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Karimi Tari P, Parsons CG, Collingridge GL, Rammes G. Memantine: Updating a rare success story in pro-cognitive therapeutics. Neuropharmacology 2024; 244:109737. [PMID: 37832633 DOI: 10.1016/j.neuropharm.2023.109737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 09/25/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023]
Abstract
The great potential for NMDA receptor modulators as druggable targets in neurodegenerative disorders has been met with limited success. Considered one of the rare exceptions, memantine has consistently demonstrated restorative and prophylactic properties in many AD models. In clinical trials memantine slows the decline in cognitive performance associated with AD. Here, we provide an overview of the basic properties including pharmacological targets, toxicology and cellular effects of memantine. Evidence demonstrating reductions in molecular, physiological and behavioural indices of AD-like impairments associated with memantine treatment are also discussed. This represents both an extension and homage to Dr. Chris Parson's considerable contributions to our fundamental understanding of a success story in the AD treatment landscape.
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Affiliation(s)
- Parisa Karimi Tari
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, M5G 1X5, Canada
| | - Chris G Parsons
- Galimedix Therapeutics, Inc., 2704 Calvend Lane, Kensington, 20895, MD, USA
| | - Graham L Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, M5G 1X5, Canada; Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada; TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, M5S 1A8, Canada.
| | - Gerhard Rammes
- Department of Anesthesiology and Intensive Care Medicine of the Technical University of Munich, School of Medicine, 22, 81675, Munich, Germany.
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2
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Madar A, Dong C, Sheffield M. BTSP, not STDP, Drives Shifts in Hippocampal Representations During Familiarization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.17.562791. [PMID: 37904999 PMCID: PMC10614909 DOI: 10.1101/2023.10.17.562791] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Synaptic plasticity is widely thought to support memory storage in the brain, but the rules determining impactful synaptic changes in-vivo are not known. We considered the trial-by-trial shifting dynamics of hippocampal place fields (PFs) as an indicator of ongoing plasticity during memory formation. By implementing different plasticity rules in computational models of spiking place cells and comparing to experimentally measured PFs from mice navigating familiar and novel environments, we found that Behavioral-Timescale-Synaptic-Plasticity (BTSP), rather than Hebbian Spike-Timing-Dependent-Plasticity, is the principal mechanism governing PF shifting dynamics. BTSP-triggering events are rare, but more frequent during novel experiences. During exploration, their probability is dynamic: it decays after PF onset, but continually drives a population-level representational drift. Finally, our results show that BTSP occurs in CA3 but is less frequent and phenomenologically different than in CA1. Overall, our study provides a new framework to understand how synaptic plasticity shapes neuronal representations during learning.
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Affiliation(s)
- A.D. Madar
- Department of Neurobiology, Neuroscience Institute, University of Chicago
| | - C. Dong
- Department of Neurobiology, Neuroscience Institute, University of Chicago
- current affiliation: Department of Neurobiology, Stanford University School of Medicine
| | - M.E.J. Sheffield
- Department of Neurobiology, Neuroscience Institute, University of Chicago
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3
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Yiu YH, Leibold C. A theory of hippocampal theta correlations accounting for extrinsic and intrinsic sequences. eLife 2023; 12:RP86837. [PMID: 37792453 PMCID: PMC10550285 DOI: 10.7554/elife.86837] [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] [Indexed: 10/05/2023] Open
Abstract
Hippocampal place cell sequences have been hypothesized to serve as diverse purposes as the induction of synaptic plasticity, formation and consolidation of long-term memories, or navigation and planning. During spatial behaviors of rodents, sequential firing of place cells at the theta timescale (known as theta sequences) encodes running trajectories, which can be considered as one-dimensional behavioral sequences of traversed locations. In a two-dimensional space, however, each single location can be visited along arbitrary one-dimensional running trajectories. Thus, a place cell will generally take part in multiple different theta sequences, raising questions about how this two-dimensional topology can be reconciled with the idea of hippocampal sequences underlying memory of (one-dimensional) episodes. Here, we propose a computational model of cornu ammonis 3 (CA3) and dentate gyrus (DG), where sensorimotor input drives the direction-dependent (extrinsic) theta sequences within CA3 reflecting the two-dimensional spatial topology, whereas the intrahippocampal CA3-DG projections concurrently produce intrinsic sequences that are independent of the specific running trajectory. Consistent with experimental data, intrinsic theta sequences are less prominent, but can nevertheless be detected during theta activity, thereby serving as running-direction independent landmark cues. We hypothesize that the intrinsic sequences largely reflect replay and preplay activity during non-theta states.
