Article
Multidisciplinary Sciences
Yiyao Zhang, Liang Cao, Viktor Varga, Miao Jing, Mursel Karadas, Yulong Li, Gyorgy Buzsaki
Summary: In mice, cholinergic signaling in the hippocampus increased in parallel with theta/gamma power during walking and REM sleep, while reaching its minimum during hippocampal sharp-wave ripples (SPW-R). Memory performance was impaired when medial septal cholinergic neurons were selectively optogenetically stimulated in a delay area. This stimulation also decreased the incidence of SPW-Rs.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Review
Neurosciences
Boxu Xie, Zhihang Zhen, Ouyang Guo, Heming Li, Moran Guo, Junli Zhen
Summary: Sharp wave ripples (SWRs) are high-frequency synchronization events generated by hippocampal neuronal circuits and are crucial for the consolidation of spatial, episodic, and social memories. SWRs originate from hippocampal CA3 and subiculum and modulate neuronal activity in cortical and subcortical regions. Different hippocampal subregions have distinct functions in learning and memory, and SWR dysregulation can contribute to cognitive impairments in neurodegenerative and neurodevelopmental diseases.
BRAIN RESEARCH BULLETIN
(2023)
Article
Biology
Roberto De Filippo, Dietmar Schmitz
Summary: Hippocampal ripples are synchronous neural events critical for memory consolidation and retrieval. This study used a large dataset to analyze ripple propagation within the hippocampal formation and found that strong ripples propagate differently depending on their generation point along the hippocampal axis. The results suggest a distinctive role of the hippocampal septal pole in conditions of high-memory demand and highlight the impact of ripple generation location on neural activity across the hippocampus.
Article
Neurosciences
Arron F. Hall, Dong V. Wang
Summary: Sharp-wave ripples are short oscillatory events with bursts of neural firing in the CA1 region of the hippocampus. They communicate with cortical ensembles during slow-wave sleep and play a critical role in the consolidation of episodic memories. The underlying mechanisms that enable ripples to consolidate memories broadly and with specificity across experiences remain unknown.
PROGRESS IN NEUROBIOLOGY
(2023)
Article
Clinical Neurology
Tomomi Tsunematsu, Sumire Matsumoto, Mirna Merkler, Shuzo Sakata
Summary: P-waves, known as an electrophysiological signature of rapid eye movement (REM) sleep, are also observed during non-REM (NREM) sleep. Recent studies have discovered that P-waves in NREM sleep are functionally coupled with hippocampal sharp wave ripples (SWRs). The waveform shapes and local neural ensemble dynamics of P-waves in NREM sleep are similar to those in REM sleep in a short timescale. However, the dynamics of mesopontine cholinergic neurons and the coupling of P-waves with SWRs differ between NREM and REM sleep.
Article
Neurosciences
Peter C. Petersen, Mihaly Voroslakos, Gyorgy Buzsaki
Summary: Biochemical mechanisms in the brain are influenced by temperature. This study demonstrates that brain temperature variations are correlated with hippocampal sharp wave ripple features, including frequency, occurrence rate, and duration. Focal manipulation of temperature in the CA1 region of the hippocampus can alter ripple frequency. Other parameters of the sharp wave-ripple complex may be determined by mechanisms upstream from the CA1 region.
JOURNAL OF NEUROPHYSIOLOGY
(2022)
Article
Biology
Jan L. Klee, Bryan C. Souza, Francesco P. Battaglia
Summary: This study used high-density electrophysiological recordings from the hippocampal CA1 area and the prefrontal cortex (PFC) in mice to investigate how sounds guide anticipatory licking during classical conditioning. The results showed distinct learning-dependent changes at the single-cell level in CA1 and PFC neurons, as well as the maintenance of cue identity at the population level. Additionally, task-related neuronal assemblies in CA1 and PFC exhibited reactivation during hippocampal awake Sharp-Wave Ripples (aSWRs), supporting the idea that persistent firing and reactivation of task-related neural activity patterns in these areas contribute to learning during classical conditioning.
