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Xiao X, Li J, Cao D, Zhang J, Jiang T. Contributions of repeated learning to memory in humans: insights from single-neuron recordings in the hippocampus and amygdala. Cereb Cortex 2024; 34:bhae244. [PMID: 38858840 DOI: 10.1093/cercor/bhae244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/21/2024] [Accepted: 05/30/2024] [Indexed: 06/12/2024] Open
Abstract
Despite the well-established phenomenon of improved memory performance through repeated learning, studies investigating the associated neural mechanisms have yielded complex and sometimes contradictory findings, and direct evidence from human neuronal recordings has been lacking. This study employs single-neuron recordings with exceptional spatial-temporal resolution, combined with representational similarity analysis, to explore the neural dynamics within the hippocampus and amygdala during repeated learning. Our results demonstrate that in the hippocampus, repetition enhances both representational specificity and fidelity, with these features predicting learning times. Conversely, the amygdala exhibits heightened representational specificity and fidelity during initial learning but does not show improvement with repetition, suggesting functional specialization of the hippocampus and amygdala during different stages of the learning repetition. Specifically, the hippocampus appears to contribute to sustained engagement necessary for benefiting from repeated learning, while the amygdala may play a role in the representation of novel items. These findings contribute to a comprehensive understanding of the intricate interplay between these brain regions in memory processes. Significance statement For over a century, understanding how repetition contributes to memory enhancement has captivated researchers, yet direct neuronal evidence has been lacking, with a primary focus on the hippocampus and a neglect of the neighboring amygdala. Employing advanced single-neuron recordings and analytical techniques, this study unveils a nuanced functional specialization within the amygdala-hippocampal circuit during various learning repetition. The results highlight the hippocampus's role in sustaining engagement for improved memory with repetition, contrasting with the amygdala's superior ability in representing novel items. This exploration not only deepens our comprehension of memory enhancement intricacies but also sheds light on potential interventions to optimize learning and memory processes.
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Affiliation(s)
- Xinyu Xiao
- Tianzi Jiang Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Li
- School of Psychology, Capital Normal University, Beijing 100048, China
| | - Dan Cao
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaqi Zhang
- Tianzi Jiang Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianzi Jiang
- Tianzi Jiang Brainnetome Center, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing 100049, China
- Research Center for Augmented Intelligence, Zhejiang Lab, Hangzhou 311100, China
- Xiaoxiang Institute for Brain Health and Yongzhou Central Hospital, Yongzhou 425000, Hunan Province, China
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2
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Dohm-Hansen S, English JA, Lavelle A, Fitzsimons CP, Lucassen PJ, Nolan YM. The 'middle-aging' brain. Trends Neurosci 2024; 47:259-272. [PMID: 38508906 DOI: 10.1016/j.tins.2024.02.001] [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: 10/16/2023] [Revised: 01/09/2024] [Accepted: 02/05/2024] [Indexed: 03/22/2024]
Abstract
Middle age has historically been an understudied period of life compared to older age, when cognitive and brain health decline are most pronounced, but the scope for intervention may be limited. However, recent research suggests that middle age could mark a shift in brain aging. We review emerging evidence on multiple levels of analysis indicating that midlife is a period defined by unique central and peripheral processes that shape future cognitive trajectories and brain health. Informed by recent developments in aging research and lifespan studies in humans and animal models, we highlight the utility of modeling non-linear changes in study samples with wide subject age ranges to distinguish life stage-specific processes from those acting linearly throughout the lifespan.
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Affiliation(s)
- Sebastian Dohm-Hansen
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; INFANT Research Centre, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Jane A English
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; INFANT Research Centre, University College Cork, Cork, Ireland
| | - Aonghus Lavelle
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Carlos P Fitzsimons
- Swammerdam Institute for Life Sciences, Brain Plasticity Group, University of Amsterdam, Amsterdam, The Netherlands
| | - Paul J Lucassen
- Swammerdam Institute for Life Sciences, Brain Plasticity Group, University of Amsterdam, Amsterdam, The Netherlands
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland.