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Affiliation(s)
- Yuk-Hoi Yiu
- Fakultät für Biologie & Bernstein Center Freiburg Albert-Ludwigs-Universität FreiburgFreiburgGermany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Christian Leibold
- Fakultät für Biologie & Bernstein Center Freiburg Albert-Ludwigs-Universität FreiburgFreiburgGermany
- BrainLinks-BrainTools, Albert-Ludwigs-Universität FreiburgFreiburgGermany
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4
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Zhang J, Qiao N, Wang J, Li B. Nuclear translocation of GluA2/ GAPDH promotes neurotoxicity after pilocarpine-induced epilepsy. Epilepsy Res 2022; 183:106945. [DOI: 10.1016/j.eplepsyres.2022.106945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 05/01/2022] [Accepted: 05/16/2022] [Indexed: 11/26/2022]
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5
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Hernandez AR, Reasor JE, Truckenbrod LM, Campos KT, Federico QP, Fertal KE, Lubke KN, Johnson SA, Clark BJ, Maurer AP, Burke SN. Dissociable effects of advanced age on prefrontal cortical and medial temporal lobe ensemble activity. Neurobiol Aging 2018; 70:217-232. [PMID: 30031931 PMCID: PMC6829909 DOI: 10.1016/j.neurobiolaging.2018.06.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 11/25/2022]
Abstract
The link between age-related cellular changes within brain regions and larger scale neuronal ensemble dynamics critical for cognition has not been fully elucidated. The present study measured neuron activity within medial prefrontal cortex (PFC), perirhinal cortex (PER), and hippocampal subregion CA1 of young and aged rats by labeling expression of the immediate-early gene Arc. The proportion of cells expressing Arc was quantified at baseline and after a behavior that requires these regions. In addition, PER and CA1 projection neurons to PFC were identified with retrograde labeling. Within CA1, no age-related differences in neuronal activity were observed in the entire neuron population or within CA1 pyramidal cells that project to PFC. Although behavior was comparable across age groups, behaviorally driven Arc expression was higher in the deep layers of both PER and PFC and lower in the superficial layers of these regions. Moreover, age-related changes in activity levels were most evident within PER cells that project to PFC. These data suggest that the PER-PFC circuit is particularly vulnerable in advanced age.
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Affiliation(s)
- Abbi R Hernandez
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Jordan E Reasor
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Leah M Truckenbrod
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Keila T Campos
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Quinten P Federico
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Kaeli E Fertal
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Katelyn N Lubke
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Sarah A Johnson
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL
| | - Benjamin J Clark
- Department of Psychology, University of New Mexico, Albuquerque, New Mexico
| | - Andrew P Maurer
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL; Department of Biomedical Engineering, University of Florida, Gainesville, FL
| | - Sara N Burke
- McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL; Institute on Aging, University of Florida, Gainesville, FL.
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6
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Robitsek J, Ratner MH, Stewart T, Eichenbaum H, Farb DH. Combined administration of levetiracetam and valproic acid attenuates age-related hyperactivity of CA3 place cells, reduces place field area, and increases spatial information content in aged rat hippocampus. Hippocampus 2015; 25:1541-55. [PMID: 25941121 PMCID: PMC4633399 DOI: 10.1002/hipo.22474] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2015] [Indexed: 01/15/2023]
Abstract
Learning and memory deficits associated with age-related mild cognitive impairment have long been attributed to impaired processing within the hippocampus. Hyperactivity within the hippocampal CA3 region that is associated with aging is mediated in part by a loss of functional inhibitory interneurons and thought to underlie impaired performance in spatial memory tasks, including the abnormal tendency in aged animals to pattern complete spatial representations. Here, we asked whether the spatial firing patterns of simultaneously recorded CA3 and CA1 neurons in young and aged rats could be manipulated pharmacologically to selectively reduce CA3 hyperactivity and thus, according to hypothesis, the associated abnormality in spatial representations. We used chronically implanted high-density tetrodes to record the spatial firing properties of CA3 and CA1 units during animal exploration for food in familiar and novel environments. Aged CA3 place cells have higher firing rates, larger place fields, less spatial information content, and respond less to a change from a familiar to a novel environment than young CA3 cells. We also find that the combination of levetiracetam (LEV) + valproic acid (VPA), previously shown to act as a cognitive enhancer in tests of spatial memory, attenuate CA3 place cell firing rates, reduce place field area, and increase spatial information content in aged but not young adult rats. This is consistent with drug enhancing the specificity of neuronal firing with respect to spatial location. Contrary to expectation, however, LEV + VPA reduces place cell discrimination between novel and familiar environments, i.e., spatial correlations increase, independent of age even though drug enhances performance in cognitive tasks. The results demonstrate that spatial information content, or the number of bits of information encoded per action potential, may be the key correlate for enhancement of spatial memory by LEV + VPA.
