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Hagena H, Manahan-Vaughan D. Interplay of hippocampal long-term potentiation and long-term depression in enabling memory representations. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230229. [PMID: 38853558 DOI: 10.1098/rstb.2023.0229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 05/07/2024] [Indexed: 06/11/2024] Open
Abstract
Hippocampal long-term potentiation (LTP) and long-term depression (LTD) are Hebbian forms of synaptic plasticity that are widely believed to comprise the physiological correlates of associative learning. They comprise a persistent, input-specific increase or decrease, respectively, in synaptic efficacy that, in rodents, can be followed for days and weeks in vivo. Persistent (>24 h) LTP and LTD exhibit distinct frequency-dependencies and molecular profiles in the hippocampal subfields. Moreover, causal and genetic studies in behaving rodents indicate that both LTP and LTD fulfil specific and complementary roles in the acquisition and retention of spatial memory. LTP is likely to be responsible for the generation of a record of spatial experience, which may serve as an associative schema that can be re-used to expedite or facilitate subsequent learning. In contrast, LTD may enable modification and dynamic updating of this representation, such that detailed spatial content information is included and the schema is rendered unique and distinguishable from other similar representations. Together, LTP and LTD engage in a dynamic interplay that supports the generation of complex associative memories that are resistant to generalization. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Hardy Hagena
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum , Bochum 44780, Germany
| | - Denise Manahan-Vaughan
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum , Bochum 44780, Germany
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Zhao F, Behnisch T. The Enigmatic CA2: Exploring the Understudied Region of the Hippocampus and Its Involvement in Parkinson's Disease. Biomedicines 2023; 11:1996. [PMID: 37509636 PMCID: PMC10377725 DOI: 10.3390/biomedicines11071996] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Parkinson's disease (PD) is a neurodegenerative disease that affects both motor and non-motor functions. Although motor impairment is a prominent clinical sign of PD, additional neurological symptoms may also occur, particularly in the preclinical and prodromal stages. Among these symptoms, social cognitive impairment is common and detrimental. This article aims to review non-motor symptoms in PD patients, focusing on social cognitive deficits. It also examines the specific characteristics of the CA2 region and its involvement in social behavior, highlighting recent advances and perspectives. Additionally, this review provides critical insights into and analysis of research conducted in rodents and humans, which may help improve the understanding of the current status of putative therapeutic strategies for social cognitive dysfunction in PD and potential avenues related to the function of the hippocampal CA2 region.
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Affiliation(s)
- Fang Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Thomas Behnisch
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
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Takeuchi Y, Yamashiro K, Noguchi A, Liu J, Mitsui S, Ikegaya Y, Matsumoto N. Machine learning-based segmentation of the rodent hippocampal CA2 area from Nissl-stained sections. Front Neuroanat 2023; 17:1172512. [PMID: 37449243 PMCID: PMC10336234 DOI: 10.3389/fnana.2023.1172512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 06/05/2023] [Indexed: 07/18/2023] Open
Abstract
The hippocampus is a center of learning, memory, and spatial navigation. This region is divided into the CA1, CA2, and CA3 areas, which are anatomically different from each other. Among these divisions, the CA2 area is unique in terms of functional relevance to sociality. The CA2 area is often manually detected based on the size, shape, and density of neurons in the hippocampal pyramidal cell layer, but this manual segmentation relying on cytoarchitecture is impractical to apply to a large number of samples and dependent on experimenters' proficiency. Moreover, the CA2 area has been defined based on expression pattern of molecular marker proteins, but it generally takes days to complete immunostaining for such proteins. Thus, we asked whether the CA2 area can be systematically segmented based on cytoarchitecture alone. Since the expression pattern of regulator of G-protein signaling 14 (RGS14) signifies the CA2 area, we visualized the CA2 area in the mouse hippocampus by RGS14-immunostaining and Nissl-counterstaining and manually delineated the CA2 area. We then established "CAseg," a machine learning-based automated algorithm to segment the CA2 area with the F1-score of approximately 0.8 solely from Nissl-counterstained images that visualized cytoarchitecture. CAseg was extended to the segmentation of the prairie vole CA2 area, which raises the possibility that the use of this algorithm can be expanded to other species. Thus, CAseg will be beneficial for investigating unique properties of the hippocampal CA2 area.
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Affiliation(s)
- Yuki Takeuchi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kotaro Yamashiro
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Asako Noguchi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Jiayan Liu
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Shinichi Mitsui
- Department of Rehabilitation Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Gunma, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
- Center for Information and Neural Networks, National Institute of Information and Communications Technology, Osaka, Japan
| | - Nobuyoshi Matsumoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
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Raghuraman R, Navakkode S, Sajikumar S. Alteration of hippocampal CA2 plasticity and social memory in adult rats impacted by juvenile stress. Hippocampus 2023; 33:745-758. [PMID: 36965045 PMCID: PMC10946601 DOI: 10.1002/hipo.23531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 03/09/2023] [Accepted: 03/11/2023] [Indexed: 03/27/2023]
Abstract
The hippocampal CA2 region has received greater attention in recent years due to its fundamental role in social memory and hippocampus-dependent memory processing. Unlike entorhinal cortical inputs, the Schaffer collateral inputs to CA2 do not support activity-dependent long-term potentiation (LTP), which serves as the basis for long-term memories. This LTP-resistant zone also expresses genes that restrict plasticity. With the aim of exploring social interaction and sociability in rats that were subjected to juvenile stress, we addressed questions about how the neural circuitry is altered and its effects on social behavior. Although there was induction of LTP in both Schaffer collateral and entorhinal cortical pathways in juvenile-stressed rats, LTP declined in both pathways after 2-3 h. Moreover, exogenous bath application of substance P, a neuropeptide that resulted in slow onset long-lasting potentiation in control animals while it failed to induce LTP in juvenile-stressed rats. Our study reveals that juvenile-stressed rats show behavioral and cellular abnormalities with a long-lasting impact in adulthood.