Article
Multidisciplinary Sciences
Ivan Skelin, Haoxin Zhang, Jie Zheng, Shiting Ma, Bryce A. Mander, Olivia Kim McManus, Sumeet Vadera, Robert T. Knight, Bruce L. McNaughton, Jack J. Lin
Summary: Studies suggest that during sleep, hippocampal sharp-wave ripples and other neural activities can modulate widespread high-frequency activity, predicting coordinated activity between different brain regions. These findings imply a mechanism where hippocampal and cortical slow-wave synchronization supports memory consolidation.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Pharmacology & Pharmacy
Logan A. Becker, Hector Penagos, Francisco J. Flores, Dara S. Manoach, Matthew A. Wilson, Carmen Varela
Summary: Sleep medications eszopiclone and zolpidem have different effects on hippocampal ripple oscillations, which are linked to memory consolidation during sleep. Eszopiclone makes ripples sparser, while zolpidem increases ripple density. In addition, eszopiclone decreases spike firing, while zolpidem has minimal effect on spikes. These findings provide an explanation for the divergent effects of eszopiclone and zolpidem on memory in humans.
FRONTIERS IN PHARMACOLOGY
(2022)
Article
Clinical Neurology
Veronique Latreille, Tamir Avigdor, John Thomas, Joelle Crane, Viviane Sziklas, Marilyn Jones-Gotman, Birgit Frauscher
Summary: This study investigated the role of sleep oscillations in memory consolidation and found that scalp spindles play an important role in memory processes in patients with drug-resistant temporal lobe epilepsy. However, the role of sleep ripples in memory abilities in epilepsy is still unclear.
Article
Biotechnology & Applied Microbiology
Muhammad Mushtaq, Rizwan ul Haq, Waqas Anwar, Lisa Marshall, Maxim Bazhenov, Kashif Zia, Hina Alam, Lars Hertel, Abdul Aleem Awan, Thomas Martinetz
Summary: The hippocampus is crucial for memory formation and learning, where memory traces are transferred from the hippocampus to neocortex for permanent storage through network oscillations. Recent studies suggest that neurotransmitters and neuromodulators suppress the activity of SPW-Rs in the hippocampus, potentially dependent on various synaptic parameters.
Article
Cell Biology
Wenbo Tang, Justin D. Shin, Shantanu P. Jadhav
Summary: This study reveals the importance of the hippocampal-prefrontal circuitry in guiding decisions during navigation and highlights how cognitive maps are transformed across this circuitry to support abstraction and generalization. The hippocampus maintains specificity of navigational information in separate environments, while the prefrontal cortex is able to generalize this information. Furthermore, the two regions have distinct representational geometries, with the prefrontal cortex enabling abstraction of rule-informative variables.
Article
Neurosciences
Heath L. Robinson, Zhibing Tan, Ivan Santiago-Marrero, Emily P. Arzola, Timothy Vladimir Dong, Wen-Cheng Xiong, Lin Mei
Summary: This study reveals the important roles of neuregulin 1 (NRG1) and its receptor ErbB4 in regulating hippocampal Sharp wave ripples (SW-Rs) and spatial working memory. The findings are further confirmed by experiments using chemical genetic mutant mice.
JOURNAL OF NEUROSCIENCE
(2022)
Article
Multidisciplinary Sciences
Manuel Valero, Ipshita Zutshi, Euisik Yoon, Gyorgy Buzsaki
Summary: This study used optogenetic pulses to investigate the subthreshold dynamics of hippocampal neuronal assemblies. The results showed that excitability decreased during sharp-wave ripples accompanied by increased inhibition. However, optogenetic probing revealed increased excitability in place cells by weakening inhibition, unmasking stable place fields in initially non-place cells. Neuronal assemblies active during sharp-wave ripples in the home cage predicted spatial overlap and sequences of place fields in both place cells and unmasked preexisting place fields of non-place cells during track running.
Article
Neurosciences
Lucie Landeck, Martin E. Kaiser, Dimitri Hefter, Andreas Draguhn, Martin Both
Summary: Behavioral flexibility relies on neuronal plasticity, which is influenced by interactions between organisms and their environment. Studying spontaneous network activity in hippocampal slices from mice exposed to an enriched environment revealed alterations in memory-related activity patterns, potentially due to changes in synaptic inhibition.
