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Marti, G.

Publications and source records attributed to Marti, G..

2 recordsLinked to original sources

Mature dentate granule cells show different intrinsic properties depending on the behavioural context of their activation

The dentate gyrus (DG) plays a crucial role in learning, memory and spatial navigation. Only a small fraction of mature dentate granule cells (mDGCs) is active during behavior, while the large majority remains silent. To date, the properties of this active subset of neurons remain poorly investigated. Using fosGFP transgenic mice, we show ex vivo that activated mDGCs, from mice maintained in their home cage, exhibit a marked lower intrinsic excitability compared to the non-activated cells. Remarkably, activated mDGCs, from mice trained in a virtual environment, are more excitable than those from mice maintained in their home cage. Therefore, we show that activated mDGCs display different intrinsic properties and excitable states depending on the context of their activation. We propose that these properties could constitute a neural signature of cell assemblies recruited in different behavioral contexts.

neuroscience

Dynamic Control of Hippocampal Spatial Coding Resolution by Local Visual Cues

The ability to flexibly navigate an environment relies on a hippocampal-dependent internal cognitive map. Explored space can be internally mapped at different spatial resolutions. However, whether hippocampal spatial coding resolution can be dynamically controlled within and between environments is unknown. In this work we recorded the firing of hippocampal principal cells in mice navigating virtual reality environments, which differed by the presence of local visual cues (virtual 3D objects). Objects improved spatial coding resolution globally with a higher proportion of place cells, smaller place fields, increased spatial selectivity and stability. Spatial coding resolution was notably enhanced locally near objects and could be rapidly tuned by their manipulations. In the presence of objects, place cells also displayed improved theta phase precession and theta timescale spike coordination. These results suggest that local visual cues can rapidly tune the resolution of the hippocampal mapping system within and between environments.

neuroscience