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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] [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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Navakkode S, Kennedy BK. Neural ageing and synaptic plasticity: prioritizing brain health in healthy longevity. Front Aging Neurosci 2024; 16:1428244. [PMID: 39161341 PMCID: PMC11330810 DOI: 10.3389/fnagi.2024.1428244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 07/24/2024] [Indexed: 08/21/2024] Open
Abstract
Ageing is characterized by a gradual decline in the efficiency of physiological functions and increased vulnerability to diseases. Ageing affects the entire body, including physical, mental, and social well-being, but its impact on the brain and cognition can have a particularly significant effect on an individual's overall quality of life. Therefore, enhancing lifespan and physical health in longevity studies will be incomplete if cognitive ageing is over looked. Promoting successful cognitive ageing encompasses the objectives of mitigating cognitive decline, as well as simultaneously enhancing brain function and cognitive reserve. Studies in both humans and animal models indicate that cognitive decline related to normal ageing and age-associated brain disorders are more likely linked to changes in synaptic connections that form the basis of learning and memory. This activity-dependent synaptic plasticity reorganises the structure and function of neurons not only to adapt to new environments, but also to remain robust and stable over time. Therefore, understanding the neural mechanisms that are responsible for age-related cognitive decline becomes increasingly important. In this review, we explore the multifaceted aspects of healthy brain ageing with emphasis on synaptic plasticity, its adaptive mechanisms and the various factors affecting the decline in cognitive functions during ageing. We will also explore the dynamic brain and neuroplasticity, and the role of lifestyle in shaping neuronal plasticity.
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Affiliation(s)
- Sheeja Navakkode
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, Centre for Healthy Longevity, National University Health System, National University of Singapore, Singapore, Singapore
- Life Sciences Institute Neurobiology Programme, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
| | - Brian K. Kennedy
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, Centre for Healthy Longevity, National University Health System, National University of Singapore, Singapore, Singapore
- Life Sciences Institute Neurobiology Programme, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Buck Institute for Research on Ageing, Novato, CA, United States
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3
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Meadows SM, Palaguachi F, Jang MW, Licht-Murava A, Barnett D, Zimmer TS, Zhou C, McDonough SR, Orr AL, Orr AG. Hippocampal astrocytes induce sex-dimorphic effects on memory. Cell Rep 2024; 43:114278. [PMID: 38795347 PMCID: PMC11234507 DOI: 10.1016/j.celrep.2024.114278] [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: 10/27/2023] [Revised: 03/19/2024] [Accepted: 05/09/2024] [Indexed: 05/27/2024] Open
Abstract
Astrocytic receptors influence cognitive function and can promote behavioral deficits in disease. These effects may vary based on variables such as biological sex, but it is not known if the effects of astrocytic receptors are dependent on sex. We leveraged in vivo gene editing and chemogenetics to examine the roles of astrocytic receptors in spatial memory and other processes. We show that reductions in metabotropic glutamate receptor 3 (mGluR3), the main astrocytic glutamate receptor in adults, impair memory in females but enhance memory in males. Similarly, increases in astrocytic mGluR3 levels have sex-dependent effects and enhance memory in females. mGluR3 manipulations also alter spatial search strategies during recall in a sex-specific manner. In addition, acute chemogenetic stimulation of Gi/o-coupled or Gs-coupled receptors in hippocampal astrocytes induces bidirectional and sex-dimorphic effects on memory. Thus, astrocytes are sex-dependent modulators of cognitive function and may promote sex differences in aging and disease.
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Affiliation(s)
- Samantha M Meadows
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Fernando Palaguachi
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Minwoo Wendy Jang
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Avital Licht-Murava
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Daniel Barnett
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Till S Zimmer
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Constance Zhou
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10021, USA
| | - Samantha R McDonough
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Adam L Orr
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA
| | - Anna G Orr
- Helen and Robert Appel Alzheimer's Disease Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA; Neuroscience Graduate Program, Weill Cornell Medicine, New York, NY 10021, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10021, USA.
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4
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Herber CS, Pratt KJ, Shea JM, Villeda SA, Giocomo LM. Spatial Coding Dysfunction and Network Instability in the Aging Medial Entorhinal Cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.588890. [PMID: 38659809 PMCID: PMC11042240 DOI: 10.1101/2024.04.12.588890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Across species, spatial memory declines with age, possibly reflecting altered hippocampal and medial entorhinal cortex (MEC) function. However, the integrity of cellular and network-level spatial coding in aged MEC is unknown. Here, we leveraged in vivo electrophysiology to assess MEC function in young, middle-aged, and aged mice navigating virtual environments. In aged grid cells, we observed impaired stabilization of context-specific spatial firing, correlated with spatial memory deficits. Additionally, aged grid networks shifted firing patterns often but with poor alignment to context changes. Aged spatial firing was also unstable in an unchanging environment. In these same mice, we identified 458 genes differentially expressed with age in MEC, 61 of which had expression correlated with spatial firing stability. These genes were enriched among interneurons and related to synaptic transmission. Together, these findings identify coordinated transcriptomic, cellular, and network changes in MEC implicated in impaired spatial memory in aging.
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Affiliation(s)
- Charlotte S. Herber
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
| | - Karishma J.B. Pratt
- Department of Anatomy, University of California San Francisco, 513 Parnassus Avenue, Box 0452, San Francisco, CA, 94143, USA
- These authors contributed equally
| | - Jeremy M. Shea
- Department of Anatomy, University of California San Francisco, 513 Parnassus Avenue, Box 0452, San Francisco, CA, 94143, USA
- These authors contributed equally
| | - Saul A. Villeda
- Department of Anatomy, University of California San Francisco, 513 Parnassus Avenue, Box 0452, San Francisco, CA, 94143, USA
- Bakar Aging Research Institute, San Francisco, CA, 94143, USA
| | - Lisa M. Giocomo
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, 94305, USA
- Lead contact
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Almeida VN. Somatostatin and the pathophysiology of Alzheimer's disease. Ageing Res Rev 2024; 96:102270. [PMID: 38484981 DOI: 10.1016/j.arr.2024.102270] [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: 07/18/2023] [Revised: 03/09/2024] [Accepted: 03/09/2024] [Indexed: 03/28/2024]
Abstract
Among the central features of Alzheimer's disease (AD) progression are altered levels of the neuropeptide somatostatin (SST), and the colocalisation of SST-positive interneurons (SST-INs) with amyloid-β plaques, leading to cell death. In this theoretical review, I propose a molecular model for the pathogenesis of AD based on SST-IN hypofunction and hyperactivity. Namely, hypofunctional and hyperactive SST-INs struggle to control hyperactivity in medial regions in early stages, leading to axonal Aβ production through excessive presynaptic GABAB inhibition, GABAB1a/APP complex downregulation and internalisation. Concomitantly, excessive SST-14 release accumulates near SST-INs in the form of amyloids, which bind to Aβ to form toxic mixed oligomers. This leads to differential SST-IN death through excitotoxicity, further disinhibition, SST deficits, and increased Aβ release, fibrillation and plaque formation. Aβ plaques, hyperactive networks and SST-IN distributions thereby tightly overlap in the brain. Conversely, chronic stimulation of postsynaptic SST2/4 on gulutamatergic neurons by hyperactive SST-INs promotes intense Mitogen-Activated Protein Kinase (MAPK) p38 activity, leading to somatodendritic p-tau staining and apoptosis/neurodegeneration - in agreement with a near complete overlap between p38 and neurofibrillary tangles. This model is suitable to explain some of the principal risk factors and markers of AD progression, including mitochondrial dysfunction, APOE4 genotype, sex-dependent vulnerability, overactive glial cells, dystrophic neurites, synaptic/spine losses, inter alia. Finally, the model can also shed light on qualitative aspects of AD neuropsychology, especially within the domains of spatial and declarative (episodic, semantic) memory, under an overlying pattern of contextual indiscrimination, ensemble instability, interference and generalisation.
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Affiliation(s)
- Victor N Almeida
- Institute of Psychiatry, Faculty of Medicine, University of São Paulo (USP), Brazil; Faculty of Languages, Federal University of Minas Gerais (UFMG), Brazil.
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6
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Nagarajan R, Lyu J, Kambali M, Wang M, Courtney CD, Christian-Hinman CA, Rudolph U. Genetic Ablation of Dentate Hilar Somatostatin-Positive GABAergic Interneurons is Sufficient to Induce Cognitive Impairment. Mol Neurobiol 2024; 61:567-580. [PMID: 37642935 PMCID: PMC11285310 DOI: 10.1007/s12035-023-03586-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023]
Abstract
Aging is often associated with a decline in cognitive function. A reduction in the number of somatostatin-positive (SOM+) interneurons in the dentate gyrus (DG) has been described in cognitively impaired but not in unimpaired aged rodents. However, it remains unclear whether the reduction in SOM + interneurons in the DG hilus is causal for age-related cognitive dysfunction. We hypothesized that hilar SOM+ interneurons play an essential role in maintaining cognitive function and that a reduction in the number of hilar SOM + interneurons might be sufficient to induce cognitive dysfunction. Hilar SOM+ interneurons were ablated by expressing a diphtheria toxin transgene specifically in these interneurons, which resulted in a reduction in the number of SOM+ /GAD-67+ neurons and dendritic spine density in the DG. C-fos and Iba-1 immunostainings were increased in DG and CA3, but not CA1, and BDNF protein expression in the hippocampus was decreased. Behavioral testing showed a reduced recognition index in the novel object recognition test, decreased alternations in the Y maze test, and longer latencies and path lengths in the learning and reversal learning phases of the Morris water maze. Our results show that partial genetic ablation of SOM+ hilar interneurons is sufficient to increase activity in DG and CA3, as has been described to occur with aging and to induce an impairment of learning and memory functions. Thus, partial ablation of hilar SOM + interneurons may be a significant contributing factor to age-related cognitive dysfunction. These mice may also be useful as a cellularly defined model of hippocampal aging.
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Affiliation(s)
- Rajasekar Nagarajan
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jinrui Lyu
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Maltesh Kambali
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Muxiao Wang
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Connor D Courtney
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Catherine A Christian-Hinman
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Uwe Rudolph
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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Puthusseryppady V, Cossio D, Chrastil ER. Spatial memory and hippocampal remapping: Who will age well? Proc Natl Acad Sci U S A 2024; 121:e2319952121. [PMID: 38190546 PMCID: PMC10801915 DOI: 10.1073/pnas.2319952121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024] Open
Affiliation(s)
| | - Daniela Cossio
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA92697
| | - Elizabeth R. Chrastil
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA92697
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8
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Hernandez AR, Barrett ME, Lubke KN, Maurer AP, Burke SN. A long-term ketogenic diet in young and aged rats has dissociable effects on prelimbic cortex and CA3 ensemble activity. Front Aging Neurosci 2023; 15:1274624. [PMID: 38155737 PMCID: PMC10753023 DOI: 10.3389/fnagi.2023.1274624] [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: 08/08/2023] [Accepted: 11/20/2023] [Indexed: 12/30/2023] Open
Abstract
Introduction Age-related cognitive decline has been linked to distinct patterns of cellular dysfunction in the prelimbic cortex (PL) and the CA3 subregion of the hippocampus. Because higher cognitive functions require both structures, selectively targeting a neurobiological change in one region, at the expense of the other, is not likely to restore normal behavior in older animals. One change with age that both the PL and CA3 share, however, is a reduced ability to utilize glucose, which can produce aberrant neural activity patterns. Methods The current study used a ketogenic diet (KD) intervention, which reduces the brain's reliance on glucose, and has been shown to improve cognition, as a metabolic treatment for restoring neural ensemble dynamics in aged rats. Expression of the immediate-early genes Arc and Homer1a were used to quantify the neural ensembles that were active in the home cage prior to behavior, during a working memory/biconditional association task, and a continuous spatial alternation task. Results Aged rats on the control diet had increased activity in CA3 and less ensemble overlap in PL between different task conditions than did the young animals. In the PL, the KD was associated with increased activation of neurons in the superficial cortical layers, establishing a clear link between dietary macronutrient content and frontal cortical activity. The KD did not lead to any significant changes in CA3 activity. Discussion These observations suggest that the availability of ketone bodies may permit the engagement of compensatory mechanisms in the frontal cortices that produce better cognitive outcomes.
