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Hernández-Frausto M, Vivar C. Entorhinal cortex-hippocampal circuit connectivity in health and disease. Front Hum Neurosci 2024; 18:1448791. [PMID: 39372192 PMCID: PMC11449717 DOI: 10.3389/fnhum.2024.1448791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 09/03/2024] [Indexed: 10/08/2024] Open
Abstract
The entorhinal cortex (EC) and hippocampal (HC) connectivity is the main source of episodic memory formation and consolidation. The entorhinal-hippocampal (EC-HC) connection is classified as canonically glutamatergic and, more recently, has been characterized as a non-canonical GABAergic connection. Recent evidence shows that both EC and HC receive inputs from dopaminergic, cholinergic, and noradrenergic projections that modulate the mnemonic processes linked to the encoding and consolidation of memories. In the present review, we address the latest findings on the EC-HC connectivity and the role of neuromodulations during the mnemonic mechanisms of encoding and consolidation of memories and highlight the value of the cross-species approach to unravel the underlying cellular mechanisms known. Furthermore, we discuss how EC-HC connectivity early neurodegeneration may contribute to the dysfunction of episodic memories observed in aging and Alzheimer's disease (AD). Finally, we described how exercise may be a fundamental tool to prevent or decrease neurodegeneration.
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Affiliation(s)
- Melissa Hernández-Frausto
- NYU Neuroscience Institute, Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York University Langone Medical Center, New York, NY, United States
| | - Carmen Vivar
- Laboratory of Neurogenesis and Neuroplasticity, Department of Physiology, Biophysics and Neuroscience, Centro de Investigacion y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
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2
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Akiyama K, Arakawa Y, Samukawa Y, Hoshikawa H. Age-related differences in olfactory profiles and surgical outcomes in eosinophilic chronic rhinosinusitis. Allergol Int 2024:S1323-8930(24)00054-6. [PMID: 39004587 DOI: 10.1016/j.alit.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/28/2024] [Accepted: 05/08/2024] [Indexed: 07/16/2024] Open
Affiliation(s)
- Kosuke Akiyama
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Kagawa, Japan.
| | - Yukako Arakawa
- Department of Respiratory Medicine, KKR Takamatsu Hospital, Kagawa, Japan
| | - Yasushi Samukawa
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Hiroshi Hoshikawa
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Kagawa, Japan
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Hernandez AR, Parker E, Babar M, Banerjee A, Ding S, Simley A, Buford TW. Microbiome-driven alterations in metabolic pathways and impaired cognition in aged female TgF344-AD rats. AGING BRAIN 2024; 5:100119. [PMID: 38881651 PMCID: PMC11179252 DOI: 10.1016/j.nbas.2024.100119] [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: 01/15/2024] [Revised: 05/09/2024] [Accepted: 05/28/2024] [Indexed: 06/18/2024] Open
Abstract
Alzheimer's disease (AD) not only affects cognition and neuropathology, but several other facets capable of negatively impacting quality of life and potentially driving impairments, including altered gut microbiome (GMB) composition and metabolism. Aged (20 + mo) female TgF344-AD and wildtype rats were cognitively characterized on several tasks incorporating several cognitive domains, including task acquisition, object recognition memory, anxiety-like behaviors, and spatial navigation. Additionally, metabolic phenotyping, GMB sequencing throughout the intestinal tract (duodenum, jejunum, ileum, colon, and feces), neuropathological burden assessment and marker gene functional abundance predictions (PICRUSt2) were conducted. TgF344-AD rats demonstrated significant cognitive impairment in multiple domains, as well as regionally specific GMB dysbiosis. Relationships between peripheral factors were investigated using Canonical Correspondence Analysis (CCA), revealing correlations between GMB changes and both cognitive and metabolic factors. Moreover, communities of gut microbes contributing to essential metabolic pathways were significantly altered in TgF344-AD rats. These data indicate dysbiosis may affect cognitive outcomes in AD through alterations in metabolism-related enzymatic pathways that are necessary for proper brain function. Moreover, these changes were mostly observed in intestinal segments required for carbohydrate digestion, not fecal samples. These data support the targeting of intestinal and microbiome health for the treatment of AD.
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Affiliation(s)
- Abbi R Hernandez
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
| | - Erik Parker
- Department of Epidemiology and Biostatistics, School of Public Health, Indiana University-Bloomington, Bloomington, IN 47405, USA
| | - Maham Babar
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
| | - Anisha Banerjee
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
| | - Sarah Ding
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
| | - Alexis Simley
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
| | - Thomas W Buford
- Department of Medicine, Division of Geriatrics, Gerontology & Palliative Care, University of Alabama at Birmingham, Birmingham, AL 35205, USA
- Birmingham/Atlanta VA GRECC, Birmingham VA Medical Center, Birmingham, AL 35244, USA
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4
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Chen Y, Branch A, Shuai C, Gallagher M, Knierim JJ. Object-place-context learning impairment correlates with spatial learning impairment in aged Long-Evans rats. Hippocampus 2024; 34:88-99. [PMID: 38073523 PMCID: PMC10843702 DOI: 10.1002/hipo.23591] [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: 02/08/2023] [Revised: 09/28/2023] [Accepted: 11/18/2023] [Indexed: 01/23/2024]
Abstract
The hippocampal formation is vulnerable to the process of normal aging. In humans, the extent of this age-related deterioration varies among individuals. Long-Evans rats replicate these individual differences as they age, and therefore they serve as a valuable model system to study aging in the absence of neurodegenerative diseases. In the Morris water maze, aged memory-unimpaired (AU) rats navigate to remembered goal locations as effectively as young rats and demonstrate minimal alterations in physiological markers of synaptic plasticity, whereas aged memory-impaired (AI) rats show impairments in both spatial navigation skills and cellular and molecular markers of plasticity. The present study investigates whether another cognitive domain is affected similarly to navigation in aged Long-Evans rats. We tested the ability of young, AU, and AI animals to recognize novel object-place-context (OPC) configurations and found that performance on the novel OPC recognition paradigm was significantly correlated with performance on the Morris water maze. In the first OPC test, young and AU rats, but not AI rats, successfully recognized and preferentially explored objects in novel OPC configurations. In a second test with new OPC configurations, all age groups showed similar OPC associative recognition memory. The results demonstrated similarities in the behavioral expression of associative, episodic-like memory between young and AU rats and revealed age-related, individual differences in functional decline in both navigation and episodic-like memory abilities.
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Affiliation(s)
- Yuxi Chen
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland, USA
| | - Audrey Branch
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Cecelia Shuai
- Undergraduate Studies, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland, USA
| | - James J Knierim
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland, USA
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland, USA
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Chang WL, Hen R. Adult Neurogenesis, Context Encoding, and Pattern Separation: A Pathway for Treating Overgeneralization. ADVANCES IN NEUROBIOLOGY 2024; 38:163-193. [PMID: 39008016 DOI: 10.1007/978-3-031-62983-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
In mammals, the subgranular zone of the dentate gyrus is one of two brain regions (with the subventricular zone of the olfactory bulb) that continues to generate new neurons throughout adulthood, a phenomenon known as adult hippocampal neurogenesis (AHN) (Eriksson et al., Nat Med 4:1313-1317, 1998; García-Verdugo et al., J Neurobiol 36:234-248, 1998). The integration of these new neurons into the dentate gyrus (DG) has implications for memory encoding, with unique firing and wiring properties of immature neurons that affect how the hippocampal network encodes and stores attributes of memory. In this chapter, we will describe the process of AHN and properties of adult-born cells as they integrate into the hippocampal circuit and mature. Then, we will discuss some methodological considerations before we review evidence for the role of AHN in two major processes supporting memory that are performed by the DG. First, we will discuss encoding of contextual information for episodic memories and how this is facilitated by AHN. Second, will discuss pattern separation, a major role of the DG that reduces interference for the formation of new memories. Finally, we will review clinical and translational considerations, suggesting that stimulation of AHN may help decrease overgeneralization-a common endophenotype of mood, anxiety, trauma-related, and age-related disorders.
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Affiliation(s)
- Wei-Li Chang
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY, USA
| | - Rene Hen
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA.
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY, USA.
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Joly-Amado A, Kulkarni N, Nash KR. Reelin Signaling in Neurodevelopmental Disorders and Neurodegenerative Diseases. Brain Sci 2023; 13:1479. [PMID: 37891846 PMCID: PMC10605156 DOI: 10.3390/brainsci13101479] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/13/2023] [Accepted: 10/17/2023] [Indexed: 10/29/2023] Open
Abstract
Reelin is an extracellular matrix glycoprotein involved in neuronal migration during embryonic brain development and synaptic plasticity in the adult brain. The role of Reelin in the developing central nervous system has been extensively characterized. Indeed, a loss of Reelin or a disruption in its signaling cascade leads to neurodevelopmental defects and is associated with ataxia, intellectual disability, autism, and several psychiatric disorders. In the adult brain, Reelin is critically involved in neurogenesis and synaptic plasticity. Reelin's signaling potentiates glutamatergic and GABAergic neurotransmission, induces synaptic maturation, and increases AMPA and NMDA receptor subunits' expression and activity. As a result, there is a growing literature reporting that a loss of function and/or reduction of Reelin is implicated in numerous neurodegenerative diseases. The present review summarizes the current state of the literature regarding the implication of Reelin and Reelin-mediated signaling during aging and neurodegenerative disorders, highlighting Reelin as a possible target in the prevention or treatment of progressive neurodegeneration.
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Affiliation(s)
- Aurelie Joly-Amado
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA; (N.K.); (K.R.N.)
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Branch AE, Glover LR, Gallagher M. Individual differences in age-related neurocognitive outcomes: within-subject assessment of memory for odors. Front Aging Neurosci 2023; 15:1238444. [PMID: 37842120 PMCID: PMC10569039 DOI: 10.3389/fnagi.2023.1238444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Cognitive decline is a common feature of aging, particularly in memory domains supported by the medial temporal lobe (MTL). The ability to identify intervention strategies to treat or prevent this decline is challenging due to substantial variability between adults in terms of age of onset, rate and severity of decline, and many factors that could influence cognitive reserve. These factors can be somewhat mitigated by use of within-subject designs. Aged outbred Long-Evans rats have proven useful for identifying translationally relevant substrates contributing to age-related decline in MTL-dependent memory. In this population, some animals show reliable impairment on MTL-dependent tasks while others perform within the range of young adult rats. However, currently there are relatively few within-subject behavior protocols for assessing MTL function over time, and most require extensive training and appetitive motivation for associative learning. In the current study, we aimed to test whether water maze learning impairments in aged Long-Evans rats would be predictive of delayed recognition memory impairments and whether these odor memory impairments would be stable within subjects over multiple rounds of testing.
