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Hanycz SA, Noorani A, Hung PSP, Walker MR, Zhang AB, Latypov TH, Hodaie M. Hippocampus diffusivity abnormalities in classical trigeminal neuralgia. Pain Rep 2024; 9:e1159. [PMID: 38655236 PMCID: PMC11037743 DOI: 10.1097/pr9.0000000000001159] [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: 03/08/2023] [Revised: 02/16/2024] [Accepted: 02/24/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction Patients with chronic pain frequently report cognitive symptoms that affect memory and attention, which are functions attributed to the hippocampus. Trigeminal neuralgia (TN) is a chronic neuropathic pain disorder characterized by paroxysmal attacks of unilateral orofacial pain. Given the stereotypical nature of TN pain and lack of negative symptoms including sensory loss, TN provides a unique model to investigate the hippocampal implications of chronic pain. Recent evidence demonstrated that TN is associated with macrostructural hippocampal abnormalities indicated by reduced subfield volumes; however, there is a paucity in our understanding of hippocampal microstructural abnormalities associated with TN. Objectives To explore diffusivity metrics within the hippocampus, along with its functional and structural subfields, in patients with TN. Methods To examine hippocampal microstructure, we utilized diffusion tensor imaging in 31 patients with TN and 21 controls. T1-weighted magnetic resonance images were segmented into hippocampal subfields and registered into diffusion-weighted imaging space. Fractional anisotropy (FA) and mean diffusivity were extracted for hippocampal subfields and longitudinal axis segmentations. Results Patients with TN demonstrated reduced FA in bilateral whole hippocampi and hippocampal body and contralateral subregions CA2/3 and CA4, indicating microstructural hippocampal abnormalities. Notably, patients with TN showed significant correlation between age and hippocampal FA, while controls did not exhibit this correlation. These effects were driven chiefly by female patients with TN. Conclusion This study demonstrates that TN is associated with microstructural hippocampal abnormalities, which may precede and potentially be temporally linked to volumetric hippocampal alterations demonstrated previously. These findings provide further evidence for the role of the hippocampus in chronic pain and suggest the potential for targeted interventions to mitigate cognitive symptoms in patients with chronic pain.
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Affiliation(s)
- Shaun Andrew Hanycz
- Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Alborz Noorani
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Peter Shih-Ping Hung
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Matthew R. Walker
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
| | - Ashley B. Zhang
- MD Program, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Timur H. Latypov
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Mojgan Hodaie
- Division of Brain, Imaging, and Behaviour—Systems Neuroscience, Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
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Aashat S, D'Angelo MC, Rosenbaum RS, Ryan JD. Effects of extended practice and unitization on relational memory in older adults and neuropsychological lesion cases. NEUROPSYCHOLOGY, DEVELOPMENT, AND COGNITION. SECTION B, AGING, NEUROPSYCHOLOGY AND COGNITION 2024:1-36. [PMID: 38415694 DOI: 10.1080/13825585.2024.2319892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 02/09/2024] [Indexed: 02/29/2024]
Abstract
Unitization - the fusion of objects into a single unit through an action/consequence sequence - can mitigate relational memory impairments, but the circumstances under which unitization is effective are unclear. Using transverse patterning (TP), we compared unitization (and its component processes of fusion, motion, and action/consequence) with extended practice on relational learning and transfer in older adults and neuropsychological cases with lesions (to varying extents) in the medial prefrontal cortex (mPFC) or hippocampus/medial temporal lobe (HC/MTL). The latter included a person with bilateral HC lesions primarily within the dentate gyrus. For older adults, TP accuracy increased, and transfer benefits were observed, with extended practice and unitization. Broadly, the lesion cases did not benefit from either extended practice or unitization, suggesting the mPFC and dentate gyrus play important roles in relational memory and in unitization. The results suggest that personalized strategy interventions must align with the cognitive and neural profiles of the user.
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Affiliation(s)
- Supreet Aashat
- The Rotman Research Institute, Baycrest Academy for Research and Education, Toronto, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
| | - Maria C D'Angelo
- The Rotman Research Institute, Baycrest Academy for Research and Education, Toronto, Canada
| | - R Shayna Rosenbaum
- The Rotman Research Institute, Baycrest Academy for Research and Education, Toronto, Canada
- Department of Psychology, York University, Toronto, Canada
| | - Jennifer D Ryan
- The Rotman Research Institute, Baycrest Academy for Research and Education, Toronto, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
- Departments of Psychology and Psychiatry, University of Toronto, Toronto, Canada
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Griego E, Galván EJ. BDNF and Lactate as Modulators of Hippocampal CA3 Network Physiology. Cell Mol Neurobiol 2023; 43:4007-4022. [PMID: 37874456 DOI: 10.1007/s10571-023-01425-6] [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: 07/02/2023] [Accepted: 10/14/2023] [Indexed: 10/25/2023]
Abstract
Growing evidence supports the notion that brain-derived neurotrophic factor (BDNF) and lactate are potent modulators of mammalian brain function. The modulatory actions of those biomolecules influence a wide range of neuronal responses, from the shaping of neuronal excitability to the induction and expression of structural and synaptic plasticity. The biological actions of BDNF and lactate are mediated by their cognate receptors and specific transporters located in the neuronal membrane. Canonical functions of BDNF occur via the tropomyosin-related kinase B receptor (TrkB), whereas lactate acts via monocarboxylate transporters or the hydroxycarboxylic acid receptor 1 (HCAR1). Both receptors are highly expressed in the central nervous system, and some of their physiological actions are particularly well characterized in the hippocampus, a brain structure involved in the neurophysiology of learning and memory. The multifarious neuronal circuitry between the axons of the dentate gyrus granule cells, mossy fibers (MF), and pyramidal neurons of area CA3 is of great interest given its role in specific mnemonic processes and involvement in a growing number of brain disorders. Whereas the modulation exerted by BDNF via TrkB has been extensively studied, the influence of lactate via HCAR1 on the properties of the MF-CA3 circuit is an emerging field. In this review, we discuss the role of both systems in the modulation of brain physiology, with emphasis on the hippocampal CA3 network. We complement this review with original data that suggest cross-modulation is exerted by these two independent neuromodulatory systems.
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Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, Cinvestav Sur, Mexico City, Mexico.
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, USA.
- Departamento de Farmacobiología, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Calzada de los Tenorios No. 235, Col. Granjas Coapa, C.P. 14330, Mexico City, Mexico.
| | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sur, Mexico City, Mexico
- Centro de Investigaciones sobre el Envejecimiento, Mexico City, Mexico
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Sapkota RP, van der Linde I, Grunwald IQ, Upadhyaya T, Lamichhane N, Pardhan S. The impact of stimulus configuration on visual short-term memory decline in normal aging and mild cognitive impairment. Brain Behav 2023; 13:e3113. [PMID: 37287417 PMCID: PMC10498075 DOI: 10.1002/brb3.3113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 05/22/2023] [Accepted: 05/25/2023] [Indexed: 06/09/2023] Open
Abstract
INTRODUCTION When we memorize simultaneous items, we not only store information about specific items and/or their locations but also how items are related to each other. Such relational information can be parsed into spatial (spatial configuration) and identity (object configuration) components. Both these configurations are found to support performance during a visual short-term memory (VSTM) task in young adults. How the VSTM performance of older adults is influenced by object/spatial configuration is less understood, which this study investigated. METHODS Twenty-nine young adults, 29 normally aging older adults, and 20 older adults with mild cognitive impairment (MCI) completed two yes-no memory-recognition experiments for four simultaneously presented items (2.5 s). Test display items were presented either at the same locations as the memory items (Experiment 1) or were globally shifted (Experiment 2). One of the test display items (target) was highlighted with a square box; participants indicated whether this item was shown in the preceding memory display. Both experiments comprised four conditions where nontarget items changed as follows: (i) nontarget items remained the same; (ii) nontarget items were replaced by new items; (iii) nontarget items switched locations; (iv) nontarget items were replaced by square boxes. RESULTS Performance (% correct) in both older groups was significantly reduced than young adults in both experiments and each condition. For the MCI adults, significantly reduced performance (vs. normal older adults) was found only for Experiment 1. CONCLUSION VSTM for simultaneous items declines significantly in normal aging; the decline is not influenced differently by spatial/object configuration change. The ability of VSTM to differentiate MCI from normal cognitive aging is apparent only where the spatial configuration of stimuli is retained at original locations. Findings are discussed in terms of the reduced ability to inhibit irrelevant items and location priming (by repetition) deficits.
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Affiliation(s)
- Raju P. Sapkota
- Vision & Eye Research Institute (VERI), School of Medicine, Faculty of Health, Education, Medicine and Social CareAnglia Ruskin UniversityCambridgeUK
| | - Ian van der Linde
- Vision & Eye Research Institute (VERI), School of Medicine, Faculty of Health, Education, Medicine and Social CareAnglia Ruskin UniversityCambridgeUK
- School of Computing and Information ScienceAnglia Ruskin UniversityCambridgeUK
| | - Iris Q. Grunwald
- Imaging Science and Technology, School of MedicineUniversity of DundeeDundeeUK
| | - Tirthalal Upadhyaya
- Department of MedicineGandaki Medical College Teaching HospitalPokharaNepal
- Diabetes, Thyroid and Endocrine Care CenterPokharaNepal
| | - Nirmal Lamichhane
- Department of PsychiatryGandaki Medical College Teaching HospitalPokharaNepal
- BG Hospital and Research CenterPokharaNepal
| | - Shahina Pardhan
- Vision & Eye Research Institute (VERI), School of Medicine, Faculty of Health, Education, Medicine and Social CareAnglia Ruskin UniversityCambridgeUK
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5
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Inactivation of the dorsal CA1 hippocampus impairs the consolidation of discriminative avoidance memory by modulating the intrinsic and extrinsic hippocampal circuitry. J Chem Neuroanat 2023; 128:102209. [PMID: 36496001 DOI: 10.1016/j.jchemneu.2022.102209] [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: 09/09/2022] [Revised: 12/04/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Abstract
Despite progress in understanding the role of the dorsal hippocampus in the acquisition, consolidation and retrieval of episodic-like memory, plastic changes within the intra- and extrahippocampal circuits for aversive memory formation and anxiety-like behaviours must still be identified since both processes contribute to multiple aspects of flexible decision-making. Here, we investigated the effect of reversible inactivation induced by a muscimol microinfusion into the dorsal CA1 subfield (dCA1) either prior to acquisition or to retrieval testing of a discriminative avoidance task performed in a plus-maze apparatus (PM-DAT). Differential cAMP-response-element-binding protein 1 (CREB-1) expression in the dorsal and ventral CA1 and CA3 of the hippocampus (dCA1, dCA3, vCA1, and vCA3), dorsal dentate gyrus (dDG), and infralimbic (IL) and prelimbic (PrL) regions of the medial prefrontal cortex was also assessed to investigate the molecular changes associated with the consolidation or retrieval of episodic-like memory and anxiety. Adult male Wistar rats were assigned to two control groups, learning (no surgery/no microinfusion, n = 7) and sham-operated (sham surgery/no microinfusion, n = 6) groups, or four experimental groups, in which the vehicle (0.5 µl per side, n = 8/per group) or a GABAA receptor agonist (0.5 µg/0.5 µl muscimol/per side) was bilaterally microinfused in the dCA1 30 min prior to training (n = 9) or prior to testing sessions (n = 6) with a 24 h intertrial interval. Memory was evaluated using the percentage of time spent in the nonaversive enclosed arms, whereas anxiety was measured by calculating the percentages of time spent and entries into open arms and the percentage of time spent self-grooming. Our findings corroborated previous data showing that the dCA1 is required for discriminative avoidance consolidation. Furthermore, additional information indicated that impaired long-term memory was associated with downregulated CREB-1 expression in the dDG and vCA3. Moreover, memory retrieval was not impaired by dCA1 inactivation prior to the testing session, which was associated with the upregulation of CREB-1 in the dCA3 and vCA1 and downregulation in the dCA1 and vCA3. Differential expression of CREB was not identified in the IL or PrL areas. These results improve our understanding of how the hippocampal circuitry mediates the acquisition and retrieval of aversive memory and anxiety.