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Affiliation(s)
- Abbi R. Hernandez
- Division of Gerontology, Geriatrics, and Palliative Care, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Maya E. Barrett
- Department of Psychology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Katelyn N. Lubke
- Department of Neuroscience, McKnight Brain Institute, and Center for Cognitive Aging and Memory, University of Florida, Gainesville, FL, United States
| | - Andrew P. Maurer
- Department of Neuroscience, McKnight Brain Institute, and Center for Cognitive Aging and Memory, University of Florida, Gainesville, FL, United States
| | - Sara N. Burke
- Department of Neuroscience, McKnight Brain Institute, and Center for Cognitive Aging and Memory, University of Florida, Gainesville, FL, United States
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Zheng L, Gao Z, Doner S, Oyao A, Forloines M, Grilli MD, Barnes CA, Ekstrom AD. Hippocampal contributions to novel spatial learning are both age-related and age-invariant. Proc Natl Acad Sci U S A 2023; 120:e2307884120. [PMID: 38055735 PMCID: PMC10723126 DOI: 10.1073/pnas.2307884120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/30/2023] [Indexed: 12/08/2023] Open
Abstract
Older adults show declines in spatial memory, although the extent of these alterations is not uniform across the healthy older population. Here, we investigate the stability of neural representations for the same and different spatial environments in a sample of younger and older adults using high-resolution functional MRI of the medial temporal lobes. Older adults showed, on average, lower neural pattern similarity for retrieving the same environment and more variable neural patterns compared to young adults. We also found a positive association between spatial distance discrimination and the distinctiveness of neural patterns between environments. Our analyses suggested that one source for this association was the extent of informational connectivity to CA1 from other subfields, which was dependent on age, while another source was the fidelity of signals within CA1 itself, which was independent of age. Together, our findings suggest both age-dependent and independent neural contributions to spatial memory performance.
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Affiliation(s)
- Li Zheng
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Zhiyao Gao
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA94305
| | - Stephanie Doner
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Alexis Oyao
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Martha Forloines
- Alzheimer’s Disease Center, Department of Neurology, University of California, Davis, Sacramento, CA95816
| | - Matthew D. Grilli
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
| | - Carol A. Barnes
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
| | - Arne D. Ekstrom
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
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10
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Berdugo‐Vega G, Dhingra S, Calegari F. Sharpening the blades of the dentate gyrus: how adult-born neurons differentially modulate diverse aspects of hippocampal learning and memory. EMBO J 2023; 42:e113524. [PMID: 37743770 PMCID: PMC11059975 DOI: 10.15252/embj.2023113524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/19/2023] [Accepted: 08/18/2023] [Indexed: 09/26/2023] Open
Abstract
For decades, the mammalian hippocampus has been the focus of cellular, anatomical, behavioral, and computational studies aimed at understanding the fundamental mechanisms underlying cognition. Long recognized as the brain's seat for learning and memory, a wealth of knowledge has been accumulated on how the hippocampus processes sensory input, builds complex associations between objects, events, and space, and stores this information in the form of memories to be retrieved later in life. However, despite major efforts, our understanding of hippocampal cognitive function remains fragmentary, and models trying to explain it are continually revisited. Here, we review the literature across all above-mentioned domains and offer a new perspective by bringing attention to the most distinctive, and generally neglected, feature of the mammalian hippocampal formation, namely, the structural separability of the two blades of the dentate gyrus into "supra-pyramidal" and "infra-pyramidal". Next, we discuss recent reports supporting differential effects of adult neurogenesis in the regulation of mature granule cell activity in these two blades. We propose a model for how differences in connectivity and adult neurogenesis in the two blades can potentially provide a substrate for subtly different cognitive functions.
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Affiliation(s)
- Gabriel Berdugo‐Vega
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
- Present address:
Laboratory of Neuroepigenetics, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale Lausanne (EPFL)LausanneSwitzerland
| | - Shonali Dhingra
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Federico Calegari
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
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11
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Zheng L, Gao Z, Doner S, Oyao A, Forloines M, Grilli MD, Barnes CA, Ekstrom AD. Hippocampal contributions to novel spatial learning are both age-related and age-invariant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.28.546918. [PMID: 37425879 PMCID: PMC10326977 DOI: 10.1101/2023.06.28.546918] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Older adults show declines in spatial memory, although the extent of these alterations is not uniform across the healthy older population. Here, we investigate the stability of neural representations for the same and different spatial environments in a sample of younger and older adults using high-resolution functional magnetic resonance imaging (fMRI) of the medial temporal lobe. Older adults showed, on average, lower neural pattern similarity for retrieving the same environment and more variable neural patterns compared to young adults. We also found a positive association between spatial distance discrimination and the distinctiveness of neural patterns between environments. Our analyses suggested that one source for this association was the extent of informational connectivity to CA1 from other subfields, which was dependent on age, while another source was the fidelity of signals within CA1 itself, which was independent of age. Together, our findings suggest both age-dependent and independent neural contributions to spatial memory performance.
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Affiliation(s)
- Li Zheng
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Zhiyao Gao
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305
| | - Stephanie Doner
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Alexis Oyao
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Martha Forloines
- Alzheimer s Disease Center, Department of Neurology, University of California, Davis, Sacramento, CA 95816
| | - Matthew D Grilli
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
| | - Carol A Barnes
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
| | - Arne D Ekstrom
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
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12
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Gray DT, Zempare M, Carey N, Khattab S, Sinakevitch I, De Biase LM, Barnes CA. Extracellular matrix proteoglycans support aged hippocampus networks: a potential cellular-level mechanism of brain reserve. Neurobiol Aging 2023; 131:52-58. [PMID: 37572527 PMCID: PMC10529564 DOI: 10.1016/j.neurobiolaging.2023.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 07/12/2023] [Accepted: 07/14/2023] [Indexed: 08/14/2023]
Abstract
One hallmark of normative brain aging is vast heterogeneity in whether older people succumb to or resist cognitive decline. Resilience describes a brain's capacity to maintain cognition in the face of aging and disease. One factor influencing resilience is brain reserve-the status of neurobiological resources available to support neuronal circuits as dysfunction accumulates. This study uses a cohort of behaviorally characterized adult, middle-aged, and aged rats to test whether neurobiological factors that protect inhibitory neurotransmission and synapse function represent key components of brain reserve. Histochemical analysis of extracellular matrix proteoglycans, which play critical roles in stabilizing synapses and modulating inhibitory neuron excitability, was conducted alongside analyses of lipofuscin-associated autofluorescence. The findings indicate that aging results in lower proteoglycan density and more lipofuscin in CA3. Aged rats with higher proteoglycan density exhibited better performance on the Morris watermaze, whereas lipofuscin abundance was not related to spatial memory. These data suggest that the local environment around neurons may protect against synapse dysfunction or hyperexcitability and could contribute to brain reserve mechanisms.
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Affiliation(s)
- Daniel T Gray
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Marc Zempare
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
| | - Natalie Carey
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
| | - Salma Khattab
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
| | - Irina Sinakevitch
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA
| | - Lindsay M De Biase
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Carol A Barnes
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ, USA; Departments of Psychology, Neurology and Neuroscience, University of Arizona, Tucson, AZ, USA.
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13
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McDermott KD, Frechou MA, Jordan JT, Martin SS, Gonçalves JT. Delayed formation of neural representations of space in aged mice. Aging Cell 2023; 22:e13924. [PMID: 37491802 PMCID: PMC10497831 DOI: 10.1111/acel.13924] [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: 03/29/2023] [Revised: 05/31/2023] [Accepted: 06/20/2023] [Indexed: 07/27/2023] Open
Abstract
Aging is associated with cognitive deficits, with spatial memory being very susceptible to decline. The hippocampal dentate gyrus (DG) is important for processing spatial information in the brain and is particularly vulnerable to aging, yet its sparse activity has led to difficulties in assessing changes in this area. Using in vivo two-photon calcium imaging, we compared DG neuronal activity and representations of space in young and aged mice walking on an unfamiliar treadmill. We found that calcium activity was significantly higher and less tuned to location in aged mice, resulting in decreased spatial information encoded in the DG. However, with repeated exposure to the same treadmill, both spatial tuning and information levels in aged mice became similar to young mice, while activity remained elevated. Our results show that spatial representations of novel environments are impaired in the aged hippocampus and gradually improve with increased familiarity. Moreover, while the aged DG is hyperexcitable, this does not disrupt neural representations of familiar environments.
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Affiliation(s)
- Kelsey D. McDermott
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative MedicineAlbert Einstein College of MedicineBronxNew YorkUSA
| | - M. Agustina Frechou
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative MedicineAlbert Einstein College of MedicineBronxNew YorkUSA
| | - Jake T. Jordan
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative MedicineAlbert Einstein College of MedicineBronxNew YorkUSA
| | - Sunaina S. Martin
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative MedicineAlbert Einstein College of MedicineBronxNew YorkUSA
| | - J. Tiago Gonçalves
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative MedicineAlbert Einstein College of MedicineBronxNew YorkUSA
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14
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Simonnet C, Sinha M, Goutierre M, Moutkine I, Daumas S, Poncer JC. Silencing KCC2 in mouse dorsal hippocampus compromises spatial and contextual memory. Neuropsychopharmacology 2023; 48:1067-1077. [PMID: 36302847 PMCID: PMC10209115 DOI: 10.1038/s41386-022-01480-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/09/2022]
Abstract
Delayed upregulation of the neuronal chloride extruder KCC2 underlies the progressive shift in GABA signaling polarity during development. Conversely, KCC2 downregulation is observed in a variety of neurological and psychiatric disorders often associated with cognitive impairment. Reduced KCC2 expression and function in mature networks may disrupt GABA signaling and promote anomalous network activities underlying these disorders. However, the causal link between KCC2 downregulation, altered brain rhythmogenesis, and cognitive function remains elusive. Here, by combining behavioral exploration with in vivo electrophysiology we assessed the impact of chronic KCC2 downregulation in mouse dorsal hippocampus and showed it compromises both spatial and contextual memory. This was associated with altered hippocampal rhythmogenesis and neuronal hyperexcitability, with increased burst firing in CA1 neurons during non-REM sleep. Reducing neuronal excitability with terbinafine, a specific Task-3 leak potassium channel opener, occluded the impairment of contextual memory upon KCC2 knockdown. Our results establish a causal relationship between KCC2 expression and cognitive performance and suggest that non-epileptiform rhythmopathies and neuronal hyperexcitability are central to the deficits caused by KCC2 downregulation in the adult mouse brain.
