Hippocampal theta states are linked to reconfiguration of population activity with respect to behavioural context

Neural activity reflects both external stimuli and the brain’s internal state, which shapes how information is processed and perceived. For example, in phase-precession in the hippocampus, the phase of theta oscillations affects the firing of single neurons (place cells) and its relation to the external world. Here, we examine a different form of relationship between oscillations and neural activity, where frequency and power of hippocampal oscillations, instead of phase, are associated with differential neural firing patterns at the population level.

Using electrophysiological recordings of rats performing an odour-memory task and a data-driven model, we identify two distinct theta states: low-power-lower-theta and high-power-higher-theta. These states are associated to modulations in hippocampal neural ensemble activity representing trial outcome. Our findings suggest that power and frequency variations within theta oscillations may be linked to the reconfiguration of neural firing at the network level.

The authors would like to thank Norbert Fortin and Keiland Cooper for providing the raw data, together with task information and insights into the data structure. D.V. is supported by a Novo Nordisk Foundation Emerging Investigator Fellowship (NNF19OC-0054895) and an ERC Starting Grant (ERC-StG-2019-850404). The authors would like to thank the Wellcome Trust for support (106183/Z/14/Z, 215573/Z/19/Z).

Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus University, Aarhus, Denmark Laura Masaracchia, Pablo Oyarzo & Diego Vidaurre Centre de Recerca Matemàtica (CRM), Bellaterra, Spain Oxford Centre for Human Brain Activity (OHBA), Department of Psychiatry, Oxford University, Oxford, UK Correspondence to Laura Masaracchia or Diego Vidaurre. The authors declare no competing interests. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Masaracchia, L., Oyarzo, P., Fredes, F. et al. Hippocampal theta states are linked to reconfiguration of population activity with respect to behavioural context.