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Nomoto M, Ohkawa N, Inokuchi K, Oishi N. Requirement for hippocampal CA3 NMDA receptors in artificial association of memory events stored in CA3 cell ensembles. Mol Brain 2023; 16:12. [PMID: 36670484 PMCID: PMC9854113 DOI: 10.1186/s13041-023-01004-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/12/2023] [Indexed: 01/21/2023] Open
Abstract
The N-methyl-D-aspartate receptors (NRs) in hippocampal CA3 are crucial for the synaptic transmission and plasticity within the CA3 recurrent circuit, which supports the hippocampal functions, such as pattern completion, and reverberatory association of sensory inputs. Previous study showed that synchronous activation of distinct cell populations in CA3, which correspond to distinct events, associated independent events, suggesting that the recurrent circuit expressing NRs in CA3 mediates the artificial association of memory events stored in CA3 ensembles. However, it is still unclear whether CA3 NRs are crucial for the artificial association of memory events stored in the CA3 ensembles. Here we report that the triple transgenic mice (cfos-tTA/KA1-Cre/NR1 flox/flox), which specifically lack NRs in the CA3 cell ensembles, showed impairment in artificial association between two events, which in control mice triggered artificial association. This result indicates that NRs in the hippocampal CA3 are required for the artificial association of memory events stored in the CA3 cell ensembles.
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Affiliation(s)
- Masanori Nomoto
- Research Centre for Idling Brain Science, University of Toyama, Toyama, 930-0194, Japan. .,Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan. .,CREST, JST, University of Toyama, Toyama, 930-0194, Japan.
| | - Noriaki Ohkawa
- Division for Memory and Cognitive Function, Research Center for Advanced Medical Science, Comprehensive Research Facilities for Advanced Medical Science, Dokkyo Medical University, Shimotsuga-Gun, Tochigi, 321-0293, Japan
| | - Kaoru Inokuchi
- Research Centre for Idling Brain Science, University of Toyama, Toyama, 930-0194, Japan. .,Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan. .,CREST, JST, University of Toyama, Toyama, 930-0194, Japan.
| | - Naoya Oishi
- Research Centre for Idling Brain Science, University of Toyama, Toyama, 930-0194, Japan.,Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan.,CREST, JST, University of Toyama, Toyama, 930-0194, Japan.,Pharmaceutical Division, Pharmaceutical Research Laboratory, Drug Discovery and Pharmacology Group, Ube Corporation, 1978-5, Kogushi, Ube, Yamaguchi, 755-8633, Japan
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7
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Nomoto M, Murayama E, Ohno S, Okubo-Suzuki R, Muramatsu SI, Inokuchi K. Hippocampus as a sorter and reverberatory integrator of sensory inputs. Nat Commun 2022; 13:7413. [PMID: 36539403 PMCID: PMC9768143 DOI: 10.1038/s41467-022-35119-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 11/17/2022] [Indexed: 12/24/2022] Open
Abstract
The hippocampus must be capable of sorting and integrating multiple sensory inputs separately but simultaneously. However, it remains to be elucidated how the hippocampus executes these processes simultaneously during learning. Here we found that synchrony between conditioned stimulus (CS)-, unconditioned stimulus (US)- and future retrieval-responsible cells occurs in the CA1 during the reverberatory phase that emerges after sensory inputs have ceased, but not during CS and US inputs. Mutant mice lacking N-methyl-D-aspartate receptors (NRs) in CA3 showed a cued-fear memory impairment and a decrease in synchronized reverberatory activities between CS- and US-responsive CA1 cells. Optogenetic CA3 silencing at the reverberatory phase during learning impaired cued-fear memory. Thus, the hippocampus uses reverberatory activity to link CS and US inputs, and avoid crosstalk during sensory inputs.
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Affiliation(s)
- Masanori Nomoto
- grid.267346.20000 0001 2171 836XResearch Centre for Idling Brain Science, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XDepartment of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XCREST, JST, University of Toyama, Toyama, 930−0194 Japan
| | - Emi Murayama
- grid.267346.20000 0001 2171 836XResearch Centre for Idling Brain Science, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XDepartment of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XCREST, JST, University of Toyama, Toyama, 930−0194 Japan
| | - Shuntaro Ohno
- grid.267346.20000 0001 2171 836XResearch Centre for Idling Brain Science, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XDepartment of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XCREST, JST, University of Toyama, Toyama, 930−0194 Japan
| | - Reiko Okubo-Suzuki
- grid.267346.20000 0001 2171 836XResearch Centre for Idling Brain Science, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XDepartment of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XCREST, JST, University of Toyama, Toyama, 930−0194 Japan
| | - Shin-ichi Muramatsu
- grid.410804.90000000123090000Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi, 329−0498 Japan ,grid.26999.3d0000 0001 2151 536XCenter for Gene and Cell Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, 108−8639 Japan
| | - Kaoru Inokuchi
- grid.267346.20000 0001 2171 836XResearch Centre for Idling Brain Science, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XDepartment of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, 930−0194 Japan ,grid.267346.20000 0001 2171 836XCREST, JST, University of Toyama, Toyama, 930−0194 Japan
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Qi S, Tan SM, Wang R, Higginbotham JA, Ritchie JL, Ibarra CK, Arguello AA, Christian RJ, Fuchs RA. Optogenetic inhibition of the dorsal hippocampus CA3 region during early-stage cocaine-memory reconsolidation disrupts subsequent context-induced cocaine seeking in rats. Neuropsychopharmacology 2022; 47:1473-1483. [PMID: 35581381 PMCID: PMC9205994 DOI: 10.1038/s41386-022-01342-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 04/11/2022] [Accepted: 05/07/2022] [Indexed: 11/09/2022]
Abstract
The dorsal hippocampus (DH) is key to the maintenance of cocaine memories through reconsolidation into long-term memory stores after retrieval-induced memory destabilization. Here, we examined the time-dependent role of the cornu ammonis 3 DH subregion (dCA3) in cocaine-memory reconsolidation by utilizing the temporal and spatial specificity of optogenetics. eNpHR3.0-eYFP- or eYFP-expressing male Sprague-Dawley rats were trained to lever press for cocaine infusions in a distinct context and received extinction training in a different context. Rats were then re-exposed to the cocaine-paired context for 15 min to destabilize cocaine memories (memory reactivation) or remained in their home cages (no-reactivation). Optogenetic dCA3 inhibition for one hour immediately after memory reactivation reduced c-Fos expression (index of neuronal activation) in dCA3 stratum pyramidale (SP) glutamatergic and GABAergic neurons and in stratum lucidum (SL) GABAergic neurons during reconsolidation. Furthermore, dCA3 inhibition attenuated drug-seeking behavior (non-reinforced lever presses) selectively in the cocaine-paired context three days later (recall test), relative to no photoinhibition. This behavioral effect was eNpHR3.0-, memory-reactivation, and time-dependent, indicating a memory-reconsolidation deficit. Based on this observation and our previous finding that protein synthesis in the DH is not necessary for cocaine-memory reconsolidation, we postulate that recurrent pyramidal neuronal activity in the dCA3 may maintain labile cocaine memories prior to protein synthesis-dependent reconsolidation elsewhere, and SL/SP interneurons may facilitate this process by limiting extraneous neuronal activity. Interestingly, SL c-Fos expression was reduced at recall concomitant with impairment in cocaine-seeking behavior, suggesting that SL neurons may also facilitate cocaine-memory retrieval by inhibiting non-engram neuronal activity.
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Affiliation(s)
- Shuyi Qi
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Shi Min Tan
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Rong Wang
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Jessica A Higginbotham
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Jobe L Ritchie
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Christopher K Ibarra
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Amy A Arguello
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Robert J Christian
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA
| | - Rita A Fuchs
- Department of Integrative Physiology and Neuroscience, Washington State University College of Veterinary Medicine, Pullman, Washington, USA.
- Alcohol and Drug Abuse Research Program, Washington State University, Pullman, Washington, USA.
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Ma L, Patel M. Mechanism of carbachol-induced 40 Hz gamma oscillations and the effects of NMDA activation on oscillatory dynamics in a model of the CA3 subfield of the hippocampus. J Theor Biol 2022; 548:111200. [PMID: 35716721 DOI: 10.1016/j.jtbi.2022.111200] [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: 03/12/2022] [Revised: 05/26/2022] [Accepted: 06/08/2022] [Indexed: 11/26/2022]
Abstract
Gamma oscillations are a prominent feature of various neural systems, including the CA3 subfield of the hippocampus. In CA3, in vitro carbachol application induces ∼40 Hz gamma oscillations in the network of glutamatergic excitatory pyramidal neurons (PNs) and local GABAergic inhibitory neurons (INs). Activation of NMDA receptors within CA3 leads to an increase in the frequency of carbachol-induced oscillations to ∼60 Hz, a broadening of the distribution of individual oscillation cycle frequencies, and a decrease in the time lag between PN and IN spike bursts. In this work, we develop a biophysical integrate-and-fire model of the CA3 subfield, we show that the dynamics of our model are in concordance with physiological observations, and we provide computational support for the hypothesis that the 'E-I' mechanism is responsible for the emergence of ∼40 Hz gamma oscillations in the absence of NMDA activation. We then incorporate NMDA receptors into our CA3 model, and we show that our model exhibits the increase in gamma oscillation frequency, broadening of the cycle frequency distribution, and decrease in the time lag between PN and IN spike bursts observed experimentally. Remarkably, we find an inverse relationship in our model between the net NMDA current delivered to PNs and INs in an oscillation cycle and cycle frequency. Furthermore, we find a disparate effect of NMDA receptors on PNs versus INs - we show that NMDA receptors on INs tend to increase oscillation frequency, while NMDA receptors on PNs tend to slightly decrease or not affect oscillation frequency. We find that these observations can be explained if NMDA activity above a threshold level causes a shift in the mechanism underlying gamma oscillations; in the absence of NMDA receptors, the 'E-I' mechanism is primarily responsible for the generation of gamma oscillations (at 40 Hz), while when NMDA receptors are active, the mechanism of gamma oscillations shifts to the 'I-I' mechanism, and we argue that within the 'I-I' regime (which displays a higher baseline oscillation frequency of ∼60 Hz), slight changes in the level of NMDA activity are inversely related to cycle frequency.
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Affiliation(s)
- Linda Ma
- Department of Mathematics, William & Mary, United States.
| | - Mainak Patel
- Department of Mathematics, William & Mary, United States.
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10
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Hu J, Wang X, Kong W, Jiang Q. Tooth Loss Suppresses Hippocampal Neurogenesis and Leads to Cognitive Dysfunction in Juvenile Sprague–Dawley Rats. Front Neurosci 2022; 16:839622. [PMID: 35573291 PMCID: PMC9095951 DOI: 10.3389/fnins.2022.839622] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/15/2022] [Indexed: 11/25/2022] Open
Abstract
Background Both animal studies and prospective observational studies on patients with neurodegenerative disease have reported a positive link between oral diseases and cognitive function. However, the effect of early tooth loss on hippocampal morphology remains unknown. Methods In this study, 6-week-old, male, juvenile Sprague–Dawley (SD) rats were randomized into the control (C) and tooth loss (TL) groups. In the TL group, all right maxillary molars of SD rats were extracted, while in the C group, no teeth were extracted. After 3 months, the learning and memory behavior were examined by Morris Water Maze (MWM), and the protein expression and mechanic signaling pathways were analyzed by real-time polymerase chain reaction, and cresyl violet staining. Results Two days after the operation, the body weight of both groups recovered and gradually returned to the level before operation. Three months after tooth extraction, the completion time of the C group in the MWM was significantly shorter than the TL group. The mRNA expression of BDNF, TrkB, AKT1, and NR2B in the C group were significantly higher than in the TL group. The pyramidal neurons in the TL group was fewer than in the C group. Conclusion Tooth loss in the juvenile SD rats will reduce the number of pyramidal neurons in the hippocampus, inhibit the expression of BDNF, TrkB, AKT1, and NR2B, and eventually lead to cognitive dysfunction.