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Affiliation(s)
- Jonathan Robitsek
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts
| | - Marcia H Ratner
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts
| | - Tara Stewart
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts
| | - Howard Eichenbaum
- Department of Psychology, Center for Memory and Brain, Boston University, Boston, Massachusetts
| | - David H Farb
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts
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7
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Effects of memantine on hippocampal long-term potentiation, gamma activity, and sensorimotor gating in freely moving rats. Neurobiol Aging 2015; 36:2544-54. [DOI: 10.1016/j.neurobiolaging.2015.05.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/25/2015] [Accepted: 05/29/2015] [Indexed: 12/20/2022]
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8
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Abstract
During movement, there is a transition of activity across the population, such that place-field centers ahead of the rat are sequentially activated in the order that they will be encountered. Although the mechanisms responsible for this sequence updating are unknown, two classes of models can be considered. The first class involves head-direction information for activating neurons in the order that their place fields will be traversed. An alternative model contends that motion and turn-related information from the posterior parietal cortex shift the subset of active hippocampal cells across the population. To explicitly test these two models, rodents were trained to run backward on a linear track, placing movement in opposition with head orientation. Although head-direction did not change between running conditions, place-field activity remapped and there was an increase in place-field size during backward running compared with forward. The population activity, however, could still be used to reconstruct the location of the rat accurately. Moreover, theta phase precession was maintained in both running conditions, indicating preservation of place-field sequences on short-time scales. The observation that sequence encoding persists even when the animal is orientated away from the direction of movement favors the concept that posterior parietal cortical mechanisms may be partially responsible for updating hippocampal activity patterns.
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9
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Bolognin S, Buffelli M, Puoliväli J, Iqbal K. Rescue of cognitive-aging by administration of a neurogenic and/or neurotrophic compound. Neurobiol Aging 2014; 35:2134-46. [PMID: 24702821 DOI: 10.1016/j.neurobiolaging.2014.02.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/18/2014] [Accepted: 02/26/2014] [Indexed: 10/25/2022]
Abstract
Aging is characterized by a progressive decline of cognitive performance, which has been partially attributed to structural and functional alterations of hippocampus. Importantly, aging is the major risk factor for the development of neurodegenerative diseases, especially Alzheimer's disease. An important therapeutic approach to counteract the age-associated memory dysfunctions is to maintain an appropriate microenvironment for successful neurogenesis and synaptic plasticity. In this study, we show that chronic oral administration of peptide 021 (P021), a small peptidergic neurotrophic compound derived from the ciliary neurotrophic factor, significantly reduced the age-dependent decline in learning and memory in 22 to 24-month-old Fisher rats. Treatment with P021 inhibited the deficit in neurogenesis in the aged rats and increased the expression of brain derived neurotrophic factor. Furthermore, P021 restored synaptic deficits both in the cortex and the hippocampus. In vivo magnetic resonance spectroscopy revealed age-dependent alterations in hippocampal content of several metabolites. Remarkably, P021 was effective in significantly reducing myoinositol (INS) concentration, which was increased in aged compared with young rats. These findings suggest that stimulating endogenous neuroprotective mechanisms is a potential therapeutic approach to cognitive aging, Alzheimer's disease, and associated neurodegenerative disorders and P021 is a promising compound for this purpose.
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Affiliation(s)
- Silvia Bolognin
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Mario Buffelli
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Jukka Puoliväli
- Department of Behavioral Studies, Charles River Finland, Kuopio, Finland
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.
