Review
Neurosciences
Jennifer C. Robinson, Jacob H. Wilmot, Michael E. Hasselmo
Summary: Encoding an event in memory requires neural activity to represent multiple dimensions of behavioral experience in space and time. Recent experiments have explored the influence of neural dynamics regulated by the medial septum on the functional encoding of space and time by neurons in the hippocampus and associated structures. This review addresses these dynamics, focusing on the role of theta rhythm, the differential effects of septal inactivation and activation on the functional coding of space and time by individual neurons, and the influence on phase coding that appears as phase precession. We also discuss data indicating that theta rhythm plays a role in timing the internal dynamics of memory encoding and retrieval, as well as the behavioral influences of these neuronal manipulations with regard to memory function.
TRENDS IN NEUROSCIENCES
(2023)
Article
Neurosciences
Minghua Li, Jessica L. Kinney, Yu-Qiu Jiang, Daniel K. Lee, Qiwen Wu, Daehoon Lee, Wen-Cheng Xiong, Qian Sun
Summary: A key mode of neuronal communication between distant brain regions is through excitatory synaptic transmission mediated by long-range glutamatergic projections. However, we found that the glutamatergic projection from the hypothalamic supramammillary nucleus (SuM) largely avoids pyramidal neurons in hippocampal CA3 region and instead targets interneurons to provide feedforward inhibition. This novel long-range glutamatergic pathway suppresses the activity of principal neurons and reveals a new means by which SuM regulates hippocampal activity.
JOURNAL OF NEUROSCIENCE
(2023)
Article
Biochemistry & Molecular Biology
Amelie F. Menke, Fatme Seval Ismail, Klaus Dornmair, Manuela Cerina, Sven G. Meuth, Nico Melzer
Summary: This study investigated the direct pathogenic effect of GABA(A)R autoantibodies on hippocampal networks and found that they play a crucial role in seizure generation in GABA(A)R autoimmune encephalitis.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Medicine, Research & Experimental
Connor M. Wander, Ya-Dong Li, Hechen Bao, Brent Asrican, Yan-Jia Luo, Heather A. Sullivan, Tzu-Hao Harry Chao, Wei-Ting Zhang, Samantha L. Chery, Dalton S. Tart, Ze-Ka Chen, Yen-Yu Ian Shih, Ian R. Wickersham, Todd J. Cohen, Juan Song
Summary: This study identifies a long-distance GABAergic circuit that undergoes structural and functional remodeling in the progression of Alzheimer's disease. The medial septum develops adaptive strategies to combat the hyperactivity of dentate gyrus interneurons.
JOURNAL OF TRANSLATIONAL MEDICINE
(2023)
Article
Multidisciplinary Sciences
Chengzhang Li, Zhenrong Li, Sihan Xu, Sanwei Jiang, Zhenli Ye, Bin Yu, Shixiang Gong, Junmei Li, Qilin Hu, Bingyan Feng, Mengmeng Wang, Chengbiao Lu
Summary: We found that exogenous AMPA can dose-dependently inhibit carbachol-induced oscillation in the CA3 area of rat hippocampal slices, but the underlying mechanism is unclear. Our results suggest that CP-AMPAR and CaMKK negatively modulate the formation of oscillation, and AMPA downregulation of oscillation may be related to the reduced recurrent excitation within the CA3 local neuronal network.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Xiaomeng Wang, Xiaotong Wu, Hao Wu, Hanyang Xiao, Sijia Hao, Bingwei Wang, Chen Li, Katherin Bleymehl, Stefan G. Kauschke, Volker Mack, Boris Ferger, Holger Klein, Ruimao Zheng, Shumin Duan, Hao Wang
Summary: Research has discovered that long-term activation of GABAergic cells in vlPAG can rescue obesity induced by high-fat diet. This treatment method reduces food intake, increases energy expenditure, and promotes browning of adipose tissue. Overexpression of CACNA2D1 gene can reverse obesity and is considered a potential target for obesity treatment.
Article
Cell Biology
Teresa M. L. Cramer, Berangere Pinan-Lucarre, Anna Cavaccini, Angeliki Damilou, Yuan-Chen Tsai, Musadiq A. Bhat, Patrizia Panzanelli, Nicolas Rama, Patrick Mehlen, Dietmar Benke, Theofanis Karayannis, Jean-Louis Bessereau, Shiva K. Tyagarajan
Summary: The study reveals the crucial role of Adamtsl3 and DCC in synapse formation and maintenance, particularly in the adaptation of GABAergic synapses. These findings are of significant importance for schizophrenia research.