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Affiliation(s)
- Audrey E. Branch
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Lucas R. Glover
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Johns Hopkins Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States
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Whitfield JF, Rennie K, Chakravarthy B. Alzheimer's Disease and Its Possible Evolutionary Origin: Hypothesis. Cells 2023; 12:1618. [PMID: 37371088 PMCID: PMC10297544 DOI: 10.3390/cells12121618] [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: 04/01/2023] [Revised: 05/29/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
The enormous, 2-3-million-year evolutionary expansion of hominin neocortices to the current enormity enabled humans to take over the planet. However, there appears to have been a glitch, and it occurred without a compensatory expansion of the entorhinal cortical (EC) gateway to the hippocampal memory-encoding system needed to manage the processing of the increasing volume of neocortical data converging on it. The resulting age-dependent connectopathic glitch was unnoticed by the early short-lived populations. It has now surfaced as Alzheimer's disease (AD) in today's long-lived populations. With advancing age, processing of the converging neocortical data by the neurons of the relatively small lateral entorhinal cortex (LEC) inflicts persistent strain and high energy costs on these cells. This may result in their hyper-release of harmless Aβ1-42 monomers into the interstitial fluid, where they seed the formation of toxic amyloid-β oligomers (AβOs) that initiate AD. At the core of connectopathic AD are the postsynaptic cellular prion protein (PrPC). Electrostatic binding of the negatively charged AβOs to the positively charged N-terminus of PrPC induces hyperphosphorylation of tau that destroys synapses. The spread of these accumulating AβOs from ground zero is supported by Aβ's own production mediated by target cells' Ca2+-sensing receptors (CaSRs). These data suggest that an early administration of a strongly positively charged, AβOs-interacting peptide or protein, plus an inhibitor of CaSR, might be an effective AD-arresting therapeutic combination.
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Affiliation(s)
- James F. Whitfield
- Human Health Therapeutics, National Research Council, Ottawa, ON K1A 0R6, Canada
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Adams JN, Márquez F, Larson MS, Janecek JT, Miranda BA, Noche JA, Taylor L, Hollearn MK, McMillan L, Keator DB, Head E, Rissman RA, Yassa MA. Differential involvement of hippocampal subfields in the relationship between Alzheimer's pathology and memory interference in older adults. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2023; 15:e12419. [PMID: 37035460 PMCID: PMC10075195 DOI: 10.1002/dad2.12419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/15/2023] [Accepted: 02/28/2023] [Indexed: 04/11/2023]
Abstract
Introduction We tested whether Alzheimer's disease (AD) pathology predicts memory deficits in non-demented older adults through its effects on medial temporal lobe (MTL) subregional volume. Methods Thirty-two, non-demented older adults with cerebrospinal fluid (CSF) (amyloid-beta [Aβ]42/Aβ40, phosphorylated tau [p-tau]181, total tau [t-tau]), positron emission tomography (PET; 18F-florbetapir), high-resolution structural magnetic resonance imaging (MRI), and neuropsychological assessment were analyzed. We examined relationships between biomarkers and a highly granular measure of memory consolidation, retroactive interference (RI). Results Biomarkers of AD pathology were related to RI. Dentate gyrus (DG) and CA3 volume were uniquely associated with RI, whereas CA1 and BA35 volume were related to both RI and overall memory recall. AD pathology was associated with reduced BA35, CA1, and subiculum volume. DG volume and Aβ were independently associated with RI, whereas CA1 volume mediated the relationship between AD pathology and RI. Discussion Integrity of distinct hippocampal subfields demonstrate differential relationships with pathology and memory function, indicating specificity in vulnerability and contribution to different memory processes.
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Affiliation(s)
- Jenna N. Adams
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Freddie Márquez
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Myra S. Larson
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - John T. Janecek
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Blake A. Miranda
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Jessica A. Noche
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Lisa Taylor
- Department of Psychiatry and Human BehaviorUniversity of CaliforniaIrvineCaliforniaUSA
| | - Martina K. Hollearn
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - Liv McMillan
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
| | - David B. Keator
- Department of Psychiatry and Human BehaviorUniversity of CaliforniaIrvineCaliforniaUSA
| | - Elizabeth Head
- Department of Pathology and Laboratory MedicineUniversity of CaliforniaIrvineCaliforniaUSA
- Department of NeurologyUniversity of CaliforniaIrvineCaliforniaUSA
- Department of NeurologyUniversity of KentuckyLexingtonKentuckyUSA
| | - Robert A. Rissman
- Department of NeurosciencesUniversity of CaliforniaSan DiegoCaliforniaUSA
- Veterans Affairs San Diego Healthcare SystemSan DiegoCaliforniaUSA
| | - Michael A. Yassa
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and MemoryUniversity of CaliforniaIrvineCaliforniaUSA
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Lee H, Wang Z, Tillekeratne A, Lukish N, Puliyadi V, Zeger S, Gallagher M, Knierim JJ. Loss of functional heterogeneity along the CA3 transverse axis in aging. Curr Biol 2022; 32:2681-2693.e4. [PMID: 35597233 PMCID: PMC9233142 DOI: 10.1016/j.cub.2022.04.077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 04/18/2022] [Accepted: 04/26/2022] [Indexed: 01/05/2023]
Abstract
Age-related deficits in pattern separation have been postulated to bias the output of hippocampal memory processing toward pattern completion, which can cause deficits in accurate memory retrieval. Although the CA3 region of the hippocampus is often conceptualized as a homogeneous network involved in pattern completion, growing evidence demonstrates a functional gradient in CA3 along the transverse axis, as pattern-separated outputs (dominant in the more proximal CA3) transition to pattern-completed outputs (dominant in the more distal CA3). We examined the neural representations along the CA3 transverse axis in young (Y), aged memory-unimpaired (AU), and aged memory-impaired (AI) rats when different changes were made to the environment. Functional heterogeneity in CA3 was observed in Y and AU rats when the environmental similarity was high (altered cues or altered environment shapes in the same room), with more orthogonalized representations in proximal CA3 than in distal CA3. In contrast, AI rats showed reduced orthogonalization in proximal CA3 but showed normal (i.e., generalized) representations in distal CA3, with little evidence of a functional gradient. Under experimental conditions when the environmental similarity was low (different rooms), representations in proximal and distal CA3 remapped in all rats, showing that CA3 of AI rats is able to encode distinctive representations for inputs with greater dissimilarity. These experiments support the hypotheses that the age-related bias toward hippocampal pattern completion is due to the loss in AI rats of the normal transition from pattern separation to pattern completion along the CA3 transverse axis.
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Affiliation(s)
- Heekyung Lee
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218,Correspondence: ;
| | - Zitong Wang
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 21205
| | - Arjuna Tillekeratne
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218
| | - Nick Lukish
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218
| | - Vyash Puliyadi
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218,Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD
| | - Scott Zeger
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 21205
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD,Kavli Neuroscience Discovery Institute, Johns Hopkins University
| | - James J. Knierim
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, 21218,Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD,Kavli Neuroscience Discovery Institute, Johns Hopkins University,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205,Lead Contact,Correspondence: ;
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Nakao Y, Yokawa S, Kohno T, Suzuki T, Hattori M. Visualization of Reelin secretion from primary cultured neurons by bioluminescence imaging. J Biochem 2022; 171:591-598. [PMID: 35171273 DOI: 10.1093/jb/mvac019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/10/2022] [Indexed: 11/14/2022] Open
Abstract
Reelin is a secreted glycoprotein important for brain development and synaptic plasticity in the adult brain. Some reports suggest that Reelin is secreted from the nerve terminals and functions as a neurotransmitter. However, the mechanism of Reelin secretion is unknown. In this study, we visualized Reelin secretion by bioluminescence imaging using a fusion protein of Reelin and Gaussia luciferase (GLase-Reelin). GLase-Reelin expressed in HEK293T cells was correctly processed and secreted. Luminescence signals from the secreted GLase-Reelin of primary cultured neurons were visualized by bioluminescence microscopy. Reelin secretory events were observed at neurites and cell bodies. Bioluminescence imaging was also performed before and after KCl depolarization to compare the secretory events of Reelin and brain-derived neurotrophic factor (BDNF). The secretion of BDNF increased markedly shortly after depolarization. In contrast, the frequency of Reelin secretion did not change significantly by depolarization. Thus, Reelin secretion from neurites might not be regulated in a neuronal activity-dependent manner.
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Affiliation(s)
- Yousuke Nakao
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
| | - Satoru Yokawa
- Department of Analytical Chemistry and Biophysics, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Takao Kohno
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
| | - Takahiro Suzuki
- Department of Biochemistry, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Mitsuharu Hattori
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
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12
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Reelin changes hippocampal learning in aging and Alzheimer's disease. Behav Brain Res 2021; 414:113482. [PMID: 34333070 DOI: 10.1016/j.bbr.2021.113482] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 11/23/2022]
Abstract
The hippocampal formation (HF) is a neuroanatomical region essential for learning and memory. As one of the earliest regions to display the histopathological hallmarks of Alzheimer's disease (AD), determining the specific mechanisms of the HF's vulnerability is of capital importance. Reelin, a glycoprotein crucial in cortical lamination during embryonic neurogenesis, has an uncommon expression pattern within the HF and has been implicated in both learning and AD pathogenesis. We hypothesized that Reelin deficiency would expedite behavioral impairments which accompany normal aging. Additionally, we hypothesized that Reelin deficiency in the presence of mutated human microtubule associated protein tau (MAPT) would further impair hippocampal function. To test our hypothesis, we utilized cohorts of aged mice, aged mice with Reelin conditional knockout (RcKO), and adult mice with both RcKO and MAPT in the Barnes maze and Trace fear conditioning. Consistent with prior literature, increased age in wild-type mice was sufficient to reduce spatial searching in the Barnes maze. Increased age both exacerbated spatial impairments and altered context learning in RcKO mice. Lastly, adult mice with both RcKO and the MAPT transgene displayed both the lowest age-of-onset and most severe spatial learning deficits. In conclusion, Reelin deficiency when combined with AD risk-factors produced consistent impairments in spatial memory tasks. Furthermore, our results further implicate Reelin's importance in both HF homeostasis and AD pathogenesis.