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Affiliation(s)
- Jiangqi Hu
- Beijing Stomatological Hospital, Capital Medical University, Beijing, China
| | - Xiaoyu Wang
- Beijing Stomatological Hospital, Capital Medical University, Beijing, China
| | - Wei Kong
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - Qingsong Jiang
- Beijing Stomatological Hospital, Capital Medical University, Beijing, China
- *Correspondence: Qingsong Jiang,
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11
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Magó Á, Kis N, Lükő B, Makara JK. Distinct dendritic Ca 2+ spike forms produce opposing input-output transformations in rat CA3 pyramidal cells. eLife 2021; 10:74493. [PMID: 34817378 PMCID: PMC8612760 DOI: 10.7554/elife.74493] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 10/29/2021] [Indexed: 01/09/2023] Open
Abstract
Proper integration of different inputs targeting the dendritic tree of CA3 pyramidal cells (CA3PCs) is critical for associative learning and recall. Dendritic Ca2+ spikes have been proposed to perform associative computations in other PC types by detecting conjunctive activation of different afferent input pathways, initiating afterdepolarization (ADP), and triggering burst firing. Implementation of such operations fundamentally depends on the actual biophysical properties of dendritic Ca2+ spikes; yet little is known about these properties in dendrites of CA3PCs. Using dendritic patch-clamp recordings and two-photon Ca2+ imaging in acute slices from male rats, we report that, unlike CA1PCs, distal apical trunk dendrites of CA3PCs exhibit distinct forms of dendritic Ca2+ spikes. Besides ADP-type global Ca2+ spikes, a majority of dendrites expresses a novel, fast Ca2+ spike type that is initiated locally without bAPs, can recruit additional Na+ currents, and is compartmentalized to the activated dendritic subtree. Occurrence of the different Ca2+ spike types correlates with dendritic structure, indicating morpho-functional heterogeneity among CA3PCs. Importantly, ADPs and dendritically initiated spikes produce opposing somatic output: bursts versus strictly single-action potentials, respectively. The uncovered variability of dendritic Ca2+ spikes may underlie heterogeneous input-output transformation and bursting properties of CA3PCs, and might specifically contribute to key associative and non-associative computations performed by the CA3 network.
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Affiliation(s)
- Ádám Magó
- Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary
| | - Noémi Kis
- Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary.,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Balázs Lükő
- Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary
| | - Judit K Makara
- Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary
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12
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Lesion of the hippocampus selectively enhances LEC's activity during recognition memory based on familiarity. Sci Rep 2021; 11:19085. [PMID: 34580354 PMCID: PMC8476609 DOI: 10.1038/s41598-021-98509-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/09/2021] [Indexed: 11/08/2022] Open
Abstract
The sense of familiarity for events is crucial for successful recognition memory. However, the neural substrate and mechanisms supporting familiarity remain unclear. A major controversy in memory research is whether the parahippocampal areas, especially the lateral entorhinal (LEC) and the perirhinal (PER) cortices, support familiarity or whether the hippocampus (HIP) does. In addition, it is unclear if LEC, PER and HIP interact within this frame. Here, we especially investigate if LEC and PER's contribution to familiarity depends on hippocampal integrity. To do so, we compare LEC and PER neural activity between rats with intact hippocampus performing on a human to rat translational task relying on both recollection and familiarity and rats with hippocampal lesions that have been shown to then rely on familiarity to perform the same task. Using high resolution Immediate Early Gene imaging, we report that hippocampal lesions enhance activity in LEC during familiarity judgments but not PER’s. These findings suggest that different mechanisms support familiarity in LEC and PER and led to the hypothesis that HIP might exert a tonic inhibition on LEC during recognition memory that is released when HIP is compromised, possibly constituting a compensatory mechanism in aging and amnesic patients.
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13
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Cholinergic basal forebrain and hippocampal structure influence visuospatial memory in Parkinson's disease. Brain Imaging Behav 2021; 16:118-129. [PMID: 34176042 DOI: 10.1007/s11682-021-00481-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
Visuospatial impairment in Parkinson's disease (PD) heralds the onset of a progressive dementia syndrome and might be associated with cholinergic dysfunction. It remains unclear however, whether degeneration of the cholinergic basal forebrain is directly related to cognitive decline, or whether relationships between this region and cognitive function are mediated by closely related brain structures such as those in the medial temporal lobe. To evaluate relationships between structure of the cholinergic basal forebrain, medial temporal lobe and cognition, 27 PD patients without dementia and 20 controls underwent neuropsychological assessment and MRI. Volumes of the cholinergic basal forebrain nuclei, the entorhinal cortex, the hippocampus and its subfields were measured. Regression models utilised basal forebrain and hippocampal volumetric measures to predict cognitive performance. In PD, visuospatial memory (but not verbal memory or executive function) was correlated with hippocampal volume, particularly CA2-3, and basal forebrain subregion Ch1-2, but not Ch4. In addition, hippocampal volume was correlated with Ch1-2 in PD. The relationship between Ch1-2 and visuospatial memory was mediated by CA2-3 integrity. There were no correlations between cognitive and volumetric measures in controls. Our data imply that the integrity of the cholinergic basal forebrain is associated with subregional hippocampal volume. Additionally, a relationship between visuospatial function and cholinergic nuclei does exist, but is fully mediated by variations in hippocampal structure. These findings are consistent with the recent hypothesis that forebrain cholinergic system degeneration results in cognitive deficits via cholinergic denervation, and subsequent structural degeneration, of its target regions.
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14
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Wirtshafter HS, Wilson MA. Lateral septum as a nexus for mood, motivation, and movement. Neurosci Biobehav Rev 2021; 126:544-559. [PMID: 33848512 DOI: 10.1016/j.neubiorev.2021.03.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/18/2021] [Accepted: 03/26/2021] [Indexed: 02/01/2023]
Abstract
The lateral septum (LS) has been implicated in a wide variety of functions, including emotional, motivational, and spatial behavior, and the LS may regulate interactions between the hippocampus and other regions that mediate goal directed behavior. In this review, we suggest that the lateral septum incorporates movement into the evaluation of environmental context with respect to motivation, anxiety, and reward to output an 'integrated movement value signal'. Specifically, hippocampally-derived contextual information may be combined with reinforcement or motivational information in the LS to inform task-relevant decisions. We will discuss how movement is represented in the LS and the literature on the LS's involvement in mood and motivation. We will then connect these results to LS movement-related literature and hypotheses about the role of the lateral septum. We suggest that the LS may communicate a movement-scaled reward signal via changes in place-, movement-, and reward-related firing, and that the LS should be considered a fundamental node of affect and locomotor pathways in the brain.
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Affiliation(s)
- Hannah S Wirtshafter
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA; Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Matthew A Wilson
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA; Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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15
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Kim KR, Kim Y, Jeong HJ, Kang JS, Lee SH, Kim Y, Lee SH, Ho WK. Impaired pattern separation in Tg2576 mice is associated with hyperexcitable dentate gyrus caused by Kv4.1 downregulation. Mol Brain 2021; 14:62. [PMID: 33785038 PMCID: PMC8011083 DOI: 10.1186/s13041-021-00774-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/23/2021] [Indexed: 12/05/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that causes memory loss. Most AD researches have focused on neurodegeneration mechanisms. Considering that neurodegenerative changes are not reversible, understanding early functional changes before neurodegeneration is critical to develop new strategies for early detection and treatment of AD. We found that Tg2576 mice exhibited impaired pattern separation at the early preclinical stage. Based on previous studies suggesting a critical role of dentate gyrus (DG) in pattern separation, we investigated functional changes in DG of Tg2576 mice. We found that granule cells in DG (DG-GCs) in Tg2576 mice showed increased action potential firing in response to long depolarizations and reduced 4-AP sensitive K+-currents compared to DG-GCs in wild-type (WT) mice. Among Kv4 family channels, Kv4.1 mRNA expression in DG was significantly lower in Tg2576 mice. We confirmed that Kv4.1 protein expression was reduced in Tg2576, and this reduction was restored by antioxidant treatment. Hyperexcitable DG and impaired pattern separation in Tg2576 mice were also recovered by antioxidant treatment. These results highlight the hyperexcitability of DG-GCs as a pathophysiologic mechanism underlying early cognitive deficits in AD and Kv4.1 as a new target for AD pathogenesis in relation to increased oxidative stress.
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Affiliation(s)
- Kyung-Ran Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Yoonsub Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Hyeon-Ju Jeong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Sang Hun Lee
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Yujin Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Suk-Ho Lee
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Korea
| | - Won-Kyung Ho
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea.
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea.
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Korea.
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16
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Lee SH, Lutz D, Drexler D, Frotscher M, Shen J. Differential modulation of short-term plasticity at hippocampal mossy fiber and Schaffer collateral synapses by mitochondrial Ca2. PLoS One 2020; 15:e0240610. [PMID: 33049001 PMCID: PMC7553293 DOI: 10.1371/journal.pone.0240610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/29/2020] [Indexed: 11/19/2022] Open
Abstract
Presynaptic mitochondrial Ca2+ plays a critical role in the regulation of synaptic transmission and plasticity. The presynaptic bouton of the hippocampal mossy fiber (MF) is much larger in size than that of the Schaffer collateral (SC) synapse. Here we compare the structural and physiological characteristics of MF and SC presynaptic boutons to reveal functional and mechanistic differences between these two synapses. Our quantitative ultrastructural analysis using electron microscopy show many more mitochondria in MF presynaptic bouton cross-section profiles compared to SC boutons. Consistent with these results, post-tetanic potentiation (PTP), a form of presynaptic short-term plasticity dependent on mitochondrial Ca2+, is reduced by inhibition of mitochondrial Ca2+ release at MF synapses but not at SC synapses. However, blockade of mitochondrial Ca2+ release results in reduction of PTP at SC synapses by disynaptic MF stimulation. Furthermore, inhibition of mitochondrial Ca2+ release selectively decreases frequency facilitation evoked by short trains of presynaptic stimulation at MF synapses, while having no effect at SC synapses. Moreover, depletion of ER Ca2+ stores leads to reduction of PTP at MF synapses, but PTP is unaffected by ER Ca2+ depletion at SC synapses. These findings show that MF and SC synapses differ in presynaptic mitochondrial content as well as mitochondrial Ca2+ dependent synaptic plasticity, highlighting differential regulatory mechanisms of presynaptic plasticity at MF and SC synapses.
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Affiliation(s)
- Sang Hun Lee
- Department of Neurology, Brigham & Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - David Lutz
- Institute for Structural Neurobiology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Dagmar Drexler
- Institute for Structural Neurobiology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michael Frotscher
- Institute for Structural Neurobiology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jie Shen
- Department of Neurology, Brigham & Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts, United States of America
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17
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Besnard A, Sahay A. Enhancing adult neurogenesis promotes contextual fear memory discrimination and activation of hippocampal-dorsolateral septal circuits. Behav Brain Res 2020; 399:112917. [PMID: 32949641 DOI: 10.1016/j.bbr.2020.112917] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/01/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022]
Abstract
Hippocampal circuitry is continuously modified by integration of adult-born dentate granule cells (DGCs). Prior work has shown that enhancing adult hippocampal neurogenesis decreases interference or overlap or conflict between ensembles of similar contexts and promotes discrimination of a shock-associated context from a similar, neutral context. However, the impact of enhanced integration of adult-born neurons on hippocampal network activity or downstream circuits such as the dorsolateral septum that mediate defensive behavioral responses is poorly understood. Here, we first replicated our finding that genetic expansion of the population of adult-born dentate granule cells (8 weeks and younger) promotes contextual fear discrimination. We found that enhanced contextual fear discrimination is associated with greater c-Fos expression in discrete hippocampal subfields along the proximo-distal and dorsoventral axis. Examination of the dorsolateral septum revealed an increase in activation of somatostatin expressing neurons consistent with recent characterization of these cells as calibrators of defensive behavior. Together, these findings begin to shed light on how genetically enhancing adult hippocampal neurogenesis affects activity of hippocampal-dorsolateral septal circuits.
