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Waking and sleeping states are privileged periods for distinct mnemonic processes. In waking behavior, rapid retrieval of previous experience aids memory-guided decision making. In sleep, a gradual series of reactivated associations supports consolidation of episodes into memory networks. Synchronized bursts of hippocampal place cells during events called sharp-wave ripples communicate associated neural patterns across distributed circuits in both waking and sleeping states. Differences between sleep and awake sharp-wave ripples, and in particular the accuracy of recapitulated experience, highlight their state-dependent roles in memory processes.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4641767 | PMC |
http://dx.doi.org/10.1016/j.conb.2015.05.001 | DOI Listing |
During navigation, animals continually sample their surrounding space and plan routes to distant goals. The brain mechanisms underlying these behaviors and how they coordinate to support memory-guided navigation in open environments are not understood. Using large-scale recordings in rats, we found two distinct types of place cell sequences within theta cycles that encoded trajectories sweeping beyond the animal's location: stereotypic left-right alternating sweeps and learning-dependent goal-directed sweeps.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2025
Forgetting Processes and Cortical Dynamics team, Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, Université Claude Bernard-Lyon 1, Lyon 69500, France.
Non-rapid eye movement (NREM) sleep facilitates memory consolidation by transferring information from the hippocampus to the neocortex. This transfer is thought to occur primarily when hippocampal sharp-wave ripples (SWRs) and thalamocortical spindles are synchronized. However, the mechanisms underlying this synchronization remain unknown.
View Article and Find Full Text PDFCommun Biol
August 2025
CHU Sainte-Justine Azrieli Research Centre, Department of Psychiatry and Addictology, University of Montréal, Montréal, QC, Canada.
We examine the neurobiology of intuition, a term often inconsistently defined in scientific literature. While researchers generally agree that intuition represents "an experienced-based process resulting in a spontaneous tendency toward a hunch or hypothesis," we establish a firmer neurobiological foundation by framing intuition evolutionarily as a pathfinding mechanism emerging from the brain's optimization of its relationship with the environment. Our review synthesizes empirical findings on intuition's neurobiological basis, including relevant brain networks and their relationship to cognitive states like insight.
View Article and Find Full Text PDFLeading theories suggest that hippocampal replay drives offline learning through coupling with an internal teaching signal such as ventral striatal dopamine (DA); however, the relationship between hippocampal replay and dopamine is unknown. Simultaneous recording of putative hippocampal replay events (dorsal CA1 sharp-wave ripples, SWRs) and fiber photometry of ventral striatal DA in mice revealed a significant increase in DA following SWRs, peaking ∼0.3 s after SWRs.
View Article and Find Full Text PDFCell Rep
August 2025
Department of Psychology, Seattle, WA 98195-1525, USA; Neuroscience Program, University of Washington, Seattle, WA 98195-1525, USA. Electronic address:
This study investigates how amyloid pathology influences hippocampal-prefrontal neural dynamics and decision-making in Alzheimer's disease (AD) using 5XFAD mice, a well-established model system characterized by pronounced early amyloid pathology. Utilizing ecologically relevant "approach food-avoid predator" foraging tasks, we show that 5XFAD mice exhibit persistent risk-taking behaviors and reduced adaptability to changing threat conditions, indicative of impaired decision-making. Multi-regional neural recordings reveal rigid hippocampal CA1 place cell fields, decreased sharp-wave ripple (SWR) frequencies, and disrupted medial prefrontal-hippocampal connectivity, all of which correspond with deficits in behavioral flexibility during spatial risk scenarios.
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