Adaptation of hippocampal spatial and contextual representations to task structure

TL;DR

This study shows how hippocampal neurons in mice adapt their activity during learning and when switching between tasks involving spatial and contextual information.

Contribution

The study reveals how hippocampal representations evolve during learning and reorganize upon context changes.

Findings

CA1PN activity develops sequentially during learning, aligning with behavioral performance.

Switching to new task conditions rapidly disorganizes neuronal activity, even in familiar environments.

Reward reversal in unchanged environments causes gradual activity changes linked to behavioral adaptation.

Abstract

The hippocampus is fundamental for spatial and contextual memory. CA1 pyramidal neurons (CA1PNs) exhibit spatially tuned activity during navigation, but how their context-dependent tuning evolves during learning and upon context change is incompletely understood. We monitored Ca2+ activity of dorsal CA1PNs in mice in a virtual go/no-go task series that required both spatial navigation and rule learning based on nonspatial environmental features. Spatial and context-dependent activity of CA1PNs developed sequentially during learning, parallel with behavioral performance. Upon switching to a new task condition involving familiar and novel environments, neuronal activity disorganized rapidly and extensively even in the unchanged environment. In contrast, reward reversal in unchanged environments induced more gradual activity changes, associated with behavioral adaptation. Our results indicate that, during learning a spatial-contextual task, CA1PNs initially generalize between environments coding primarily spatial position, but, with experience, their activity gradually reorganizes to form partially distinct representations within a shared contextual framework.

Hippocampal neuronal maps are actively restructured during learning and upon context change to represent task structure.

Figures