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Affiliation(s)
- Antoine Besnard
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Harvard Stem Cell Institute, Cambridge, MA, 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Harvard Stem Cell Institute, Cambridge, MA, 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA; BROAD Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
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18
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Tyrtyshnaia A, Manzhulo I, Konovalova S, Zagliadkina A. Neuropathic Pain Causes a Decrease in the Dendritic Tree Complexity of Hippocampal CA3 Pyramidal Neurons. Cells Tissues Organs 2020; 208:89-100. [DOI: 10.1159/000506812] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 02/26/2020] [Indexed: 11/19/2022] Open
Abstract
The International Pain Association defines neuropathic pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.” Recent studies show that chronic neuropathic pain causes both morphological and functional changes within brain structures. Due to the impact of supraspinal centers on pain signal processing, patients with chronic pain often suffer from depression, anxiety, memory impairment, and learning disabilities. Changes in hippocampal neuronal and glial plasticity can play a substantial role in the development of these symptoms. Given the special role of the CA3 hippocampal area in chronic stress reactions, we suggested that this region may undergo significant morphological changes as a result of persistent pain. Since the CA3 area is involved in the implementation of hippocampus-dependent memory, changes in the neuronal morphology can cause cognitive impairment observed in chronic neuropathic pain. This study aimed to elucidate the structural and plastic changes within the hippocampus associated with dendritic tree atrophy of CA3 pyramidal neurons in mice with chronic sciatic nerve constriction. Behavioral testing revealed impaired working and long-term memory in mice with a chronic constriction injury. Using the Golgi-Cox method, we revealed a decrease in the number of branches and dendritic length of CA3 pyramidal neurons. The dendritic spine number was decreased, predominantly due to a reduction in mushroom spines. An immunohistochemical study showed changes in astro- and microglial activity, which could affect the morphology of neurons both directly and indirectly via the regulation of neurotrophic factor synthesis. Using ELISA, we found a decrease in brain-derived neurotrophic factor production and an increase in neurotrophin-3 production. Morphological and biochemical changes in the CA3 area are accompanied by impaired working and long-term memory of animals. Thus, we can conclude that morphological and biochemical changes within the CA3 hippocampal area may underlie the cognitive impairment in neuropathic pain.
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19
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Kapucu A, Üzüm G, Kaptan Z, Akgün-Dar K. Effects of erythropoietin pretreatment on single dose pentylentetrazole-induced seizures in rats. Biotech Histochem 2020; 95:418-427. [DOI: 10.1080/10520295.2020.1713398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Ayşegul Kapucu
- Department of Biology, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Gülay Üzüm
- Department of Physiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Zülal Kaptan
- Department of Physiology, Faculty of Medicine, Beykent University, Istanbul, Turkey
| | - Kadriye Akgün-Dar
- Department of Biology, Faculty of Science, Istanbul University, Istanbul, Turkey
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20
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Mendell AL, Creighton SD, Wilson HA, Jardine KH, Isaacs L, Winters BD, MacLusky NJ. Inhibition of 5α Reductase Impairs Cognitive Performance, Alters Dendritic Morphology and Increases Tau Phosphorylation in the Hippocampus of Male 3xTg-AD Mice. Neuroscience 2020; 429:185-202. [PMID: 31954826 DOI: 10.1016/j.neuroscience.2020.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/09/2019] [Accepted: 01/07/2020] [Indexed: 10/25/2022]
Abstract
Recent work has suggested that 5α-reduced metabolites of testosterone may contribute to the neuroprotection conferred by their parent androgen, as well as to sex differences in the incidence and progression of Alzheimer's disease (AD). This study investigated the effects of inhibiting 5α-reductase on object recognition memory (ORM), hippocampal dendritic morphology and proteins involved in AD pathology, in male 3xTg-AD mice. Male 6-month old wild-type or 3xTg-AD mice received daily injections of finasteride (50 mg/kg i.p.) or vehicle (18% β-cyclodextrin, 1% v/b.w.) for 20 days. Female wild-type and 3xTg-AD mice received only the vehicle. Finasteride treatment differentially impaired ORM in males after short-term (3xTg-AD only) or long-term (3xTg-AD and wild-type) retention delays. Dendritic spine density and dendritic branching of pyramidal neurons in the CA3 hippocampal subfield were significantly lower in 3xTg-AD females than in males. Finasteride reduced CA3 dendritic branching and spine density in 3xTg-AD males, to within the range observed in vehicle-treated females. In the CA1 hippocampal subfield, dendritic branching and spine density were reduced in both male and female 3xTg-AD mice, compared to wild type controls. Hippocampal amyloid β levels were substantially higher in 3xTg-AD females compared to both vehicle and finasteride-treated 3xTg-AD males. Site-specific Tau phosphorylation was higher in 3xTg-AD mice compared to sex-matched wild-type controls, increasing slightly after finasteride treatment. These results suggest that 5α-reduced neurosteroids may play a role in testosterone-mediated neuroprotection and may contribute to sex differences in the development and severity of AD.
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Affiliation(s)
| | | | | | | | | | - Boyer D Winters
- Psychology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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21
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Cembrowski MS, Spruston N. Heterogeneity within classical cell types is the rule: lessons from hippocampal pyramidal neurons. Nat Rev Neurosci 2019; 20:193-204. [PMID: 30778192 DOI: 10.1038/s41583-019-0125-5] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mechanistic operation of brain regions is often interpreted by partitioning constituent neurons into 'cell types'. Historically, such cell types were broadly defined by their correspondence to gross features of the nervous system (such as cytoarchitecture). Modern-day neuroscientific techniques, enabling a more nuanced examination of neuronal properties, have illustrated a wealth of heterogeneity within these classical cell types. Here, we review the extent of this within-cell-type heterogeneity in one of the simplest cortical regions of the mammalian brain, the rodent hippocampus. We focus on the mounting evidence that the classical CA3, CA1 and subiculum pyramidal cell types all exhibit prominent and spatially patterned within-cell-type heterogeneity, and suggest these cell types provide a model system for exploring the organization and function of such heterogeneity. Given that the hippocampus is structurally simple and evolutionarily ancient, within-cell-type heterogeneity is likely to be a general and crucial feature of the mammalian brain.
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Affiliation(s)
- Mark S Cembrowski
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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22
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Cox BM, Cox CD, Gunn BG, Le AA, Inshishian VC, Gall CM, Lynch G. Acquisition of temporal order requires an intact CA3 commissural/associational (C/A) feedback system in mice. Commun Biol 2019; 2:251. [PMID: 31286068 PMCID: PMC6610080 DOI: 10.1038/s42003-019-0494-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/30/2019] [Indexed: 12/31/2022] Open
Abstract
Episodic memory, an essential element of orderly thinking, requires the organization of serial events into narratives about the identity of cues along with their locations and temporal order (what, where, and when). The hippocampus plays a central role in the acquisition and retrieval of episodes with two of its subsystems being separately linked to what and where information. The substrates for the third element are poorly understood. Here we report that in hippocampal slices field CA3 maintains self-sustained activity for remarkable periods following a brief input and that this effect is extremely sensitive to minor network perturbations. Using behavioral tests, that do not involve training or explicit rewards, we show that partial silencing of the CA3 commissural/associational network in mice blocks acquisition of temporal order, but not the identity or location, of odors. These results suggest a solution to the question of how hippocampus adds time to episodic memories.
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Affiliation(s)
- Brittney M. Cox
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
| | - Conor D. Cox
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
| | - Benjamin G. Gunn
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
| | - Aliza A. Le
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
| | | | - Christine M. Gall
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697 USA
| | - Gary Lynch
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697 USA
- Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697 USA
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23
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Dubovyk V, Manahan-Vaughan D. Distinct Time-Course of Alterations of Groups I and II Metabotropic Glutamate Receptor and GABAergic Receptor Expression Along the Dorsoventral Hippocampal Axis in an Animal Model of Psychosis. Front Behav Neurosci 2019; 13:98. [PMID: 31139061 PMCID: PMC6519509 DOI: 10.3389/fnbeh.2019.00098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/23/2019] [Indexed: 01/13/2023] Open
Abstract
Psychosis is a clinical state that encompasses a range of abnormal conditions, including distortions in sensory information processing and the resultant delusional thinking, emotional discordance and cognitive impairments. Upon developing this condition, the rate at which cognitive and behavioral deteriorations progress steadily increases suggesting an active contribution of the first psychotic event to the progression of structural and functional abnormalities and disease establishment in diagnosed patients. Changes in GABAergic and glutamatergic function, or expression, in the hippocampus have been proposed as a key factor in the pathophysiology of psychosis. However, little is known as to the time-point of onset of putative changes, to what extent they are progressive, and their relation to disease stabilization. Here, we characterized the expression and distribution patterns of groups I and II metabotropic glutamate (mGlu) receptors and GABA receptors 1 week and 3 months after systemic treatment with an N-methyl-D-aspartate receptor (NMDAR) antagonist (MK801) that is used to model a psychosis-like state in adult rats. We found an early alteration in the expression of mGlu1, mGlu2/3, and GABAB receptors across the hippocampal dorsoventral and transverse axes. This expanded to include an up-regulation of mGlu5 levels across the entire CA1 region and a reduction in GABAB expression, as well as GAD67-positive interneurons particularly in the dorsal hippocampus that appeared 3 months after treatment. Our findings indicate that a reduction of excitability may occur in the hippocampus soon after first-episode psychosis. This changes, over time, into increased excitability. These hippocampus-specific alterations are likely to contribute to the pathophysiology and stabilization of psychosis.
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Affiliation(s)
- Valentyna Dubovyk
- Department of Neurophysiology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr-University Bochum, Bochum, Germany
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24
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Hippocampal Mossy Fibers Synapses in CA3 Pyramidal Cells Are Altered at an Early Stage in a Mouse Model of Alzheimer's Disease. J Neurosci 2019; 39:4193-4205. [PMID: 30886015 DOI: 10.1523/jneurosci.2868-18.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/20/2019] [Accepted: 03/08/2019] [Indexed: 12/13/2022] Open
Abstract
Early Alzheimer's disease (AD) affects the brain non-uniformly, causing hippocampal memory deficits long before wide-spread brain degeneration becomes evident. Here we addressed whether mossy fiber inputs from the dentate gyrus onto CA3 principal cells are affected in an AD mouse model before amyloid β plaque deposition. We recorded from CA3 pyramidal cells in a slice preparation from 6-month-old male APP/PS1 mice, and studied synaptic properties and intrinsic excitability. In parallel we performed a morphometric analysis of mossy fiber synapses following viral based labeling and 3D-reconstruction. We found that the basal structural and functional properties as well as presynaptic short-term plasticity at mossy fiber synapses are unaltered at 6 months in APP/PS1 mice. However, transient potentiation of synaptic transmission mediated by activity-dependent release of lipids was abolished. Whereas the presynaptic form of mossy fiber long-term potentiation (LTP) was not affected, the postsynaptic LTP of NMDAR-EPSCs was reduced. In addition, we also report an impairment in feedforward inhibition in CA3 pyramidal cells. This study, together with our previous work describing deficits at CA3-CA3 synapses, provides evidence that early AD affects synapses in a projection-dependent manner at the level of a single neuronal population.SIGNIFICANCE STATEMENT Because loss of episodic memory is considered the cognitive hallmark of Alzheimer's disease (AD), it is important to study whether synaptic circuits involved in the encoding of episodic memory are compromised in AD mouse models. Here we probe alterations in the synaptic connections between the dentate gyrus and CA3, which are thought to be critical for enabling episodic memories to be formed and stored in CA3. We found that forms of synaptic plasticity specific to these synaptic connections are markedly impaired at an early stage in a mouse model of AD, before deposition of β amyloid plaques. Together with previous work describing deficits at CA3-CA3 synapses, we provide evidence that early AD affects synapses in an input-dependent manner within a single neuronal population.