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Amani M, Lauterborn JC, Le AA, Cox BM, Wang W, Quintanilla J, Cox CD, Gall CM, Lynch G. Rapid Aging in the Perforant Path Projections to the Rodent Dentate Gyrus. J Neurosci 2021; 41:2301-2312. [PMID: 33514675 PMCID: PMC8018768 DOI: 10.1523/jneurosci.2376-20.2021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 01/04/2021] [Accepted: 01/16/2021] [Indexed: 12/15/2022] Open
Abstract
Why layers II/III of entorhinal cortex (EC) deteriorate in advance of other regions during the earliest stages of Alzheimer's disease is poorly understood. Failure of retrograde trophic support from synapses to cell bodies is a common cause of neuronal atrophy, and we accordingly tested for early-life deterioration in projections of rodent layer II EC neurons. Using electrophysiology and quantitative imaging, changes in EC terminals during young adulthood were evaluated in male rats and mice. Field excitatory postsynaptic potentials, input/output curves, and frequency following capacity by lateral perforant path (LPP) projections from lateral EC to dentate gyrus were unchanged from 3 to 8-10 months of age. In contrast, the unusual presynaptic form of long-term potentiation (LTP) expressed by the LPP was profoundly impaired by 8 months in rats and mice. This impairment was accompanied by a reduction in the spine to terminal endocannabinoid signaling needed for LPP-LTP induction and was offset by an agent that enhances signaling. There was a pronounced age-related increase in synaptophysin within LPP terminals, an effect suggestive of incipient pathology. Relatedly, presynaptic levels of TrkB-receptors mediating retrograde trophic signaling-were reduced in the LPP terminal field. LTP and TrkB content were also reduced in the medial perforant path of 8- to 10-month-old rats. As predicted, performance on an LPP-dependent episodic memory task declined by late adulthood. We propose that memory-related synaptic plasticity in EC projections is unusually sensitive to aging, which predisposes EC neurons to pathogenesis later in life.SIGNIFICANCE STATEMENT Neurons within human superficial entorhinal cortex are particularly vulnerable to effects of aging and Alzheimer's disease, although why this is the case is not understood. Here we report that perforant path projections from layer II entorhinal cortex to the dentate gyrus exhibit rapid aging in rodents, including reduced synaptic plasticity and abnormal protein content by 8-10 months of age. Moreover, there was a substantial decline in the performance of an episodic memory task that depends on entorhinal cortical projections at the same ages. Overall, the results suggest that the loss of plasticity and related trophic signaling predispose the entorhinal neurons to functional decline in relatively young adulthood.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Gary Lynch
- Departments of Anatomy & Neurobiology
- Psychiatry & Human Behavior, University of California, Irvine, Irvine, California 92697
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Despotovski V, Vivekanandarajah A, Waters KA, Machaalani R. Expression of reelin with age in the human hippocampal formation. Hippocampus 2021; 31:493-502. [PMID: 33539623 DOI: 10.1002/hipo.23310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 12/30/2020] [Accepted: 01/23/2021] [Indexed: 12/23/2022]
Abstract
Reelin plays a key role in neuronal migration and lamination in the cortex and hippocampus. Animal studies have shown that reelin expression decreases with age. The aim of this study was to evaluate the expression of reelin in all layers of the human hippocampal formation across three age groups. We used immunohistochemistry in formalin fixed and paraffin embedded hippocampal tissue from infants (1-10 months; n = 9), children (4-10 years; n = 4), and adults (45-60 years; n = 6) to stain for reelin. Expression was quantified (measured as the number of positive reelin cells/mm2 ) in the granule cell layer of the dentate gyrus (DG), the molecular layer of the dentate gyrus (ML), the hippocampal fissure (HF), stratum lacunosum moleculare (SLM), CA4/Hilus and the stratum pyramidale layer of CA3, CA2, and CA1. Expression of reelin was highest in the HF irrespective of age, followed by the SLM and ML. Minimal to no expression was seen in the stratum pyramidale layer of CA1-3. With age, reelin expression decreased and was statistically significant from infancy to childhood in the HF (p = .02). This study confirms that reelin expression decreases with age in the human hippocampus, and shows for the first time that the major decrease occurs between infancy and early childhood.
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Affiliation(s)
- Vanessa Despotovski
- Discipline of Medicine, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Arunnjah Vivekanandarajah
- Discipline of Medicine, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Karen A Waters
- Discipline of Medicine, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Rita Machaalani
- Discipline of Medicine, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Discipline of Child and Adolescent Health, Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
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15
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Heterogeneity of Age-Related Neural Hyperactivity along the CA3 Transverse Axis. J Neurosci 2021; 41:663-673. [PMID: 33257325 DOI: 10.1523/jneurosci.2405-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/12/2020] [Accepted: 11/19/2020] [Indexed: 02/08/2023] Open
Abstract
Age-related memory deficits are correlated with neural hyperactivity in the CA3 region of the hippocampus. Abnormal CA3 hyperactivity in aged rats has been proposed to contribute to an imbalance between pattern separation and pattern completion, resulting in overly rigid representations. Recent evidence of functional heterogeneity along the CA3 transverse axis suggests that proximal CA3 supports pattern separation while distal CA3 supports pattern completion. It is not known whether age-related CA3 hyperactivity is uniformly represented along the CA3 transverse axis. We examined the firing rates of CA3 neurons from young and aged, male, Long-Evans rats along the CA3 transverse axis. Consistent with prior studies, young CA3 cells showed an increasing gradient in mean firing rate from proximal to distal CA3. However, aged CA3 cells showed an opposite, decreasing trend, in that CA3 cells in aged rats were hyperactive in proximal CA3, but possibly hypoactive in distal CA3, compared with young (Y) rats. We suggest that, in combination with altered inputs from the entorhinal cortex and dentate gyrus (DG), the proximal CA3 region of aged rats may switch from its normal function that reflects the pattern separation output of the DG and instead performs a computation that reflects an abnormal bias toward pattern completion. In parallel, distal CA3 of aged rats may create weaker attractor basins that promote abnormal, bistable representations under certain conditions.SIGNIFICANCE STATEMENT Prior work suggested that age-related CA3 hyperactivity enhances pattern completion, resulting in rigid representations. Implicit in prior studies is the notion that hyperactivity is present throughout a functionally homogeneous CA3 network. However, more recent work has demonstrated functional heterogeneity along the CA3 transverse axis, in that proximal CA3 is involved in pattern separation and distal CA3 is involved in pattern completion. Here, we show that age-related hyperactivity is present only in proximal CA3, with potential hypoactivity in distal CA3. This result provides new insight in the role of CA3 in age-related memory impairments, suggesting that the rigid representations in aging result primarily from dysfunction of computational circuits involving the dentate gyrus (DG) and proximal CA3.
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16
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Costa LG, Cole TB, Dao K, Chang YC, Coburn J, Garrick JM. Effects of air pollution on the nervous system and its possible role in neurodevelopmental and neurodegenerative disorders. Pharmacol Ther 2020; 210:107523. [PMID: 32165138 PMCID: PMC7245732 DOI: 10.1016/j.pharmthera.2020.107523] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/25/2020] [Indexed: 02/06/2023]
Abstract
Recent extensive evidence indicates that air pollution, in addition to causing respiratory and cardiovascular diseases, may also negatively affect the brain and contribute to central nervous system diseases. Air pollution is comprised of ambient particulate matter (PM) of different sizes, gases, organic compounds, and metals. An important contributor to PM is represented by traffic-related air pollution, mostly ascribed to diesel exhaust (DE). Epidemiological and animal studies have shown that exposure to air pollution may be associated with multiple adverse effects on the central nervous system. In addition to a variety of behavioral abnormalities, the most prominent effects caused by air pollution are oxidative stress and neuro-inflammation, which are seen in both humans and animals, and are supported by in vitro studies. Among factors which can affect neurotoxic outcomes, age is considered most relevant. Human and animal studies suggest that air pollution may cause developmental neurotoxicity, and may contribute to the etiology of neurodevelopmental disorders, including autism spectrum disorder. In addition, air pollution exposure has been associated with increased expression of markers of neurodegenerative disease pathologies, such as alpha-synuclein or beta-amyloid, and may thus contribute to the etiopathogenesis of neurodegenerative diseases, particularly Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Lucio G Costa
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Dept. of Medicine & Surgery, University of Parma, Italy.
| | - Toby B Cole
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, University of Washington, Seattle, WA, USA
| | - Khoi Dao
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Yu-Chi Chang
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Jacki Coburn
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Jacqueline M Garrick
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
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17
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Koh MT, Branch A, Haberman R, Gallagher M. Significance of inhibitory recruitment in aging with preserved cognition: limiting gamma-aminobutyric acid type A α5 function produces memory impairment. Neurobiol Aging 2020; 91:1-4. [PMID: 32240868 DOI: 10.1016/j.neurobiolaging.2020.02.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/30/2019] [Accepted: 02/22/2020] [Indexed: 01/27/2023]
Abstract
Numerous aging studies have identified a shift in the excitatory/inhibitory (E/I) balance with heightened hippocampal neural activity associated with age-related memory impairment across species, including rats, monkeys, and humans. Neurobiological investigations directed at the hippocampal formation have demonstrated that unimpaired aged rats performing on par with young adult rats in a spatial memory task exhibit gene expression profiles, mechanisms for plasticity, and altered circuit/network function, which are distinct from younger rats. Particularly striking is a convergence of observational evidence that aged unimpaired rats augment recruitment of mechanisms associated with neural inhibition, a finding that may represent an adaptive homeostatic adjustment necessary to maintain neural plasticity and memory function in aging. In this study, we test the effect of limiting inhibition via administration of TB21007, a negative allosteric modulator of the alpha 5 subtype of gamma-aminobutyric acid type A α5 receptor, on a radial arm maze assessment of memory function. Impaired memory performance produced by this intervention in otherwise high-performing aged rats supports an adaptive role for gamma-aminobutyric acid in the functional maintenance of intact cognition in aging.
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Affiliation(s)
- Ming Teng Koh
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Audrey Branch
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Rebecca Haberman
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
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18
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Long JM, Perez EJ, Roberts JA, Roberts MT, Rapp PR. Reelin in the Years: decline in the number of reelin immunoreactive neurons in layer II of the entorhinal cortex in aged monkeys with memory impairment. Neurobiol Aging 2019; 87:132-137. [PMID: 31952867 DOI: 10.1016/j.neurobiolaging.2019.12.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/12/2019] [Accepted: 12/12/2019] [Indexed: 01/17/2023]
Abstract
The glycoprotein reelin has been implicated in both memory-related synaptic plasticity and Alzheimer's disease pathogenesis. Aged rats with memory impairment display decreased reelin expression in layer II of the entorhinal cortex (EC) relative to memory-intact subjects, and here we tested whether this effect extends to the primate brain. Seven young adult (8-10 years) and 14 aged (27-38 years) rhesus monkeys (Macaca mulatta) were examined, including 7 old animals classified as impaired based on their scores from a delayed nonmatching-to-sample recognition memory test. Histological sections spanning the rostrocaudal extent of the intermediate and caudal divisions of EC were processed by immunohistochemistry and the total number of reelin-positive neurons in layer II was estimated using design-based stereological techniques. The main finding was that the number of reelin-expressing neurons in EC layer II is decreased selectively in aged monkeys with memory deficits relative to young adult and aged subjects with intact memory. The results add to evidence implicating EC-hippocampal integrity in neurocognitive aging, and they suggest that disrupted reelin signaling may be among the mechanisms that mediate the associated vulnerability of this circuitry in Alzheimer's disease.
