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Poster Session B: Wednesday, August 13, 1:00 – 4:00 pm, de Brug & E‑Hall

Efficient spatial learning in the hippocampus via left-right theta sweeps in the entorhinal cortex

Callum Marshall¹, Zilong Ji¹, Neil Burgess²; ¹University College London, University of London, ²University College London

Presenter: Callum Marshall

Recent findings show that grid cells in the medial entorhinal cortex (MEC) generate an internal positional signal that sweeps outward from the animal’s current location into the surrounding environment. These sweeps alternate stereotypically between leftward and rightward directions across successive theta cycles, suggesting an intrinsic mechanism for spatial sampling. Here, we propose that left-right sweeps in grid cells support efficient spatial learning of recurrent connectivity between place cells in hippocampal region CA3. We extend a recent model that produces left-right sweeps in grid cells to show that: (1) synchronised left-right sweeps across grid modules drive coherent sweeps in downstream hippocampal place cells; (2) such sweeps accelerate the learning of place cell connectivity, facilitating rapid spatial map formation; and (3) disruption of theta oscillations abolishes sweep dynamics and impairs map formation. These findings suggest that grid cell theta sweeps provide an intrinsic scaffold for efficient spatial learning in the hippocampus. The model also generates testable predictions for how circuit-level disruptions—such as those arising during normal ageing or in the early stages of Alzheimer's disease—may lead to spatial deficits.

Topic Area: Memory, Spatial Cognition & Skill Learning

Extended Abstract: Full Text PDF