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10
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Cavarsan CF, Queiroz CM, dos Santos JG, Xavier GF, Mello LE, Covolan L. Reduced hippocampal dentate cell proliferation and impaired spatial memory performance in aged-epileptic rats. Front Neurol 2013; 4:106. [PMID: 23898322 PMCID: PMC3724058 DOI: 10.3389/fneur.2013.00106] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/12/2013] [Indexed: 11/13/2022] Open
Abstract
Increased adult neurogenesis is observed after training in hippocampal-dependent tasks and also after acutely induced status epilepticus (SE) although the specific roles of these cells are still a matter of debate. In this study, we investigated hippocampal cell proliferation and differentiation and the spatial learning performance in young or aged chronically epileptic rats. Status was induced by pilocarpine in 3 or 20-month old rats. Either 2 or 20 months later, rats were treated with bromodeoxyuridine (BrdU) and subsequently underwent to 8-day schedule of water maze (WM) tests. As expected, learning curves were faster in young than in aged animals (P < 0.001). Chronically epileptic animals exhibited impaired learning curves compared to age-matched controls. Interestingly, the duration of epilepsy (2 or 20 months) did not correlate with the memory impairment of aged-epileptic animals. The number of BrdU-positive cells was greater in young-epileptic subjects than in age-matched controls. In contrast, cell proliferation was not increased in aged-epileptic animals, irrespective of the time of SE induction. Finally, dentate cell proliferation was not related to performance in the WM. Based on the present results we conclude that even though aging and epilepsy lead to impairments in spatial learning, their effects are not additive.
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Affiliation(s)
- Clarissa F. Cavarsan
- Department of Physiology, Universidade Federal de São Paulo – UNIFESP, São Paulo, Brazil
| | - Claudio M. Queiroz
- Brain Institute, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | | | - Gilberto F. Xavier
- Department of Physiology, Biosciences Institute, Universidade de São Paulo – USP, São Paulo, Brazil
| | - Luiz Eugênio Mello
- Department of Physiology, Universidade Federal de São Paulo – UNIFESP, São Paulo, Brazil
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo – UNIFESP, São Paulo, Brazil
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11
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Searcy JL, Phelps JT, Pancani T, Kadish I, Popovic J, Anderson KL, Beckett TL, Murphy MP, Chen KC, Blalock EM, Landfield PW, Porter NM, Thibault O. Long-term pioglitazone treatment improves learning and attenuates pathological markers in a mouse model of Alzheimer's disease. J Alzheimers Dis 2013; 30:943-61. [PMID: 22495349 DOI: 10.3233/jad-2012-111661] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Thiazolidinediones (TZDs) are agonists at peroxisome proliferator-activated gamma-type (PPAR-γ) receptors and are used clinically for the treatment of type 2 diabetes where they have been shown to reestablish insulin sensitivity, improve lipid profiles, and reduce inflammation. Recent work also suggests that TZDs may be beneficial in Alzheimer's disease (AD), ameliorating cognitive decline early in the disease process. However, there have been only a few studies identifying mechanisms through which cognitive benefits may be exerted. Starting at 10 months of age, the triple transgenic mouse model of AD (3xTg-AD) with accelerated amyloid-β (Aβ) deposition and tau pathology was treated with the TZD pioglitazone (PIO-Actos) at 18 mg/Kg body weight/day. After four months, PIO-treated animals showed multiple beneficial effects, including improved learning on the active avoidance task, reduced serum cholesterol, decreased hippocampal amyloid-β and tau deposits, and enhanced short- and long-term plasticity. Electrophysiological membrane properties and post-treatment blood glucose levels were unchanged by PIO. Gene microarray analyses of hippocampal tissue identified predicted transcriptional responses following TZD treatment as well as potentially novel targets of TZDs, including facilitation of estrogenic processes and decreases in glutamatergic and lipid metabolic/cholesterol dependent processes. Taken together, these results confirm prior animal studies showing that TZDs can ameliorate cognitive deficits associated with AD-related pathology, but also extend these findings by pointing to novel molecular targets in the brain.
