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Hernández-Frausto M, Bilash OM, Masurkar AV, Basu J. Local and long-range GABAergic circuits in hippocampal area CA1 and their link to Alzheimer's disease. Front Neural Circuits 2023; 17:1223891. [PMID: 37841892 PMCID: PMC10570439 DOI: 10.3389/fncir.2023.1223891] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/08/2023] [Indexed: 10/17/2023] Open
Abstract
GABAergic inhibitory neurons are the principal source of inhibition in the brain. Traditionally, their role in maintaining the balance of excitation-inhibition has been emphasized. Beyond homeostatic functions, recent circuit mapping and functional manipulation studies have revealed a wide range of specific roles that GABAergic circuits play in dynamically tilting excitation-inhibition coupling across spatio-temporal scales. These span from gating of compartment- and input-specific signaling, gain modulation, shaping input-output functions and synaptic plasticity, to generating signal-to-noise contrast, defining temporal windows for integration and rate codes, as well as organizing neural assemblies, and coordinating inter-regional synchrony. GABAergic circuits are thus instrumental in controlling single-neuron computations and behaviorally-linked network activity. The activity dependent modulation of sensory and mnemonic information processing by GABAergic circuits is pivotal for the formation and maintenance of episodic memories in the hippocampus. Here, we present an overview of the local and long-range GABAergic circuits that modulate the dynamics of excitation-inhibition and disinhibition in the main output area of the hippocampus CA1, which is crucial for episodic memory. Specifically, we link recent findings pertaining to GABAergic neuron molecular markers, electrophysiological properties, and synaptic wiring with their function at the circuit level. Lastly, given that area CA1 is particularly impaired during early stages of Alzheimer's disease, we emphasize how these GABAergic circuits may contribute to and be involved in the pathophysiology.
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Affiliation(s)
- Melissa Hernández-Frausto
- Neuroscience Institute, New York University Langone Health, New York, NY, United States
- Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, United States
| | - Olesia M. Bilash
- Neuroscience Institute, New York University Langone Health, New York, NY, United States
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Arjun V. Masurkar
- Neuroscience Institute, New York University Langone Health, New York, NY, United States
- Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, United States
- Center for Cognitive Neurology, Department of Neurology, New York University Grossman School of Medicine, New York, NY, United States
| | - Jayeeta Basu
- Neuroscience Institute, New York University Langone Health, New York, NY, United States
- Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, United States
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, United States
- Center for Neural Science, New York University, New York, NY, United States
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Cangalaya C, Wegmann S, Sun W, Diez L, Gottfried A, Richter K, Stoyanov S, Pakan J, Fischer KD, Dityatev A. Real-time mechanisms of exacerbated synaptic remodeling by microglia in acute models of systemic inflammation and tauopathy. Brain Behav Immun 2023; 110:245-259. [PMID: 36906076 DOI: 10.1016/j.bbi.2023.02.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 03/13/2023] Open
Abstract
Remodeling of synapses by microglia is essential for synaptic plasticity in the brain. However, during neuroinflammation and neurodegenerative diseases, microglia can induce excessive synaptic loss, although the precise underlying mechanisms are unknown. To directly observe microglia-synapse interactions under inflammatory conditions, we performed in vivo two-photon time-lapse imaging of microglia-synapse interactions after bacterial lipopolysaccharide administration to model systemic inflammation, or after inoculation of Alzheimer's disease (AD) brain extracts to model disease-associated neuroinflammatory microglial response. Both treatments prolonged microglia-neuron contacts, decreased basal surveillance of synapses and promoted synaptic remodeling in response to synaptic stress induced by focal single-synapse photodamage. Spine elimination correlated with the expression of microglial complement system/phagocytic proteins and the occurrence of synaptic filopodia. Microglia were observed contacting spines, then stretching and phagocytosing spine head filopodia. Thus, in response to inflammatory stimuli microglia exacerbated spine remodeling through prolonged microglial contact and elimination of spines 'tagged' by synaptic filopodia.
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Affiliation(s)
- Carla Cangalaya
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Magdeburg, Germany; ESF International Graduate School on Analysis, Imaging and Modelling of Neuronal and Inflammatory Processes, Magdeburg, Germany
| | - Susanne Wegmann
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Weilun Sun
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Lisa Diez
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Anna Gottfried
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Magdeburg, Germany
| | - Karin Richter
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Magdeburg, Germany
| | - Stoyan Stoyanov
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Janelle Pakan
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Klaus-Dieter Fischer
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Magdeburg, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany; Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
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