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3
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Suwabe K, Kuwamizu R, Hyodo K, Yoshikawa T, Otsuki T, Zempo-Miyaki A, Yassa MA, Soya H. Improvement of mnemonic discrimination with acute light exercise is mediated by pupil-linked arousal in healthy older adults. Neurobiol Aging 2024; 133:107-114. [PMID: 37939430 PMCID: PMC10843052 DOI: 10.1016/j.neurobiolaging.2023.09.006] [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: 05/11/2023] [Revised: 09/17/2023] [Accepted: 09/18/2023] [Indexed: 11/10/2023]
Abstract
Physical exercise has positive impacts on hippocampal memory decline with aging. One of the postulated neurobiological mechanisms of the decline is reduced catecholaminergic projections from the locus coeruleus to the hippocampus. Recent human studies revealed that very light exercise rapidly enhances memory and pupil diameter, which suggests that light exercise may improve memory via neural circuits involved in the ascending arousal system, including the locus coeruleus, even in older adults. Thus, we aimed to clarify the effects of a single bout of light-intensity exercise (60% ventilatory threshold) on mnemonic discrimination performance, an index of hippocampal memory function, in healthy older adults using a randomized crossover design. Pupil diameter was measured during exercise as a physiological marker of the ascending arousal system. Discrimination of highly similar stimuli to the targets improved after exercise when compared to the resting control performance. Importantly, causal mediation analysis showed that pupil dilation during exercise mediated the memory improvement. These results suggest that brief light exercise rapidly enhances memory, possibly by upregulating the ascending arousal system.
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Affiliation(s)
- Kazuya Suwabe
- Faculty of Health and Sport Sciences, Ryutsu Keizai University, Ibaraki, Japan; Sports Neuroscience Division, Department of Mind, Advanced Research Initiative for Human High Performance (ARIHHP), Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan.
| | - Ryuta Kuwamizu
- Laboratory of Exercise Biochemistry and Neuroendocrinology, Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; Graduate School of Letters, Kyoto University, Kyoto, Japan
| | - Kazuki Hyodo
- Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, Japan
| | - Toru Yoshikawa
- Faculty of Health and Sport Sciences, Ryutsu Keizai University, Ibaraki, Japan
| | - Takeshi Otsuki
- Faculty of Health and Sport Sciences, Ryutsu Keizai University, Ibaraki, Japan
| | - Asako Zempo-Miyaki
- Faculty of Health and Sport Sciences, Ryutsu Keizai University, Ibaraki, Japan
| | - Michael A Yassa
- Sports Neuroscience Division, Department of Mind, Advanced Research Initiative for Human High Performance (ARIHHP), Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; Department of Neurobiology and Behavior, University of California, Irvine, CA, USA; Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA, USA
| | - Hideaki Soya
- Sports Neuroscience Division, Department of Mind, Advanced Research Initiative for Human High Performance (ARIHHP), Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; Laboratory of Exercise Biochemistry and Neuroendocrinology, Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
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4
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Perera Molligoda Arachchige AS, Garner AK. Seven Tesla MRI in Alzheimer's disease research: State of the art and future directions: A narrative review. AIMS Neurosci 2023; 10:401-422. [PMID: 38188012 PMCID: PMC10767068 DOI: 10.3934/neuroscience.2023030] [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: 07/27/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 01/09/2024] Open
Abstract
Seven tesla magnetic resonance imaging (7T MRI) is known to offer a superior spatial resolution and a signal-to-noise ratio relative to any other non-invasive imaging technique and provides the possibility for neuroimaging researchers to observe disease-related structural changes, which were previously only apparent on post-mortem tissue analyses. Alzheimer's disease is a natural and widely used subject for this technology since the 7T MRI allows for the anticipation of disease progression, the evaluation of secondary prevention measures thought to modify the disease trajectory, and the identification of surrogate markers for treatment outcome. In this editorial, we discuss the various neuroimaging biomarkers for Alzheimer's disease that have been studied using 7T MRI, which include morphological alterations, molecular characterization of cerebral T2*-weighted hypointensities, the evaluation of cerebral microbleeds and microinfarcts, biochemical changes studied with MR spectroscopy, as well as some other approaches. Finally, we discuss the limitations of the 7T MRI regarding imaging Alzheimer's disease and we provide our outlook for the future.