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Affiliation(s)
- Clémence Simonnet
- Inserm UMR-S 1270, 75005, Paris, France
- Sorbonne Université, 75005, Paris, France
- Institut du Fer à Moulin, 75005, Paris, France
- Basic Neuroscience Department, Centre Medical Universitaire, 1211, Geneva, Switzerland
| | - Manisha Sinha
- Inserm UMR-S 1270, 75005, Paris, France
- Sorbonne Université, 75005, Paris, France
- Institut du Fer à Moulin, 75005, Paris, France
| | - Marie Goutierre
- Inserm UMR-S 1270, 75005, Paris, France
- Sorbonne Université, 75005, Paris, France
- Institut du Fer à Moulin, 75005, Paris, France
| | - Imane Moutkine
- Inserm UMR-S 1270, 75005, Paris, France
- Sorbonne Université, 75005, Paris, France
- Institut du Fer à Moulin, 75005, Paris, France
| | - Stéphanie Daumas
- Sorbonne Université, 75005, Paris, France
- Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), 75005, Paris, France
| | - Jean Christophe Poncer
- Inserm UMR-S 1270, 75005, Paris, France.
- Sorbonne Université, 75005, Paris, France.
- Institut du Fer à Moulin, 75005, Paris, France.
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15
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Zott B, Konnerth A. Impairments of glutamatergic synaptic transmission in Alzheimer's disease. Semin Cell Dev Biol 2023; 139:24-34. [PMID: 35337739 DOI: 10.1016/j.semcdb.2022.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/09/2022] [Accepted: 03/09/2022] [Indexed: 12/31/2022]
Abstract
One of the hallmarks of Alzheimer's disease (AD) is structural cell damage and neuronal death in the brains of affected individuals. As these changes are irreversible, it is important to understand their origins and precursors in order to develop treatment strategies against AD. Here, we review evidence for AD-specific impairments of glutamatergic synaptic transmission by relating evidence from human AD subjects to functional studies in animal models of AD. The emerging picture is that early in the disease, the accumulation of toxic β-amyloid aggregates, particularly dimers and low molecular weight oligomers, disrupts glutamate reuptake, which leads to its extracellular accumulation causing neuronal depolarization. This drives the hyperactivation of neurons and might facilitate neuronal damage and degeneration through glutamate neurotoxicity.
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Affiliation(s)
- Benedikt Zott
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany; Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany; Department of Neuroradiology, Klinikum Rechts der Isar, Technical University of Munich, 81675 Munich, Germany.
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany; Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
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16
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McDermott KD, Frechou MA, Jordan JT, Martin SS, Gonçalves JT. Delayed formation of neural representations of space in aged mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.03.531021. [PMID: 37034736 PMCID: PMC10081265 DOI: 10.1101/2023.03.03.531021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Aging is associated with cognitive deficits, with spatial memory being very susceptible to decline. The hippocampal dentate gyrus (DG) is important for processing spatial information in the brain and is particularly vulnerable to aging, yet its sparse activity has led to difficulties in assessing changes in this area. Using in vivo two-photon calcium imaging, we compared DG neuronal activity and representations of space in young and aged mice walking on an unfamiliar treadmill. We found that calcium activity was significantly higher and less tuned to location in aged mice, resulting in decreased spatial information encoded in the DG. However, with repeated exposure to the same treadmill, both spatial tuning and information levels in aged mice became similar to young mice, while activity remained elevated. Our results show that spatial representations of novel environments are impaired in the aged hippocampus and gradually improve with increased familiarity. Moreover, while the aged DG is hyperexcitable, this does not disrupt neural representations of familiar environments.
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Affiliation(s)
- Kelsey D. McDermott
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - M. Agustina Frechou
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - Jake T. Jordan
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - Sunaina S. Martin
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - J. Tiago Gonçalves
- Dominick P. Purpura Department of Neuroscience and Gottesmann Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY
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17
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Chen L, Francisco TR, Baggetta AM, Zaki Y, Ramirez S, Clem RL, Shuman T, Cai DJ. Ensemble-specific deficit in neuronal intrinsic excitability in aged mice. Neurobiol Aging 2023; 123:92-97. [PMID: 36652783 PMCID: PMC9892234 DOI: 10.1016/j.neurobiolaging.2022.12.007] [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: 03/30/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
With the prevalence of age-related cognitive deficits on the rise, it is essential to identify cellular and circuit alterations that contribute to age-related memory impairment. Increased intrinsic neuronal excitability after learning is important for memory consolidation, and changes to this process could underlie memory impairment in old age. Some studies find age-related deficits in hippocampal neuronal excitability that correlate with memory impairment but others do not, possibly due to selective changes only in activated neural ensembles. Thus, we tagged CA1 neurons activated during learning and recorded their intrinsic excitability 5 hours or 7 days post-training. Adult mice exhibited increased neuronal excitability 5 hours after learning, specifically in ensemble (learning-activated) CA1 neurons. As expected, ensemble excitability returned to baseline 7 days post-training. In aged mice, there was no ensemble-specific excitability increase after learning, which was associated with impaired hippocampal memory performance. These results suggest that CA1 may be susceptible to age-related impairments in post-learning ensemble excitability and underscore the need to selectively measure ensemble-specific changes in the brain.
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Affiliation(s)
- Lingxuan Chen
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Taylor R Francisco
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Austin M Baggetta
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yosif Zaki
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steve Ramirez
- Psychological and Brain Sciences, Boston University, Boston, MA, USA
| | - Roger L Clem
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Tristan Shuman
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Denise J Cai
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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18
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Hernandez AR, Barrett ME, Lubke KN, Maurer AP, Burke SN. A long-term ketogenic diet in young and aged rats has dissociable effects on prelimbic cortex and CA3 ensemble activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.18.529095. [PMID: 36824737 PMCID: PMC9949134 DOI: 10.1101/2023.02.18.529095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Age-related cognitive decline has been linked to distinct patterns of cellular dysfunction in the prelimbic cortex (PL) and the CA3 subregion of the hippocampus. Because higher cognitive functions require both structures, selectively targeting a neurobiological change in one region, at the expense of the other, is not likely to restore normal behavior in older animals. One change with age that both the PL and CA3 share, however, is a reduced ability to utilize glucose, which can produce aberrant neural activity patterns. The current study used a ketogenic diet (KD) intervention, which reduces the brain’s reliance on glucose, and has been shown to improve cognition, as a metabolic treatment for restoring neural ensemble dynamics in aged rats. Expression of the immediate-early genes Arc and Homer 1a were used to quantify the neural ensembles that were active in the home cage prior to behavior, during a working memory/biconditional association task, and a continuous spatial alternation task. Aged rats on the control diet had increased activity in CA3 and less ensemble overlap in PL between different task conditions than did the young animals. In the PL, the KD was associated with increased activation of neurons in the superficial cortical layers. The KD did not lead to any significant changes in CA3 activity. These observations suggest that the KD does not restore neuron activation patterns in aged animals, but rather the availability of ketone bodies in the frontal cortices may permit the engagement of compensatory mechanisms that produce better cognitive outcomes. Significance Statement This study extends understanding of how a ketogenic diet (KD) intervention may improve cognitive function in older adults. Young and aged rats were given 3 months of a KD or a calorie-match control diet and then expression of the immediate-early genes Arc and Homer 1a were measured to examine neural ensemble dynamics during cognitive testing. The KD diet was associated with increased activation of neurons in the superficial layers of the PL, but there were no changes in CA3. These observations are significant because they suggest that compensatory mechanisms for improving cognition are engaged in the presence of elevated ketone bodies. This metabolic shift away from glycolysis can meet the energetic needs of the frontal cortices when glucose utilization is compromised.
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19
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van den Berg M, Toen D, Verhoye M, Keliris GA. Alterations in theta-gamma coupling and sharp wave-ripple, signs of prodromal hippocampal network impairment in the TgF344-AD rat model. Front Aging Neurosci 2023; 15:1081058. [PMID: 37032829 PMCID: PMC10075364 DOI: 10.3389/fnagi.2023.1081058] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 02/27/2023] [Indexed: 04/11/2023] Open
Abstract
Alzheimer's disease (AD) is a severe neurodegenerative disorder caused by the accumulation of toxic proteins, amyloid-beta (Aβ) and tau, which eventually leads to dementia. Disease-modifying therapies are still lacking, due to incomplete insights into the neuropathological mechanisms of AD. Synaptic dysfunction is known to occur before cognitive symptoms become apparent and recent studies have demonstrated that imbalanced synaptic signaling drives the progression of AD, suggesting that early synaptic dysfunction could be an interesting therapeutic target. Synaptic dysfunction results in altered oscillatory activity, which can be detected with electroencephalography and electrophysiological recordings. However, the majority of these studies have been performed at advanced stages of AD, when extensive damage and cognitive symptoms are already present. The current study aimed to investigate if the hippocampal oscillatory activity is altered at pre-plaque stages of AD. The rats received stereotactic surgery to implant a laminar electrode in the CA1 layer of the right hippocampus. Electrophysiological recordings during two consecutive days in an open field were performed in 4-5-month-old TgF344-AD rats when increased concentrations of soluble Aβ species were observed in the brain, in the absence of Aβ-plaques. We observed a decreased power of high theta oscillations in TgF344-AD rats compared to wild-type littermates. Sharp wave-ripple (SWR) analysis revealed an increased SWR power and a decreased duration of SWR during quiet wake in TgF344-AD rats. The alterations in properties of SWR and the increased power of fast oscillations are suggestive of neuronal hyperexcitability, as has been demonstrated to occur during presymptomatic stages of AD. In addition, decreased strength of theta-gamma coupling, an important neuronal correlate of memory encoding, was observed in the TgF344-AD rats. Theta-gamma phase amplitude coupling has been associated with memory encoding and the execution of cognitive functions. Studies have demonstrated that mild cognitive impairment patients display decreased coupling strength, similar to what is described here. The current study demonstrates altered hippocampal network activity occurring at pre-plaque stages of AD and provides insights into prodromal network dysfunction in AD. The alterations observed could aid in the detection of AD during presymptomatic stages.
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Affiliation(s)
- Monica van den Berg
- Bio-Imaging Lab, University of Antwerp, Wilrijk, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
- *Correspondence: Monica van den Berg, ; Georgios A. Keliris,
| | - Daniëlle Toen
- Bio-Imaging Lab, University of Antwerp, Wilrijk, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Marleen Verhoye
- Bio-Imaging Lab, University of Antwerp, Wilrijk, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Georgios A. Keliris
- Bio-Imaging Lab, University of Antwerp, Wilrijk, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
- Institute of Computer Science, Foundation for Research and Technology – Hellas, Heraklion, Crete, Greece
- *Correspondence: Monica van den Berg, ; Georgios A. Keliris,
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20
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Belliart-Guérin G, Planche V. Mnemonic Discrimination Performance in a Memory Clinic: A Pilot Study. J Alzheimers Dis 2023; 94:1527-1534. [PMID: 37458033 PMCID: PMC10473128 DOI: 10.3233/jad-230221] [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] [Accepted: 06/08/2023] [Indexed: 07/18/2023]
Abstract
BACKGROUND Mnemonic discrimination is the behavioral ability stemming from pattern separation, which is the neural process of establishing independent and non-overlapping new memories. Over the past two decades, its assessment in various populations has contributed to a better conceptual understanding of age-related memory decline. OBJECTIVE To assess the clinical relevance of mnemonic discrimination in the memory clinics setting. METHODS This retrospective study was performed in 90 patients with a Mini-Mental State Examination (MMSE)>18 who consulted our memory clinic for the first time. All patients were tested with the Mnemonic Similarity Task, a freely available computerized test. Global cognitive function, executive function, visuoconstructional abilities, and verbal and visual episodic memory were also collected, together with the diagnosis after the initial clinical assessment (subjective cognitive complaint [SCC], mild cognitive impairment [MCI], or mild dementia). RESULTS Mnemonic discrimination performance was correlated with global cognitive function, executive function, and visual and verbal episodic memory scores, independent of age. It discriminated patients with SCC from those with MCI (amnestic or non-amnestic) with moderate accuracy (AUC = 0.77-0.78), similar to MMSE and the Frontal Assessment Battery (AUC = 0.74-0.84). Mnemonic discrimination performance did not distinguish between amnestic and non-amnestic MCI and the variability of the measure was important within groups. CONCLUSION Mnemonic discrimination performance involves many cognitive domains and discriminates between patients with SCC and MCI with performance equivalent to "paper-and-pencil" screening tests. Further dedicated prospective studies will determine whether this task is of interest beyond research purposes, as a diagnostic or screening tool in primary care.
