fast, positive local-field potential events taking place in the DG during immobility and sleep, and they have been connected to memory consolidation in rodents. DSs are a result of signaling from the entorhinal cortex (EC) to the DG, and they suppress firing of pyramidal cells in the CA3 and CA1. To study the effects of DSs to signaling in the hippocampal tri-synaptic loop, we electrically stimulated the afferent fibers of the DG, CA3, and CA1 in adult male Sprague–Dawley rats at different delays from DSs. Responses to stimulation were increased in the EC-DG synapse during DSs, and the effect was amplified after theta-burst stimulation. We concluded that DSs strengthen the excitatory signal from the EC to the DG, which is reinforced by synapse potentiation and increased excitability of granule cells after theta-burst stimulation. This signal boosting may function in enhancing plastic changes in the DG-CA3 synapse. As responses in the CA3 and CA1 remained unaffected by the DS, the DS-contingent silencing of pyramidal cells seems to be a result of a decrease in excitatory input rather than a decrease in the excitability of the pyramidal cells themselves. In addition, we found that the DSs occur asynchronously in the left and right hippocampi, giving novel evidence of lateralization of the rodent hippocampus.

Keywords: electrophysiology; hippocampus; memory (cognition); brain; cerebral cortex

Free keywords: dentate gyrus; electrophysiology; hippocampus; lateralization; synaptic transmission

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Ministry reporting: Yes

Reporting Year: 2022

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