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Ding Y, Li L, Wang S, Cao Y, Yang M, Dai Y, Lin H, Li J, Liu Y, Wang Z, Liu W, Tao J. Electroacupuncture promotes neurogenesis in the dentate gyrus and improves pattern separation in an early Alzheimer's disease mouse model. Biol Res 2023; 56:65. [PMID: 38041203 PMCID: PMC10693055 DOI: 10.1186/s40659-023-00472-z] [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: 11/08/2022] [Accepted: 11/03/2023] [Indexed: 12/03/2023] Open
Abstract
BACKGROUND Impaired pattern separation occurs in the early stage of Alzheimer's disease (AD), and hippocampal dentate gyrus (DG) neurogenesis participates in pattern separation. Here, we investigated whether spatial memory discrimination impairment can be improved by promoting the hippocampal DG granule cell neogenesis-mediated pattern separation in the early stage of AD by electroacupuncture (EA). METHODS Five familial AD mutations (5 × FAD) mice received EA treatment at Baihui and Shenting points for 4 weeks. During EA, mice were intraperitoneally injected with BrdU (50 mg/kg) twice a day. rAAV containing Wnt5a shRNA was injected into the bilateral DG region, and the viral efficiency was evaluated by detecting Wnt5a mRNA levels. Cognitive behavior tests were conducted to assess the impact of EA treatment on cognitive function. The hippocampal DG area Aβ deposition level was detected by immunohistochemistry after the intervention; The number of BrdU+/CaR+ cells and the gene expression level of calretinin (CaR) and prospero homeobox 1(Prox1) in the DG area of the hippocampus was detected to assess neurogenesis by immunofluorescence and western blotting after the intervention; The gene expression levels of FZD2, Wnt5a, DVL2, p-DVL2, CaMKII, and p-CaMKII in the Wnt signaling pathway were detected by Western blotting after the intervention. RESULTS Cognitive behavioral tests showed that 5 × FAD mice had impaired pattern separation (P < 0.001), which could be improved by EA (P < 0.01). Immunofluorescence and Western blot showed that the expression of Wnt5a in the hippocampus was decreased (P < 0.001), and the neurogenesis in the DG was impaired (P < 0.001) in 5 × FAD mice. EA could increase the expression level of Wnt5a (P < 0.05) and promote the neurogenesis of immature granule cells (P < 0.05) and the development of neuronal dendritic spines (P < 0.05). Interference of Wnt5a expression aggravated the damage of neurogenesis (P < 0.05), weakened the memory discrimination ability (P < 0.05), and inhibited the beneficial effect of EA (P < 0.05) in AD mice. The expression level of Wnt pathway related proteins such as FZD2, DVL2, p-DVL2, CAMKII, p-CAMKII increased after EA, but the effect of EA was inhibited after Wnt5a was knocked down. In addition, EA could reduce the deposition of Aβ plaques in the DG without any impact on Wnt5a. CONCLUSION EA can promote hippocampal DG immature granule cell neogenesis-mediated pattern separation to improve spatial memory discrimination impairment by regulating Wnt5a in 5 × FAD mice.
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Affiliation(s)
- Yanyi Ding
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Long Li
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Sinuo Wang
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Yajun Cao
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Minguang Yang
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Yaling Dai
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Huawei Lin
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Jianhong Li
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Yulu Liu
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China
| | - Zhifu Wang
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fuzhou, Fujian, 350122, China
- Fujian Key Laboratory of Cognitive Rehabilitation, Affiliated Rehabilitation Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, 350001, China
| | - Weilin Liu
- The Institute of Rehabilitation Industry, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China.
| | - Jing Tao
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, 350122, China.
- Fujian Key Laboratory of Rehabilitation Technology, Affiliated Rehabilitation Hospital of Fujian University of Traditional Chinese Medicine, Fuzhou, 350001, China.
- Provincial and Ministerial Co-founded Collaborative Innovation Center of Rehabilitation Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China.