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Affiliation(s)
- Ghislain Belliart-Guérin
- CHU de Bordeaux, Pôle de Neurosciences Cliniques, Centre Mémoire de Ressources et de Recherche, Bordeaux, France
| | - Vincent Planche
- CHU de Bordeaux, Pôle de Neurosciences Cliniques, Centre Mémoire de Ressources et de Recherche, Bordeaux, France
- Université Bordeaux, CNRS UMR 5293, Institut des Maladies Neurodégénératives, Bordeaux, France
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21
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Lester AW, Jordan GA, Blum CJ, Philpot ZP, Barnes CA. Differential effects in young and aged rats' navigational accuracy following instantaneous rotation of environmental cues. Behav Neurosci 2022; 136:561-574. [PMID: 36395015 PMCID: PMC10482423 DOI: 10.1037/bne0000536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Successful navigation depends critically upon two broad categories of spatial navigation strategies that include allocentric and egocentric reference frames, relying on external or internal spatial information, respectively. As with older adults, aged rats show robust impairments on a number of different spatial navigation tasks. There is some evidence that these navigation impairments are accompanied by a bias toward relying on egocentric over allocentric navigation strategies. To test the degree to which young and aged animals utilize these two navigation approaches, a novel behavioral arena was used in which rats are trained to traverse a circular track and to stop at a learned goal location that is fixed with respect to a panorama of visual cues projected onto the surrounding walls. By instantaneously rotating the cues, allocentric and egocentric reference frames were put in direct and immediate conflict and goal navigation performance was assessed with respect to how accurately young and aged animals were able to utilize the rotated cues. Behavioral data collected from nine young and eight aged animals revealed that both age groups were able to update their navigation performance following cue rotation. Contrary to what was expected, however, aged animals showed more accurate overall goal navigation performance, stronger allocentric strategy use, and more evident changes in behavior in response to cue rotation compared to younger animals. The young rats appeared to mix egocentric and allocentric strategies for ICR task solution. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
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Affiliation(s)
| | | | | | | | - Carol A. Barnes
- Evelyn F. McKnight Brain Institute
- Departments of Psychology, Neurology and Neuroscience, University of Arizona, Tucson, AZ
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22
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Adams JN, Kim S, Rizvi B, Sathishkumar M, Taylor L, Harris AL, Mikhail A, Keator DB, McMillan L, Yassa MA. Entorhinal-Hippocampal Circuit Integrity Is Related to Mnemonic Discrimination and Amyloid-β Pathology in Older Adults. J Neurosci 2022; 42:8742-8753. [PMID: 36302636 PMCID: PMC9671577 DOI: 10.1523/jneurosci.1165-22.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/30/2022] [Accepted: 10/04/2022] [Indexed: 11/21/2022] Open
Abstract
Mnemonic discrimination, a cognitive process that relies on hippocampal pattern separation, is one of the first memory domains to decline in aging and preclinical Alzheimer's disease. We tested whether functional connectivity (FC) within the entorhinal-hippocampal circuit, measured with high-resolution resting state fMRI, is associated with mnemonic discrimination and amyloid-β (Aβ) pathology in a sample of 64 cognitively normal human older adults (mean age, 71.3 ± 6.4 years; 67% female). FC was measured between entorhinal-hippocampal circuit nodes with known anatomical connectivity, as well as within cortical memory networks. Aβ pathology was measured with 18F-florbetapir-PET, and neurodegeneration was assessed with subregional volume from structural MRI. Participants performed both object and spatial versions of a mnemonic discrimination task outside of the scanner and were classified into low-performing and high-performing groups on each task using a median split. Low object mnemonic discrimination performance was specifically associated with increased FC between anterolateral entorhinal cortex (alEC) and dentate gyrus (DG)/CA3, supporting the importance of this connection to object memory. This hyperconnectivity between alEC and DG/CA3 was related to Aβ pathology and decreased entorhinal cortex volume. In contrast, spatial mnemonic discrimination was not associated with altered FC. Aβ was further associated with dysfunction within hippocampal subfields, particularly with decreased FC between CA1 and subiculum as well as reduced volume in these regions. Our findings suggest that Aβ may indirectly lead to memory impairment through entorhinal-hippocampal circuit dysfunction and neurodegeneration and provide a mechanism for increased vulnerability of object mnemonic discrimination.SIGNIFICANCE STATEMENT Mnemonic discrimination is a critical episodic memory process that is performed in the dentate gyrus (DG) and CA3 subfield of the hippocampus, relying on input from entorhinal cortex. Mnemonic discrimination is particularly vulnerable to decline in older adults; however, the mechanisms behind this vulnerability are still unknown. We demonstrate that object mnemonic discrimination impairment is related to hyperconnectivity between the anterolateral entorhinal cortex and DG/CA3. This hyperconnectivity was associated with amyloid-β pathology and neurodegeneration in entorhinal cortex, suggesting aberrantly increased network activity is a pathological process. Our findings provide a mechanistic explanation of the vulnerability of object compared to spatial mnemonic discrimination in older adults and has translational implications for choice of outcome measures in clinical trials for Alzheimer's disease.
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Affiliation(s)
- Jenna N Adams
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Soyun Kim
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Batool Rizvi
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Mithra Sathishkumar
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Lisa Taylor
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, California 92697
| | - Alyssa L Harris
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Abanoub Mikhail
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - David B Keator
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, California 92697
| | - Liv McMillan
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
| | - Michael A Yassa
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, California 92697
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, California 92697
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23
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Merkin A, Sghirripa S, Graetz L, Smith AE, Hordacre B, Harris R, Pitcher J, Semmler J, Rogasch NC, Goldsworthy M. Do age-related differences in aperiodic neural activity explain differences in resting EEG alpha? Neurobiol Aging 2022; 121:78-87. [DOI: 10.1016/j.neurobiolaging.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 08/12/2022] [Accepted: 09/08/2022] [Indexed: 11/15/2022]
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24
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DiCola NM, Lacy AL, Bishr OJ, Kimsey KM, Whitney JL, Lovett SD, Burke SN, Maurer AP. Advanced age has dissociable effects on hippocampal CA1 ripples and CA3 high frequency events in male rats. Neurobiol Aging 2022; 117:44-58. [PMID: 35665647 PMCID: PMC9392897 DOI: 10.1016/j.neurobiolaging.2022.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 02/01/2023]
Abstract
Sharp wave/ripples/high frequency events (HFEs) are transient bursts of depolarization in hippocampal subregions CA3 and CA1 that occur during rest and pauses in behavior. Previous studies have reported that CA1 ripples in aged rats have lower frequency than those detected in young animals. While CA1 ripples are thought to be driven by CA3, HFEs in CA3 have not been examined in aged animals. The current study obtained simultaneous recordings from CA1 and CA3 in young and aged rats to examine sharp wave/ripples/HFEs in relation to age. While CA1 ripple frequency was reduced with age, there were no age differences in the frequency of CA3 HFEs, although power and length were lower in old animals. While there was a proportion of CA1 ripples that co-occurred with a CA3 HFE, none of the age-related differences in CA1 ripples could be explained by alterations in CA3 HFE characteristics. These findings suggest that age differences in CA1 are not due to altered CA3 activity, but instead reflect distinct mechanisms of ripple generation with age.
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Affiliation(s)
- Nicholas M. DiCola
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Alexa L. Lacy
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Omar J. Bishr
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Kathryn M. Kimsey
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Jenna L. Whitney
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Sarah D. Lovett
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Sara N. Burke
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA,Corresponding author at: University of Florida, Neuroscience, McKnight Brain Institute, P.O. Box 100244, 1149 Newell Dr, RM L1-100G, Gainesville, FL 32610, USA. (S.N. Burke)
| | - Andrew P. Maurer
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA,Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA,Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA,Corresponding author at: McKnight Brain Institute, 1149 Newell Dr, RM L1-100E, University of Florida, Gainesville, FL 32610, USA. (A.P. Maurer)
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25
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Zheng XY, Zhang HC, Lv YD, Jin FY, Wu XJ, Zhu J, Ruan Y. Levetiracetam alleviates cognitive decline in Alzheimer’s disease animal model by ameliorating the dysfunction of the neuronal network. Front Aging Neurosci 2022; 14:888784. [PMID: 36092803 PMCID: PMC9452890 DOI: 10.3389/fnagi.2022.888784] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/28/2022] [Indexed: 11/16/2022] Open
Abstract
Background Patients with Alzheimer’s disease (AD) have a significantly higher risk of seizures than other individuals in an age-matched population, suggesting a close association between epilepsy and AD. We aimed to examine the effects of levetiracetam (LEV)—a drug for treating seizures—on learning and memory and the neuropathological features of AD. Methods We crossbred APP23 mice with microtubule-associated protein tau (MAPT) transgenic mice to generate APP23/MAPT mice. These mice were treated with different concentrations of LEV in the presence of kainic acid (KA) for 3 months. Results Low doses of LEV alleviated the effects of KA on memory defects in APP23/MAPT mice. Mechanistic investigations showed that low concentrations of LEV decreased tau phosphorylation by reducing the activities of cyclin-dependent kinase 5 and glycogen synthase kinase 3α/β, thus rescuing neurons from synaptic dystrophy and apoptosis. Low doses of LEV inhibited the effects of KA (i.e., inducing neuroinflammation and impairing the autophagy of amyloid β-peptide), thus improving cognitive decline. High concentrations of LEV decreased the production and deposition of amyloid β-peptide (Aβ) by reducing the expression of β-site APP-cleaving enzyme 1 and presenilin 1. However, high concentrations of LEV also induced neuronal apoptosis, decreased movement ability in mice, and did not alleviate cognitive decline in AD mice. Conclusion Our results support the hypothesis that aberrant network activity contributes to the synaptic and cognitive deficits in APP23/MAPT mice. A low concentration of LEV may help ameliorate abnormalities of AD; however, a high LEV concentration did not induce similar results.