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Affiliation(s)
- James L Searcy
- Department of Molecular and Biomedical Pharmacology, University of Kentucky Medical Center, Lexington, KY 40536-0084, USA
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12
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Thome A, Erickson CA, Lipa P, Barnes CA. Differential effects of experience on tuning properties of macaque MTL neurons in a passive viewing task. Hippocampus 2012; 22:2000-11. [PMID: 22987678 PMCID: PMC3537226 DOI: 10.1002/hipo.22070] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The structures of the medial temporal lobe (MTL) have been shown to be causally involved in episodic and recognition memory. However, recent work in a number of species has demonstrated that impairments in recognition memory seen following lesions of the perirhinal cortex (PRh) can be accounted for by deficits in perceptual discrimination. These findings suggest that object representation, rather than explicit recognition memory signals, may be crucial to the mnemonic process. Given the large amount of visual information encountered by primates, there must be a reconsideration of the mechanisms by which the brain efficiently stores visually presented information. Previous neurophysiological recordings from MTL structures in primates have largely focused on tasks that implicitly define object familiarity (i.e., novel vs. familiar) or contain significant mnemonic demands (e.g., conditional associations between two stimuli), limiting their utility in understanding the mechanisms underlying visual object recognition and information storage. To clarify how different regions in the MTL may contribute to visual recognition, we recorded from three rhesus macaques performing a passive viewing task. The task design systematically varies the relative familiarity of different stimuli enabling an examination of how neural activity changes as a function of experience. The data collected during this passive viewing task revealed that neurons in the MTL are generally not sensitive to the relative familiarity of a stimulus. In addition, when the specificity (i.e., which images a neuron was selective for) of individual neurons was analyzed, there was a significant dissociation between different medial temporal regions, with only neurons in TF, but not CA3 or the PRh, altering their activity as stimuli became familiar. The implications of these findings are discussed in the context of how MTL structures process information during a passive viewing paradigm.
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Affiliation(s)
- Alexander Thome
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
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13
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Morris KA, Gold PE. Age-related impairments in memory and in CREB and pCREB expression in hippocampus and amygdala following inhibitory avoidance training. Mech Ageing Dev 2012; 133:291-9. [PMID: 22445851 PMCID: PMC3359401 DOI: 10.1016/j.mad.2012.03.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 02/27/2012] [Accepted: 03/06/2012] [Indexed: 01/09/2023]
Abstract
This experiment examined whether age-related changes in CREB and pCREB contribute to the rapid forgetting seen in aged animals. Young (3-month-old) and aged (24-month-old) Fischer-344 rats received inhibitory avoidance training with a low (0.2 mA, 0.4 s) or moderate (0.5 mA, 0.5 s) foot shock; memory was measured 7 days later. Other rats were euthanized 30 min after training, and CREB and pCREB expression levels were examined in the hippocampus, amygdala, and piriform cortex using immunohistochemistry. CREB levels decreased with age in the hippocampus and amygdala. After training with either shock level, young rats exhibited good memory and increases in pCREB levels in the hippocampus and amygdala. Aged rats exhibited good memory for the moderate but not the low shock but did not show increases in pCREB levels after either shock intensity. These results suggest that decreases in total CREB and in pCREB activation in the hippocampus and amygdala may contribute to rapid forgetting in aged rats. After moderate foot shock, the stable memory in old rats together with absence of CREB activation suggests either that CREB was phosphorylated in a spatiotemporal pattern other than analyzed here or that the stronger training conditions engaged alternate mechanisms that promote long-lasting memory.
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Affiliation(s)
- Ken A. Morris
- Neuroscience Program, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
- College of Medicine, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
| | - Paul E. Gold
- Neuroscience Program, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
- Departments of Psychology, Psychiatry, Molecular and Integrative Physiology, and Bioengineering, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
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14
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Roth ED, Yu X, Rao G, Knierim JJ. Functional differences in the backward shifts of CA1 and CA3 place fields in novel and familiar environments. PLoS One 2012; 7:e36035. [PMID: 22558316 PMCID: PMC3338615 DOI: 10.1371/journal.pone.0036035] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 03/26/2012] [Indexed: 11/18/2022] Open
Abstract
Insight into the processing dynamics and other neurophysiological properties of different hippocampal subfields is critically important for understanding hippocampal function. In this study, we compared shifts in the center of mass (COM) of CA3 and CA1 place fields in a familiar and completely novel environment. Place fields in CA1 and CA3 were simultaneously recorded as rats ran along a closed loop track in a familiar room followed by a session in a completely novel room. This process was repeated each day over a 4-day period. CA3 place fields shifted backward (opposite to the direction of motion of the rat) only in novel environments. This backward shift gradually diminished across days, as the novel environment became more familiar with repeated exposures. Conversely, CA1 place fields shifted backward across all days in both familiar and novel environments. Prior studies demonstrated that CA1 place fields on average do not exhibit a backward shift during the first exposure to an environment in which the familiar cues are rearranged into a novel configuration, although CA3 place fields showed a strong backward shift. Under the completely novel conditions of the present study, no dissociation was observed between CA3 and CA1 during the first novel session (although a strong dissociation was observed in the familiar sessions and the later novel sessions). In summary, this is the first study to use simultaneous recordings in CA1 and CA3 to compare place field COM shift and other associated properties in truly novel and familiar environments. This study further demonstrates functional differentiation between CA1 and CA3 as the plasticity of CA1 place fields is affected differently by exposure to a completely novel environment in comparison to an altered, familiar environment, whereas the plasticity of CA3 place fields is affected similarly during both types of environmental novelty.
