The hippocampal dentate gyrus is an important relay conveying sensory information from the entorhinal cortex to the hippocampus proper. During exploration, the dentate gyrus has been proposed to act as a pattern separator. However, the dentate gyrus also shows structured activity during immobility and sleep. The properties of these activity patterns at cellular resolution, and their role in hippocampal-dependent memory processes have remained unclear. Using dual-color in-vivo two-photon Ca2+ imaging, we show that in immobile mice dentate granule cells generate sparse, synchronized activity patterns associated with entorhinal cortex activation. These population events are structured and modified by changes in the environment; and they incorporate place- and speed cells. Importantly, they are more similar than expected by chance to population patterns evoked during self-motion. Using optogenetic inhibition, we show that granule cell activity is not only required during exploration, but also during immobility in order to form dentate gyrus-dependent spatial memories.
Binarized imaging traces of all cells from all experiment sessions are available on Dryad. https://doi.org/10.5061/dryad.mkkwh70z6.
Synchronous activity patterns in the dentate gyrus during immobilityDryad Digital Repository, doi:10.5061/dryad.mkkwh70z6.
- Heinz Beck
- Jakob H Macke
- Heinz Beck
- Kurtulus Golcuk
- Oliver Braganza
- Laura A Ewell
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All animal experiments were conducted in accordance with European (2010/63/EU) and federal law (TierSchG, TierSchVersV) on animal care and use and approved by the county of North-Rhine Westphalia (LANUV AZ 84-02.04.2015.A524, AZ 81-02.04.2019.A216).
- Laura L Colgin, University of Texas at Austin, United States
© 2021, Pofahl et al.
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