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Affiliation(s)
- Xiang-Yu Zheng
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
- *Correspondence: Xiang-Yu Zheng,
| | - Hai-Chen Zhang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Yu-Dan Lv
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Feng-Yan Jin
- Department of Hematology, Cancer Center, The First Hospital of Jilin University, Changchun, China
| | - Xiu-Juan Wu
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Jie Zhu
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
- Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
| | - Yang Ruan
- Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, China
- Yang Ruan,
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26
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Canatelli-Mallat M, Chiavellini P, Lehmann M, Goya RG, Morel GR. AGE-RELATED LOSS OF RECOGNITION MEMORY AND ITS CORRELATION WITH HIPPOCAMPAL AND PERIRHINAL CORTEX CHANGES IN FEMALE SPRAGUE-DAWLEY RATS. Behav Brain Res 2022; 435:114026. [DOI: 10.1016/j.bbr.2022.114026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/20/2022] [Accepted: 07/24/2022] [Indexed: 11/02/2022]
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27
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Cooper TL, Thompson JJ, Turner SM, Watson C, Lubke KN, Logan CN, Maurer AP, Burke SN. Unilateral Perforant Path Transection Does Not Alter Lateral Entorhinal Cortical or Hippocampal CA3 Arc Expression. Front Syst Neurosci 2022; 16:920713. [PMID: 35844245 PMCID: PMC9279555 DOI: 10.3389/fnsys.2022.920713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
It is well established that degradation of perforant path fibers is associated with age-related cognitive dysfunction and CA3 hyperactivity. Whether this fiber loss triggers a cascade of other functional changes within the hippocampus circuit has not been causatively established, however. Thus, the current study evaluated the effect of perforant path fiber loss on neuronal activity in CA3 and layer II of the lateral entorhinal cortex (LEC) in relation to mnemonic similarity task performance. Expression of the immediate early gene Arc was quantified in rats that received a unilateral right hemisphere transection of the perforant path or sham surgery that cut the cortex but left the fibers intact. Behavior-related expression of Arc mRNA was measured to test the hypothesis that fiber loss leads to elevated activation of CA3 and LEC neurons, as previously observed in aged rats that were impaired on the mnemonic similarity task. Transection of perforant path fibers, which has previously been shown to lead to a decline in mnemonic similarity task performance, did not alter Arc expression. Arc expression in CA3, however, was correlated with task performance on the more difficult discrimination trials across both surgical groups. These observations further support a link between CA3 activity and mnemonic similarity task performance but suggest the reduced input from the entorhinal cortex to the hippocampus, as observed in old age, does not causatively elevate CA3 activity.
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Affiliation(s)
- Tara L. Cooper
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
- Graduate Program in Biomedical Sciences, Neuroscience Concentration, University of Florida, Gainesville, FL, United States
| | - John J. Thompson
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Sean M. Turner
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Cory Watson
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Katelyn N. Lubke
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Carly N. Logan
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Andrew P. Maurer
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
| | - Sara N. Burke
- Department of Neuroscience, Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL, United States
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28
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Targa Dias Anastacio H, Matosin N, Ooi L. Neuronal hyperexcitability in Alzheimer's disease: what are the drivers behind this aberrant phenotype? Transl Psychiatry 2022; 12:257. [PMID: 35732622 PMCID: PMC9217953 DOI: 10.1038/s41398-022-02024-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/01/2022] [Accepted: 06/08/2022] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder leading to loss of cognitive abilities and ultimately, death. With no cure available, limited treatments mostly focus on symptom management. Identifying early changes in the disease course may provide new therapeutic targets to halt or reverse disease progression. Clinical studies have shown that cortical and hippocampal hyperactivity are a feature shared by patients in the early stages of disease, progressing to hypoactivity during later stages of neurodegeneration. The exact mechanisms causing neuronal excitability changes are not fully characterized; however, animal and cell models have provided insights into some of the factors involved in this phenotype. In this review, we summarize the evidence for neuronal excitability changes over the course of AD onset and progression and the molecular mechanisms underpinning these differences. Specifically, we discuss contributors to aberrant neuronal excitability, including abnormal levels of intracellular Ca2+ and glutamate, pathological amyloid β (Aβ) and tau, genetic risk factors, including APOE, and impaired inhibitory interneuron and glial function. In light of recent research indicating hyperexcitability could be a predictive marker of cognitive dysfunction, we further argue that the hyperexcitability phenotype could be leveraged to improve the diagnosis and treatment of AD, and present potential targets for future AD treatment development.
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Affiliation(s)
- Helena Targa Dias Anastacio
- grid.510958.0Illawarra Health and Medical Research Institute, Wollongong, NSW 2522 Australia ,grid.1007.60000 0004 0486 528XMolecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522 Australia
| | - Natalie Matosin
- grid.510958.0Illawarra Health and Medical Research Institute, Wollongong, NSW 2522 Australia ,grid.1007.60000 0004 0486 528XMolecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522 Australia
| | - Lezanne Ooi
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia. .,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.
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29
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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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30
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Crown LM, Gray DT, Schimanski LA, Barnes CA, Cowen SL. Aged Rats Exhibit Altered Behavior-Induced Oscillatory Activity, Place Cell Firing Rates, and Spatial Information Content in the CA1 Region of the Hippocampus. J Neurosci 2022; 42:4505-4516. [PMID: 35477900 PMCID: PMC9172068 DOI: 10.1523/jneurosci.1855-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 03/18/2022] [Accepted: 04/14/2022] [Indexed: 11/21/2022] Open
Abstract
Hippocampal gamma and theta oscillations are associated with mnemonic and navigational processes and adapt to changes in the behavioral state of an animal to optimize spatial information processing. It has been shown that locomotor activity modulates gamma and theta frequencies in rats, although how age alters this modulation has not been well studied. Here, we examine gamma and theta local-field potential and place cell activity in the hippocampus CA1 region of young and old male rats as they performed a spatial eye-blink conditioning task across 31 d. Although mean gamma frequency was similar in both groups, gamma frequency increased with running speed at a slower rate in old animals. By contrast, theta frequencies scaled with speed similarly in both groups but were lower across speeds in old animals. Although these frequencies scaled equally well with deceleration and speed, acceleration was less correlated with gamma frequency in both age groups. Additionally, spike phase-locking to gamma, but not theta, was greater in older animals. Finally, aged rats had reduced within-field firing rates but greater spatial information per spike within the field. These data support a strong relationship between locomotor behavior and local-field potential activity and suggest that age significantly affects this relationship. Furthermore, observed changes in CA1 place cell firing rates and information content lend support to the hypothesis that age may result in more general and context-invariant hippocampal representations over more detailed information. These results may explain the observation that older adults tend to recall the gist of an experience rather than the details.SIGNIFICANCE STATEMENT Hippocampal oscillations and place cell activity are sensitive to sensorimotor input generated from active locomotion, yet studies of aged hippocampal function often do not account for this. By considering locomotion and spatial location, we identify novel age-associated differences in the scaling of oscillatory activity with speed, spike-field coherence, spatial information content, and within-field firing rates of CA1 place cells. These results indicate that age has an impact on the relationship between locomotion and hippocampal oscillatory activity, perhaps indicative of alterations to afferent input. These data also support the hypothesis that aged hippocampal place cells, compared with young, may more often represent more general spatial information. If true, these results may help explain why older humans tend to recall less specific and more gist-like information.
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Affiliation(s)
- Lindsey M Crown
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Department of Psychology, University of Arizona, Tucson, Arizona 85721
| | - Daniel T Gray
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Departments of Neurology and Neuroscience, University of Arizona, Tucson, Arizona 85724
| | - Lesley A Schimanski
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
| | - Carol A Barnes
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Department of Psychology, University of Arizona, Tucson, Arizona 85721
- Departments of Neurology and Neuroscience, University of Arizona, Tucson, Arizona 85724
| | - Stephen L Cowen
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Department of Psychology, University of Arizona, Tucson, Arizona 85721
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31
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Abstract
Sex and gender differences are seen in cognitive disturbances in a variety of neurological and psychiatry diseases. Men are more likely to have cognitive symptoms in schizophrenia whereas women are more likely to have more severe cognitive symptoms with major depressive disorder and Alzheimer's disease. Thus, it is important to understand sex and gender differences in underlying cognitive abilities with and without disease. Sex differences are noted in performance across various cognitive domains - with males typically outperforming females in spatial tasks and females typically outperforming males in verbal tasks. Furthermore, there are striking sex differences in brain networks that are activated during cognitive tasks and in learning strategies. Although rarely studied, there are also sex differences in the trajectory of cognitive aging. It is important to pay attention to these sex differences as they inform researchers of potential differences in resilience to age-related cognitive decline and underlying mechanisms for both healthy and pathological cognitive aging, depending on sex. We review literature on the progressive neurodegenerative disorder, Alzheimer's disease, as an example of pathological cognitive aging in which human females show greater lifetime risk, neuropathology, and cognitive impairment, compared to human males. Not surprisingly, the relationships between sex and cognition, cognitive aging, and Alzheimer's disease are nuanced and multifaceted. As such, this chapter will end with a discussion of lifestyle factors, like education and diet, as modifiable factors that can alter cognitive aging by sex. Understanding how cognition changes across age and contributing factors, like sex differences, will be essential to improving care for older adults.
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32
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Burjanadze MA, Dashniani MG, Solomonia RO, Beselia GV, Tsverava L, Lagani V, Chkhikvishvili NC, Naneishvili TL, Kruashvili LB, Chighladze MR. Age-related changes in medial septal cholinergic and GABAergic projection neurons and hippocampal neurotransmitter receptors: relationship with memory impairment. Exp Brain Res 2022; 240:1589-1604. [PMID: 35357523 DOI: 10.1007/s00221-022-06354-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/21/2022] [Indexed: 11/24/2022]
Abstract
The hippocampus, which provides cognitive functions, has been shown to become highly vulnerable during aging. One important modulator of the hippocampal neural network is the medial septum (MS). The present study attempts to determine how age-related mnemonic dysfunction is associated with neurochemical changes in the septohippocampal (SH) system, using behavioral and immunochemical experiments performed on young-adult, middle-aged and aged rats. According to these behavioral results, the aged and around 52.8% of middle-aged rats (within the "middle-aged-impaired" sub-group) showed both impaired spatial reference memory in the Morris water maze and habituation in the open field. Immunohistochemical studies revealed a significant decrease in the number of MS choline acetyltransferase immunoreactive cells in the aged and all middle-aged rats, in comparison to the young; however the number of gamma-aminobutyric acid-ergic (GABAergic) parvalbumin immunoreactive cells was higher in middle-aged-impaired and older rats compared to young and middle-aged-unimpaired rats. Western Blot analysis moreover showed a decrease in the level of expression of cholinergic, GABAergic and glutamatergic receptors in the hippocampus of middle-aged-impaired and aged rats in contrast to middle-aged-unimpaired and young rats. The present results demonstrate for the first time that a decrease in the expression level of hippocampal receptors in naturally aged rats with impaired cognitive abilities occurs in parallel with an increase in the number of GABAergic neurons in the MS, and it highlights the particular importance of inhibitory signaling in the SH network for memory function.
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Affiliation(s)
- Maia A Burjanadze
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia.
| | - Manana G Dashniani
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia
| | - Revaz O Solomonia
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia.,Institute of Chemical Biology, Ilia State University, 0162, Tbilisi, Georgia
| | - Gela V Beselia
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia.,Department of Physiology and Pharmacology, Petre Shotadze Tbilisi Medical Academy, 0144, Tbilisi, Georgia
| | - Lia Tsverava
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia.,Institute of Chemical Biology, Ilia State University, 0162, Tbilisi, Georgia
| | - Vincenzo Lagani
- Institute of Chemical Biology, Ilia State University, 0162, Tbilisi, Georgia
| | - Nino C Chkhikvishvili
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia
| | - Temur L Naneishvili
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia
| | - Lali B Kruashvili
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia
| | - Mariam R Chighladze
- Department of Behavior and Cognitive Function, I. Beritashvili Center of Experimental Biomedicine, 0160, Tbilisi, Georgia
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33
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Hernandez CM, Hernandez AR, Hoffman JM, King PH, McMahon LL, Buford TW, Carter C, Bizon JL, Burke SN. A Neuroscience Primer for Integrating Geroscience With the Neurobiology of Aging. J Gerontol A Biol Sci Med Sci 2022; 77:e19-e33. [PMID: 34623396 PMCID: PMC8751809 DOI: 10.1093/gerona/glab301] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Indexed: 11/13/2022] Open
Abstract
Neuroscience has a rich history of studies focusing on neurobiology of aging. However, much of the aging studies in neuroscience occur outside of the gerosciences. The goal of this primer is 2-fold: first, to briefly highlight some of the history of aging neurobiology and second, to introduce to geroscientists the broad spectrum of methodological approaches neuroscientists use to study the neurobiology of aging. This primer is accompanied by a corresponding geroscience primer, as well as a perspective on the current challenges and triumphs of the current divide across these 2 fields. This series of manuscripts is intended to foster enhanced collaborations between neuroscientists and geroscientists with the intent of strengthening the field of cognitive aging through inclusion of parameters from both areas of expertise.