Article
Biochemistry & Molecular Biology
Laurel Watkins de Jong, Mohammadreza Mohagheghi Nejad, Euisik Yoon, Sen Cheng, Kamran Diba
Summary: Recurrent connectivity and feedback inhibition from inhibitory neurons play crucial roles in determining the dynamics and computational properties of neuronal circuits. Through optogenetic manipulations and large-scale unit recordings, paradoxical responses were observed in both CA1 and CA3 regions of the hippocampus, where subsets of cells increased firing during photoinhibition while others decreased firing during photoexcitation. These paradoxical responses were more prominent in CA3 and simulations confirmed that both CA1 and CA3 hippocampal regions exhibit inhibition-stabilized networks with strong recurrent excitation.
Article
Neurosciences
Ream Al-Hasani, Raajaram Gowrishankar, Gavin P. Schmitz, Christian E. Pedersen, David J. Marcus, Sofia E. Shirley, Taylor E. Hobbs, Abigail J. Elerding, Sophie J. Renaud, Miao Jing, Yulong Li, Veronica A. Alvarez, Julia C. Lemos, Michael R. Bruchas
Summary: This study reveals the significant role of long-range GABAergic projections from the VTA to the NAc shell in modulating reward behavior, particularly by inhibiting cholinergic activity and promoting reinforcement. These findings deepen our understanding of neuropsychiatric conditions like depression and addiction that involve these neural circuits.
NATURE NEUROSCIENCE
(2021)
Article
Biochemistry & Molecular Biology
Yi Lu, Hong Wang, Junqing Yang, Wengao Jiang, Hong Xin, Ying Luo, Santiago Loya-Lopez, Huaiyu Gu, Dongzhi Ran
Summary: This study investigated the effects of MEHP on the central nervous system by assessing the electrophysiological properties of rat CA3 hippocampal neurons. The results showed that MEHP decreased the amplitude of spontaneous action potential and the frequency of mini-excitatory postsynaptic currents. It also inhibited the activity of ion channels, suggesting its distinct role in neural transmission.
Article
Cell Biology
Giorgio Rizzi, Zhuoliang Li, Norbert Hogrefe, Kelly R. Tan
Summary: This study explored the involvement of midbrain neurons in conditioned learning and how GABA and glutamate cells affect fear-conditioned learning through specific connections. Inhibiting specific sub-circuits of dmCIN neurons led to varying impairments in learning, with Vglut2-expressing cells and Vgat-positive neurons associating with different stimuli. It suggests that each component of the network carries information relevant to different subdomains of the behavioral strategy.
Article
Cell Biology
Junfeng Su, Fengwen Huang, Yu Tian, Ran Tian, Qianqian Gao, Stephen Temitayo Bello, Dingxaun Zeng, Peter Jendrichovsky, C. Geoffrey Lau, Wenjun Xiong, Daiguan Yu, Micky Tortorella, Xi Chen, Jufang He
Summary: This study reveals the critical role of cholecystokinin (CCK) in heterosynaptic neuromodulation from the medial entorhinal cortex (MEC) to the hippocampus, affecting CA3-CA1 LTP and space-related performance.
Article
Cell Biology
Shovan Naskar, Jia Qi, Francisco Pereira, Charles R. Gerfen, Soohyun Lee
Summary: Extensive hierarchical yet highly reciprocal interactions among cortical areas are crucial for information processing, but the specificity and rules governing corticocortical connections are poorly understood. The study shows that long-range projections from different areas preferentially engage specific sets of GABAergic neurons in the primary somatosensory cortex, leading to distinct feedback mechanisms between neurons.