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Affiliation(s)
- Eric D. Roth
- Department of Psychology, University of Delaware, Newark, Delaware, United States of America
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Xintian Yu
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Geeta Rao
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - James J. Knierim
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas, United States of America
- Department of Neuroscience and Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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15
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Maurer AP, Burke SN, Lipa P, Skaggs WE, Barnes CA. Greater running speeds result in altered hippocampal phase sequence dynamics. Hippocampus 2011; 22:737-47. [PMID: 21538659 DOI: 10.1002/hipo.20936] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2011] [Indexed: 11/07/2022]
Abstract
Hebb (1949) described a "phase sequence" to be the sequential activation of sets of cell assemblies. Within the hippocampus, cell assemblies have been described as groups of coactive neurons whose place fields overlap. Membership of assemblies in a phase sequence changes systematically as a rat travels through an environment, serving to accelerate the temporal order that place fields are encountered during a single theta cycle. This sweeping forward of network activity ("look ahead"), results in locations in front of the animal being transiently represented. In this experiment, a population vector-based reconstruction method was used to capture the look ahead and reveals that the composition of the phase sequence changes with velocity, such that more cell assemblies are active within a theta cycle at higher running speeds. These results are consistent with hypotheses suggesting that hippocampal networks generate short time scale predictions of future events to optimize behavior.
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16
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Burger C. Region-specific genetic alterations in the aging hippocampus: implications for cognitive aging. Front Aging Neurosci 2010; 2:140. [PMID: 21048902 PMCID: PMC2967426 DOI: 10.3389/fnagi.2010.00140] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 08/17/2010] [Indexed: 01/31/2023] Open
Abstract
Aging is associated with cognitive decline in both humans and animals and of all brain regions, the hippocampus appears to be particularly vulnerable to senescence. Age-related spatial learning deficits result from alterations in hippocampal connectivity and plasticity. These changes are differentially expressed in each of the hippocampal fields known as cornu ammonis 1 (CA1), cornu ammonis 3 (CA3), and the dentate gyrus. Each sub-region displays varying degrees of susceptibility to aging. For example, the CA1 region is particularly susceptible in Alzheimer's disease while the CA3 region shows vulnerability to stress and glucocorticoids. Further, in animals, aging is the main factor associated with the decline in adult neurogenesis in the dentate gyrus. This review discusses the relationship between region-specific hippocampal connectivity, morphology, and gene expression alterations and the cognitive deficits associated with senescence. In particular, data are reviewed that illustrate how the molecular changes observed in the CA1, CA3, and dentate regions are associated with age-related learning deficits. This topic is of importance because increased understanding of how gene expression patterns reflect individual differences in cognitive performance is critical to the process of identifying new and clinically useful biomarkers for cognitive aging.
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Affiliation(s)
- Corinna Burger
- Department of Neurology, Medical Sciences Center, University of WisconsinMadison, USA
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17
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Molecular changes in brain aging and Alzheimer's disease are mirrored in experimentally silenced cortical neuron networks. Neurobiol Aging 2010; 33:205.e1-18. [PMID: 20947216 DOI: 10.1016/j.neurobiolaging.2010.08.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/19/2010] [Accepted: 08/21/2010] [Indexed: 12/22/2022]
Abstract
Activity-dependent modulation of neuronal gene expression promotes neuronal survival and plasticity, and neuronal network activity is perturbed in aging and Alzheimer's disease (AD). Here we show that cerebral cortical neurons respond to chronic suppression of excitability by downregulating the expression of genes and their encoded proteins involved in inhibitory transmission (GABAergic and somatostatin) and Ca(2+) signaling; alterations in pathways involved in lipid metabolism and energy management are also features of silenced neuronal networks. A molecular fingerprint strikingly similar to that of diminished network activity occurs in the human brain during aging and in AD, and opposite changes occur in response to activation of N-methyl-D-aspartate (NMDA) and brain-derived neurotrophic factor (BDNF) receptors in cultured cortical neurons and in mice in response to an enriched environment or electroconvulsive shock. Our findings suggest that reduced inhibitory neurotransmission during aging and in AD may be the result of compensatory responses that, paradoxically, render the neurons vulnerable to Ca(2+)-mediated degeneration.