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Purcell J, Wiley R, Won J, Callow D, Weiss L, Alfini A, Wei Y, Carson Smith J. Increased neural differentiation after a single session of aerobic exercise in older adults. Neurobiol Aging 2023; 132:67-84. [PMID: 37742442 DOI: 10.1016/j.neurobiolaging.2023.08.008] [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: 12/22/2022] [Revised: 08/19/2023] [Accepted: 08/24/2023] [Indexed: 09/26/2023]
Abstract
Aging is associated with decreased cognitive function. One theory posits that this decline is in part due to multiple neural systems becoming dedifferentiated in older adults. Exercise is known to improve cognition in older adults, even after only a single session. We hypothesized that one mechanism of improvement is a redifferentiation of neural systems. We used a within-participant, cross-over design involving 2 sessions: either 30 minutes of aerobic exercise or 30 minutes of seated rest (n = 32; ages 55-81 years). Both functional Magnetic Resonance Imaging (fMRI) and Stroop performance were acquired soon after exercise and rest. We quantified neural differentiation via general heterogeneity regression. There were 3 prominent findings following the exercise. First, participants were better at reducing Stroop interference. Second, while there was greater neural differentiation within the hippocampal formation and cerebellum, there was lower neural differentiation within frontal cortices. Third, this greater neural differentiation in the cerebellum and temporal lobe was more pronounced in the older ages. These data suggest that exercise can induce greater neural differentiation in healthy aging.
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Affiliation(s)
- Jeremy Purcell
- Department of Kinesiology, University of Maryland, College Park, MD, USA; Maryland Neuroimaging Center, University of Maryland, College Park, MD, USA.
| | - Robert Wiley
- Department of Psychology, University of North Carolina at Greensboro, Greensboro, NC, USA
| | - Junyeon Won
- Department of Kinesiology, University of Maryland, College Park, MD, USA; Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, TX, USA
| | - Daniel Callow
- Department of Kinesiology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
| | - Lauren Weiss
- Department of Kinesiology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
| | - Alfonso Alfini
- National Center on Sleep Disorders Research, Division of Lung Diseases, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Yi Wei
- Maryland Neuroimaging Center, University of Maryland, College Park, MD, USA
| | - J Carson Smith
- Department of Kinesiology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA.
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7
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Homayouni R, Canada KL, Saifullah S, Foster DJ, Thill C, Raz N, Daugherty AM, Ofen N. Age-related differences in hippocampal subfield volumes across the human lifespan: A meta-analysis. Hippocampus 2023; 33:1292-1315. [PMID: 37881160 PMCID: PMC10841547 DOI: 10.1002/hipo.23582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 08/31/2023] [Accepted: 09/28/2023] [Indexed: 10/27/2023]
Abstract
The human hippocampus (Hc) is critical for memory function across the lifespan. It is comprised of cytoarchitectonically distinct subfields: dentate gyrus (DG), cornu ammonis sectors (CA) 1-4, and subiculum, each of which may be differentially susceptible to neurodevelopmental and neurodegenerative mechanisms. Identifying age-related differences in Hc subfield volumes can provide insights into neural mechanisms of memory function across the lifespan. Limited evidence suggests that DG and CA3 volumes differ across development while other regions remain relatively stable, and studies of adulthood implicate a downward trend in all subfield volumes with prominent age effects on CA1. Due to differences in methods and limited sampling for any single study, the magnitude of age effects on Hc subfield volumes and their probable lifespan trajectories remain unclear. Here, we conducted a meta-analysis on cross-sectional studies (n = 48,278 participants, ages = 4-94 years) to examine the association between age and Hc subfield volumes in development (n = 11 studies), adulthood (n = 30 studies), and a combined lifespan sample (n = 41 studies) while adjusting estimates for sample sizes. In development, age was positively associated with DG and CA3-4 volumes, whereas in adulthood a negative association was observed with all subfield volumes. Notably, the observed age effects were not different across subfield volumes within each age group. All subfield volumes showed a nonlinear age pattern across the lifespan with DG and CA3-4 volumes showing a more distinct age trajectory as compared to the other subfields. Lastly, among all the study-level variables, only female percentage of the study sample moderated the age effect on CA1 volume: a higher female-to-male ratio in the study sample was linked to the greater negative association between age and CA1 volume. These results document that Hc subfield volumes differ as a function of age offering broader implications for constructing theoretical models of lifespan memory development.