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Affiliation(s)
- Jeffrey M Long
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Evelyn J Perez
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | | | - Mary T Roberts
- California National Primate Research Center, Davis, CA, USA
| | - Peter R Rapp
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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19
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Vandrey B, Garden DLF, Ambrozova V, McClure C, Nolan MF, Ainge JA. Fan Cells in Layer 2 of the Lateral Entorhinal Cortex Are Critical for Episodic-like Memory. Curr Biol 2019; 30:169-175.e5. [PMID: 31839450 PMCID: PMC6947484 DOI: 10.1016/j.cub.2019.11.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/11/2019] [Accepted: 11/07/2019] [Indexed: 11/28/2022]
Abstract
Episodic memory requires different types of information to be bound together to generate representations of experiences. The lateral entorhinal cortex (LEC) and hippocampus are required for episodic-like memory in rodents [1, 2]. The LEC is critical for integrating spatial and contextual information about objects [2, 3, 4, 5, 6]. Further, LEC neurons encode objects in the environment and the locations where objects were previously experienced and generate representations of time during the encoding and retrieval of episodes [7, 8, 9, 10, 11, 12]. However, it remains unclear how specific populations of cells within the LEC contribute to the integration of episodic memory components. Layer 2 (L2) of LEC manifests early pathology in Alzheimer’s disease (AD) and related animal models [13, 14, 15, 16]. Projections to the hippocampus from L2 of LEC arise from fan cells in a superficial sub-layer (L2a) that are immunoreactive for reelin and project to the dentate gyrus [17, 18]. Here, we establish an approach for selectively targeting fan cells using Sim1:Cre mice. Whereas complete lesions of the LEC were previously found to abolish associative recognition memory [2, 3], we report that, after selective suppression of synaptic output from fan cells, mice can discriminate novel object-context configurations but are impaired in recognition of novel object-place-context associations. Our results suggest that memory functions are segregated between distinct LEC networks. Sim1:Cre mice provide access to DG-projecting fan cells in lateral entorhinal cortex Fan cells are not required for novel object or object-context recognition Fan cells are required to discriminate novel object-place-context configurations Episodic-like memory impairment is correlated with extent of fan-cell inactivation
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Affiliation(s)
- Brianna Vandrey
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, 15 George Square, Edinburgh EH8 9XE, Scotland; School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews KY16 9JP, Scotland
| | - Derek L F Garden
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, 15 George Square, Edinburgh EH8 9XE, Scotland
| | - Veronika Ambrozova
- School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews KY16 9JP, Scotland
| | - Christina McClure
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, 15 George Square, Edinburgh EH8 9XE, Scotland
| | - Matthew F Nolan
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, 15 George Square, Edinburgh EH8 9XE, Scotland.
| | - James A Ainge
- School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews KY16 9JP, Scotland.
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20
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Guo X, Keenan BT, Sarantopoulou D, Lim DC, Lian J, Grant GR, Pack AI. Age attenuates the transcriptional changes that occur with sleep in the medial prefrontal cortex. Aging Cell 2019; 18:e13021. [PMID: 31549781 PMCID: PMC6826131 DOI: 10.1111/acel.13021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/13/2019] [Accepted: 07/14/2019] [Indexed: 12/29/2022] Open
Abstract
Sleep abnormalities are common with aging. Studies show that sleep plays important roles in brain functions, and loss of sleep is associated with increased risks for neurological diseases. Here, we used RNA sequencing to explore effects of age on transcriptome changes between sleep and sleep deprivation (SD) in medial prefrontal cortex and found that transcriptional changes with sleep are attenuated in old. In particular, old mice showed a 30% reduction in the number of genes significantly altered between sleep/wake and, in general, had smaller magnitudes of changes in differentially expressed genes compared to young mice. Gene ontology analysis revealed differential age effects on certain pathways. Compared to young mice, many of the wake‐active functions were similarly induced by SD in old mice, whereas many of the sleep‐active pathways were attenuated in old mice. We found similar magnitude of changes in synaptic homeostasis genes (Fos, Arc, and Bdnf) induced by SD, suggesting intact synaptic upscaling on the transcript level during extended wakefulness with aging. However, sleep‐activated processes, such as DNA repair, synaptogenesis, and axon guidance, were sensitive to the effect of aging. Old mice expressed elevated levels of immune response genes when compared to young mice, and enrichment analysis using cell‐type‐specific markers indicated upregulation of microglia and oligodendrocyte genes in old mice. Moreover, gene sets of the two cell types showed age‐specific sleep/wake regulation. Ultimately, this study enhances understanding of the transcriptional changes with sleep and aging, providing potential molecular targets for future studies of age‐related sleep abnormalities and neurological disorders.
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Affiliation(s)
- Xiaofeng Guo
- Division of Sleep Medicine Department of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Brendan T. Keenan
- Division of Sleep Medicine Department of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Dimitra Sarantopoulou
- Institute for Translational Medicine and Therapeutics University of Pennsylvania Philadelphia Pennsylvania
| | - Diane C. Lim
- Division of Sleep Medicine Department of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Jie Lian
- Division of Sleep Medicine Department of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Gregory R. Grant
- Institute for Translational Medicine and Therapeutics University of Pennsylvania Philadelphia Pennsylvania
- Department of Genetics University of Pennsylvania Philadelphia Pennsylvania
| | - Allan I. Pack
- Division of Sleep Medicine Department of Medicine University of Pennsylvania Philadelphia Pennsylvania
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Reduced cognitive performance in aged rats correlates with increased excitation/inhibition ratio in the dentate gyrus in response to lateral entorhinal input. Neurobiol Aging 2019; 82:120-127. [DOI: 10.1016/j.neurobiolaging.2019.07.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/16/2019] [Accepted: 07/16/2019] [Indexed: 11/18/2022]
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Horwitz A, Klemp M, Horwitz H, Thomsen MD, Rostrup E, Mortensen EL, Osler M, Lauritzen M, Benedek K. Brain Responses to Passive Sensory Stimulation Correlate With Intelligence. Front Aging Neurosci 2019; 11:201. [PMID: 31474849 PMCID: PMC6702683 DOI: 10.3389/fnagi.2019.00201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 07/17/2019] [Indexed: 11/13/2022] Open
Abstract
This study investigates the association between intelligence and brain power responses to a passive audiovisual stimulation. We measure the power of gamma-range steady-state responses (SSRs) as well as intelligence and other aspects of neurocognitive function in 40 healthy males born in 1953. The participants are a part of a Danish birth cohort study and the data therefore include additional information measured earlier in life. Our main power measure is the difference in power between a visual stimulation and a combined audiovisual stimulation. We hypothesize and establish empirically that the power measure is associated with intelligence. In particular, we find a highly significant correlation between the power measure and present intelligence scores. The association is robust to controlling for size-at-birth measures, length of education, speed of processing as well as a range of other potentially confounding factors. Interestingly, we find that intelligence scores measured earlier in life (childhood, youth, late midlife), are also correlated with the present-day power measure, suggesting a deep connection between intelligence and the power measure. Finally, we find that the power measure has a high sensitivity for detection of an intelligence score below the average.
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Affiliation(s)
- Anna Horwitz
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Marc Klemp
- Department of Economics, University of Copenhagen, Copenhagen, Denmark
- Department of Economics, Population Studies and Training Center, Brown University, Providence, RI, United States
| | - Henrik Horwitz
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Mia Dyhr Thomsen
- Department of Clinical Neurophysiology, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Egill Rostrup
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Erik Lykke Mortensen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Merete Osler
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- Research Center for Prevention and Health, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Martin Lauritzen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet Glostrup, Glostrup, Denmark
| | - Krisztina Benedek
- Department of Clinical Neurophysiology, Rigshospitalet Glostrup, Glostrup, Denmark
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Haberman RP, Monasterio A, Branch A, Gallagher M. Aged rats with intact memory show distinctive recruitment in cortical regions relative to young adults in a cue mismatch task. Behav Neurosci 2019; 133:537-544. [PMID: 31246080 DOI: 10.1037/bne0000332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Similar to elderly humans, aged Long-Evans rats exhibit individual differences in performance on tasks that critically depend on the medial temporal lobe memory system. Although reduced memory performance is common, close to half of aged rats in this outbred rodent population perform within the range of young subjects, exhibiting a stable behavioral phenotype that may signal a resilience to memory decline. Increasing evidence from research on aging in the Long-Evans study population supports the existence of adaptive neural change rather than avoidance of detrimental effects of aging on the brain, indicating a malleability of brain function over the life span that may preserve optimal function. Augmenting prior work that centered on hippocampal function, the current study extends investigation to cortical regions functionally interconnected with the hippocampal formation, including medial temporal lobe cortices and posterior components of the default mode network. In response to an environmental manipulation that creates a mismatch in the expected cue orientation, aged rats with preserved memory show greater activation across an extended network of cortical regions as measured by immediate early gene expression. In contrast, young subjects, behaviorally similar to the aged rats in this study, show a more limited cortical response. This distinctive cortical recruitment in aged unimpaired rats, set against a background of comparable activation across hippocampal subregions, may represent adaptive cortical recruitment consistent with evidence in human studies of neurocognitive aging. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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The role of APOE4 in Alzheimer's disease: strategies for future therapeutic interventions. Neuronal Signal 2019; 3:NS20180203. [PMID: 32269835 PMCID: PMC7104324 DOI: 10.1042/ns20180203] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 12/25/2022] Open
Abstract
Alzheimer’s disease (AD) is the leading cause of dementia affecting almost 50 million people worldwide. The ε4 allele of Apolipoprotein E (APOE) is the strongest known genetic risk factor for late-onset AD cases, with homozygous APOE4 carriers being approximately 15-times more likely to develop the disease. With 25% of the population being APOE4 carriers, understanding the role of this allele in AD pathogenesis and pathophysiology is crucial. Though the exact mechanism by which ε4 allele increases the risk for AD is unknown, the processes mediated by APOE, including cholesterol transport, synapse formation, modulation of neurite outgrowth, synaptic plasticity, destabilization of microtubules, and β-amyloid clearance, suggest potential therapeutic targets. This review will summarize the impact of APOE on neurons and neuronal signaling, the interactions between APOE and AD pathology, and the association with memory decline. We will then describe current treatments targeting APOE4, complications associated with the current therapies, and suggestions for future areas of research and treatment.
