Hippocampal sharp-wave ripples (SPW-Rs) are critical for memory consolidation and retrieval. The neuronal content of spiking during SPW-Rs is believed to be under the influence of neocortical inputs via the entorhinal cortex (EC). Optogenetic silencing of the medial EC (mEC) reduced the incidence of SPW-Rs with minor impacts on their magnitude or duration, similar to local CA1 silencing. The effect of mEC silencing on CA1 firing and field potentials was comparable to the effect of transient cortex-wide DOWN states of non-REM (NREM) sleep, implying that decreased SPW-R incidence in both cases is due to tonic disfacilitation of hippocampal circuits. The neuronal composition of CA1 pyramidal neurons during SPW-Rs was altered by mEC silencing but was restored immediately after silencing. We suggest that the mEC provides both tonic and transient influences on hippocampal network states by timing the occurrence of SPW-Rs and altering their neuronal content.
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http://dx.doi.org/10.1016/j.cub.2023.07.039 | DOI Listing |
PLoS Biol
January 2025
Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States of America.
Worrying about perceived threats is a hallmark of multiple psychological disorders including anxiety. This concern about future events is particularly important when an individual is faced with an approach-avoidance conflict. Potential goals to approach are known to be represented in the dorsal hippocampus during theta cycles.
View Article and Find Full Text PDFNature
January 2025
Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
Recently acquired memories are reactivated in the hippocampus during sleep, an initial step for their consolidation. This process is concomitant with the hippocampal reactivation of previous memories, posing the problem of how to prevent interference between older and recent, initially labile, memory traces. Theoretical work has suggested that consolidating multiple memories while minimizing interference can be achieved by randomly interleaving their reactivation.
View Article and Find Full Text PDFProg Neurobiol
December 2024
Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, United States; Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712, United States; Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, United States. Electronic address:
Hippocampal region CA2 is essential for social memory processing. Interaction with social stimuli induces changes in CA2 place cell firing during active exploration and sharp wave-ripples during rest following a social interaction. However, it is unknown whether these changes in firing patterns are caused by integration of multimodal social stimuli or by a specific sensory modality associated with a social interaction.
View Article and Find Full Text PDFNeuropharmacology
March 2025
Institute of Physiology and Pathophysiology, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany.
Neuropeptide Y (NPY) is the most abundant neuropeptide in the brain. It exerts anxiolytic and anticonvulsive actions, reduces stress and suppresses fear memory. While its effects at the behavioral and cellular levels have been well studied, much less is known about the modulation of physiological activity patterns at the network level.
View Article and Find Full Text PDFbioRxiv
October 2024
Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78701.
Fragile X Syndrome (FXS) is a neurodevelopmental disorder that can cause impairments in spatial cognition and memory. The hippocampus is thought to support spatial cognition through the activity of place cells, neurons with spatial receptive fields. Coordinated firing of place cell populations is organized by different oscillatory patterns in the hippocampus during specific behavioral states.
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