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Affiliation(s)
- Roya Homayouni
- Institute of Gerontology, Wayne State University, Detroit, Michigan, USA
- Department of Psychology, Wayne State University, Detroit, Michigan, USA
| | - Kelsey L Canada
- Institute of Gerontology, Wayne State University, Detroit, Michigan, USA
| | - Samaah Saifullah
- School of Medicine, Wayne State University, Detroit, Michigan, USA
| | - Da' Jonae Foster
- Department of Psychology, Wayne State University, Detroit, Michigan, USA
| | - Charlotte Thill
- School of Medicine, Wayne State University, Detroit, Michigan, USA
| | - Naftali Raz
- Department of Psychology, Stony Brook University, Stony Brook, New York, USA
- Max Planck Institute for Human Development, Berlin, Germany
| | - Ana M Daugherty
- Institute of Gerontology, Wayne State University, Detroit, Michigan, USA
- Department of Psychology, Wayne State University, Detroit, Michigan, USA
| | - Noa Ofen
- Institute of Gerontology, Wayne State University, Detroit, Michigan, USA
- Department of Psychology, Wayne State University, Detroit, Michigan, USA
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DeKraker J, Palomero-Gallagher N, Kedo O, Ladbon-Bernasconi N, Muenzing SEA, Axer M, Amunts K, Khan AR, Bernhardt BC, Evans AC. Evaluation of surface-based hippocampal registration using ground-truth subfield definitions. eLife 2023; 12:RP88404. [PMID: 37956092 PMCID: PMC10642966 DOI: 10.7554/elife.88404] [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: 11/15/2023] Open
Abstract
The hippocampus is an archicortical structure, consisting of subfields with unique circuits. Understanding its microstructure, as proxied by these subfields, can improve our mechanistic understanding of learning and memory and has clinical potential for several neurological disorders. One prominent issue is how to parcellate, register, or retrieve homologous points between two hippocampi with grossly different morphologies. Here, we present a surface-based registration method that solves this issue in a contrast-agnostic, topology-preserving manner. Specifically, the entire hippocampus is first analytically unfolded, and then samples are registered in 2D unfolded space based on thickness, curvature, and gyrification. We demonstrate this method in seven 3D histology samples and show superior alignment with respect to subfields using this method over more conventional registration approaches.
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Affiliation(s)
- Jordan DeKraker
- Montreal Neurological Institute and Hospital, McGill UniversityMontrealCanada
| | - Nicola Palomero-Gallagher
- Institute of Neuroscience and Medicine INM-1, Research Centre JülichJülichGermany
- C. & O. Vogt Institute for Brain Research, University Hospital Düsseldorf, Heinrich-Heine-UniversityDüsseldorfGermany
| | - Olga Kedo
- Institute of Neuroscience and Medicine INM-1, Research Centre JülichJülichGermany
| | | | - Sascha EA Muenzing
- Institute of Neuroscience and Medicine INM-1, Research Centre JülichJülichGermany
| | - Markus Axer
- Institute of Neuroscience and Medicine INM-1, Research Centre JülichJülichGermany
| | - Katrin Amunts
- Institute of Neuroscience and Medicine INM-1, Research Centre JülichJülichGermany
- C. & O. Vogt Institute for Brain Research, University Hospital Düsseldorf, Heinrich-Heine-UniversityDüsseldorfGermany
| | - Ali R Khan
- Robarts Research Institute, University of Western OntarioLondonCanada
| | - Boris C Bernhardt
- Montreal Neurological Institute and Hospital, McGill UniversityMontrealCanada
| | - Alan C Evans
- Montreal Neurological Institute and Hospital, McGill UniversityMontrealCanada
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Christopher-Hayes NJ, Embury CM, Wiesman AI, May PE, Schantell M, Johnson CM, Wolfson SL, Murman DL, Wilson TW. Piecing it together: atrophy profiles of hippocampal subfields relate to cognitive impairment along the Alzheimer's disease spectrum. Front Aging Neurosci 2023; 15:1212197. [PMID: 38020776 PMCID: PMC10644116 DOI: 10.3389/fnagi.2023.1212197] [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: 04/25/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction People with Alzheimer's disease (AD) experience more rapid declines in their ability to form hippocampal-dependent memories than cognitively normal healthy adults. Degeneration of the whole hippocampal formation has previously been found to covary with declines in learning and memory, but the associations between subfield-specific hippocampal neurodegeneration and cognitive impairments are not well characterized in AD. To improve prognostic procedures, it is critical to establish in which hippocampal subfields atrophy relates to domain-specific cognitive declines among people along the AD spectrum. In this study, we examine high-resolution structural magnetic resonance imaging (MRI) of the medial temporal lobe and extensive neuropsychological data from 29 amyloid-positive people on the AD spectrum and 17 