Signatures of rapid plasticity in hippocampal CA1 representations during novel experiences

• Published in: Neuron (Cambridge, Mass.) Vol. 110; no. 12; pp. 1978 - 1992.e6
• Main Authors: Priestley, James B., Bowler, John C., Rolotti, Sebi V., Fusi, Stefano, Losonczy, Attila
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.2022
• Subjects: Animals; BTSP; CA1 Region, Hippocampal - physiology; calcium imaging; Hippocampus; Hippocampus - physiology; learning; Learning - physiology; memory; Mice; Neuronal Plasticity - physiology; Neurons - physiology; novelty; place cell; Place Cells; plasticity; BTSP; memory; novelty; plasticity; learning; place cell; calcium imaging; Hippocampus
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2022.03.026

Neurons in the hippocampus exhibit a striking selectivity for specific combinations of sensory features, forming representations that are thought to subserve episodic memory. Even during completely novel experiences, hippocampal “place cells” are rapidly configured such that the population sparsely encodes visited locations, stabilizing within minutes of the first exposure to a new environment. What mechanisms enable this fast encoding of experience? Using virtual reality and neural population recordings in mice, we dissected the effects of novelty and experience on the dynamics of place field formation. During place field formation, many CA1 neurons immediately modulated the amplitude of their activity and shifted the location of their field, rapid changes in tuning predicted by behavioral timescale synaptic plasticity (BTSP). Signatures of BTSP were particularly enriched during the exploration of a novel context and decayed with experience. Our data suggest that novelty modulates the effective learning rate in CA1, favoring rapid mechanisms of field formation to encode a new experience. •Population recordings in mouse hippocampus during familiar and novel exploration•CA1 place field dynamics predicted by behavioral timescale synaptic plasticity (BTSP)•BTSP-like features were highly experience dependent and enriched during novelty By combining virtual reality and two-photon calcium imaging, Priestley et. al. find pervasive signatures of rapid neural plasticity mechanisms in the mouse hippocampus during new experiences. Their study highlights a strong regulation of neural feature tuning in CA1 by novelty, which could contribute to quickly encoding new memories.