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Endothelial Adora2a Activation Promotes Blood-Brain Barrier Breakdown and Cognitive Impairment in Mice with Diet-Induced Insulin Resistance. J Neurosci 2019; 39:4179-4192. [PMID: 30886019 DOI: 10.1523/jneurosci.2506-18.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/18/2019] [Accepted: 03/06/2019] [Indexed: 02/07/2023] Open
Abstract
Obesity and insulin resistance elicit blood-brain barrier (BBB) breakdown in humans and animal models, but the relative contributions of the two pathologies remain poorly understood. These studies initially addressed the temporal progression of cerebrovascular dysfunction relative to dietary obesity or diet-induced insulin resistance in male mice. Obesity increased BBB permeability to the low molecular weight fluorophore sodium fluorescein (NaFl), whereas diet-induced insulin resistance increased permeability to both NaFl and Evans blue, which forms a high molecular weight complex with serum albumin. Serial section transmission electron microscopy analysis of hippocampal capillaries revealed that diabetes promotes involution of tight junctions, fenestration of endothelial cells, and pericyte regression. Chronic activation of adenosine receptor 2a (Adora2a) erodes tight junctions between endothelial cells of the cerebral vasculature in other models of chronic neuropathology, and we observed that acute Adora2a antagonism normalized BBB permeability in wild-type mice with diet-induced insulin resistance. Experiments in mice with inducible deletion of Adora2a in endothelial cells revealed protection against BBB breakdown with diet-induced insulin resistance, despite comparable metabolic dysfunction relative to nontransgenic littermates. Protection against BBB breakdown was associated with decreased vascular inflammation, recovery of hippocampal synaptic plasticity, and restoration of hippocampus-dependent memory. These findings indicate that Adora2a-mediated signaling in vascular endothelial cells disrupts the BBB in dietary obesity, and implicate cerebrovascular dysfunction as the underlying mechanism for deficits in synaptic plasticity and cognition with obesity and insulin resistance.SIGNIFICANCE STATEMENT The blood-brain barrier (BBB) restricts the entry of circulating factors into the brain, but obesity promotes BBB breakdown in humans and animal models. We used transgenic mice with resistance to BBB breakdown to investigate the role of neurovascular dysfunction in high-fat diet (HFD)-induced cognitive impairment. Transgenic mice with inducible ablation of Adora2a in endothelial cells were protected against BBB breakdown on HFD, despite comparable metabolic impairments relative to normal mice. Transgenic mice were also resistant to HFD-induced cognitive dysfunction and were protected against deficits in hippocampal synaptic plasticity. These findings indicate that Adora2a-mediated signaling in endothelial cells mediates obesity-induced BBB breakdown, and implicate cerebrovascular dysfunction as the mechanism for deficits in synaptic plasticity and cognition with obesity and diabetes.
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Brietzke E, Trevizol AP, Fries GR, Subramaniapillai M, Kapczinski F, McIntyre RS, Mansur RB. The impact of body mass index in gene expression of reelin pathway mediators in individuals with schizophrenia and mood disorders: A post-mortem study. J Psychiatr Res 2018; 102:186-191. [PMID: 29680575 DOI: 10.1016/j.jpsychires.2018.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/09/2018] [Accepted: 04/12/2018] [Indexed: 12/19/2022]
Abstract
The objective of this study was to compare the expression of genes involved in the reelin pathway, in the post-mortem brain of individuals with schizophrenia (SZ) and mood disorders (MD) with a healthy control (HC) group; and to investigate the role f body mass index (BMI) as a potential mediator. The "Gene Expression in Postmortem dlPFC and Hippocampus from Schizophrenia and Mood Disorders" study holds microarray data on individuals with SZ, MD and HCs (from whom 849 specimens are from the dlPFC and 579 from the hippocampus). mRNA data was obtained using HumanHT-12 v4 BeadChip arrays (Illumina). Multivariate analysis of covariance were used to investigate the main effects of group and relevant covariates on RELNm, NOTCH1, GRIN1m, GRIN3A, CAMK2Gm, CAMK2A, CAMK2Bm, CAMK2N2, GRIN2Bm, GRIN2A, CREBBPm, APOE, LDLR and DAB1 gene expression. In the dlPFC, individuals with SZ had higher expression, relative to HCs, of APOE. Individuals with MD had higher expression, relative to HCs, of CAMK2A, CAMK2N2, and GRIN2Bm. Moreover, individuals with MD had higher expression, relative to SZ patients, of CAMK2N2. There were significant group by BMI effects for expression of RELN, CAMK2A, CAMK2N2, and GRIN2A. In the hippocampus, individuals with MD had lower expression, relative to HCs, of APOE. The results of this study suggest that the expression of genes related to the reelin pathway could be different between individuals with SZ and MD and healthy controls, with a greater vulnerability associated with greater BMI.
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Affiliation(s)
- Elisa Brietzke
- Mood Disorders Psychopharmacology Unit (MDPU), University Health Network, Toronto, Canada; Department of Psychiatry, Universidade Federal de São Paulo, São Paulo, Brazil; Research Group in Molecular and Behavioral Neuroscience of Bipolar Disorder, Department of Psychiatry, Universidade Federal de São Paulo, SP, Brazil; University of Toronto, Toronto, Canada
| | - Alisson P Trevizol
- Mood Disorders Psychopharmacology Unit (MDPU), University Health Network, Toronto, Canada; University of Toronto, Toronto, Canada
| | - Gabriel R Fries
- Department of Psychiatry and Behavioral Sciences, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, USA
| | - Mehala Subramaniapillai
- Mood Disorders Psychopharmacology Unit (MDPU), University Health Network, Toronto, Canada; Department of Psychiatry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Flavio Kapczinski
- Department of Psychiatry & Behavioral Neurosciences, Mcmaster University, Hamilton, Canada
| | - Roger S McIntyre
- Mood Disorders Psychopharmacology Unit (MDPU), University Health Network, Toronto, Canada; University of Toronto, Toronto, Canada
| | - Rodrigo B Mansur
- Mood Disorders Psychopharmacology Unit (MDPU), University Health Network, Toronto, Canada; University of Toronto, Toronto, Canada.
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27
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Tran T, Gallagher M, Kirkwood A. Enhanced postsynaptic inhibitory strength in hippocampal principal cells in high-performing aged rats. Neurobiol Aging 2018; 70:92-101. [PMID: 30007169 DOI: 10.1016/j.neurobiolaging.2018.06.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 05/28/2018] [Accepted: 06/03/2018] [Indexed: 11/20/2022]
Abstract
Hyperactivity within the hippocampal formation, frequently observed in aged individuals, is thought to be a potential contributing mechanism to the memory decline often associated with aging. Consequently, we evaluated the postsynaptic strength of excitatory and inhibitory synapses in the granule cells of the dentate gyrus and CA1 pyramidal cells of a rat model of aging, in which each individual was behaviorally characterized as aged impaired (AI) or aged unimpaired (AU, with performance comparable to young (Y) individuals). In hippocampal slices of these 3 aged groups (Y, AI, AU), we found that compared to the young, the miniature excitatory and inhibitory currents (mEPSCs and mIPSCs) were larger in amplitude in the granule cells of the AU group and smaller in the AI group. In contrast, in CA1 cells, neither the mEPSCs nor the mIPSCs were affected by age, whereas the extrasynaptic conductance responsible for tonic inhibition was selectively enhanced in CA1 cells of AU individuals. Tonic inhibition conductance was not affected by age in the granule cells. These results support the notion that upregulation of synaptic inhibition could be a necessary condition for the maintenance of performance during aging. These findings also underscore the notions that successful aging requires adaptive upregulation, not merely the preservation of youthful functionality, and that age effects are not homogeneous across hippocampal subfields.
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Affiliation(s)
- Trinh Tran
- Mind/Brain Institute and Department of Neurosciences, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA.
| | - Alfredo Kirkwood
- Mind/Brain Institute and Department of Neurosciences, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA.
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28
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Reagh ZM, Noche JA, Tustison NJ, Delisle D, Murray EA, Yassa MA. Functional Imbalance of Anterolateral Entorhinal Cortex and Hippocampal Dentate/CA3 Underlies Age-Related Object Pattern Separation Deficits. Neuron 2018; 97:1187-1198.e4. [PMID: 29518359 PMCID: PMC5937538 DOI: 10.1016/j.neuron.2018.01.039] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 12/20/2017] [Accepted: 01/19/2018] [Indexed: 02/08/2023]
Abstract
The entorhinal cortex (EC) is among the earliest brain areas to deteriorate in Alzheimer's disease (AD). However, the extent to which functional properties of the EC are altered in the aging brain, even in the absence of clinical symptoms, is not understood. Recent human fMRI studies have identified a functional dissociation within the EC, similar to what is found in rodents. Here, we used high-resolution fMRI to identify a specific hypoactivity in the anterolateral EC (alEC) commensurate with major behavioral deficits on an object pattern separation task in asymptomatic older adults. Only subtle deficits were found in a comparable spatial condition, with no associated differences in posteromedial EC between young and older adults. We additionally linked this condition to dentate/CA3 hyperactivity, and the ratio of activity between the regions was associated with object mnemonic discrimination impairment. These results provide novel evidence of alEC-dentate/CA3 circuit dysfunction in cognitively normal aged humans.
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Affiliation(s)
- Zachariah M Reagh
- Department of Neurology, Center for Neuroscience, University of California Davis, Davis, CA 95616, USA.
| | - Jessica A Noche
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, UC Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697, USA
| | - Nicholas J Tustison
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA 22904, USA
| | - Derek Delisle
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, UC Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697, USA
| | - Elizabeth A Murray
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, UC Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697, USA
| | - Michael A Yassa
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, UC Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA 92697, USA.
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29
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Shabani S, Farbood Y, Mard SA, Sarkaki A, Ahangarpour A, Khorsandi L. The regulation of pituitary-thyroid abnormalities by peripheral administration of levothyroxine increased brain-derived neurotrophic factor and reelin protein expression in an animal model of Alzheimer’s disease. Can J Physiol Pharmacol 2018; 96:275-280. [DOI: 10.1139/cjpp-2016-0434] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Alzheimer’s disease (AD) is associated with decreased serum levels of thyroid hormones (THs), increased levels of thyroid-stimulating hormone (TSH), and decreased protein expression of brain-derived neurotrophic factor (BDNF) and reelin in the hippocampus. In this study, we have evaluated the effect of subcutaneous administration of levothyroxine (L-T4) on levels of THs and TSH as well as protein expression of BDNF and reelin in AD rats. To make an animal model of AD, amyloid-beta peptide (Aβ) plus ibotenic acid were infused intrahippocampally, and rats were treated with L-T4 and (or) saline for 10 days. The levels of THs and TSH were measured by ELISA kits. Protein synthesis was detected by Western blotting method. Results have been shown that serum level of THs, BDNF, and reelin protein expression in the hippocampus were significantly decreased (P < 0.001) in AD animals and elevated significantly in AD rats treated with L-T4 (P < 0.01). Data showed that TSH level significantly decreased in AD rats treated with L-T4 (P < 0.05). These findings indicated that L-T4 increased BDNF and reelin protein expression by regulation of serum THs and TSH level in Aβ-induced AD rats.