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25
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Das T, Hwang JJ, Poston KL. Episodic recognition memory and the hippocampus in Parkinson's disease: A review. Cortex 2018; 113:191-209. [PMID: 30660957 DOI: 10.1016/j.cortex.2018.11.021] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 10/02/2018] [Accepted: 11/15/2018] [Indexed: 01/09/2023]
Abstract
Parkinson's disease is a progressive neurodegenerative disorder of aging. The hallmark pathophysiology includes the development of neuronal Lewy bodies in the substantia nigra of the midbrain with subsequent loss of dopaminergic neurons. These neuronal losses lead to the characteristic motor symptoms of bradykinesia, rigidity, and rest tremor. In addition to these cardinal motor symptoms patients with PD experience a wide range of non-motor symptoms, the most important being cognitive impairments that in many circumstances lead to dementia. People with PD experience a wide range of cognitive impairments; in this review we will focus on memory impairment in PD and specifically episodic memory, which are memories of day-to-day events of life. Importantly, these memory impairments severely impact the lives of patients and caregivers alike. Traditionally episodic memory is considered to be markedly dependent on the hippocampus; therefore, it is important to understand the exact nature of PD episodic memory deficits in relation to hippocampal function and dysfunction. In this review, we discuss an aspect of episodic memory called recognition memory and its subcomponents called recollection and familiarity. Recognition memory is believed to be impaired in PD; thus, we discuss what aspects of the hippocampus are expected to be deficient in function as they relate to these recognition memory impairments. In addition to the hippocampus as a whole, we will discuss the role of hippocampal subfields in recognition memory impairments.
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Affiliation(s)
- Tanusree Das
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA.
| | - Jaclyn J Hwang
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA; Department of Neuroscience, University of Pittsburgh, USA.
| | - Kathleen L Poston
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA; Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA.
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26
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Dubovyk V, Manahan-Vaughan D. Time-Dependent Alterations in the Expression of NMDA Receptor Subunits along the Dorsoventral Hippocampal Axis in an Animal Model of Nascent Psychosis. ACS Chem Neurosci 2018; 9:2241-2251. [PMID: 29634239 DOI: 10.1021/acschemneuro.8b00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Psychosis is a mental condition that is characterized by hallucinations, delusions, disordered thought, as well as socio-emotional and cognitive impairments. Once developed, it tends to progress into a chronic psychotic illness. Here, the duration of untreated psychosis plays a crucial role: the earlier the treatment begins, relative to the first episode of the disease, the better the patient's functional prognosis. To what extent the success of early interventions relate to progressive changes at the neurotransmitter receptor level is as yet unclear. In fact, very little is known as to how molecular changes develop, transform, and become established following the first psychotic event. One neurotransmitter receptor for which a specific role in psychosis has been discussed is the N-methyl-d-aspartate receptor (NMDAR). This receptor is especially important for information encoding in the hippocampus. The hippocampus is one of the loci of functional change in psychosis, to which a role in the pathophysiology of psychosis has been ascribed. Here, we examined whether changes in NMDAR subunit expression occur along the dorsoventral axis of the hippocampus 1 week and 3 months after systemic treatment with an NMDAR antagonist (MK801) that initiates a psychosis-like state in adult rats. We found early (1 week) upregulation of the GluN2B levels in the dorso-intermediate hippocampus and late (3 month) downregulation of GluN2A expression across the entire CA1 region. The ventral hippocampus did not exhibit subunit expression changes. These data suggest that a differing vulnerability of the hippocampal longitudinal axis may occur in response to MK801-treatment and provide a time-resolved view of the putative development of pathological changes of NMDAR subunit expression in the hippocampus that initiate with an emulated first episode and progress through to the chronic stabilization of a psychosis-like state in rodents.
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27
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Unfolding the cognitive map: The role of hippocampal and extra-hippocampal substrates based on a systems analysis of spatial processing. Neurobiol Learn Mem 2018; 147:90-119. [DOI: 10.1016/j.nlm.2017.11.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 11/17/2017] [Accepted: 11/21/2017] [Indexed: 01/03/2023]
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28
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Adams SL, Benayoun L, Tilton K, Mellott TJ, Seshadri S, Blusztajn JK, Delalle I. Immunohistochemical Analysis of Activin Receptor-Like Kinase 1 (ACVRL1/ALK1) Expression in the Rat and Human Hippocampus: Decline in CA3 During Progression of Alzheimer's Disease. J Alzheimers Dis 2018; 63:1433-1443. [PMID: 29843236 PMCID: PMC5988976 DOI: 10.3233/jad-171065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The pathophysiology of Alzheimer's disease (AD) includes signaling defects mediated by the transforming growth factor β-bone morphogenetic protein-growth and differentiation factor (TGFβ-BMP-GDF) family of proteins. In animal models of AD, administration of BMP9/GDF2 improves memory and reduces amyloidosis. The best characterized type I receptor of BMP9 is ALK1. We characterized ALK1 expression in the hippocampus using immunohistochemistry. In the rat, ALK1 immunoreactivity was found in CA pyramidal neurons, most frequently and robustly in the CA2 and CA3 fields. In addition, there were sporadic ALK1-immunoreactive cells in the stratum oriens, mainly in CA1. The ALK1 expression pattern in human hippocampus was similar to that of rat. Pyramidal neurons within the CA2, CA3, and CA4 were strongly ALK1-immunoreactive in hippocampi of cognitively intact subjects with no neurofibrillary tangles. ALK1 signal was found in the axons of alveus and fimbria, and in the neuropil across CA fields. Relatively strongest ALK1 neuropil signal was observed in CA1 where pyramidal neurons were occasionally ALK1-immunoractive. As in the rat, horizontally oriented neurons in the stratum oriens of CA1 were both ALK1- and GAD67-immunoreactive. Analysis of ALK1 immunoreactivity across stages of AD pathology revealed that disease progression was characterized by overall reduction of the ALK1 signal in CA3 in advanced, but not early, stages of AD. These data suggest that the CA3 pyramidal neurons may remain responsive to the ALK1 ligands, e.g., BMP9, during initial stages of AD and that ALK1 may constitute a therapeutic target in early and moderate AD.
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Affiliation(s)
- Stephanie L. Adams
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Laurent Benayoun
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Kathy Tilton
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Tiffany J. Mellott
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Sudha Seshadri
- Framingham Heart Study, Boston University School of Medicine, Boston, MA, USA
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Jan Krzysztof Blusztajn
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Ivana Delalle
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA, USA
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29
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Babayan BM, Watilliaux A, Viejo G, Paradis AL, Girard B, Rondi-Reig L. A hippocampo-cerebellar centred network for the learning and execution of sequence-based navigation. Sci Rep 2017; 7:17812. [PMID: 29259243 PMCID: PMC5736633 DOI: 10.1038/s41598-017-18004-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/05/2017] [Indexed: 12/29/2022] Open
Abstract
How do we translate self-motion into goal-directed actions? Here we investigate the cognitive architecture underlying self-motion processing during exploration and goal-directed behaviour. The task, performed in an environment with limited and ambiguous external landmarks, constrained mice to use self-motion based information for sequence-based navigation. The post-behavioural analysis combined brain network characterization based on c-Fos imaging and graph theory analysis as well as computational modelling of the learning process. The study revealed a widespread network centred around the cerebral cortex and basal ganglia during the exploration phase, while a network dominated by hippocampal and cerebellar activity appeared to sustain sequence-based navigation. The learning process could be modelled by an algorithm combining memory of past actions and model-free reinforcement learning, which parameters pointed toward a central role of hippocampal and cerebellar structures for learning to translate self-motion into a sequence of goal-directed actions.
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Affiliation(s)
- Benedicte M Babayan
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Cerebellum Navigation and Memory team (CeZaMe), 75005, Paris, France
| | - Aurélie Watilliaux
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Cerebellum Navigation and Memory team (CeZaMe), 75005, Paris, France
| | - Guillaume Viejo
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC), CNRS UMR 7222, Institut des Systèmes Intelligents et de Robotique (ISIR), F-75005, Paris, France
| | - Anne-Lise Paradis
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Cerebellum Navigation and Memory team (CeZaMe), 75005, Paris, France
| | - Benoît Girard
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC), CNRS UMR 7222, Institut des Systèmes Intelligents et de Robotique (ISIR), F-75005, Paris, France
| | - Laure Rondi-Reig
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Cerebellum Navigation and Memory team (CeZaMe), 75005, Paris, France.
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30
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Shen Y, Tian M, Zheng Y, Gong F, Fu AKY, Ip NY. Stimulation of the Hippocampal POMC/MC4R Circuit Alleviates Synaptic Plasticity Impairment in an Alzheimer's Disease Model. Cell Rep 2017; 17:1819-1831. [PMID: 27829153 DOI: 10.1016/j.celrep.2016.10.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 07/27/2016] [Accepted: 10/13/2016] [Indexed: 02/07/2023] Open
Abstract
Hippocampal synaptic plasticity is modulated by neuropeptides, the disruption of which might contribute to cognitive deficits observed in Alzheimer's disease (AD). Although pro-opiomelanocortin (POMC)-derived neuropeptides and melanocortin 4 receptor (MC4R) are implicated in hippocampus-dependent synaptic plasticity, how the POMC/MC4R system functions in the hippocampus and its role in synaptic dysfunction in AD are largely unknown. Here, we mapped a functional POMC circuit in the mouse hippocampus, wherein POMC neurons in the cornu ammonis 3 (CA3) activate MC4R in the CA1. Suppression of hippocampal MC4R activity in the APP/PS1 transgenic mouse model of AD exacerbates long-term potentiation impairment, which is alleviated by the replenishment of hippocampal POMC/MC4R activity or activation of hippocampal MC4R-coupled Gs signaling. Importantly, MC4R activation rescues amyloid-β-induced synaptic dysfunction via a Gs/cyclic AMP (cAMP)/PKA/cAMP-response element binding protein (CREB)-dependent mechanism. Hence, disruption of this hippocampal POMC/MC4R circuit might contribute to synaptic dysfunction observed in AD, revealing a potential therapeutic target for the disease.
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Affiliation(s)
- Yang Shen
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Min Tian
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yuqiong Zheng
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Fei Gong
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Amy K Y Fu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Nancy Y Ip
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
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31
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Atucha E, Karew A, Kitsukawa T, Sauvage MM. Recognition memory: Cellular evidence of a massive contribution of the LEC to familiarity and a lack of involvement of the hippocampal subfields CA1 and CA3. Hippocampus 2017; 27:1083-1092. [PMID: 28667695 DOI: 10.1002/hipo.22754] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/17/2017] [Accepted: 06/20/2017] [Indexed: 11/08/2022]
Abstract
A highly debated issue in memory research is whether familiarity is supported by the parahippocampal region, especially the lateral (LEC) and the perirhinal (PER) cortices, or whether it is supported by the same brain structure as recollection: the hippocampus. One reason for this is that conflicting results have emerged regarding the contribution of the hippocampus to familiarity. This might stem from the lack of dissociation between hippocampal subfields CA1 and CA3 as these areas are involved to a different extent in processes which are pertinent to familiarity. Another reason is that empirical evidence for a contribution of the LEC is still missing. Furthermore, it is unclear whether the superficial and the deep layers of the LEC would equally contribute to this process as these layers are differentially recruited during memory retrieval which partly relies on familiarity. To identify the specific contribution of the LEC, CA1, and CA3, we imaged with cellular resolution activity in the brain of rats performing a version of a standard human memory task adapted to rats that yields judgments based on familiarity. Using this translational approach, we report that in striking contrast to CA1 and CA3, the LEC is recruited for familiarity-judgments and that its contribution is comparable to that of the PER. These results show for the first time that the LEC, specifically its deep layers, contributes to familiarity and constitute the first cellular evidence that the hippocampus does not, thus establishing that familiarity does not share the same neural substrate as recollection.
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Affiliation(s)
- Erika Atucha
- Mercator Research Group, Functional Architecture of Memory Unit, Ruhr-University, Bochum, 44780, Germany.,Functional Architecture of Memory Department, Leibniz-Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Artem Karew
- Mercator Research Group, Functional Architecture of Memory Unit, Ruhr-University, Bochum, 44780, Germany
| | | | - Magdalena M Sauvage
- Mercator Research Group, Functional Architecture of Memory Unit, Ruhr-University, Bochum, 44780, Germany.,Functional Architecture of Memory Department, Leibniz-Institute for Neurobiology, Magdeburg, 39118, Germany.,Medical Faculty, Functional Neuroplasticity Department, Otto von Guericke University, Magdeburg, 39120, Germany.,Otto von Guericke University, Center for Behavioral Brain Sciences, Magdeburg, 39106, Germany
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32
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Abstract
One of the mysteries of memory is that it can last despite changes in the underlying synaptic architecture. How can we, for example, maintain an internal spatial map of an environment over months or years when the underlying network is full of transient connections? In the following, we propose a computational model for describing the emergence of the hippocampal cognitive map in a network of transient place cell assemblies and demonstrate, using methods of algebraic topology, how such a network can maintain spatial memory over time.