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Affiliation(s)
- Caesar M Hernandez
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Abigail R Hernandez
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jessica M Hoffman
- Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Peter H King
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Neurology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Birmingham Veterans Affairs Medical Center, Birmingham, Alabama, USA
| | - Lori L McMahon
- Department of Cellular, Development, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Nathan Shock Center for the Basic Biology of Aging, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Integrative Center for Aging Research, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Thomas W Buford
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Nathan Shock Center for the Basic Biology of Aging, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,UAB Integrative Center for Aging Research, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Geriatric Research Education and Clinical Center, Birmingham VA Medical Center, Birmingham, Alabama, USA
| | - Christy Carter
- Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama, USA.,Department of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Bizon
- Department of Neuroscience, Center for Cognitive Aging and Memory, and the McKnight Brain Institute, The University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Sara N Burke
- Department of Neuroscience, Center for Cognitive Aging and Memory, and the McKnight Brain Institute, The University of Florida, College of Medicine, Gainesville, Florida, USA
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34
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Tran TT, Speck CL, Gallagher M, Bakker A. Lateral Entorhinal Cortex Dysfunction in Amnestic Mild Cognitive Impairment. Neurobiol Aging 2021; 112:151-160. [PMID: 35182842 PMCID: PMC8976714 DOI: 10.1016/j.neurobiolaging.2021.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/24/2021] [Accepted: 12/26/2021] [Indexed: 11/16/2022]
Abstract
The entorhinal cortex is the site of some of the earliest pathological changes in Alzheimer's disease, including neuronal, synaptic and volumetric loss. Specifically, the lateral entorhinal cortex shows significant accumulation of tau neurofibrillary tangles in the amnestic mild cognitive impairment (aMCI) phase of Alzheimer's disease. Although decreased entorhinal cortex activation has been observed in patients with aMCI in the context of impaired memory function, it remains unclear if functional changes in the entorhinal cortex can be localized to the lateral or medial entorhinal cortex. To assess subregion specific changes in the lateral and medial entorhinal cortex, patients with aMCI and healthy aged-matched control participants underwent high-resolution structural and functional magnetic resonance imaging. Patients with aMCI showed significantly reduced volume, and decreased activation localized to the lateral entorhinal cortex but not the medial entorhinal cortex. These results show that structural and functional changes associated with impaired memory function differentially engage the lateral entorhinal cortex in patients with aMCI, consistent with the locus of early disease related pathology.
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Affiliation(s)
- Tammy T Tran
- Department of Psychological and Brain Sciences, Johns Hopkins University School of Arts and Sciences, Baltimore, MD, USA
| | - Caroline L Speck
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University School of Arts and Sciences, Baltimore, MD, USA
| | - Arnold Bakker
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Differential Effects of Human P301L Tau Expression in Young versus Aged Mice. Int J Mol Sci 2021; 22:ijms222111637. [PMID: 34769068 PMCID: PMC8583766 DOI: 10.3390/ijms222111637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
The greatest risk factor for developing Alzheimer’s disease (AD) is increasing age. Understanding the changes that occur in aging that make an aged brain more susceptible to developing AD could result in novel therapeutic targets. In order to better understand these changes, the current study utilized mice harboring a regulatable mutant P301L human tau transgene (rTg(TauP301L)4510), in which P301L tau expression can be turned off or on by the addition or removal of doxycycline in the drinking water. This regulatable expression allowed for assessment of aging independent of prolonged mutant tau expression. Our results suggest that P301L expression in aged mice enhances memory deficits in the Morris water maze task. These behavioral changes may be due to enhanced late-stage tau pathology, as evidenced by immunoblotting and exacerbated hippocampal dysregulation of glutamate release and uptake measured by the microelectrode array technique. We additionally observed changes in proteins important for the regulation of glutamate and tau phosphorylation that may mediate these age-related changes. Thus, age and P301L tau interact to exacerbate tau-induced detrimental alterations in aged animals.
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36
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Ratner MH, Downing SS, Guo O, Odamah KE, Stewart TM, Kumaresan V, Robitsek RJ, Xia W, Farb DH. Prodromal dysfunction of α5GABA-A receptor modulated hippocampal ripples occurs prior to neurodegeneration in the TgF344-AD rat model of Alzheimer's disease. Heliyon 2021; 7:e07895. [PMID: 34568591 PMCID: PMC8449175 DOI: 10.1016/j.heliyon.2021.e07895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 11/20/2022] Open
Abstract
Decades of research attempting to slow the onset of Alzheimer's disease (AD) indicates that a better understanding of memory will be key to the discovery of effective therapeutic approaches. Here, we ask whether prodromal neural network dysfunction might occur in the hippocampal trisynaptic circuit by using α5IA (an established memory enhancer and selective negative allosteric modulator of extrasynaptic tonically active α5GABA-A receptors) as a probe drug in TgF344-AD transgenic rats, a model for β-amyloid induced early onset AD. The results demonstrate that orally bioavailable α5IA increases CA1 pyramidal cell mean firing rates during foraging and peak ripple amplitude during wakeful immobility in wild type F344 rats in a familiar environment. We further demonstrate that CA1 ripples in TgF344-AD rats are nonresponsive to α5IA by 9 months of age, prior to the onset of AD-like pathology and memory dysfunction. TgF344-AD rats express human β-amyloid precursor protein (with the Swedish mutation) and human presenilin-1 (with a Δ exon 9 mutation) and we found high serum Aβ42 and Aβ40 levels by 3 months of age. When taken together, this demonstrates, to the best of our knowledge, the first evidence for prodromal α5GABA-A receptor dysfunction in the ripple-generating hippocampal trisynaptic circuit of AD-like transgenic rats. As α5GABA-A receptors are found at extrasynaptic and synaptic contacts, we posit that negative modulation of α5GABA-A receptor mediated tonic as well as phasic inhibition augments CA1 ripples and memory consolidation but that this modulatory mechanism is lost at an early stage of AD onset.
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Affiliation(s)
- Marcia H. Ratner
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Scott S. Downing
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Ouyang Guo
- Department of Biology, Boston University, Boston, Massachusetts, USA
| | - KathrynAnn E. Odamah
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Tara M. Stewart
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Vidhya Kumaresan
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - R. Jonathan Robitsek
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Weiming Xia
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
- Geriatric Research Education and Clinical Center, Bedford Veterans Administration Healthcare System, Bedford, Massachusetts, USA
| | - David H. Farb
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
- Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA
- Corresponding author.
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Differential Retinoic Acid Signaling in the Hippocampus of Aged Rats with and without Memory Impairment. eNeuro 2021; 8:ENEURO.0120-21.2021. [PMID: 34417282 PMCID: PMC8442538 DOI: 10.1523/eneuro.0120-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/09/2021] [Accepted: 08/17/2021] [Indexed: 12/21/2022] Open
Abstract
Retinoic acid (RA), a metabolite of vitamin A, has many physiological functions, and mounting evidence points to important roles in cognition. In vitro experiments indicate that RA is involved in homeostatic synaptic scaling in the hippocampus, which supports overall network stability during learning. It has been previously determined that disrupted RA signaling in the hippocampus causes deterioration of memory, that RA signaling declines with age in brain, and that application of RA reverses this decline. Here, we explore whether RA signaling is altered in an animal model of neurocognitive aging. We used a Morris water maze protocol to study cognitive decline in aged rats, which assesses hippocampus-dependent spatial memory and reveals substantial interindividual differences in aged animals. Aged unimpaired (AU) rats perform on par with young (Y), while aged impaired (AI) animals exhibit spatial memory deficits. We show that the major substrate for RA, retinol binding protein 4 (RBP4), is decreased in AU rats, and retinol cell surface receptor declines with chronological age. Other affected components of RA signaling include selective increases in AI animals in hippocampal synthesis (RALDH1) and catabolism of RA (CYP26B1), RA receptor α, the RA regulated ionotropic glutamate receptor (GluR1), as well as fragile X mental retardation protein (FMRP). The results support the conclusion that, surprisingly, increased RA signaling in the aged hippocampus is associated with poor cognitive outcome.
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Memel M, Staffaroni AM, Cobigo Y, Casaletto KB, Fonseca C, Bettcher BM, Yassa MA, Elahi FM, Wolf A, Rosen HJ, Kramer JH. APOE moderates the effect of hippocampal blood flow on memory pattern separation in clinically normal older adults. Hippocampus 2021; 31:845-857. [PMID: 33835624 PMCID: PMC8295213 DOI: 10.1002/hipo.23327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/25/2021] [Accepted: 03/07/2021] [Indexed: 11/10/2022]
Abstract
Pattern separation, the ability to differentiate new information from previously experienced similar information, is highly sensitive to hippocampal structure and function and declines with age. Functional MRI studies have demonstrated hippocampal hyperactivation in older adults compared to young, with greater task-related activation associated with worse pattern separation performance. The current study was designed to determine whether pattern separation was sensitive to differences in task-free hippocampal cerebral blood flow (CBF) in 130 functionally intact older adults. Given prior evidence that apolipoprotein E e4 (APOE e4) status moderates the relationship between CBF and episodic memory, we predicted a stronger negative relationship between hippocampal CBF and pattern separation in APOE e4 carriers. An interaction between APOE group and right hippocampal CBF was present, such that greater right hippocampal CBF was related to better lure discrimination in noncarriers, whereas the effect reversed directionality in e4 carriers. These findings suggest that neurovascular changes in the medial temporal lobe may underlie memory deficits in cognitively normal older adults who are APOE e4 carriers.
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Affiliation(s)
- Molly Memel
- San Francisco VA Medical Center, San Francisco, California
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Adam M. Staffaroni
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Yann Cobigo
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Kaitlin B. Casaletto
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Corrina Fonseca
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Brianne M. Bettcher
- Department of Neurology, University of Colorado Anschutz Medical Campus, CU Alzheimer’s and Cognition Center, Aurora, Colorado
| | - Michael A. Yassa
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California, Irvine, California
| | - Fanny M. Elahi
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Amy Wolf
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Howard J. Rosen
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Joel H. Kramer
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
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Jiménez-Balado J, Eich TS. GABAergic dysfunction, neural network hyperactivity and memory impairments in human aging and Alzheimer's disease. Semin Cell Dev Biol 2021; 116:146-159. [PMID: 33573856 PMCID: PMC8292162 DOI: 10.1016/j.semcdb.2021.01.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/25/2021] [Accepted: 01/30/2021] [Indexed: 02/07/2023]
Abstract
In this review, we focus on the potential role of the γ-aminobutyric acidergic (GABAergic) system in age-related episodic memory impairments in humans, with a particular focus on Alzheimer's disease (AD). Well-established animal models have shown that GABA plays a central role in regulating and synchronizing neuronal signaling in the hippocampus, a brain area critical for episodic memory that undergoes early and significant morphologic and functional changes in the course of AD. Neuroimaging research in humans has documented hyperactivity in the hippocampus and losses of resting state functional connectivity in the Default Mode Network, a network that itself prominently includes the hippocampus-presaging episodic memory decline in individuals at-risk for AD. Apolipoprotein ε4, the highest genetic risk factor for AD, is associated with GABAergic dysfunction in animal models, and episodic memory impairments in humans. In combination, these findings suggest that GABA may be the linchpin in a complex system of factors that eventually leads to the principal clinical hallmark of AD: episodic memory loss. Here, we will review the current state of literature supporting this hypothesis. First, we will focus on the molecular and cellular basis of the GABAergic system and its role in memory and cognition. Next, we report the evidence of GABA dysregulations in AD and normal aging, both in animal models and human studies. Finally, we outline a model of GABAergic dysfunction based on the results of functional neuroimaging studies in humans, which have shown hippocampal hyperactivity to episodic memory tasks concurrent with and even preceding AD diagnosis, along with factors that may modulate this association.