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Affiliation(s)
- Sahreh Shabani
- Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Yaghoob Farbood
- Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Seyyed Ali Mard
- Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Alireza Sarkaki
- Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Akram Ahangarpour
- Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Science, Ahvaz, Iran
| | - Layasadat Khorsandi
- Cellular & Molecular Research Center, Department of Anatomical Sciences, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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30
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Leal SL, Yassa MA. Integrating new findings and examining clinical applications of pattern separation. Nat Neurosci 2018; 21:163-173. [PMID: 29371654 PMCID: PMC5898810 DOI: 10.1038/s41593-017-0065-1] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 10/28/2017] [Indexed: 11/09/2022]
Abstract
Pattern separation, the ability to independently represent and store similar experiences, is a crucial facet of episodic memory. Growing evidence suggests that the hippocampus possesses unique circuitry that is computationally capable of resolving mnemonic interference by using pattern separation. In this Review, we discuss recent advances in the understanding of this process and evaluate the caveats and limitations of linking across animal and human studies. We summarize clinical and translational studies using methods that are sensitive to pattern separation impairments, an approach that stems from the fact that the hippocampus is a major site of disruption in many brain disorders. We critically evaluate the assumptions that guide fundamental and translational studies in this area. Finally, we suggest guidelines for future research and offer ways to overcome potential interpretational challenges to increase the utility of pattern separation as a construct that can further understanding of both memory processes and brain disease.
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Affiliation(s)
- Stephanie L Leal
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Michael A Yassa
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, USA.
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31
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Horwitz A, Mortensen EL, Osler M, Fagerlund B, Lauritzen M, Benedek K. Passive Double-Sensory Evoked Coherence Correlates with Long-Term Memory Capacity. Front Hum Neurosci 2017; 11:598. [PMID: 29311868 PMCID: PMC5735981 DOI: 10.3389/fnhum.2017.00598] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/24/2017] [Indexed: 01/22/2023] Open
Abstract
HIGHLIGHTS Memory correlates with the difference between single and double-sensory evoked steady-state coherence in the gamma range (ΔC).The correlation is most pronounced for the anterior brain region (ΔCA ).The correlation is not driven by birth size, education, speed of processing, or intelligence.The sensitivity of ΔCA for detecting low memory capacity is 90%. Cerebral rhythmic activity and oscillations are important pathways of communication between cortical cell assemblies and may be key factors in memory. We asked whether memory performance is related to gamma coherence in a non-task sensory steady-state stimulation. We investigated 40 healthy males born in 1953 who were part of a Danish birth cohort study. Coherence was measured in the gamma range in response to a single-sensory visual stimulation (36 Hz) and a double-sensory combined audiovisual stimulation (auditive: 40 Hz; visual: 36 Hz). The individual difference in coherence (ΔC) between the bimodal and monomodal stimulation was calculated for each subject and used as the main explanatory variable. ΔC in total brain were significantly negatively correlated with long-term verbal recall. This correlation was pronounced for the anterior region. In addition, the correlation between ΔC and long-term memory was robust when controlling for working memory, as well as a wide range of potentially confounding factors, including intelligence, length of education, speed of processing, visual attention and executive function. Moreover, we found that the difference in anterior coherence (ΔCA ) is a better predictor of memory than power in multivariate models. The sensitivity of ΔCA for detecting low memory capacity is 92%. Finally, ΔCA was also associated with other types of memory: verbal learning, visual recognition, and spatial memory, and these additional correlations were also robust enough to control for a range of potentially confounding factors. Thus, the ΔC is a predictor of memory performance may be useful in cognitive neuropsychological testing.
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Affiliation(s)
- Anna Horwitz
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology, Rigshospitalet - Glostrup, Glostrup, Denmark
| | - Erik L Mortensen
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.,Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Merete Osler
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark.,Research Center for Prevention and Health, Rigshospitalet - Glostrup, Glostrup, Denmark
| | - Birgitte Fagerlund
- Center for Neuropsychiatric Schizophrenia Research, Psychiatric Center Glostrup, Glostrup, Denmark.,Center for Clinical Intervention and Neuropsychiatric Schizophrenia Research, Psychiatric Center Glostrup, Glostrup, Denmark
| | - Martin Lauritzen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology, Rigshospitalet - Glostrup, Glostrup, Denmark
| | - Krisztina Benedek
- Department of Clinical Neurophysiology, Rigshospitalet - Glostrup, Glostrup, Denmark
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32
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Haberman RP, Branch A, Gallagher M. Targeting Neural Hyperactivity as a Treatment to Stem Progression of Late-Onset Alzheimer's Disease. Neurotherapeutics 2017; 14:662-676. [PMID: 28560709 PMCID: PMC5509635 DOI: 10.1007/s13311-017-0541-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sporadic late-onset Alzheimer's disease (LOAD), the most common form of dementia in the elderly, causes progressive and severe loss of cognitive abilities. With greater numbers of people living to advanced ages, LOAD will increasingly burden both the healthcare system and society. There are currently no available disease-modifying therapies, and the failure of several recent pathology-based strategies has highlighted the urgent need for effective therapeutic targets. With aging as the greatest risk factor for LOAD, targeting mechanisms by which aging contributes to disease could prove an effective strategy to delay progression to clinical dementia by intervention in elderly individuals in an early prodromal stage of disease. Excess neural activity in the hippocampus, a recently described phenomenon associated with age-dependent memory loss, was first identified in animal models of aging and subsequently translated to clinical conditions of aging and early-stage LOAD. Critically, elevated activity was similarly localized to specific circuits within the hippocampal formation in aged animals and humans. Here we review evidence for hippocampal hyperactivity as a significant contributor to age-dependent cognitive decline and the progressive accumulation of pathology in LOAD. We also describe studies demonstrating the efficacy of reducing hyperactivity with an initial test therapy, levetiracetam (Keppra), an atypical antiepileptic. By targeting excess neural activity, levetiracetam may improve cognition and attenuate the accumulation of pathology contributing to progression to the dementia phase of LOAD.
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Affiliation(s)
- Rebecca P Haberman
- Department of Psychological and Brain Sciences, The Johns Hopkins University, 3400 North Charles Street, 116 Dunning Hall, Baltimore, MD, 21218, USA.
| | - Audrey Branch
- Department of Psychological and Brain Sciences, The Johns Hopkins University, 3400 North Charles Street, 116 Dunning Hall, Baltimore, MD, 21218, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, The Johns Hopkins University, 3400 North Charles Street, 116 Dunning Hall, Baltimore, MD, 21218, USA
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33
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Dey A, Hao S, Wosiski-Kuhn M, Stranahan AM. Glucocorticoid-mediated activation of GSK3β promotes tau phosphorylation and impairs memory in type 2 diabetes. Neurobiol Aging 2017; 57:75-83. [PMID: 28609678 DOI: 10.1016/j.neurobiolaging.2017.05.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 04/04/2017] [Accepted: 05/11/2017] [Indexed: 12/17/2022]
Abstract
Type 2 diabetes is increasingly recognized as a risk factor for Alzheimer's disease, but the underlying mechanisms remain poorly understood. Hyperphosphorylation of the microtubule-associated protein tau has been reported in rodent models of diabetes, including db/db mice, which exhibit insulin resistance and chronically elevated glucocorticoids due to leptin receptor insufficiency. In this report, we investigated endocrine mechanisms for hippocampal tau phosphorylation in db/db and wild-type mice. By separately manipulating peripheral and intrahippocampal corticosterone levels, we determined that hippocampal corticosteroid exposure promotes tau phosphorylation and activates glycogen synthase kinase 3β (GSK3β). Subsequent experiments in hippocampal slice preparations revealed evidence for a nongenomic interaction between glucocorticoids and GSK3β. To examine whether GSK3β activation mediates tau phosphorylation and impairs memory in diabetes, db/db and wild-type mice received intrahippocampal infusions of TDZD-8, a non-ATP competitive thiadiazolidinone inhibitor of GSK3β. Intrahippocampal TDZD-8 blocked tau hyperphosphorylation and normalized hippocampus-dependent memory in db/db mice, suggesting that pathological synergy between diabetes and Alzheimer's disease may involve glucocorticoid-mediated activation of GSK3β.
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Affiliation(s)
- Aditi Dey
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Shuai Hao
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Marlena Wosiski-Kuhn
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Alexis M Stranahan
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA.
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34
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Abstract
As the world's population continues to age, an understanding of the aging brain becomes increasingly crucial. This review focuses on several recent ideas and findings in the study of neurocognitive aging, specifically focusing on episodic memory, and discusses how they can be considered and used to guide us moving forward. Topics include dysfunction in neural circuits, the roles of neurogenesis and inhibitory signaling, vulnerability in the entorhinal cortex, individual differences, and comorbidities. These avenues of study provide a brief overview of promising themes in the field and together provide a snapshot of what we believe will be important emerging topics in selective vulnerabilities in the aging brain.
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Affiliation(s)
- Zachariah Reagh
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Michael Yassa
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
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35
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Horwitz A, Dyhr Thomsen M, Wiegand I, Horwitz H, Klemp M, Nikolic M, Rask L, Lauritzen M, Benedek K. Visual steady state in relation to age and cognitive function. PLoS One 2017; 12:e0171859. [PMID: 28245274 PMCID: PMC5330460 DOI: 10.1371/journal.pone.0171859] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 01/26/2017] [Indexed: 12/25/2022] Open
Abstract
Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age.