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33
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Chavlis S, Poirazi P. Pattern separation in the hippocampus through the eyes of computational modeling. Synapse 2017; 71. [PMID: 28316111 DOI: 10.1002/syn.21972] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/02/2017] [Accepted: 03/14/2017] [Indexed: 12/24/2022]
Abstract
Pattern separation is a mnemonic process that has been extensively studied over the years. It entails the ability -of primarily hippocampal circuits- to distinguish between highly similar inputs, via generating different neuronal activity (output) patterns. The dentate gyrus (DG) in particular has long been hypothesized to implement pattern separation by detecting and storing similar inputs as distinct representations. The ways in which these distinct representations can be generated have been explored in a number of theoretical and computational modeling studies. Here, we review two categories of pattern separation models: those that address the phenomenon in an abstract mathematical fashion and those that delve into the underlying biological mechanisms by taking into account the anatomy and/or physiology of hippocampal circuits. We summarize the strategies, findings and limitations of these modeling approaches in the light of new experimental findings and propose a unifying framework whereby different network, cellular and sub-cellular mechanisms converge to a common goal: controlling sparsity, the key determinant of pattern separation in the DG.
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Affiliation(s)
- Spyridon Chavlis
- Institute of Molecular Biology & Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), N. Plastira 100, Heraklion, Crete, 70013, Greece.,Department of Biology, University of Crete, Vasilika Vouton, P.O. Box 2208, Heraklion, Crete, 71409, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology & Biotechnology (IMBB), Foundation for Research and Technology - Hellas (FORTH), N. Plastira 100, Heraklion, Crete, 70013, Greece
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34
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Rebola N, Carta M, Mulle C. Operation and plasticity of hippocampal CA3 circuits: implications for memory encoding. Nat Rev Neurosci 2017; 18:208-220. [DOI: 10.1038/nrn.2017.10] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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35
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Scharkowski F, Frotscher M, Lutz D, Korte M, Michaelsen-Preusse K. Altered Connectivity and Synapse Maturation of the Hippocampal Mossy Fiber Pathway in a Mouse Model of the Fragile X Syndrome. Cereb Cortex 2017; 28:852-867. [DOI: 10.1093/cercor/bhw408] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 12/22/2016] [Indexed: 12/12/2022] Open
Affiliation(s)
- F Scharkowski
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, 38106 Braunschweig, Germany
| | - Michael Frotscher
- ZMNH, Institute for Structural Neurobiology, D-20251 Hamburg, Germany
| | - David Lutz
- ZMNH, Institute for Structural Neurobiology, D-20251 Hamburg, Germany
| | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, 38106 Braunschweig, Germany
- Helmholtz Centre for Infection Research, AG NIND, 38124 Braunschweig, Germany
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36
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De Shetler NG, Rissman J. Dissociable profiles of generalization/discrimination in the human hippocampus during associative retrieval. Hippocampus 2016; 27:115-121. [PMID: 27863445 DOI: 10.1002/hipo.22684] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/24/2016] [Accepted: 11/16/2016] [Indexed: 01/21/2023]
Abstract
When encountering stimuli that vary slightly from previous experiences, neural signals within the CA3 and dentate gyrus (CA3 DG) hippocampal subfields are thought to facilitate mnemonic discrimination, whereas CA1 may be less sensitive to minor stimulus changes, allowing for generalization across similar events. Studies have also posited a critical role for CA1 in the comparison of events to memory-derived expectations, but the degree to which these processes are impacted by explicit retrieval demands is yet unclear. To evaluate extant accounts of hippocampal subfield function, we acquired high-resolution fMRI data as participants performed a task in which famous names were used to cue the retrieval of previously paired images. Although both left CA3 DG and CA1 showed match enhancement effects, responding more to original paired images (targets) than to never-before-seen images (novels), the sensitivity of these subfields to stimulus changes and task demands diverged. CA3 DG showed a goal-independent, yet highly specific, preference for previously encountered stimuli, responding equally strongly to targets and mispaired associates, while showing equally weak responses to close lures and novels. In contrast, recognition signals in CA1 were goal-dependent (i.e., not evoked by mispaired associates), yet accommodating of subtle stimulus differences, such that close lures evoked comparable activity as targets. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Natalie G De Shetler
- Department of Psychology, University of California Los Angeles, Los Angeles, California
| | - Jesse Rissman
- Department of Psychology, University of California Los Angeles, Los Angeles, California.,Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California.,Brain Research Institute, University of California Los Angeles, Los Angeles, California.,Integrative Center for Learning and Memory, University of California Los Angeles, Los Angeles, California
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37
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Viana da Silva S, Haberl MG, Zhang P, Bethge P, Lemos C, Gonçalves N, Gorlewicz A, Malezieux M, Gonçalves FQ, Grosjean N, Blanchet C, Frick A, Nägerl UV, Cunha RA, Mulle C. Early synaptic deficits in the APP/PS1 mouse model of Alzheimer's disease involve neuronal adenosine A2A receptors. Nat Commun 2016; 7:11915. [PMID: 27312972 PMCID: PMC4915032 DOI: 10.1038/ncomms11915] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/12/2016] [Indexed: 01/24/2023] Open
Abstract
Synaptic plasticity in the autoassociative network of recurrent connections among hippocampal CA3 pyramidal cells is thought to enable the storage of episodic memory. Impaired episodic memory is an early manifestation of cognitive deficits in Alzheimer's disease (AD). In the APP/PS1 mouse model of AD amyloidosis, we show that associative long-term synaptic potentiation (LTP) is abolished in CA3 pyramidal cells at an early stage. This is caused by activation of upregulated neuronal adenosine A2A receptors (A2AR) rather than by dysregulation of NMDAR signalling or altered dendritic spine morphology. Neutralization of A2AR by acute pharmacological inhibition, or downregulation driven by shRNA interference in a single postsynaptic neuron restore associative CA3 LTP. Accordingly, treatment with A2AR antagonists reverts one-trial memory deficits. These results provide mechanistic support to encourage testing the therapeutic efficacy of A2AR antagonists in early AD patients.
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MESH Headings
- Adenosine A2 Receptor Antagonists/pharmacology
- Alzheimer Disease/drug therapy
- Alzheimer Disease/genetics
- Alzheimer Disease/metabolism
- Alzheimer Disease/physiopathology
- Amyloid beta-Protein Precursor/genetics
- Amyloid beta-Protein Precursor/metabolism
- Animals
- CA3 Region, Hippocampal/drug effects
- CA3 Region, Hippocampal/metabolism
- CA3 Region, Hippocampal/pathology
- Dendritic Spines/drug effects
- Dendritic Spines/metabolism
- Dendritic Spines/ultrastructure
- Disease Models, Animal
- Gene Expression Regulation
- Humans
- Long-Term Potentiation
- Memory, Episodic
- Mice
- Mice, Transgenic
- Neuroprotective Agents/pharmacology
- Presenilin-1/genetics
- Presenilin-1/metabolism
- Pyrimidines/pharmacology
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Receptor, Adenosine A2A/genetics
- Receptor, Adenosine A2A/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Signal Transduction
- Synapses/drug effects
- Synapses/metabolism
- Synapses/ultrastructure
- Triazines/pharmacology
- Triazoles/pharmacology
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Affiliation(s)
- Silvia Viana da Silva
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
- BEB PhD program CNC Coimbra, 3004-517 Coimbra, Portugal
| | | | - Pei Zhang
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Philipp Bethge
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Cristina Lemos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Nélio Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Adam Gorlewicz
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Meryl Malezieux
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Francisco Q. Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Noëlle Grosjean
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Christophe Blanchet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Andreas Frick
- University of Bordeaux, Neurocentre Magendie, INSERM U862, F-33000 Bordeaux, France
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
| | - Rodrigo A. Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS UMR 5297, F-33000 Bordeaux, France
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38
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Engin E, Smith KS, Gao Y, Nagy D, Foster RA, Tsvetkov E, Keist R, Crestani F, Fritschy JM, Bolshakov VY, Hajos M, Heldt SA, Rudolph U. Modulation of anxiety and fear via distinct intrahippocampal circuits. eLife 2016; 5:e14120. [PMID: 26971710 PMCID: PMC4816644 DOI: 10.7554/elife.14120] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 02/24/2016] [Indexed: 11/13/2022] Open
Abstract
Recent findings indicate a high level of specialization at the level of microcircuits and cell populations within brain structures with regards to the control of fear and anxiety. The hippocampus, however, has been treated as a unitary structure in anxiety and fear research despite mounting evidence that different hippocampal subregions have specialized roles in other cognitive domains. Using novel cell-type- and region-specific conditional knockouts of the GABAA receptor α2 subunit, we demonstrate that inhibition of the principal neurons of the dentate gyrus and CA3 via α2-containing GABAA receptors (α2GABAARs) is required to suppress anxiety, while the inhibition of CA1 pyramidal neurons is required to suppress fear responses. We further show that the diazepam-modulation of hippocampal theta activity shows certain parallels with our behavioral findings, suggesting a possible mechanism for the observed behavioral effects. Thus, our findings demonstrate a double dissociation in the regulation of anxiety versus fear by hippocampal microcircuitry. DOI:http://dx.doi.org/10.7554/eLife.14120.001 Fear and anxiety can be thought of as different but related emotional states. Fear is triggered by specific harmful situations, such as the immediate presence of a predator. Anxiety instead results from the possibility of an obscure threat, such as being in an exposed environment, which increases the chance of being detected by a predator. Evidence suggests that slightly different areas of the brain control fear and anxiety, but much remains unknown about the specific brain regions that help to regulate these two emotional states. One brain region that has been implicated in both anxiety and fear – as well as in learning and memory – is the hippocampus. Named after the Greek word for seahorse because of its shape, the hippocampus is made up of three subregions: CA1, CA3 and the dentate gyrus. Each of these subregions has a distinct role in learning and memory. However, their individual contributions to the control of fear and anxiety were not known. An inhibitory receptor protein found in the surface of some hippocampal neurons had previously been shown to be involved in controlling fear and anxiety. Now, Engin et al. have studied three different groups of genetically modified mice, each of which lacks the receptor protein in a different subregion of the hippocampus. The mice completed tests that stimulated anxiety or fear, some while under the influence of the anxiety and fear-reducing drug diazepam. Notably, diazepam failed to reduce fear in animals that lacked the inhibitory receptor protein in the CA1 subregion of the hippocampus, suggesting that this subregion participates in the fear response. However, mice that lacked the receptor in the dentate gyrus or CA3 responded normally to the drug (they showed reduced fear when given diazepam). In tests of anxiety, the picture was exactly the opposite. Diazepam failed to reduce anxiety in animals lacking the inhibitory receptor in the dentate gyrus or CA3, indicating that these subregions are involved in the regulation of anxiety. However, the drug still reduced anxiety in mice that lacked the receptor protein in the CA1 subregion. Further studies are now needed to clarify how manipulating specific subregions of the hippocampus alters how it communicates with other brain structures to generate changes in anxiety or fear-related behaviors. DOI:http://dx.doi.org/10.7554/eLife.14120.002
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Affiliation(s)
- Elif Engin
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, United States.,Department of Psychiatry, Harvard Medical School, Boston, United States
| | - Kiersten S Smith
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, United States.,Department of Psychiatry, Harvard Medical School, Boston, United States
| | - Yudong Gao
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, United States
| | - David Nagy
- Section of Comparative Medicine, Yale School of Medicine, New Haven, United States
| | - Rachel A Foster
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, United States.,Department of Psychiatry, Harvard Medical School, Boston, United States
| | - Evgeny Tsvetkov
- Department of Psychiatry, Harvard Medical School, Boston, United States.,Cellular Neurobiology Laboratory, McLean Hospital, Belmont, United States.,Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Ruth Keist
- Institute for Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Florence Crestani
- Institute for Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Jean-Marc Fritschy
- Institute for Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Vadim Y Bolshakov
- Department of Psychiatry, Harvard Medical School, Boston, United States.,Cellular Neurobiology Laboratory, McLean Hospital, Belmont, United States
| | - Mihaly Hajos
- Section of Comparative Medicine, Yale School of Medicine, New Haven, United States
| | - Scott A Heldt
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, United States
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, United States.,Department of Psychiatry, Harvard Medical School, Boston, United States
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39
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Scharfman HE, Myers CE. Corruption of the dentate gyrus by "dominant" granule cells: Implications for dentate gyrus function in health and disease. Neurobiol Learn Mem 2016; 129:69-82. [PMID: 26391451 PMCID: PMC4792754 DOI: 10.1016/j.nlm.2015.09.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/02/2015] [Accepted: 09/06/2015] [Indexed: 12/31/2022]
Abstract
The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell 'backprojections' play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance--'mossy fiber variance'--which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become 'dominant,' one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of 'dominant' GCs--subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network.
