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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-tekijät tai -toimittajat

Nokia, Miriam
Gureviciene, Irina
Waselius, Tomi
Penttonen, Markku

Julkaisun tiedot

Julkaisun kaikki tekijät tai toimittajat: Nokia, Miriam; Gureviciene, Irina; Waselius, Tomi; Tanila, Heikki; Penttonen, Markku

Lehti tai sarja: Journal of Physiology

ISSN: 0022-3751

eISSN: 1469-7793

Julkaisuvuosi: 2017

Volyymi: 595

Lehden numero: 14

Artikkelin sivunumerot: 4961-4971

Kustantaja: Blackwell

Julkaisumaa: Britannia

Julkaisun kieli: englanti

DOI: https://doi.org/10.1113/JP274023

Julkaisun avoin saatavuus: Ei avoin

Julkaisukanavan avoin saatavuus:

Julkaisu on rinnakkaistallennettu (JYX): https://jyx.jyu.fi/handle/123456789/54982

Tiivistelmä

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.

YSO-asiasanat: hippokampus

Vapaat asiasanat: hippocampal electrical stimulation; associative learning; dentate spikes

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