FRONTIERS IN NEURAL CIRCUITS
(2021)
Article
Pharmacology & Pharmacy
Laura Monni, Larissa Kraus, Matthias Dipper-Wawra, Patricio Soares-da-Silva, Nikolaus Maier, Dietmar Schmitz, Martin Holtkamp, Pawel Fidzinski
Summary: This study investigated the effects of eslicarbazepine acetate (ESL) in a mouse model of KCNQ2-related diseases. The results showed that S-Lic could modulate hippocampal oscillations and block epileptic activity, and ESL displayed dose-dependent protection against seizures in both genotypes.
BRITISH JOURNAL OF PHARMACOLOGY
(2022)
Article
Neurosciences
Barbara Imbrosci, Dietmar Schmitz, Marta Orlando
Summary: In this study, we developed an algorithm that utilizes convolutional neural networks (CNNs) to automatically detect and localize synaptic vesicles in electron micrographs, improving the efficiency of data collection. The algorithm performs well on synapses from different species and preparations, and provides a user interface for data analysis and proof-reading.
Article
Multidisciplinary Sciences
Noam Nitzan, Rachel Swanson, Dietmar Schmitz, Gyorgy Buzsaki
Summary: The study found that sharp wave ripples (SPW-Rs) coincided with a transient brain-wide increase in functional connectivity, and the diversity in SPW-R features was correlated with their intrahippocampal topography along the septotemporal axis. Furthermore, variations in SPW-R features were related to the timing, sign, and magnitude of downstream responses.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Biochemistry & Molecular Biology
Bettina Schmerl, Niclas Gimber, Benno Kuropka, Alexander Stumpf, Jakob Rentsch, Stella-Amrei Kunde, Judith von Sivers, Helge Ewers, Dietmar Schmitz, Christian Freund, Jan Schmoranzer, Nils Rademacher, Sarah A. Shoichet
Summary: Recent advances in imaging technology have revealed the arrangement of scaffold proteins and receptors in subsynaptic nanodomains. The discovery of MPP2 as a peripheral protein in the postsynaptic density (PSD) and its interaction with GABA(A) receptor subunits suggest its function as a scaffold in the assembly and/or modulation of GABA(A) receptors, as well as its role in regulating inhibitory synaptic transmission.
Article
Medicine, General & Internal
Claudia Schwarz, Gloria S. Benson, Nora Horn, Katharina Wurdack, Ulrike Grittner, Ralph Schilling, Stefanie Maerschenz, Theresa Koebe, Sebastian J. Hofer, Christoph Magnes, Slaven Stekovic, Tobias Eisenberg, Stephan J. Sigrist, Dietmar Schmitz, Miranka Wirth, Frank Madeo, Agnes Floeel
Summary: This 12-month randomized, double-masked, placebo-controlled clinical trial found that longer-term spermidine supplementation did not modify memory and biomarkers in participants with subjective cognitive decline.
Review
Neurosciences
Benjamin R. Rost, Jonas Wietek, Ofer Yizhar, Dietmar Schmitz
Summary: This review provides a comprehensive overview of the presynaptic applications of optogenetic tools, discussing the challenges, limitations, and future directions. Optogenetic actuators enable precise control of presynaptic functions, such as light-mediated neurotransmitter release, presynaptic inhibition, induction of synaptic plasticity, and manipulation of individual components of the presynaptic machinery.
NATURE NEUROSCIENCE
(2022)
Article
Multidisciplinary Sciences
Janina Hesse, Jan-Hendrik Schleimer, Nikolaus Maier, Dietmar Schmitz, Susanne Schreiber
Summary: Based on mathematical modeling, the authors explore a type of action potential dynamics that can induce synchronization patterns in neural networks. This type of dynamics may be prevalent in the brain and has the potential to impact neural network states and processes of encoding information.
NATURE COMMUNICATIONS
(2022)
Article
Neurosciences
Lucie Y. Li, Jakob Kreye, Malgorzata Burek, Cesar Cordero-Gomez, Paula C. Barthel, Elisa Sanchez-Sendin, Hans-Christian Kornau, Dietmar Schmitz, Madeleine Scharf, Patrick Meybohm, S. Momsen Reincke, Harald Pruess, Markus Hoeltje
Summary: This study identifies autoantibodies to brain blood vessels in patients with autoimmune encephalitis, suggesting their potential role in disrupting the blood-brain barrier.
