Medial entorhinal cortex plays a specialized role in learning of flexible, context-dependent interval timing behavior

• Published in: bioRxiv
• Main Authors: Bigus, Erin R, Lee, Hyun-Woo, Bowler, John C, Shi, Jiani, Heys, James G
• Format: Journal Article
• Language: English
• Published: United States 13.01.2024
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/2023.01.18.524598

Episodic memory requires encoding the temporal structure of experience and relies on brain circuits in the medial temporal lobe, including the medial entorhinal cortex (MEC). Recent studies have identified MEC 'time cells', which fire at specific moments during interval timing tasks, collectively tiling the entire timing period. It has been hypothesized that MEC time cells could provide temporal information necessary for episodic memories, yet it remains unknown whether MEC time cells display learning dynamics required for encoding different temporal contexts. To explore this, we developed a novel behavioral paradigm that requires distinguishing temporal contexts. Combined with methods for cellular resolution calcium imaging, we find that MEC time cells display context-dependent neural activity that emerges with task learning. Through chemogenetic inactivation we find that MEC activity is necessary for learning of context-dependent interval timing behavior. Finally, we find evidence of a common circuit mechanism that could drive sequential activity of both time cells and spatially selective neurons in MEC. Our work suggests that the clock-like firing of MEC time cells can be modulated by learning, allowing the tracking of various temporal structures that emerge through experience.