Biology subjects

Aleman-Zapata, A.

Publications and source records attributed to Aleman-Zapata, A..

4 recordsLinked to original sources

bioRxiv2025

Uncovering Sleep's Hippocampal-Cortical Dialogue: The Role of Deltas' and Spindles' Cross-Area Synchronization and Ripple Subtypes

Hippocampal ripples, critical for sleep-related memory consolidation, are heterogeneous events with various sources and functions. Here we applied principal component analysis to identify ripple sub-types and relate them to hippocampal-cortical interactions as well as their role in consolidating simple and complex semantic-like memories in rats. Three main ripple types were discovered: baseline, large-input, and small-input ripples. Small-input ripples, were associated with increased prefrontal cortex to hippocampus connectivity, followed hippocampal delta waves, and were sufficient for simple learning. In contrast, large-input ripples exhibited increased hippocampus to prefrontal cortex connectivity, occurred during hippocampal spindles together as a doublet with a small-input ripple, and were critical for complex memory consolidation. Finally, learning induced heightened coupling between hippocampal delta and spindle oscillations and their cortical counterparts, consequently leading to an increased synchronization of ripples with cortical oscillations. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/644132v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@b94b1borg.highwire.dtl.DTLVardef@f1fff0org.highwire.dtl.DTLVardef@1da0c00org.highwire.dtl.DTLVardef@4a0008_HPS_FORMAT_FIGEXP M_FIG C_FIG Significance StatementThis pioneering, data-driven approach is the first to connect distinct ripple sub-types to precise cross- brain computational states, revealing their role in consolidating various types of memories.

neuroscience↗

bioRxiv2024

Differential Contributions of CA3 and Entorhinal Cortex Inputs to Ripple Patterns in the Hippocampus Under Cannabidiol

Cannabidiol (CBD), increasingly recognized for its potential to treat insomnia, notably extends NonREM sleep phases and modifies sleep-associated ripple dynamics. Utilizing a threshold-based approach, our study differentiated distinct ripple types in rats, clarifying the contributions of intra-hippocampal (CA3) and cortical (mEC) regions to these events. The findings reveal that CBD primarily influences the CA3s input to the CA1, resulting in an increased occurrence of short ripples predominantly induced by cortical (mEC) activity and a corresponding decrease in long, intra-hippocampal sharp-wave-ripples. This study highlights the critical interplay between the CA3 and entorhinal cortex dynamics in shaping the characteristics of hippocampal ripples under the influence of CBD.

neuroscience↗

bioRxiv2023

CBD lengthens sleep, shortens ripples and leads to intact simple but worse cumulative memory

Cannabidiol (CBD) is on the rise as over-the-counter medication to treat sleep disturbances, anxiety, pain and epilepsy due to its action on the excitatory/inhibitory balance in the brain. However, it remains unclear if CBD also leads to adverse effects via changes of sleep macro- and microarchitecture. To investigate the effect of CBD on sleep and sleep-related memory consolidation, we performed two experiments using the Object Space Task testing both simple and cumulative memory in rats. We show that oral CBD administration extended the sleep period but changed the properties of NonREM sleep oscillations (delta, spindle, ripples). Specifically, CBD also led to less long (>100ms) ripples and consequently worse cumulative memory consolidation. In contrast, simple memories were not affected. In sum, we can confirm the beneficial effect of CBD on sleep, however, this comes with changes in NonREM oscillations that negatively impact memory consolidation.

neuroscience↗

bioRxiv2022

Learning Fast and Slow: Increased cortical plasticity leads to memory interference and enhanced hippocampal-cortical interactions

Our brain is continuously challenged by daily experiences. Thus, how to avoid systematic erasing of previously encoded memories? While it has been proposed that a dual-learning system with "slow" learning in the cortex and "fast" learning in the hippocampus could protect previous knowledge from interference, this has never been observed in the living organism. Here, we report that increasing plasticity via the viral-induced overexpression of RGS14414 in the prelimbic cortex leads to better one-trial memory, but that this comes at the price of increased interference in semantic-like memory. Indeed, electrophysiological recordings showed that this manipulation also resulted in shorter NonREM-sleep bouts, smaller delta-waves and decreased neuronal firing rates. In contrast, hippocampal-cortical interactions in form of theta coherence during wake and REM-sleep as well as oscillatory coupling during NonREM-sleep were enhanced. Thus, we provide the first experimental evidence for the long-standing and unproven fundamental idea that high thresholds for plasticity in the cortex protects preexisting memories and modulating these thresholds affects both memory encoding and consolidation mechanisms.

neuroscience↗