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Affiliation(s)
- Joan Jiménez-Balado
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | - Teal S Eich
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA.
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40
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Rechnitz O, Slutsky I, Morris G, Derdikman D. Hippocampal sub-networks exhibit distinct spatial representation deficits in Alzheimer's disease model mice. Curr Biol 2021; 31:3292-3302.e6. [PMID: 34146487 DOI: 10.1016/j.cub.2021.05.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 01/03/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022]
Abstract
Not much is known about how the dentate gyrus (DG) and hippocampal CA3 networks, critical for memory and spatial processing, malfunction in Alzheimer's disease (AD). While studies of associative memory deficits in AD have focused mainly on behavior, here, we directly measured neurophysiological network dysfunction. We asked what the pattern of deterioration of different networks is during disease progression. We investigated how the associative memory-processing capabilities in different hippocampal subfields are affected by familial AD (fAD) mutations leading to amyloid-β dyshomeostasis. Specifically, we focused on the DG and CA3, which are known to be involved in pattern completion and separation and are susceptible to pathological alterations in AD. To identify AD-related deficits in neural-ensemble dynamics, we recorded single-unit activity in wild-type (WT) and fAD model mice (APPSwe+PSEN1/ΔE9) in a novel tactile morph task, which utilizes the extremely developed somatosensory modality of mice. As expected from the sub-network regional specialization, we found that tactile changes induced lower rate map correlations in the DG than in CA3 of WT mice. This reflects DG pattern separation and CA3 pattern completion. In contrast, in fAD model mice, we observed pattern separation deficits in the DG and pattern completion deficits in CA3. This demonstration of region-dependent impairments in fAD model mice contributes to understanding of brain networks deterioration during fAD progression. Furthermore, it implies that the deterioration cannot be studied generally throughout the hippocampus but must be researched at a finer resolution of microcircuits. This opens novel systems-level approaches for analyzing AD-related neural network deficits.
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Affiliation(s)
- Ohad Rechnitz
- Department of Neuroscience, Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, 31096 Haifa, Israel
| | - Inna Slutsky
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Genela Morris
- Department of Neuroscience, Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, 31096 Haifa, Israel
| | - Dori Derdikman
- Department of Neuroscience, Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, 31096 Haifa, Israel.
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41
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Wynn JS, Buchsbaum BR, Ryan JD. Encoding and retrieval eye movements mediate age differences in pattern completion. Cognition 2021; 214:104746. [PMID: 34034008 DOI: 10.1016/j.cognition.2021.104746] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 01/10/2023]
Abstract
Older adults often mistake new information as 'old', yet the mechanisms underlying this response bias remain unclear. Typically, false alarms by older adults are thought to reflect pattern completion - the retrieval of a previously encoded stimulus in response to partial input. However, other work suggests that age-related retrieval errors can be accounted for by deficient encoding processes. In the present study, we used eye movement monitoring to quantify age-related changes in behavioral pattern completion as a function of eye movements during both encoding and partially cued retrieval. Consistent with an age-related encoding deficit, older adults executed more gaze fixations and more similar eye movements across repeated image presentations than younger adults, and such effects were predictive of subsequent recognition memory. Analysis of eye movements at retrieval further indicated that in response to partial lure cues, older adults reactivated the similar studied image, indexed by the similarity between encoding and retrieval gaze patterns, and did so more than younger adults. Critically, reactivation of encoded image content via eye movements was associated with lure false alarms in older adults, providing direct evidence for a pattern completion bias. Together, these findings suggest that age-related changes in both encoding and retrieval processes, indexed by eye movements, underlie older adults' increased vulnerability to memory errors.
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Affiliation(s)
- Jordana S Wynn
- Department of Psychology, University of Toronto, Toronto, ON, Canada; Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada.
| | - Bradley R Buchsbaum
- Department of Psychology, University of Toronto, Toronto, ON, Canada; Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada
| | - Jennifer D Ryan
- Department of Psychology, University of Toronto, Toronto, ON, Canada; Rotman Research Institute, Baycrest Hospital, Toronto, ON, Canada
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42
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Diersch N, Valdes-Herrera JP, Tempelmann C, Wolbers T. Increased Hippocampal Excitability and Altered Learning Dynamics Mediate Cognitive Mapping Deficits in Human Aging. J Neurosci 2021; 41:3204-3221. [PMID: 33648956 PMCID: PMC8026345 DOI: 10.1523/jneurosci.0528-20.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 01/15/2021] [Accepted: 01/20/2021] [Indexed: 11/28/2022] Open
Abstract
Learning the spatial layout of a novel environment is associated with dynamic activity changes in the hippocampus and in medial parietal areas. With advancing age, the ability to learn spatial environments deteriorates substantially but the underlying neural mechanisms are not well understood. Here, we report findings from a behavioral and a fMRI experiment where healthy human older and younger adults of either sex performed a spatial learning task in a photorealistic virtual environment (VE). We modeled individual learning states using a Bayesian state-space model and found that activity in retrosplenial cortex (RSC)/parieto-occipital sulcus (POS) and anterior hippocampus did not change systematically as a function learning in older compared with younger adults across repeated episodes in the environment. Moreover, effective connectivity analyses revealed that the age-related learning deficits were linked to an increase in hippocampal excitability. Together, these results provide novel insights into how human aging affects computations in the brain's navigation system, highlighting the critical role of the hippocampus.SIGNIFICANCE STATEMENT Key structures of the brain's navigation circuit are particularly vulnerable to the deleterious consequences of aging, and declines in spatial navigation are among the earliest indicators for a progression from healthy aging to neurodegenerative diseases. Our study is among the first to provide a mechanistic account about how physiological changes in the aging brain affect the formation of spatial knowledge. We show that neural activity in the aging hippocampus and medial parietal areas is decoupled from individual learning states across repeated episodes in a novel spatial environment. Importantly, we find that increased excitability of the anterior hippocampus might constitute a potential neural mechanism for cognitive mapping deficits in old age.
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Affiliation(s)
- Nadine Diersch
- Aging and Cognition Research Group, German Center for Neurodegenerative Diseases (DZNE), Magdeburg 39120, Germany
| | - Jose P Valdes-Herrera
- Aging and Cognition Research Group, German Center for Neurodegenerative Diseases (DZNE), Magdeburg 39120, Germany
| | - Claus Tempelmann
- Department of Neurology, Otto-von-Guericke University Magdeburg, Magdeburg 39120, Germany
| | - Thomas Wolbers
- Aging and Cognition Research Group, German Center for Neurodegenerative Diseases (DZNE), Magdeburg 39120, Germany
- Department of Neurology, Otto-von-Guericke University Magdeburg, Magdeburg 39120, Germany
- Center for Behavioural Brain Sciences (CBBS), Otto-von-Guericke University Magdeburg, Magdeburg 39120, Germany
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Buss EW, Corbett NJ, Roberts JG, Ybarra N, Musial TF, Simkin D, Molina-Campos E, Oh KJ, Nielsen LL, Ayala GD, Mullen SA, Farooqi AK, D'Souza GX, Hill CL, Bean LA, Rogalsky AE, Russo ML, Curlik DM, Antion MD, Weiss C, Chetkovich DM, Oh MM, Disterhoft JF, Nicholson DA. Cognitive aging is associated with redistribution of synaptic weights in the hippocampus. Proc Natl Acad Sci U S A 2021; 118:e1921481118. [PMID: 33593893 PMCID: PMC7923642 DOI: 10.1073/pnas.1921481118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Behaviors that rely on the hippocampus are particularly susceptible to chronological aging, with many aged animals (including humans) maintaining cognition at a young adult-like level, but many others the same age showing marked impairments. It is unclear whether the ability to maintain cognition over time is attributable to brain maintenance, sufficient cognitive reserve, compensatory changes in network function, or some combination thereof. While network dysfunction within the hippocampal circuit of aged, learning-impaired animals is well-documented, its neurobiological substrates remain elusive. Here we show that the synaptic architecture of hippocampal regions CA1 and CA3 is maintained in a young adult-like state in aged rats that performed comparably to their young adult counterparts in both trace eyeblink conditioning and Morris water maze learning. In contrast, among learning-impaired, but equally aged rats, we found that a redistribution of synaptic weights amplifies the influence of autoassociational connections among CA3 pyramidal neurons, yet reduces the synaptic input onto these same neurons from the dentate gyrus. Notably, synapses within hippocampal region CA1 showed no group differences regardless of cognitive ability. Taking the data together, we find the imbalanced synaptic weights within hippocampal CA3 provide a substrate that can explain the abnormal firing characteristics of both CA3 and CA1 pyramidal neurons in aged, learning-impaired rats. Furthermore, our work provides some clarity with regard to how some animals cognitively age successfully, while others' lifespans outlast their "mindspans."
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Affiliation(s)
- Eric W Buss
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Nicola J Corbett
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Joshua G Roberts
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Natividad Ybarra
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Timothy F Musial
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Dina Simkin
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | | | - Kwang-Jin Oh
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Lauren L Nielsen
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Gelique D Ayala
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Sheila A Mullen
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Anise K Farooqi
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Gary X D'Souza
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Corinne L Hill
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Linda A Bean
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Annalise E Rogalsky
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Matthew L Russo
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612
| | - Dani M Curlik
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Marci D Antion
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Craig Weiss
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Dane M Chetkovich
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - M Matthew Oh
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Disterhoft
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611;
| | - Daniel A Nicholson
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612;
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44
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Rao G, Lee H, Gallagher M, Knierim JJ. Decreased investigatory head scanning during exploration in learning-impaired, aged rats. Neurobiol Aging 2021; 98:1-9. [PMID: 33221571 PMCID: PMC8639103 DOI: 10.1016/j.neurobiolaging.2020.10.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/23/2020] [Accepted: 10/08/2020] [Indexed: 01/04/2023]
Abstract
"Head scanning" is an investigatory behavior that has been linked to spatial exploration and the one-trial formation or strengthening of place cells in the hippocampus. Previous studies have demonstrated that a subset of aged rats with normal spatial learning performance show head scanning rates during a novel, local-global cue-mismatch manipulation that are similar to those of young rats. However, these aged rats demonstrated different patterns of expression of neural activity markers in brain regions associated with spatial learning, perhaps suggesting neural mechanisms that compensate for age-related brain changes. These prior studies did not investigate the head scanning properties of aged rats that had spatial learning impairments. The present study analyzed head scanning behavior in young, aged-unimpaired, and aged-impaired Long Evans rats. Aged-impaired rats performed the head scan behavior at a lower rate than the young rats. These results suggest that decreased attention to spatial landmarks may be a contributing factor to the spatial learning deficits shown by the aged-impaired rats.
