Cortico-hippocampal synaptic and circuit dynamics during learning and memory recall

Using state-of-the-art high-resolution two-photon imaging and electrophysiology combined with chemogenetic and optogenetic circuit manipulations,  head-fixed behavioral paradigms for spatial and contextual learning, and analytical approaches, we are studying behaviorally driven compartment-specific dynamics in synapses, axons, dendrites, soma, cell types, and ensembles in the cortico-hippocampal circuit. First, we found that the activity dynamics and temporal stability of spatial representations in soma versus dendrites of hippocampal pyramidal neurons differ (Moore et al., Nature Communications, 2025) and may be modulated by GABAergic microcircuit dynamics. Finally, we found that entorhinal cortex axonal projections to the hippocampus convey both contextually salient and spatially tuned input and are modulated by hippocampal feedback projections to the entorhinal cortex (Butola et al., Nature Neuroscience, 2025). Glutamatergic and GABAergic input from both LEC to CA1 (Basu et al . Science 2016; Bilash et al., Cell Reports 2023, Hernandez Frausto in preparation) versus CA3 (Robert et al., Science 2025, O’Neil et al., 2026 bioRxiv) targets different interneuron microcircuits to differentially modulate excitatory output in a compartment and pathway-specific manner and play distinct functional roles in learning vs. recall of memory behaviors. The Glutamatergic and GABAergic LEC inputs conjunctively modulate learning and context-driven stability and remapping of place maps in CA3 (Robert et al., Science 2025), whereas glutamatergic input from LEC is crucial for supporting memory recall and stability of task-selective place ensembles during a high-demand goal-oriented learning task (Hopkins et al., 2026 bioRxiv; Zemla et al., Cell Reports, 2022).

Dr. Jayeeta Basu is an Assistant Professor at New York University.

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