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Affiliation(s)
- Helen E Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, United States; Departments of Child & Adolescent Psychiatry, Physiology & Neuroscience, and Psychiatry, New York University Langone Medical Center, United States.
| | - Catherine E Myers
- VA New Jersey Health Care System, VA Medical Center, NeuroBehavioral Research Lab (Mail Stop 15a), 385 Tremont Avenue, East Orange, NJ 07018, United States; Department of Pharmacology, Physiology & Neuroscience, Rutgers-New Jersey Medical School, United States
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40
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Göttlich M, Jandl NM, Sprenger A, Wojak JF, Münte TF, Krämer UM, Helmchen C. Hippocampal gray matter volume in bilateral vestibular failure. Hum Brain Mapp 2016; 37:1998-2006. [PMID: 26918638 DOI: 10.1002/hbm.23152] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 02/11/2016] [Indexed: 01/26/2023] Open
Abstract
Bilateral vestibular failure (BVF) is a severe chronic disorder of the labyrinth or the eighth cranial nerve characterized by unsteadiness of gait and disabling oscillopsia during head movements. According to animal data, vestibular input to the hippocampus is proposed to contribute to spatial memory and spatial navigation. Except for one seminal study showing the association of impaired spatial navigation and hippocampal atrophy, patient data in BVF are lacking. Therefore, we performed a voxel-wise comparison of the hippocampal gray matter volume (GMV) in a clinically representative sample of 27 patients with incomplete BVF and 29 age- and gender-matched healthy controls to test the hypothesis of hippocampal atrophy in BVF. Although the two groups did not generally differ in their hippocampal GMV, a reduction of GMV in the bilateral hippocampal CA3 region was significantly correlated with increased vestibulopathy-related clinical impairment. We propose that GMV reduction in the hippocampus of BVF patients is related to the severity of vestibular-induced disability which is in line with combined hippocampal atrophy and disorders of spatial navigation in complete vestibular deafferentation due to bilateral nerve section. Clinically, however, the most frequent etiologies of BVF cause incomplete lesions. Accordingly, hippocampus atrophy and deficits in spatial navigation occur possibly less frequently than previously suspected. Hum Brain Mapp 37:1998-2006, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Martin Göttlich
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Nico M Jandl
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Andreas Sprenger
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany.,Institute of Psychology II, University of Lübeck, Lübeck, Germany
| | - Jann F Wojak
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Thomas F Münte
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany.,Institute of Psychology II, University of Lübeck, Lübeck, Germany
| | - Ulrike M Krämer
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany.,Institute of Psychology II, University of Lübeck, Lübeck, Germany
| | - Christoph Helmchen
- Department of Neurology, University of Lübeck and University Hospital Schleswig-Holstein, Lübeck, Germany
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41
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Lin HC, Pan HC, Lin SH, Lo YC, Shen ETH, Liao LD, Liao PH, Chien YW, Liao KD, Jaw FS, Chu KW, Lai HY, Chen YY. Central Thalamic Deep-Brain Stimulation Alters Striatal-Thalamic Connectivity in Cognitive Neural Behavior. Front Neural Circuits 2016; 9:87. [PMID: 26793069 PMCID: PMC4710746 DOI: 10.3389/fncir.2015.00087] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 12/18/2015] [Indexed: 02/03/2023] Open
Abstract
Central thalamic deep brain stimulation (CT-DBS) has been proposed as an experimental therapeutic approach to produce consistent sustained regulation of forebrain arousal for several neurological diseases. We investigated local field potentials (LFPs) induced by CT-DBS from the thalamic central lateral nuclei (CL) and the striatum as potential biomarkers for the enhancement of lever-pressing skill learning. LFPs were simultaneously recorded from multiple sites in the CL, ventral striatum (Vstr), and dorsal striatum (Dstr). LFP oscillation power and functional connectivity were assessed and compared between the CT-DBS and sham control groups. The theta and alpha LFP oscillations were significantly increased in the CL and striatum in the CT-DBS group. Furthermore, interhemispheric coherences between bilateral CL and striatum were increased in the theta band. Additionally, enhancement of c-Fos activity, dopamine D2 receptor (Drd2), and α4-nicotinic acetylcholine receptor (α4-nAChR) occurred after CT-DBS treatment in the striatum and hippocampus. CT-DBS strengthened thalamic-striatal functional connectivity, which demonstrates that the inter-regional connectivity enhancement might contribute to synaptic plasticity in the striatum. Altered dopaminergic and cholinergic receptors resulted in modulation of striatal synaptic plasticity's ability to regulate downstream signaling cascades for higher brain functions of lever-pressing skill learning.
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Affiliation(s)
- Hui-Ching Lin
- Department and Institute of Physiology, School of Medicine, National Yang Ming UniversityTaipei, Taiwan; Brain Research Center, National Yang Ming UniversityTaipei, Taiwan
| | - Han-Chi Pan
- Institute of Neuroscience, National Yang Ming University Taipei, Taiwan
| | - Sheng-Huang Lin
- Department of Neurology, Tzu Chi General Hospital, Tzu Chi UniversityHualien, Taiwan; Institute of Biomedical Engineering, National Taiwan UniversityTaipei, Taiwan
| | - Yu-Chun Lo
- Institute of Medical Device and Imaging, National Taiwan University College of Medicine Taipei, Taiwan
| | | | - Lun-De Liao
- Centre for Life Sciences, Singapore Institute for Neurotechnology, National University of SingaporeSingapore, Singapore; Institute of Biomedical Engineering and Nanomedicine, National Health Research InstitutesMiaoli, Taiwan
| | - Pei-Han Liao
- Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan
| | - Yi-Wei Chien
- Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan
| | - Kuei-Da Liao
- Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University Taipei, Taiwan
| | - Fu-Shan Jaw
- Institute of Biomedical Engineering, National Taiwan University Taipei, Taiwan
| | - Kai-Wen Chu
- Department and Institute of Physiology, School of Medicine, National Yang Ming University Taipei, Taiwan
| | - Hsin-Yi Lai
- Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies, Zhejiang University Hangzhou, China
| | - You-Yin Chen
- Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan
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42
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Hersman S, Rodriguez Barrera V, Fanselow M. Assigning Function to Adult-Born Neurons: A Theoretical Framework for Characterizing Neural Manipulation of Learning. Front Syst Neurosci 2016; 9:182. [PMID: 26778981 PMCID: PMC4700131 DOI: 10.3389/fnsys.2015.00182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/07/2015] [Indexed: 12/26/2022] Open
Abstract
Neuroscientists are concerned with neural processes or computations, but these may not be directly observable. In the field of learning, a behavioral procedure is observed to lead to performance outcomes, but differing inferences on underlying internal processes can lead to difficulties in interpreting conflicting results. An example of this challenge is how many functions have been attributed to adult-born granule cells in the dentate gyrus. Some of these functions were suggested by computational models of the properties of these neurons, while others were hypothesized after manipulations of adult-born neurons resulted in changes to behavioral metrics. This review seeks to provide a framework, based in learning theory classification of behavioral procedures, of the processes that may be underlying behavioral results after manipulating procedure and observing performance. We propose that this framework can serve to clarify experimental findings on adult-born neurons as well as other classes of neural manipulations and their effects on behavior.
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Affiliation(s)
- Sarah Hersman
- Department of Psychology, University of California, Los AngelesLos Angeles, CA, USA
| | | | - Michael Fanselow
- Department of Psychology, University of California, Los AngelesLos Angeles, CA, USA
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los AngelesLos Angeles, CA, USA
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43
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Wiera G, Mozrzymas JW. Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus. Front Cell Neurosci 2015; 9:427. [PMID: 26582976 PMCID: PMC4631828 DOI: 10.3389/fncel.2015.00427] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 10/09/2015] [Indexed: 02/04/2023] Open
Abstract
Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed long-term potentiation (LTP) that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tissue plasminogen activator (tPA)/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.
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Affiliation(s)
- Grzegorz Wiera
- Department of Animal Molecular Physiology, Institute of Experimental Biology, Wroclaw University Wroclaw, Poland ; Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University Wroclaw, Poland
| | - Jerzy W Mozrzymas
- Department of Animal Molecular Physiology, Institute of Experimental Biology, Wroclaw University Wroclaw, Poland ; Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University Wroclaw, Poland
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44
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Comba R, Gervais N, Mumby D, Holahan M. Emergence of spatial behavioral function and associated mossy fiber connectivity and c-Fos labeling patterns in the hippocampus of rats. F1000Res 2015; 4:396. [PMID: 26925223 PMCID: PMC4712777 DOI: 10.12688/f1000research.6822.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 11/28/2022] Open
Abstract
Improvement on spatial tasks is observed during a late, postnatal developmental period (PND18 – PND24). The purpose of the current work was 1) to determine whether the emergence of spatial-behavioral function was based on the ability to generate appropriate behavioral output; 2) to assess whether mossy fiber connectivity patterns preceded the emergence of spatial-behavioral function; 3) to explore functional changes in the hippocampus to determine whether activity in hippocampal networks occurred in a training-dependent or developmentally-dependent fashion. To these ends, male, Long Evans rats were trained on a spatial water or dry maze task for one day (PND16, PND18 or PND20) then euthanized. Training on these 2 tasks with opposing behavioral demands (swimming versus exploration) was hypothesized to control for behavioral topology. Only at PND20 was there evidence of spatial-behavioral function for both tasks. Examination of synaptophysin staining in the CA3 region (i.e., mossy fiber projections) revealed enhanced connectivity patterns that preceded the emergence of spatial behavior. Analysis of c-Fos labeling (functional changes) revealed developmentally-dependent increases in c-Fos positive cells in the dentate gyrus, CA3 and CA1 regions whereas training-dependent increases were noted in the CA3 and CA1 regions for the water-maze trained groups. Results suggest that changes in mossy fiber connectivity in association with enhanced hippocampal functioning precede the emergence of spatial behavior observed at PND20. The combination of neuroanatomical and behavioural results confirms the hypothesis that this time represents a sensitive period for hippocampal development and modification and the emergence of spatial/ cognitive function.