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Affiliation(s)
- Anna Horwitz
- Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3, Copenhagen, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
- * E-mail:
| | - Mia Dyhr Thomsen
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
| | - Iris Wiegand
- Department of Psychology, University of Copenhagen, Øster Farimagsgade 2A, Copenhagen, Denmark
| | - Henrik Horwitz
- Department of Clinical Pharmacology, Bispebjerg Hospital, Bispebjerg Bakke 23, København NV, Denmark
| | - Marc Klemp
- Department of Economics and Population Studies & Training Center, Brown University, Providence, Rhode Island, United States of America
- Department of Economics, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, Denmark
| | - Miki Nikolic
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
| | - Lene Rask
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
| | - Martin Lauritzen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Blegdamsvej 3, Copenhagen, Denmark
- Center for Healthy Aging, University of Copenhagen, Blegdamsvej 3, Copenhagen, Denmark
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
| | - Krisztina Benedek
- Department of Clinical Neurophysiology, Rigshospitalet–Glostrup, Nordre Ringvej 57, Glostrup, Denmark
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36
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Traffic-Related Air Pollution and Neurodegenerative Diseases: Epidemiological and Experimental Evidence, and Potential Underlying Mechanisms. ADVANCES IN NEUROTOXICOLOGY 2017. [DOI: 10.1016/bs.ant.2017.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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37
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Mata A, Urrea L, Vilches S, Llorens F, Thüne K, Espinosa JC, Andréoletti O, Sevillano AM, Torres JM, Requena JR, Zerr I, Ferrer I, Gavín R, Del Río JA. Reelin Expression in Creutzfeldt-Jakob Disease and Experimental Models of Transmissible Spongiform Encephalopathies. Mol Neurobiol 2016; 54:6412-6425. [PMID: 27726110 DOI: 10.1007/s12035-016-0177-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/28/2016] [Indexed: 12/22/2022]
Abstract
Reelin is an extracellular glycoprotein involved in key cellular processes in developing and adult nervous system, including regulation of neuronal migration, synapse formation, and plasticity. Most of these roles are mediated by the intracellular phosphorylation of disabled-1 (Dab1), an intracellular adaptor molecule, in turn mediated by binding Reelin to its receptors. Altered expression and glycosylation patterns of Reelin in cerebrospinal and cortical extracts have been reported in Alzheimer's disease. However, putative changes in Reelin are not described in natural prionopathies or experimental models of prion infection or toxicity. With this is mind, in the present study, we determined that Reelin protein and mRNA levels increased in CJD human samples and in mouse models of human prion disease in contrast to murine models of prion infection. However, changes in Reelin expression appeared only at late terminal stages of the disease, which prevent their use as an efficient diagnostic biomarker. In addition, increased Reelin in CJD and in in vitro models does not correlate with Dab1 phosphorylation, indicating failure in its intracellular signaling. Overall, these findings widen our understanding of the putative changes of Reelin in neurodegeneration.
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Affiliation(s)
- Agata Mata
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Laura Urrea
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Silvia Vilches
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Franc Llorens
- Department of Neurology, German Center for Neurodegenerative Diseases - DZNE, Universitätsmedizin Göttingen, Bonn, Germany
| | - Katrin Thüne
- Department of Neurology, German Center for Neurodegenerative Diseases - DZNE, Universitätsmedizin Göttingen, Bonn, Germany
| | - Juan-Carlos Espinosa
- Centro de Investigación en Sanidad Animal (CISA-INIA), Madrid, Valdeolmos, Spain
| | - Olivier Andréoletti
- UMR INRA ENVT 1225, Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076, Toulouse, France
| | - Alejandro M Sevillano
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782, Santiago de Compostela, Spain
- Department of Medicine, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Juan María Torres
- Centro de Investigación en Sanidad Animal (CISA-INIA), Madrid, Valdeolmos, Spain
| | - Jesús Rodríguez Requena
- CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782, Santiago de Compostela, Spain
- Department of Medicine, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Inga Zerr
- Department of Neurology, German Center for Neurodegenerative Diseases - DZNE, Universitätsmedizin Göttingen, Bonn, Germany
| | - Isidro Ferrer
- Institut de Neuropatologia, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Rosalina Gavín
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - José Antonio Del Río
- Molecular and Cellular Neurobiotechnology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, Baldiri Reixac 15-21, 08028, Barcelona, Spain.
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain.
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain.
- Institute of Neuroscience, University of Barcelona, Barcelona, Spain.
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Leal SL, Noche JA, Murray EA, Yassa MA. Age-related individual variability in memory performance is associated with amygdala-hippocampal circuit function and emotional pattern separation. Neurobiol Aging 2016; 49:9-19. [PMID: 27723500 DOI: 10.1016/j.neurobiolaging.2016.08.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 12/27/2022]
Abstract
While aging is generally associated with episodic memory decline, not all older adults exhibit memory loss. Furthermore, emotional memories are not subject to the same extent of forgetting and appear preserved in aging. We conducted high-resolution fMRI during a task involving pattern separation of emotional information in older adults with and without age-related memory impairment (characterized by performance on a word-list learning task: low performers: LP vs. high performers: HP). We found signals consistent with emotional pattern separation in hippocampal dentate (DG)/CA3 in HP but not in LP individuals, suggesting a deficit in emotional pattern separation. During false recognition, we found increased DG/CA3 activity in LP individuals, suggesting that hyperactivity may be associated with overgeneralization. We additionally observed a selective deficit in basolateral amygdala-lateral entorhinal cortex-DG/CA3 functional connectivity in LP individuals during pattern separation of negative information. During negative false recognition, LP individuals showed increased medial temporal lobe functional connectivity, consistent with overgeneralization. Overall, these results suggest a novel mechanistic account of individual differences in emotional memory alterations exhibited in aging.
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Affiliation(s)
- Stephanie L Leal
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA; Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Jessica A Noche
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Elizabeth A Murray
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | - Michael A Yassa
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA.
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Leal SL, Noche JA, Murray EA, Yassa MA. Positivity effect specific to older adults with subclinical memory impairment. ACTA ACUST UNITED AC 2016; 23:415-21. [PMID: 27421893 PMCID: PMC4947236 DOI: 10.1101/lm.042010.116] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/18/2016] [Indexed: 11/24/2022]
Abstract
Numerous studies have suggested that older adults preferentially remember positive information (“positivity effect”), however others have reported mixed results. One potential source of conflict is that aging is not a unitary phenomenon and individual differences exist. We modified a standard neuropsychological test to vary emotional content and tested memory at three time points (immediate/20 min/1 wk). Cognitively normal older adults were stratified into those with and without subclinical memory impairment. We found that the positivity effect was limited to those with subclinical memory impairment, suggesting that consideration of subclinical memory impairment is necessary for understanding age-related emotional memory alterations.
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Affiliation(s)
- Stephanie L Leal
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92697, USA Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Jessica A Noche
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92697, USA
| | - Elizabeth A Murray
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92697, USA
| | - Michael A Yassa
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California 92697, USA
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40
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Botterill JJ, Nogovitsyn N, Caruncho HJ, Kalynchuk LE. Selective plasticity of hippocampal GABAergic interneuron populations following kindling of different brain regions. J Comp Neurol 2016; 525:389-406. [PMID: 27362579 DOI: 10.1002/cne.24071] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/06/2016] [Accepted: 06/28/2016] [Indexed: 12/20/2022]
Abstract
The vulnerability and plasticity of hippocampal GABAergic interneurons is a topic of broad interest and debate in the field of epilepsy. In this experiment, we used the electrical kindling model of epilepsy to determine whether seizures that originate in different brain regions have differential effects on hippocampal interneuron subpopulations. Long-Evans rats received 99 electrical stimulations of the hippocampus, amygdala, or caudate nucleus, followed by sacrifice and immunohistochemical or western blot analyses. We analyzed markers of dendritic (somatostatin), perisomatic (parvalbumin), and interneuron-selective (calretinin) inhibition, as well as an overall indicator (GAD67) of interneuron distribution across all major hippocampal subfields. Our results indicate that kindling produces selective effects on the number and morphology of different functional classes of GABAergic interneurons. In particular, limbic kindling appears to enhance dendritic inhibition, indicated by a greater number of somatostatin-immunoreactive (-ir) cells in the CA1 pyramidal layer and robust morphological sprouting in the dentate gyrus. We also found a reduction in the number of interneuron-selective calretinin-ir cells in the dentate gyrus of hippocampal-kindled rats, which suggests a possible reduction of synchronized dendritic inhibition. In contrast, perisomatic inhibition indicated by parvalbumin immunoreactivity appears to be largely resilient to the effects of kindling. Finally, we found a significant induction in the number of GAD67-cells in caudate-kindled rats in the dentate gyrus and CA3 hippocampal subfields. Taken together, our results demonstrate that kindling has subfield-selective effects on the different functional classes of hippocampal GABAergic interneurons. J. Comp. Neurol. 525:389-406, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- J J Botterill
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, Canada
| | - N Nogovitsyn
- Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - H J Caruncho
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada
| | - L E Kalynchuk
- Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Cuchillo-Ibañez I, Balmaceda V, Mata-Balaguer T, Lopez-Font I, Sáez-Valero J. Reelin in Alzheimer’s Disease, Increased Levels but Impaired Signaling: When More is Less. J Alzheimers Dis 2016; 52:403-16. [DOI: 10.3233/jad-151193] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Inmaculada Cuchillo-Ibañez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d’Alacant, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Valeria Balmaceda
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d’Alacant, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Trinidad Mata-Balaguer
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d’Alacant, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Inmaculada Lopez-Font
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d’Alacant, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Javier Sáez-Valero
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d’Alacant, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
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Reagh ZM, Ho HD, Leal SL, Noche JA, Chun A, Murray EA, Yassa MA. Greater loss of object than spatial mnemonic discrimination in aged adults. Hippocampus 2016; 26:417-22. [PMID: 26691235 PMCID: PMC5918289 DOI: 10.1002/hipo.22562] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2015] [Indexed: 11/12/2022]
Abstract
Previous studies across species have established that the aging process adversely affects certain memory-related brain regions earlier than others. Behavioral tasks targeted at the function of vulnerable regions can provide noninvasive methods for assessing the integrity of particular components of memory throughout the lifespan. The present study modified a previous task designed to separately but concurrently test detailed memory for object identity and spatial location. Memory for objects or items is thought to rely on perirhinal and lateral entorhinal cortices, among the first targets of Alzheimer's related neurodegeneration. In line with prior work, we split an aged adult sample into "impaired" and "unimpaired" groups on the basis of a standardized word-learning task. The "impaired" group showed widespread difficulty with memory discrimination, whereas the "unimpaired" group showed difficulty with object, but not spatial memory discrimination. These findings support the hypothesized greater age-related impacts on memory for objects or items in older adults, perhaps even with healthy aging. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Zachariah M Reagh
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
| | - Huy D Ho
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
| | - Stephanie L Leal
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
- Department of Psychological and Brain Sciences, Johns Hopkins University
| | - Jessica A Noche
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
| | - Amanda Chun
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
| | - Elizabeth A Murray
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
| | - Michael A Yassa
- Department of Neurobiology and Behavior, UC Institute for Memory Impairments and Neurological Disorders, Center for the Neurobiology of Learning and Memory, University of California, Irvine
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Lussier AL, Weeber EJ, Rebeck GW. Reelin Proteolysis Affects Signaling Related to Normal Synapse Function and Neurodegeneration. Front Cell Neurosci 2016; 10:75. [PMID: 27065802 PMCID: PMC4809875 DOI: 10.3389/fncel.2016.00075] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/11/2016] [Indexed: 01/13/2023] Open
Abstract
Reelin is a neurodevelopmental protein important in adult synaptic plasticity and learning and memory. Recent evidence points to the importance for Reelin proteolysis in normal signaling and in cognitive function. Support for the dysfunction of Reelin proteolysis in neurodegeneration and cognitive dysfunction comes from postmortem analysis of Alzheimer’s diseases (AD) tissues including cerebral spinal fluid (CSF), showing that levels of Reelin fragments are altered in AD compared to control. Potential key proteases involved in Reelin proteolysis have recently been defined, identifying processes that could be altered in neurodegeneration. Introduction of full-length Reelin and its proteolytic fragments into several mouse models of neurodegeneration and neuropsychiatric disorders quickly promote learning and memory. These findings support a role for Reelin in learning and memory and suggest further understanding of these processes are important to harness the potential of this pathway in treating cognitive symptoms in neuropsychiatric and neurodegenerative diseases.
