Kemere, Caleb T2024-01-222024-01-222023-122023-10-26December 2Dutta, Shayok. "Interrogating the role of hippocampal sharp-wave ripples in spontaneous learning." (2023) PhD diss., Rice University. https://hdl.handle.net/1911/115342https://hdl.handle.net/1911/115342EMBARGO NOTE: This item is embargoed until 2025-12-01Rodents naturally explore novelty in contexts, objects, or locations, showing a preference for the unfamiliar. Lesion studies establish this novelty preference as dependent on the hippocampus, particularly through object recognition memory (ORM) paradigms. Recent research links hippocampal CA1 LFP signatures, including fast-gamma and beta-band oscillations, to object-place recognition memory. This work observes predictable increases in transient hippocampal events like sharp-wave ripples (SWRs). Although SWRs increase after encoding novelty, the associated spiking activity does not necessarily align with object-place pairings, raising questions about the role of SWRs in curiosity-driven spontaneous learning tasks. This thesis employs selective modulation of SWR activity using a previously engineered open-source, closed-loop SWR detection system in an ORM displaced object paradigm. Results reveal that suppressing SWR activity during object encoding and post-encoding rest sessions significantly impairs object-place recognition memory. Analysis of recorded CA1 LFP data shows statistical changes in SWR rates between disruption and control groups, while preserving general exploratory behavior across these groups. Further analysis correlates changes in SWR duration from pre-encoding to post-encoding rest sessions with discrimination measures. These correlations suggest that longer ripple durations lead to higher novelty preference scores. To investigate this phenomenon, the study employs a novel algorithm for the selective interrogation of longer-duration ripples during post-encoding rest sessions. In conclusion, the findings indicate that SWRs, particularly longer-duration ripples, critically influence object-place recognition memory driven by curiosity. This work advances our understanding of memory consolidation and the processing of spontaneous memories, extending beyond the traditionally studied realm of food or reward-driven spatial memories.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.sharp-wave rippleslearning and memoryThesis2024-01-22