Article
Multidisciplinary Sciences
Mickael Zbili, Sylvain Rama, Maria-Jose Benitez, Laure Fronzaroli-Molinieres, Andrzej Bialowas, Norah Boumedine-Guignon, Juan Jose Garrido, Dominique Debanne
Summary: Blocking excitatory synaptic receptors leads to an increase in synaptic transmission and intrinsic excitability in the CA3 region, with intrinsic plasticity mediated by a reduction in Kv1.1 channel density. Activity-deprived neurons show down-regulation of axonal Kv1.1 channels, resulting in functional synergy between synaptic strength and intrinsic excitability.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Review
Neurosciences
Hugo Balleza-Tapia, Luis Enrique Arroyo-Garcia, Arturo G. Isla, Raul Loera-Valencia, Andre Fisahn
Summary: Gamma oscillations in the hippocampal area CA3 are crucial for memory function. Recent studies have found that pyramidal cells (PCs) in CA3 are organized into different functional subpopulations, which play important roles in cognition-related network dynamics.
PROGRESS IN NEUROBIOLOGY
(2022)
Article
Anatomy & Morphology
Linda Katona, Katja Hartwich, Ryohei Tomioka, Jozsef Somogyi, J. David B. Roberts, Kristina Wagner, Abhilasha Joshi, Thomas Klausberger, Kathleen S. Rockland, Peter Somogyi
BRAIN STRUCTURE & FUNCTION
(2020)
Article
Anatomy & Morphology
Abhilasha Joshi, Peter Somogyi
BRAIN STRUCTURE & FUNCTION
(2020)
Article
Biochemistry & Molecular Biology
Helen C. Barron, Hayley M. Reeve, Renee S. Koolschijn, Pavel Perestenko, Anna Shpektor, Hamed Nili, Roman Rothaermel, Natalia Campo-Urriza, Jill X. O'Reilly, David M. Bannerman, Timothy E. J. Behrens, David Dupret
Article
Biology
Helen C. Barron, Rogier B. Mars, David Dupret, Jason P. Lerch, Cassandra Sampaio-Baptista
Summary: Researchers propose adopting a cross-species approach to close the explanatory gap in neuroscience by translating different measures of neural activity into a common space. This has the potential to transform basic neuroscience and advance neuropsychiatric drug development.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2021)
Article
Neurosciences
Manuel Valero, Tim J. Viney, Robert Machold, Sara Mederos, Ipshita Zutshi, Benjamin Schuman, Yuta Senzai, Bernardo Rudy, Gyorgy Buzsaki
Summary: A unique neuron type called down state-active (DSA) neurons has been identified in mice and rats, which show anti-correlated spiking activity with principal cells and interneurons during non-REM sleep, especially during the down state. Despite their sparsity, DSA neurons play critical roles in physiological functions, shaping the firing sequence of neurons during down-up transitions and interfering with memory consolidation during NREM sleep.
NATURE NEUROSCIENCE
(2021)
Article
Neurosciences
Giuseppe P. Gava, Stephen B. McHugh, Laura Lefevre, Vitor Lopes-dos-Santos, Stephanie Trouche, Mohamady El-Gaby, Simon R. Schultz, David Dupret
Summary: By investigating the topology of neuronal co-activity in the mouse hippocampus network, researchers found that high-activity principal cells form the core of memories, while low-activity cells join co-activity motifs across different operational axes. This organizational principle reveals continuous integration and interaction of hippocampal memories. Gava et al. explore how new associative memories integrate into the network and restructure neural patterns representing prior memories from a graph theoretical perspective.
NATURE NEUROSCIENCE
(2021)
Article
Neurosciences
Mohamady El-Gaby, Hayley M. Reeve, Vitor Lopes-dos-Santos, Natalia Campo-Urriza, Pavel Perestenko, Alexander Morley, Lauren A. M. Strickland, Istvan P. Lukacs, Ole Paulsen, David Dupret
Summary: The study shows that millisecond-timescale neural coactivity plays a key role in encoding behavioral information and supporting memory retrieval. Coactivity among hippocampal CA1 neurons can discriminate short-lived behavioral contingencies independently of individual neuron tuning. Optogenetic suppression of inputs from the upstream CA3 region impairs coactivity-based contingency information and subsequent dynamic memory retrieval.
NATURE NEUROSCIENCE
(2021)
Article
Neurosciences
Andrew J. Quinn, Vitor Lopes-dos-Santos, Norden Huang, Wei-Kuang Liang, Chi-Hung Juan, Jia-Rong Yeh, Anna C. Nobre, David Dupret, Mark W. Woolrich
Summary: This study introduces an analytical framework for quantifying nonsinusoidal waveform shapes in neuronal oscillations. Using a masked empirical mode decomposition method, the study shows that instantaneous frequency accurately tracks nonsinusoidal shapes. The research also demonstrates how principal component analysis can identify theta cycle waveform motifs associated with cycle amplitude, duration, and animal movement speed.