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18
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Schimanski LA, Barnes CA. Neural Protein Synthesis during Aging: Effects on Plasticity and Memory. Front Aging Neurosci 2010; 2. [PMID: 20802800 PMCID: PMC2928699 DOI: 10.3389/fnagi.2010.00026] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 06/15/2010] [Indexed: 12/13/2022] Open
Abstract
During aging, many experience a decline in cognitive function that includes memory loss. The encoding of long-term memories depends on new protein synthesis, and this is also reduced during aging. Thus, it is possible that changes in the regulation of protein synthesis contribute to the memory impairments observed in older animals. Several lines of evidence support this hypothesis. For instance, protein synthesis is required for a longer period following learning to establish long-term memory in aged rodents. Also, under some conditions, synaptic activity or pharmacological activation can induce de novo protein synthesis and lasting changes in synaptic transmission in aged, but not young, rodents; the opposite results can be observed in other conditions. These changes in plasticity likely play a role in manifesting the altered place field properties observed in awake and behaving aged rats. The collective evidence suggests a link between memory loss and the regulation of protein synthesis in senescence. In fact, pharmaceuticals that target the signaling pathways required for induction of protein synthesis have improved memory, synaptic plasticity, and place cell properties in aged animals. We suggest that a better understanding of the mechanisms that lead to different protein expression patterns in the neural circuits that change as a function of age will enable the development of more effective therapeutic treatments for memory loss.
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Affiliation(s)
- Lesley A Schimanski
- Evelyn F. McKnight Brain Institute and Division of Neural Systems, Memory and Aging, Arizona Research Laboratories, University of Arizona Tucson, AZ, USA
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19
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Penner MR, Roth TL, Chawla MK, Hoang LT, Roth ED, Lubin FD, Sweatt JD, Worley PF, Barnes CA. Age-related changes in Arc transcription and DNA methylation within the hippocampus. Neurobiol Aging 2010; 32:2198-210. [PMID: 20189687 DOI: 10.1016/j.neurobiolaging.2010.01.009] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 01/12/2010] [Accepted: 01/14/2010] [Indexed: 11/26/2022]
Abstract
The transcription of genes that support memory processes are likely to be impacted by the normal aging process. Because Arc is necessary for memory consolidation and enduring synaptic plasticity, we examined Arc transcription within the aged hippocampus. Here, we report that Arc transcription is reduced within the aged hippocampus compared to the adult hippocampus during both "off line" periods of rest, and following spatial behavior. This reduction is observed within ensembles of CA1 "place cells", which make less mRNA per cell, and in the dentate gyrus (DG) where fewer granule cells are activated by behavior. In addition, we present data suggesting that aberrant changes in methylation of the Arc gene may be responsible for age-related decreases in Arc transcription within CA1 and the DG. Given that Arc is necessary for normal memory function, these subregion-specific epigenetic and transcriptional changes may result in less efficient memory storage and retrieval during aging.
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Affiliation(s)
- M R Penner
- ARL Division of Neural Systems, Memory & Aging and Evelyn F McKnight Brain Institute, University of Arizona, Tucson, AZ 85724, USA
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20
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Burke SN, Barnes CA. Senescent synapses and hippocampal circuit dynamics. Trends Neurosci 2010; 33:153-61. [PMID: 20071039 DOI: 10.1016/j.tins.2009.12.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 11/30/2009] [Accepted: 12/15/2009] [Indexed: 01/11/2023]
Abstract
Excitatory synaptic transmission is altered during aging in hippocampal granule cells, and in CA3 and CA1 pyramidal cells. These functional changes contribute to age-associated impairments in experimentally-induced plasticity in each of these primary hippocampal subregions. In CA1, plasticity evoked by stimulation shares common mechanisms with the synaptic modification observed following natural behavior. Aging results in deficits in both artificially- and behaviorally-induced plasticity, and this could in part reflect age-related changes in Ca2+ homeostasis. Other observations, however, suggest that increased intracellular Ca2+ levels are beneficial under some circumstances. This review focuses on age-associated changes in synaptic function, how these alterations might contribute to cognitive decline, and the extent to which altered hippocampal circuit properties are detrimental or reflect compensatory processes.
