Abstract Body

AIMS: Hippocampal activity is crucial for navigation and memory abilities. However, understanding how hippocampal representations are influenced by different cognitive demands remains challenging. One example is sharp-wave ripple (SWR) events underlying memory retrieval and consolidation. Yet, whether changes in SWR follow specific trends in response to learning, novelty and memory remains unclear.

METHODS: We recorded freely moving mice exposed to different types of tasks using either tetrodes or multi-site silicon probes. They explored familiar or novel open fields, and learnt running for water reward in an automatized maze that allows implementation of different navigational strategies. SWR were recorded before, during and after these several tasks, both in awake and sleep condition. SWR features were studied using standard spectral analysis and unsupervised classification algorithms.

RESULTS: We identify specific trends of SWR features influenced by novelty, habituation and learning of different tasks. Novelty and learning had a significant impact in modulating SWR frequency, amplitude and spectral entropy during wake conditions. These changes however tended to habituate upon repeated expositions to the task. After the first learning session of a linear maze, SWR dynamic was strongly influenced by sleep and exhibited consistent segregation of frequency but neither of amplitude nor entropy. Unsupervised evaluation of SWR topological features suggests specific modulatory trends depending on task demands.

CONCLUSION: SWR dynamics evolve distinctly under the influences of different cognitive demands.