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Affiliation(s)
- April L Lussier
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Disease Institute, University of South Florida Tampa, FL, USA
| | - Edwin J Weeber
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Disease Institute, University of South Florida Tampa, FL, USA
| | - G William Rebeck
- Department of Neuroscience, Georgetown University Washington, DC, USA
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Morphometric analysis of the age-related changes of synaptophysin immunoreactivity in the human parahippocampal region. J ANAT SOC INDIA 2015. [DOI: 10.1016/j.jasi.2015.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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45
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Neurocognitive Aging and the Hippocampus across Species. Trends Neurosci 2015; 38:800-812. [PMID: 26607684 DOI: 10.1016/j.tins.2015.10.003] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/27/2015] [Accepted: 10/18/2015] [Indexed: 11/23/2022]
Abstract
There is extensive evidence that aging is associated with impairments in episodic memory. Many of these changes have been ascribed to neurobiological alterations to the hippocampal network and its input pathways. A cross-species consensus is beginning to emerge suggesting that subtle synaptic and functional changes within this network may underlie the majority of age-related memory impairments. In this review we survey convergent data from animal and human studies that have contributed significantly to our understanding of the brain-behavior relationships in this network, particularly in the aging brain. We utilize a cognitive as well as a neurobiological perspective and synthesize data across approaches and species to reach a more detailed understanding of age-related alterations in hippocampal memory function.
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Yang YJ, Chen HB, Wei B, Wang W, Zhou PL, Zhan JQ, Hu MR, Yan K, Hu B, Yu B. Cognitive decline is associated with reduced surface GluR1 expression in the hippocampus of aged rats. Neurosci Lett 2015; 591:176-181. [DOI: 10.1016/j.neulet.2015.02.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/27/2015] [Accepted: 02/13/2015] [Indexed: 10/24/2022]
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47
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Bakker A, Albert MS, Krauss G, Speck CL, Gallagher M. Response of the medial temporal lobe network in amnestic mild cognitive impairment to therapeutic intervention assessed by fMRI and memory task performance. NEUROIMAGE-CLINICAL 2015; 7:688-98. [PMID: 25844322 PMCID: PMC4377841 DOI: 10.1016/j.nicl.2015.02.009] [Citation(s) in RCA: 204] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Studies of individuals with amnestic mild cognitive impairment (aMCI) have detected hyperactivity in the hippocampus during task-related functional magnetic resonance imaging (fMRI). Such elevated activation has been localized to the hippocampal dentate gyrus/CA3 (DG/CA3) during performance of a task designed to detect the computational contributions of those hippocampal circuits to episodic memory. The current investigation was conducted to test the hypothesis that greater hippocampal activation in aMCI represents a dysfunctional shift in the normal computational balance of the DG/CA3 regions, augmenting CA3-driven pattern completion at the expense of pattern separation mediated by the dentate gyrus. We tested this hypothesis using an intervention based on animal research demonstrating a beneficial effect on cognition by reducing excess hippocampal neural activity with low doses of the atypical anti-epileptic levetiracetam. In a within-subject design we assessed the effects of levetiracetam in three cohorts of aMCI participants, each receiving a different dose of levetiracetam. Elevated activation in the DG/CA3 region, together with impaired task performance, was detected in each aMCI cohort relative to an aged control group. We observed significant improvement in memory task performance under drug treatment relative to placebo in the aMCI cohorts at the 62.5 and 125 mg BID doses of levetiracetam. Drug treatment in those cohorts increased accuracy dependent on pattern separation processes and reduced errors attributable to an over-riding effect of pattern completion while normalizing fMRI activation in the DG/CA3 and entorhinal cortex. Similar to findings in animal studies, higher dosing at 250 mg BID had no significant benefit on either task performance or fMRI activation. Consistent with predictions based on the computational functions of the DG/CA3 elucidated in basic animal research, these data support a dysfunctional encoding mechanism detected by fMRI in individuals with aMCI and therapeutic intervention using fMRI to detect target engagement in response to treatment. Patients with aMCI show increased fMRI activation in DG/CA3 relative to controls. Low dose levetiracetam treatment decreases excess DG/CA3 activation in aMCI. Low dose levetiracetam treatment normalizes decreased entorhinal activation in aMCI. Low dose levetiracetam treatment improves task related memory performance in aMCI. Targeting excess hippocampal activity has therapeutic potential in amnestic MCI.
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Affiliation(s)
- Arnold Bakker
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Marilyn S Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Gregory Krauss
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Caroline L Speck
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins School of Arts and Sciences, Baltimore, MD 21218, USA
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Spiegel AM, Sewal AS, Rapp PR. Epigenetic contributions to cognitive aging: disentangling mindspan and lifespan. ACTA ACUST UNITED AC 2014; 21:569-74. [PMID: 25227252 PMCID: PMC4175498 DOI: 10.1101/lm.033506.113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Epigenetic modifications of chromatin structure provide a mechanistic interface for gene–environment interactions that impact the individualization of health trajectories across the lifespan. A growing body of research indicates that dysfunctional epigenetic regulation contributes to poor cognitive outcomes among aged populations. Here we review neuroepigenetic research as it relates to cognitive aging, focusing specifically on memory function mediated by the hippocampal system. Recent work that differentiates epigenetic contributions to chronological aging from influences on mindspan, or the preservation of normal cognitive abilities across the lifespan, is also highlighted. Together, current evidence indicates that while age-related memory impairment is associated with dysfunction in the coordinated regulation of chromatin modification, animal models that show individual differences in cognitive outcome underscore the enormous mechanistic complexity that surrounds epigenetic dynamics in the aged hippocampus.
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Affiliation(s)
- Amy M Spiegel
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224, USA
| | - Angila S Sewal
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224, USA
| | - Peter R Rapp
- Neurocognitive Aging Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224, USA
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He F, Lupu DS, Niculescu MD. Perinatal α-linolenic acid availability alters the expression of genes related to memory and to epigenetic machinery, and the Mecp2 DNA methylation in the whole brain of mouse offspring. Int J Dev Neurosci 2014; 36:38-44. [PMID: 24866706 DOI: 10.1016/j.ijdevneu.2014.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/15/2014] [Accepted: 05/15/2014] [Indexed: 01/07/2023] Open
Abstract
Many animal and human studies indicated that dietary ω-3 fatty acids could have beneficial roles on brain development, memory, and learning. However, the exact mechanisms involved are far from being clearly understood, especially for α-linolenic acid (ALA), which is the precursor for the ω-3 elongation and desaturation pathways. This study investigated the alterations induced by different intakes of flaxseed oil (containing 50% ALA), during gestation and lactation, upon the expression of genes involved in neurogenesis, memory-related molecular processes, and DNA methylation, in the brains of mouse offspring at the end of lactation (postnatal day 19, P19). In addition, DNA methylation status for the same genes was investigated. Maternal flaxseed oil supplementation during lactation increased the expression of Mecp2, Ppp1cc, and Reelin, while decreasing the expression of Ppp1cb and Dnmt3a. Dnmt1 expression was decreased by postnatal flaxseed oil supplementation but this effect was offset by ALA deficiency during gestation. Mecp2 DNA methylation was decreased by maternal ALA deficiency during gestation, with a more robust effect in the lactation-deficient group. In addition, linear regression analysis revealed positive correlations between Mecp2, Reelin, and Ppp1cc, between Gadd45b, Bdnf, and Creb1, and between Egr1 and Dnmt1, respectively. However, there were no correlations, in any gene, between DNA methylation and gene expression. In summary, the interplay between ALA availability during gestation and lactation differentially altered the expression of genes involved in neurogenesis and memory, in the whole brain of the offspring at the end of lactation. The Mecp2 epigenetic status was correlated with ALA availability during gestation. However, the epigenetic status of the genes investigated was not associated with transcript levels, suggesting that either the regulation of these genes is not necessarily under epigenetic control, or that the whole brain model is not adequate for the exploration of epigenetic regulation in the context of this study.
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Affiliation(s)
- Fuli He
- Department of Nutrition and Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
| | - Daniel S Lupu
- Department of Nutrition and Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
| | - Mihai D Niculescu
- Department of Nutrition and Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA.
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Abstract
Adipose tissue is a known source of proinflammatory cytokines in obese humans and animal models, including the db/db mouse, in which obesity arises as a result of leptin receptor insensitivity. Inflammatory cytokines induce cognitive deficits across numerous conditions, but no studies have determined whether obesity-induced inflammation mediates synaptic dysfunction. To address this question, we used a treadmill training paradigm in which mice were exposed to daily training sessions or an immobile belt, with motivation achieved by delivery of compressed air on noncompliance. Treadmill training prevented hippocampal microgliosis, abolished expression of microglial activation markers, and also blocked the functional sensitization observed in isolated cells after ex vivo exposure to lipopolysaccharide. Reduced microglial reactivity with exercise was associated with reinstatement of hippocampus-dependent memory, reversal of deficits in long-term potentiation, and normalization of hippocampal dendritic spine density. Because treadmill training evokes broad responses not limited to the immune system, we next assessed whether directly manipulating adiposity through lipectomy and fat transplantation influences inflammation, cognition, and synaptic plasticity. Lipectomy prevents and fat transplantation promotes systemic and central inflammation, with associated alterations in cognitive and synaptic function. Levels of interleukin 1β (IL1β) emerged as a correlate of adiposity and cognitive impairment across both the treadmill and lipectomy studies, so we manipulated hippocampal IL1 signaling using intrahippocampal delivery of IL1 receptor antagonist (IL1ra). Intrahippocampal IL1ra prevented synaptic dysfunction, proinflammatory priming, and cognitive impairment. This pattern supports a central role for IL1-mediated neuroinflammation as a mechanism for cognitive deficits in obesity and diabetes.
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