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Affiliation(s)
- Radha Raghuraman
- Department of PhysiologyNational University of SingaporeSingapore117593Singapore
- Life Sciences Institute Neurobiology ProgrammeCentre for Life Sciences, National University of SingaporeSingapore117456Singapore
- Present address:
Taub Institute for Research on Alzheimer's Disease and the Aging BrainColumbia University Irving Medical CenterNew YorkNew York10032USA
| | - Sheeja Navakkode
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingapore308232Singapore
| | - Sreedharan Sajikumar
- Department of PhysiologyNational University of SingaporeSingapore117593Singapore
- Life Sciences Institute Neurobiology ProgrammeCentre for Life Sciences, National University of SingaporeSingapore117456Singapore
- Healthy Longevity Translational Research ProgrammeYong Loo Lin School of Medicine, National University of SingaporeSingapore117456Singapore
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Olson ML, Badenoch B, Blatti M, Buching C, Glewwe N. Muscarinic Cholinergic Receptor Antagonism Impairs Spatial Memory Retrieval and Minimizes Retrieval-Induced Alterations in Matrix Metalloproteinase-9. Behav Brain Res 2023; 448:114460. [PMID: 37119978 DOI: 10.1016/j.bbr.2023.114460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 04/26/2023] [Accepted: 04/26/2023] [Indexed: 05/01/2023]
Abstract
Cholinergic dysfunction in the hippocampus causes memory impairment, and degradation of the forebrain cholinergic system has been implicated in several neurological disorders. One such disorder, Alzheimer's Disease (AD) is associated with the abnormal expression of various proteins including matrix metalloproteinase-9 (MMP-9), an enzyme known to regulate hippocampus-dependent memory. Memory involves several stages including acquisition, consolidation, and retrieval, but the neurobiological correlates of retrieval have been studied much less than other stages of memory. We sought to investigate the potential relationship between cholinergic signaling and hippocampal MMP-9 expression and the involvement of each in spatial memory retrieval. We trained rats in the water maze until the task was well-learned, then, seven days later, we allowed some to retrieve the memory after an intracerebroventricular injection of scopolamine or vehicle. Western blot analysis of hippocampal tissue shows elevated levels of a truncated form of MMP-9 associated with spatial memory retrieval. Additionally, our results indicate that centrally administered scopolamine both impairs spatial memory retrieval and prevents retrieval-induced elevations in MMP-9. These findings provide evidence for a potential link between cholinergic dysregulation and abnormal MMP-9 levels seen in the brains of AD patients. An important, yet unresolved question is whether MMP-9 serves to support memory retrieval itself or if it is involved in maintaining the ongoing stability of a retrieved memory.
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Affiliation(s)
- Mikel L Olson
- Department of Psychology, Concordia College, Moorhead, MN.
| | | | - Megan Blatti
- Department of Psychology, Concordia College, Moorhead, MN.
| | | | - Nic Glewwe
- Department of Psychology, Concordia College, Moorhead, MN.
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Lehr AB, Luboeinski J, Tetzlaff C. Neuromodulator-dependent synaptic tagging and capture retroactively controls neural coding in spiking neural networks. Sci Rep 2022; 12:17772. [PMID: 36273097 PMCID: PMC9588040 DOI: 10.1038/s41598-022-22430-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/14/2022] [Indexed: 01/19/2023] Open
Abstract
Events that are important to an individual's life trigger neuromodulator release in brain areas responsible for cognitive and behavioral function. While it is well known that the presence of neuromodulators such as dopamine and norepinephrine is required for memory consolidation, the impact of neuromodulator concentration is, however, less understood. In a recurrent spiking neural network model featuring neuromodulator-dependent synaptic tagging and capture, we study how synaptic memory consolidation depends on the amount of neuromodulator present in the minutes to hours after learning. We find that the storage of rate-based and spike timing-based information is controlled by the level of neuromodulation. Specifically, we find better recall of temporal information for high levels of neuromodulation, while we find better recall of rate-coded spatial patterns for lower neuromodulation, mediated by the selection of different groups of synapses for consolidation. Hence, our results indicate that in minutes to hours after learning, the level of neuromodulation may alter the process of synaptic consolidation to ultimately control which type of information becomes consolidated in the recurrent neural network.
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Affiliation(s)
- Andrew B. Lehr
- grid.7450.60000 0001 2364 4210Department of Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Department of Computational Synaptic Physiology, University of Göttingen, Göttingen, Germany
| | - Jannik Luboeinski
- grid.7450.60000 0001 2364 4210Department of Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Department of Computational Synaptic Physiology, University of Göttingen, Göttingen, Germany
| | - Christian Tetzlaff
- grid.7450.60000 0001 2364 4210Department of Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany ,grid.7450.60000 0001 2364 4210Department of Computational Synaptic Physiology, University of Göttingen, Göttingen, Germany
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