FRONTIERS IN CELLULAR NEUROSCIENCE
(2023)
Article
Neurosciences
Ellen Knierim, Johannes Vogt, Michael Kintscher, Alexey Ponomarenko, Jan Baumgart, Prateep Beed, Tatiana Korotkova, Thorsten Trimbuch, Axel Panzer, Ortrud K. Steinlein, Ulrich Stephani, Andrew Escayg, Mahmoud Koko, Yuanyuan Liu, Holger Lerche, Dietmar Schmitz, Robert Nitsch, Markus Schuelke
Summary: The PLPPR4 gene encodes the PRG-1 protein, which modulates cortical excitatory transmission. Variants in the PLPPR4 gene are associated with BFNS/BFIS. The study found that partial loss-of-function of the Plppr4 gene has an impact on the development of BFNS/BFIS.
Article
Neurosciences
Kazi Atikur Rahman, Marta Orlando, Ayub Boulos, Ewa Andrzejak, Dietmar Schmitz, Noam E. Ziv, Harald Pruess, Craig C. Garner, Aleksandra Ichkova
Summary: Autoantibodies against NMDA receptors can cause internalization and loss of receptors, leading to the pathogenesis of NMDAR encephalitis. This study shows that microglia, a type of immune cells, play a role in removing the antibody-bound NMDARs, contributing to receptor and synapse loss. Mutations blocking the interaction between the antibody and microglia attenuate the loss of receptors and synapses, highlighting the critical involvement of microglia in autoimmune encephalitis.
Article
Biology
Roberto De Filippo, Dietmar Schmitz
Summary: Hippocampal ripples are synchronous neural events critical for memory consolidation and retrieval. This study used a large dataset to analyze ripple propagation within the hippocampal formation and found that strong ripples propagate differently depending on their generation point along the hippocampal axis. The results suggest a distinctive role of the hippocampal septal pole in conditions of high-memory demand and highlight the impact of ripple generation location on neural activity across the hippocampus.
Article
Multidisciplinary Sciences
Jakob Kreye, S. Momsen Reincke, Stefan Edelburg, Lara M. Jeworowski, Hans-Christian Kornau, Jakob Trimpert, Peter Hombach, Sophia Halbe, Volker Noelle, Martin Meyer, Stefanie Kattenbach, Elisa Sanchez-Sendin, Marie L. Schmidt, Tatjana Schwarz, Ruben Rose, Andi Krumbholz, Sophie Merz, Julia M. Adler, Kathrin Eschke, Azza Abdelgawad, Dietmar Schmitz, Leif E. Sander, Uwe Janssen, Victor M. Corman, Harald Pruess
Summary: The emergence of novel viral variants of concern (VOCs) that evade preexisting antibody immunity poses a continuous challenge for developing updated therapies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, the patient-derived antibody CV38-142 was selected for preclinical development as a therapeutic due to its potency and breadth against multiple VOCs. CV38-142 demonstrated efficacy in vivo against VOC infection in a Syrian hamster model and showed favorable safety characteristics in human protein library screening and tissue cross-reactivity analysis. However, it did not neutralize the Omicron lineages BA.1 and BA.2, underscoring the need for developing broadly neutralizing variant-proof antibodies against SARS-CoV-2.
Article
Biochemistry & Molecular Biology
S. Momsen Reincke, Niels von Wardenburg, Marie A. Homeyer, Hans-Christian Kornau, Gregorio Spagni, Lucie Y. Li, Jakob Kreye, Elisa Sanchez-Sendin, Sonja Blumenau, Dominik Stappert, Helena Radbruch, Anja E. Hauser, Annette Kuenkele, Inan Edes, Dietmar Schmitz, Harald Pruess
Summary: NMDAR-CAAR T cells selectively eliminate anti-NMDAR B cells and disease-causing autoantibodies, offering a promising new approach for the treatment of NMDAR encephalitis.
Review
Neurosciences
Alexandra Tzilivaki, John J. Tukker, Nikolaus Maier, Panayiota Poirazi, Rosanna P. Sammons, Dietmar Schmitz
Summary: This article explores the brain's ability to capture and store information, focusing on the types, plasticity, and activity patterns of interneurons in the hippocampus and their impact on memory processing.