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Affiliation(s)
- Rachel Comba
- Department of Neuroscience, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Nicole Gervais
- Department of Psychology, Concordia University, Montreal, QC, H4B 1R6, Canada
| | - Dave Mumby
- Department of Psychology, Concordia University, Montreal, QC, H4B 1R6, Canada
| | - Matthew Holahan
- Department of Neuroscience, Carleton University, Ottawa, ON, K1S 5B6, Canada
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45
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Kassab R, Alexandre F. Integration of exteroceptive and interoceptive information within the hippocampus: a computational study. Front Syst Neurosci 2015; 9:87. [PMID: 26097448 PMCID: PMC4456570 DOI: 10.3389/fnsys.2015.00087] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 05/22/2015] [Indexed: 12/25/2022] Open
Abstract
Many episodic memory studies have critically implicated the hippocampus in the rapid binding of sensory information from the perception of the external environment, reported by exteroception. Other structures in the medial temporal lobe, especially the amygdala, have been more specifically linked with emotional dimension of episodic memories, reported by interoception. The hippocampal projection to the amygdala is proposed as a substrate important for the formation of extero-interoceptive associations, allowing adaptive behaviors based on past experiences. Recently growing evidence suggests that hippocampal activity observed in a wide range of behavioral tasks could reflect associations between exteroceptive patterns and their emotional valences. The hippocampal computational models, therefore, need to be updated to elaborate better interpretation of hippocampal-dependent behaviors. In earlier models, interoceptive features, if not neglected, are bound together with other exteroceptive features through autoassociative learning mechanisms. This way of binding integrates both kinds of features at the same level, which is not always suitable for example in the case of pattern completion. Based on the anatomical and functional heterogeneity along the septotemporal and transverse axes of the hippocampus, we suggest instead that distinct hippocampal subregions may be engaged in the representation of these different types of information, each stored apart in autoassociative memories but linked together in a heteroassociative way. The model is developed within the hard constraint of rapid, even single trial, learning of episodic memories. The performance of the model is assessed quantitatively and its resistance to interference is demonstrated through a series of numerical experiments. An experiment of reversal learning in patients with amnesic cognitive impairment is also reproduced.
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Affiliation(s)
- Randa Kassab
- INRIA Bordeaux Sud-Ouest Talence, France ; LaBRI, UMR 5800, Centre National de la Recherche Scientifique, Bordeaux INP, Université de Bordeaux Talence, France ; Institut des Maladies Neurodégénératives, UMR 5293, Centre National de la Recherche Scientifique, Université de Bordeaux Bordeaux, France
| | - Frédéric Alexandre
- INRIA Bordeaux Sud-Ouest Talence, France ; LaBRI, UMR 5800, Centre National de la Recherche Scientifique, Bordeaux INP, Université de Bordeaux Talence, France ; Institut des Maladies Neurodégénératives, UMR 5293, Centre National de la Recherche Scientifique, Université de Bordeaux Bordeaux, France
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46
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André MAE, Wolf OT, Manahan-Vaughan D. Beta-adrenergic receptors support attention to extinction learning that occurs in the absence, but not the presence, of a context change. Front Behav Neurosci 2015; 9:125. [PMID: 26074793 PMCID: PMC4444826 DOI: 10.3389/fnbeh.2015.00125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/29/2015] [Indexed: 11/13/2022] Open
Abstract
The noradrenergic (NA)-system is an important regulator of cognitive function. It contributes to extinction learning (EL), and in disorders where EL is impaired NA-dysfunction has been postulated. We explored whether NA acting on beta-adrenergic-receptors (β-AR), regulates EL that depends on context, but is not fear-associated. We assessed behavior in an "AAA" or "ABA" paradigm: rats were trained for 3 days in a T-maze (context-A) to learn that a reward is consistently found in the goal arm, despite low reward probability. This was followed on day 4 by EL (unrewarded), whereby in the ABA-paradigm, EL was reinforced by a context change (B), and in the AAA-paradigm, no context change occurred. On day 5, re-exposure to the A-context (unrewarded) occurred. Typically, in control "AAA" animals EL occurred on day 4 that progressed further on day 5. In control "ABA" animals, EL also occurred on day 4, followed by renewal of the previously learned (A) behavior on day 5, that was succeeded (on day 5) by extinction of this behavior, as the animals realised that no food reward would be given. Treatment with the β-AR-antagonist, propranolol, prior to EL on day 4, impaired EL in the AAA-paradigm. In the "ABA" paradigm, antagonist treatment on day 4, had no effect on extinction that was reinforced by a context change (B). Furthermore, β-AR-antagonism prior to renewal testing (on day 5) in the ABA-paradigm, resulted in normal renewal behavior, although subsequent extinction of responses during day 5 was prevented by the antagonist. Thus, under both treatment conditions, β-AR-antagonism prevented extinction of the behavior learned in the "A" context. β-AR-blockade during an overt context change did not prevent EL, whereas β-AR were required for EL in an unchanging context. These data suggest that β-AR may support EL by reinforcing attention towards relevant changes in the previously learned experience, and that this process supports extinction learning in constant-context conditions.
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Affiliation(s)
| | - Oliver T Wolf
- International Graduate School for Neuroscience, Ruhr University Bochum Bochum, Germany ; Faculty of Psychology, Department of Cognitive Psychology, Ruhr University Bochum Bochum, Germany
| | - Denise Manahan-Vaughan
- International Graduate School for Neuroscience, Ruhr University Bochum Bochum, Germany ; Medical Faculty, Department of Neurophysiology, Ruhr University Bochum Bochum, Germany
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47
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Keller MK, Draguhn A, Both M, Reichinnek S. Activity-dependent plasticity of mouse hippocampal assemblies in vitro. Front Neural Circuits 2015; 9:21. [PMID: 26041998 PMCID: PMC4435105 DOI: 10.3389/fncir.2015.00021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 04/27/2015] [Indexed: 11/13/2022] Open
Abstract
Memory formation is associated with the generation of transiently stable neuronal assemblies. In hippocampal networks, such groups of functionally coupled neurons express highly ordered spatiotemporal activity patterns which are coordinated by local network oscillations. One of these patterns, sharp wave-ripple complexes (SPW-R), repetitively activates previously established groups of memory-encoding neurons, thereby supporting memory consolidation. This function implies that repetition of specific SPW-R induces plastic changes which render the underlying neuronal assemblies more stable. We modeled this repetitive activation in an in vitro model of SPW-R in mouse hippocampal slices. Weak electrical stimulation upstream of the CA3-CA1 networks reliably induced SPW-R of stereotypic waveform, thus representing re-activation of similar neuronal activity patterns. Frequent repetition of these patterns (100 times) reduced the variance of both, evoked and spontaneous SPW-R waveforms, indicating stabilization of pre-existing assemblies. These effects were most pronounced in the CA1 subfield and depended on the timing of stimulation relative to spontaneous SPW-R. Additionally, plasticity of SPW-R was blocked by application of a NMDA receptor antagonist, suggesting a role for associative synaptic plasticity in this process. Thus, repetitive activation of specific patterns of SPW-R causes stabilization of memory-related networks.
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Affiliation(s)
- Martin K Keller
- Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany
| | - Martin Both
- Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany
| | - Susanne Reichinnek
- Institute of Physiology and Pathophysiology, University of Heidelberg Heidelberg, Germany ; Mediterranean Institute of Neurobiology (INMED), INSERM Marseille, France
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48
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Hansen N, Manahan-Vaughan D. Hippocampal long-term potentiation that is elicited by perforant path stimulation or that occurs in conjunction with spatial learning is tightly controlled by beta-adrenoreceptors and the locus coeruleus. Hippocampus 2015; 25:1285-98. [PMID: 25727388 PMCID: PMC6680149 DOI: 10.1002/hipo.22436] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2015] [Indexed: 11/19/2022]
Abstract
The noradrenergic system, driven by locus coeruleus (LC) activation, plays a key role in the regulating and directing of changes in hippocampal synaptic efficacy. The LC releases noradrenaline in response to novel experience and LC activation leads to an enhancement of hippocampus‐based learning, and facilitates synaptic plasticity in the form of long‐term depression (LTD) and long‐term potentiation (LTP) that occur in association with spatial learning. The predominant receptor for mediating these effects is the β‐adrenoreceptor. Interestingly, the dependency of synaptic plasticity on this receptor is different in the hippocampal subfields whereby in the CA1 in vivo, LTP, but not LTD requires β‐adrenoreceptor activation, whereas in the mossy fiber synapse LTP and LTD do not depend on this receptor. By contrast, synaptic plasticity that is facilitated by spatial learning is highly dependent on β‐adrenoreceptor activation in both hippocampal subfields. Here, we explored whether LTP induced by perforant‐path (pp) stimulation in vivo or that is facilitated by spatial learning depends on β‐adrenoreceptors. We found that under both LTP conditions, antagonising the receptors disabled the persistence of LTP. β‐adrenoreceptor‐antagonism also prevented spatial learning. Strikingly, activation of the LC before high‐frequency stimulation (HFS) of the pp prevented short‐term potentiation but not LTP, and LC stimulation after pp‐HFS‐induced depotentiation of LTP. This depotentiation was prevented by β‐adrenoreceptor‐antagonism. These data suggest that β‐adrenoreceptor‐activation, resulting from noradrenaline release from the LC during enhanced arousal and learning, comprises a mechanism whereby the duration and degree of LTP is regulated and fine tuned. This may serve to optimize the creation of a spatial memory engram by means of LTP and LTD. This process can be expected to support the special role of the dentate gyrus as a crucial subregional locus for detecting and processing novelty within the hippocampus. © 2015 The Authors Hippocampus Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Niels Hansen
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
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Geukes S, Gaskell MG, Zwitserlood P. Stroop effects from newly learned color words: effects of memory consolidation and episodic context. Front Psychol 2015; 6:278. [PMID: 25814973 PMCID: PMC4357220 DOI: 10.3389/fpsyg.2015.00278] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/25/2015] [Indexed: 11/13/2022] Open
Abstract
The Stroop task is an excellent tool to test whether reading a word automatically activates its associated meaning, and it has been widely used in mono- and bilingual contexts. Despite of its ubiquity, the task has not yet been employed to test the automaticity of recently established word-concept links in novel-word-learning studies, under strict experimental control of learning and testing conditions. In three experiments, we thus paired novel words with native language (German) color words via lexical association and subsequently tested these words in a manual version of the Stroop task. Two crucial findings emerged: When novel word Stroop trials appeared intermixed among native-word trials, the novel-word Stroop effect was observed immediately after the learning phase. If no native color words were present in a Stroop block, the novel-word Stroop effect only emerged 24 h later. These results suggest that the automatic availability of a novel word's meaning depends either on supportive context from the learning episode and/or on sufficient time for memory consolidation. We discuss how these results can be reconciled with the complementary learning systems account of word learning.
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Affiliation(s)
- Sebastian Geukes
- Institut für Psychologie, Westfälische Wilhelms-Universität Münster Münster, Germany
| | | | - Pienie Zwitserlood
- Institut für Psychologie, Westfälische Wilhelms-Universität Münster Münster, Germany
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Dangmann R. An insulin based model to explain changes and interactions in human breath-holding. Med Hypotheses 2015; 84:532-8. [PMID: 25801485 DOI: 10.1016/j.mehy.2015.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 12/15/2014] [Accepted: 02/19/2015] [Indexed: 12/17/2022]
Abstract
Until now oxygen was thought to be the leading factor of hypoxic conditions. Whereas now it appears that insulin is the key regulator of hypoxic conditions. Insulin seems to regulate the redox state of the organism and to determine the breakpoint of human breath-holding. This new hypoxia-insulin hypotheses might have major clinical relevance. Besides the clinical relevance, this hypothesis could explain, for the first time, why the training of the diaphragm, among other factors, results in an increase in breath-holding performance. Elite freedivers/apnea divers are able to reach static breath-holding times to over 6 min. Untrained persons exhibit an unpleasant feeling after more or less a minute. Breath-holding is stopped at the breakpoint. The partial oxygen pressure as well as the carbon dioxide pressure failed to directly influence the breakpoint in earlier studies. The factors that contribute to the breakpoint are still under debate. Under hypoxic conditions the organism needs more glucose, because it changes from the oxygen consuming pentose phosphate (36 ATP/glucose molecule) to the anaerobic glycolytic pathway (2ATP/glucose molecule). Hence insulin, as it promotes the absorption of glucose, is set in the center of interest regarding hypoxic conditions. This paper provides an insulin based model that could explain the changes and interactions in human breath-holding. The correlation between hypoxia and reactive oxygen species (ROS) and their influence on the sympathetic nerve system and hypoxia-inducible factor 1 alpha (HIF-1α) is dealt with. It reviews as well the direct interrelation of HIF-1α and insulin. The depression of insulin secretion through the vagus nerve activation via inspiration is discussed. Furthermore the paper describes the action of insulin on the carotid bodies and the diaphragm and therefore a possible role in respiration pattern. Freedivers that go over the breakpoint of breath-holding could exhibit seizures and thus the effect of insulin, blood glucose levels and corticosteroids in hippocampal seizures is highlighted.
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