JOURNAL OF NEUROPHYSIOLOGY
(2021)
Article
Biology
Renee S. Koolschijn, Anna Shpektor, William T. Clarke, I. Betina Ip, David Dupret, Uzay E. Emir, Helen C. Barron
Summary: Memories are stored by distributed groups of neurons in the brain, with individual neurons contributing to multiple memories. The hippocampus and neocortex coordinate their activity to switch memories on and off by changing the balance of excitatory and inhibitory activity in neocortex. The hippocampus reactivates memories stored in neocortex by temporarily increasing excitatory activity to release memories from inhibitory control.
Article
Neurosciences
Stephen B. McHugh, Vitor Lopes-dos-Santos, Giuseppe P. Gava, Katja Hartwich, Shu K. E. Tam, David M. Bannerman, David Dupret
Summary: The study reveals the crucial role of adult-born granule cells (abDGCs) in controlling the information processing in the hippocampus by promoting sparser population firing and enhancing responses to novel stimuli.
NATURE NEUROSCIENCE
(2022)
Article
Cell Biology
Tim J. Viney, Barbara Sarkany, A. Tugrul Ozdemir, Katja Hartwich, Judith Schweimer, David Bannerman, Peter Somogyi
Summary: This study investigates the impact of hyperphosphorylated Tau (pTau) on cellular and network activity in the hippocampal formation of tauopathy model mice. The accumulation of pTau in deep-layer pyramidal neurons and its spread to oligodendrocytes lead to neurodegeneration. Despite reduced short-term familiarity, spatial working and reference memory remain normal in transgenic mice. It is hypothesized that preserved subcortical network mechanisms maintain cortical neuronal coordination and counteract the effects of pTau aggregation and neurodegeneration.
Article
Multidisciplinary Sciences
Abhilasha Joshi, Eric L. Denovellis, Abhijith Mankili, Yagiz Meneksedag, Thomas J. Davidson, Anna K. Gillespie, Jennifer A. Guidera, Demetris Roumis, Loren M. Frank
Summary: The hippocampus expresses spatial representations and is crucial for navigation, while the details of locomotor processes are primarily computed and represented in subcortical circuits. This study found a coordination between hippocampal spatial representations and the forelimb stepping cycle in freely behaving rats, with precise timing during spatial decisions.
Review
Neurosciences
Antonio Fernandez-Ruiz, Anton Sirota, Vitor Lopes-dos-Santos, David Dupret
Summary: Gamma oscillations (-30-150 Hz) are widespread correlates of neural circuit functions. These network activity patterns have been described across multiple animal species, brain structures, and behaviors, and are usually identified based on their spectral peak frequency. However, whether gamma oscillations implement specific brain functions or represent a general dynamic mode of neural circuit operation remains unclear. This perspective reviews recent advances in the study of gamma oscillations and proposes shifting the attention from a frequency-based to a circuit-level definition.
Article
Multidisciplinary Sciences
Balint Kiraly, Andor Domonkos, Marta Jelitai, Vitor Lopes-dos-Santos, Sergio Martinez-Bellver, Barnabas Kocsis, Daniel Schlingloff, Abhilasha Joshi, Minas Salib, Richard Fiath, Peter Bartho, Istvan Ulbert, Tamas F. Freund, Tim J. Viney, David Dupret, Viktor Varga, Balazs Hangya
Summary: The medial septum orchestrates hippocampal network activity at multiple temporal scales likely mediating memory encoding and retrieval.
NATURE COMMUNICATIONS
(2023)
Article
Cell Biology
Bjorn Neumann, Michael Segel, Tanay Ghosh, Chao Zhao, Panagiotis Tourlomousis, Adam Young, Sarah Forster, Amar Sharma, Civia Zi-Yu Chen, Juan F. Cubillos, Khalil S. Rawji, Kevin J. Chalut, Robin J. M. Franklin
Summary: Research indicates that during aging, the functionality of oligodendrocyte progenitor cells is impaired, but the expression of c-Myc can drive their functional rejuvenation, providing important insights for regeneration.