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Affiliation(s)
- Sara N Burke
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85724, USA
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21
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Overexpression of type I adenylyl cyclase in the forebrain impairs spatial memory in aged but not young mice. J Neurosci 2009; 29:10835-42. [PMID: 19726641 DOI: 10.1523/jneurosci.0553-09.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Hippocampus-dependent memory requires a cAMP signal that is generated by Ca2+-stimulated adenylyl cyclases (AC1, AC8). Young transgenic mice overexpressing AC1 in the forebrain (AC1+ mice) have enhanced hippocampal long-term potentiation, superior memory for novel object recognition and more persistent remote contextual memory. To determine whether increasing AC1 expression improves memory when older mice are trained, we analyzed fear, recognition, and spatial memory in mice aged to 25 months. Here we report that young adult AC1+ mice have enhanced social recognition memory, and normal fear and spatial memory. Surprisingly, aged AC1+ mice had poorer spatial memory than age-matched wild-type littermates. These data suggest that the decrease in Ca2+-stimulated adenylyl cyclase activity during aging of wild-type mice may be an adaptive mechanism required to maintain spatial memory function.
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22
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Assini FL, Duzzioni M, Takahashi RN. Object location memory in mice: pharmacological validation and further evidence of hippocampal CA1 participation. Behav Brain Res 2009; 204:206-11. [PMID: 19523494 DOI: 10.1016/j.bbr.2009.06.005] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 05/28/2009] [Accepted: 06/04/2009] [Indexed: 01/18/2023]
Abstract
Object location task (OLT) has been used as a model of hippocampal-dependent memory. Despite this application, there is neither a consistent pharmacological validation of NMDA receptor modulation nor an evaluation of hippocampal participation in mice. In the OLT, mice were placed in the open field with two identical objects for 3 min and, after a delay of 30, 90, 180 or 360 min, one object was moved to a new location and the time spent exploring the objects in new, (novel) and old (familiar) locations was recorded. Our results showed that the mice were able to discriminate object location when tested either 90 or 180 min after training. Intraperitoneal administration of MK801 (NMDA receptors antagonist) or scopolamine (mACh antagonist) induced amnesic effects. On the other hand, D-cycloserine (NMDA agonist) or tacrine (cholinesterase inhibitor) were able to improve memory in the mice tested. In addition, lidocaine infusion in the hippocampal CA1 region 10 min before training blocked object location memory. In short, this work indicates that OLT is susceptible to modulation of NMDA receptors, cholinergic neurotransmission and it is the first to characterize the participation of the hippocampal CA1 region, in this task.
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Affiliation(s)
- Fabrício Luiz Assini
- Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, UFSC, Campus Universitário, Trindade, Florianópolis, SC, Brazil
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23
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Gerrard JL, Burke SN, McNaughton BL, Barnes CA. Sequence reactivation in the hippocampus is impaired in aged rats. J Neurosci 2008; 28:7883-90. [PMID: 18667620 PMCID: PMC2703197 DOI: 10.1523/jneurosci.1265-08.2008] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/08/2008] [Accepted: 05/21/2008] [Indexed: 11/21/2022] Open
Abstract
The hippocampus is thought to coordinate memory consolidation by reactivating traces from behavioral experience when the brain is not actively processing new input. In fact, during slow-wave sleep, the patterns of CA1 pyramidal cell ensemble activity correlations are reactivated in both young and aged rats. In addition to correlated activity patterns, repetitive track running also creates a recurring sequence of pyramidal cell activity. The present study compared CA1 sequence activity pattern replay in young and old animals during rest periods after behavior. Whereas the young rats exhibited significant sequence reactivation, it was markedly impaired in the aged animals. When the spatial memory scores of all animals were compared with the degree of sequence reactivation, there was a significant correlation. The novel finding that weak replay of temporal patterns has behavioral consequences, strengthens the idea that reactivation processes are integral to memory consolidation.
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Affiliation(s)
- Jason L. Gerrard
- Arizona Research Laboratories Division of Neural Systems, Memory and Aging, and
| | - Sara N. Burke
- Evelyn F. McKnight Brain Institute
- Arizona Research Laboratories Division of Neural Systems, Memory and Aging, and
| | - Bruce L. McNaughton
- Evelyn F. McKnight Brain Institute
- Arizona Research Laboratories Division of Neural Systems, Memory and Aging, and
- Departments of Psychology
- Physiology, University of Arizona, Tucson, Arizona 85724
| | - Carol A. Barnes
- Evelyn F. McKnight Brain Institute
- Arizona Research Laboratories Division of Neural Systems, Memory and Aging, and
- Departments of Psychology
- Neurology, and
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