A1 Journal article (refereed)
Hippocampal electrical stimulation disrupts associative learning when targeted at dentate spikes (2017)

Nokia, M., Gureviciene, I., Waselius, T., Tanila, H., & Penttonen, M. (2017). Hippocampal electrical stimulation disrupts associative learning when targeted at dentate spikes. Journal of Physiology, 595(14), 4961-4971. https://doi.org/10.1113/JP274023

JYU authors or editors

Publication details

All authors or editorsNokia, Miriam; Gureviciene, Irina; Waselius, Tomi; Tanila, Heikki; Penttonen, Markku

Journal or seriesJournal of Physiology



Publication year2017


Issue number14

Pages range4961-4971


Publication countryUnited Kingdom

Publication languageEnglish


Publication open accessNot open

Publication channel open access

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/54982


Hippocampal electrophysiological oscillations, namely theta and ripples, have been implicated in encoding and consolidation of new memories, respectively. According to existing literature, hippocampal dentate spikes are prominent, short‐duration (<30 ms), large‐amplitude (∼2–4 mV) fluctuations in hilar local‐field potentials that take place during awake immobility and sleep. Interestingly, previous studies indicate that during dentate spikes dentate gyrus granule cells increase their firing while firing of CA1 pyramidal cells are suppressed, thus resulting in momentary uncoupling of the two hippocampal subregions. To date, the behavioural significance of dentate spikes is unknown. Here, to study the possible role of dentate spikes in learning, we trained adult male Sprague–Dawley rats in trace eyeblink classical conditioning. For 1 h immediately following each conditioning session, one group of animals received hippocampal stimulation via the ventral hippocampal commissure (vHC) contingent on dentate spikes to disrupt the uncoupling between the dentate gyrus and the CA1 subregions. A yoked control group was stimulated during immobility, irrespective of brain state, and another control group was not stimulated at all. As a result, learning was impaired only in the group where vHC stimulation was administered contingent on dentate spikes. Our results suggest dentate spikes and/or the associated uncoupling of the dentate gyrus and the CA1 play a significant role in memory consolidation. Dentate spikes could possibly reflect reactivation and refinement of a memory trace within the dentate gyrus triggered by input from the entorhinal cortex.


Free keywordshippocampal electrical stimulation; associative learning; dentate spikes

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Ministry reportingYes

Reporting Year2017

JUFO rating3

Last updated on 2024-08-01 at 21:31