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Affiliation(s)
- Geeta Rao
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Heekyung Lee
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - James J Knierim
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA; Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
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45
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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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Koike R, Takaichi Y, Soeda Y, Takashima A. Memory formation in old age requires GSK-3β. AGING BRAIN 2021; 1:100022. [PMID: 36911517 PMCID: PMC9997123 DOI: 10.1016/j.nbas.2021.100022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/02/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Glycogen synthase kinase 3β (GSK-3β) is a therapeutic target for various age-related neurodegenerative diseases. It is linked to the two main pathological features of Alzheimer's disease (AD), tau and amyloid β (Aβ); GSK-3β is a major candidate to pathologically hyperphosphorylate tau and modulate Aβ production. However, inhibition of GSK-3β in clinical studies in humans has been found to not significantly improve cognitive function of AD patients, prompting us to study the physiological role of GSK-3β in old mice. Using a contextual fear-conditioning paradigm, we now report that old gsk-3β+/- mice are deficient in both short-term and long-term memory formation, suggesting that GSK-3β is required for memory formation at old age. Biochemical and immunohistochemical analyses showed that the number of synapses does not differ between gsk-3β+/- and age-matched wild-type (wt) littermate mice. Based on these observations, we propose that, GSK-3β may contribute to help maintain brain function during aging. Our results may explain the poor efficacy of GSK-3β inhibitors in preserving memory capacity in AD patients.
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Affiliation(s)
- Riki Koike
- Laboratory for Alzheimer's Disease, Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
| | - Yuta Takaichi
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yoshiyuki Soeda
- Laboratory for Alzheimer's Disease, Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
| | - Akihiko Takashima
- Laboratory for Alzheimer's Disease, Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
- Corresponding author.
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Stark SM, Frithsen A, Stark CE. Age-related alterations in functional connectivity along the longitudinal axis of the hippocampus and its subfields. Hippocampus 2021; 31:11-27. [PMID: 32918772 PMCID: PMC8354549 DOI: 10.1002/hipo.23259] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 07/31/2020] [Accepted: 08/07/2020] [Indexed: 12/13/2022]
Abstract
Hippocampal circuit alterations that differentially affect hippocampal subfields are associated with age-related memory decline. Additionally, functional organization along the longitudinal axis of the hippocampus has revealed distinctions between anterior and posterior (A-P) connectivity. Here, we examined the functional connectivity (FC) differences between young and older adults at high-resolution within the medial temporal lobe network (entorhinal, perirhinal, and parahippocampal cortices), allowing us to explore how hippocampal subfield connectivity across the longitudinal axis of the hippocampus changes with age. Overall, we found reliably greater connectivity for younger adults than older adults between the hippocampus and parahippocampal cortex (PHC) and perirhinal cortex (PRC). This drop in functional connectivity was more pronounced in the anterior regions of the hippocampus than the posterior ones, consistent for each of the hippocampal subfields. Further, intra-hippocampal connectivity also reflected an age-related decrease in functional connectivity within the anterior hippocampus in older adults that was offset by an increase in posterior hippocampal functional connectivity. Interestingly, the anterior-posterior dysfunction in older adults between hippocampus and PHC was predictive of lure discrimination performance on the Mnemonic similarity task (MST), suggesting a role in memory performance. While age-related dysfunction within the hippocampal subfields has been well-documented, these results suggest that the age-related dysfunction in hippocampal connectivity across the longitudinal axis may also contribute significantly to memory decline in older adults.
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Affiliation(s)
- Shauna M. Stark
- Department of Neurobiology and Behavior, University of California Irvine
| | - Amy Frithsen
- Department of Neurobiology and Behavior, University of California Irvine
| | - Craig E.L. Stark
- Department of Neurobiology and Behavior, University of California Irvine
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Li Q, Marcu DC, Palazzo O, Turner F, King D, Spires-Jones TL, Stefan MI, Busch KE. High neural activity accelerates the decline of cognitive plasticity with age in Caenorhabditis elegans. eLife 2020; 9:59711. [PMID: 33228848 PMCID: PMC7685709 DOI: 10.7554/elife.59711] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/18/2020] [Indexed: 12/11/2022] Open
Abstract
The ability to learn progressively declines with age. Neural hyperactivity has been implicated in impairing cognitive plasticity with age, but the molecular mechanisms remain elusive. Here, we show that chronic excitation of the Caenorhabditis elegans O2-sensing neurons during ageing causes a rapid decline of experience-dependent plasticity in response to environmental O2 concentration, whereas sustaining lower activity of O2-sensing neurons retains plasticity with age. We demonstrate that neural activity alters the ageing trajectory in the transcriptome of O2-sensing neurons, and our data suggest that high-activity neurons redirect resources from maintaining plasticity to sustaining continuous firing. Sustaining plasticity with age requires the K+-dependent Na+/Ca2+ (NCKX) exchanger, whereas the decline of plasticity with age in high-activity neurons acts through calmodulin and the scaffold protein Kidins220. Our findings demonstrate directly that the activity of neurons alters neuronal homeostasis to govern the age-related decline of neural plasticity and throw light on the mechanisms involved.
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Affiliation(s)
- Qiaochu Li
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Daniel-Cosmin Marcu
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ottavia Palazzo
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Frances Turner
- Edinburgh Genomics (Genome Science), Ashworth Laboratories, The University of Edinburgh, Edinburgh, United Kingdom
| | - Declan King
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,United Kingdom Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Tara L Spires-Jones
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,United Kingdom Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Melanie I Stefan
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,ZJU-UoE Institute, Zhejiang University, Haining, China
| | - Karl Emanuel Busch
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom
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49
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Francavilla R, Guet-McCreight A, Amalyan S, Hui CW, Topolnik D, Michaud F, Marino B, Tremblay MÈ, Skinner FK, Topolnik L. Alterations in Intrinsic and Synaptic Properties of Hippocampal CA1 VIP Interneurons During Aging. Front Cell Neurosci 2020; 14:554405. [PMID: 33173468 PMCID: PMC7591401 DOI: 10.3389/fncel.2020.554405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/10/2020] [Indexed: 12/21/2022] Open
Abstract
Learning and memory deficits are hallmarks of the aging brain, with cortical neuronal circuits representing the main target in cognitive deterioration. While GABAergic inhibitory and disinhibitory circuits are critical in supporting cognitive processes, their roles in age-related cognitive decline remain largely unknown. Here, we examined the morphological and physiological properties of the hippocampal CA1 vasoactive intestinal peptide/calretinin-expressing (VIP+/CR+) type 3 interneuron-specific (I-S3) cells across mouse lifespan. Our data showed that while the number and morphological features of I-S3 cells remained unchanged, their firing and synaptic properties were significantly altered in old animals. In particular, the action potential duration and the level of steady-state depolarization were significantly increased in old animals in parallel with a significant decrease in the maximal firing frequency. Reducing the fast-delayed rectifier potassium or transient sodium conductances in I-S3 cell computational models could reproduce the age-related changes in I-S3 cell firing properties. However, experimental data revealed no difference in the activation properties of the Kv3.1 and A-type potassium currents, indicating that transient sodium together with other ion conductances may be responsible for the observed phenomena. Furthermore, I-S3 cells in aged mice received a stronger inhibitory drive due to concomitant increase in the amplitude and frequency of spontaneous inhibitory currents. These age-associated changes in the I-S3 cell properties occurred in parallel with an increased inhibition of their target interneurons and were associated with spatial memory deficits and increased anxiety. Taken together, these data indicate that VIP+/CR+ interneurons responsible for local circuit disinhibition survive during aging but exhibit significantly altered physiological properties, which may result in the increased inhibition of hippocampal interneurons and distorted mnemonic functions.
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Affiliation(s)
- Ruggiero Francavilla
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Alexandre Guet-McCreight
- Krembil Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Sona Amalyan
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Chin Wai Hui
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Dimitry Topolnik
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Félix Michaud
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Beatrice Marino
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
- Department of Molecular Medicine, Faculty of Medicine, Université Laval, Québec, QC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Frances K. Skinner
- Krembil Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Departments of Medicine (Neurology) and Physiology, University of Toronto, Toronto, ON, Canada
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC, Canada
- Neuroscience Axis, Centre Hospitalier Universitaire (CHU) de Québec Research Center – Université Laval, Québec, QC, Canada
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50
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Fielder E, Tweedy C, Wilson C, Oakley F, LeBeau FEN, Passos JF, Mann DA, von Zglinicki T, Jurk D. Anti-inflammatory treatment rescues memory deficits during aging in nfkb1 -/- mice. Aging Cell 2020; 19:e13188. [PMID: 32915495 PMCID: PMC7576267 DOI: 10.1111/acel.13188] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/29/2020] [Accepted: 06/14/2020] [Indexed: 12/11/2022] Open
Abstract
Chronic inflammation is a common feature of many age-related conditions including neurodegenerative diseases such as Alzheimer's disease. Cellular senescence is a state of irreversible cell-cycle arrest, thought to contribute to neurodegenerative diseases partially via induction of a chronic pro-inflammatory phenotype. In this study, we used a mouse model of genetically enhanced NF-κB activity (nfκb1-/- ), characterized by low-grade chronic inflammation and premature aging, to investigate the impact of inflammaging on cognitive decline. We found that during aging, nfkb1-/- mice show an early onset of memory loss, combined with enhanced neuroinflammation and increased frequency of senescent cells in the hippocampus and cerebellum. Electrophysiological measurements in the hippocampus of nfkb1-/- mice in vitro revealed deficits in gamma frequency oscillations, which could explain the decline in memory capacity. Importantly, treatment with the nonsteroidal anti-inflammatory drug (NASID) ibuprofen reduced neuroinflammation and senescent cell burden resulting in significant improvements in cognitive function and gamma frequency oscillations. These data support the hypothesis that chronic inflammation is a causal factor in the cognitive decline observed during aging.
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Affiliation(s)
- Edward Fielder
- Biosciences InstituteAgeing Research LaboratoriesCampus for Ageing and VitalityNewcastle UniversityNewcastle upon TyneUK
| | - Clare Tweedy
- Biosciences InstituteFaculty of Medical SciencesNewcastle UniversityNewcastleUK
| | - Caroline Wilson
- Bioscience InstituteImmunity and InflammationNewcastle Fibrosis Research GroupFaculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Fiona Oakley
- Bioscience InstituteImmunity and InflammationNewcastle Fibrosis Research GroupFaculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Fiona E. N. LeBeau
- Biosciences InstituteFaculty of Medical SciencesNewcastle UniversityNewcastleUK
| | - João F. Passos
- Robert and Arlene Kogod Center on AgingMayo ClinicRochesterMNUSA
- Department of Physiology and Biomedical EngineeringMayo ClinicRochesterMNUSA
| | - Derek A. Mann
- Bioscience InstituteImmunity and InflammationNewcastle Fibrosis Research GroupFaculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Thomas von Zglinicki
- Biosciences InstituteAgeing Research LaboratoriesCampus for Ageing and VitalityNewcastle UniversityNewcastle upon TyneUK
| | - Diana Jurk
- Biosciences InstituteAgeing Research LaboratoriesCampus for Ageing and VitalityNewcastle UniversityNewcastle upon TyneUK
- Robert and Arlene Kogod Center on AgingMayo ClinicRochesterMNUSA
- Department of Physiology and Biomedical EngineeringMayo ClinicRochesterMNUSA
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