demographically-matched amyloid-negative healthy controls. Methods Participants completed a battery of neuropsychological exams including select tests of immediate recollection, delayed recollection, and general cognitive status (i.e., performance on the Mini-Mental State Examination [MMSE] and Montreal Cognitive Assessment [MoCA]). Hippocampal subfield volumes (CA1, CA2, CA3, dentate gyrus, and subiculum) were measured using a dedicated MRI slab sequence targeting the medial temporal lobe and used to compute distance metrics to quantify AD spectrum-specific atrophic patterns and their impact on cognitive outcomes. Results Our results replicate prior studies showing that CA1, dentate gyrus, and subiculum hippocampal subfield volumes were significantly reduced in AD spectrum participants compared to amyloid-negative controls, whereas CA2 and CA3 did not exhibit such patterns of atrophy. Moreover, degeneration of the subiculum along the AD spectrum was linked to a significant decline in general cognitive status measured by the MMSE, while degeneration scores of the CA1 and dentate gyrus were more widely associated with declines on the MMSE and tests of learning and memory. Discussion These findings provide evidence that subfield-specific patterns of hippocampal degeneration, in combination with cognitive assessments, may constitute a sensitive prognostic approach and could be used to better track disease trajectories among individuals on the AD spectrum.
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Affiliation(s)
- Nicholas J. Christopher-Hayes
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- Center for Mind and Brain, University of California, Davis, CA, United States
| | - Christine M. Embury
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- Department of Psychology, University of Nebraska at Omaha, Omaha, NE, United States
| | - Alex I. Wiesman
- Montreal Neurological Institute, McGill University, Montréal, QC, Canada
| | - Pamela E. May
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, United States
| | - Mikki Schantell
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- College of Medicine, UNMC, Omaha, NE, United States
| | | | | | - Daniel L. Murman
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, United States
- Memory Disorders and Behavioral Neurology Program, UNMC, Omaha, NE, United States
| | - Tony W. Wilson
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- College of Medicine, UNMC, Omaha, NE, United States
- Department of Pharmacology and Neuroscience, Creighton University, Omaha, NE, United States
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10
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Jensen A, Karpov G, Collin CA, Davidson PSR. Executive Function Predicts Older Adults' Lure Discrimination Difficulties on the Mnemonic Similarity Task. J Gerontol B Psychol Sci Soc Sci 2023; 78:1642-1650. [PMID: 37330622 DOI: 10.1093/geronb/gbad091] [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: 01/12/2023] [Indexed: 06/19/2023] Open
Abstract
OBJECTIVES Older adults often have difficulty remembering the details of recently encountered objects. We previously found this with the Mnemonic Similarity Task (MST). Surprisingly, the older adults' MST Lure Discrimination Index (LDI) was significantly correlated with visual acuity but not with memory or executive function. Here we ran a replication with new, larger samples of young (N = 45) and older adults (N = 70). We then combined the original and replication older adult samples (N = 108) to critically examine the relative contributions of visual acuity, memory, and executive function composite scores to LDI performance using dominance analysis. This provided, to our knowledge, the first direct statistical comparison of all 3 of these factors and their interactions on LDI. METHODS Participants completed the MST and a battery assessing visual acuity, memory, and executive function. We examined age group differences on MST performance in the new (i.e., replication) young and older adult samples and performed multiple regression and dominance analysis on the combined older adult sample. RESULTS Consistent with previous findings, the older adults showed significantly poorer LDI but preserved item recognition. LDI was significantly correlated with both memory and executive function but not with visual acuity. In the combined older adult sample, all 3 composites predicted LDI, but dominance analysis indicated that executive function was the most important predictor. DISCUSSION Older adults' MST LDI difficulty may be predicted by their executive function and visual acuity. These factors should be considered when interpreting older adults' MST performance.
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Affiliation(s)
- Adelaide Jensen
- School of Psychology, University of Ottawa, Ottawa, Ontario, Canada
| | - Galit Karpov
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, New Jersey, USA
| | - Charles A Collin
- School of Psychology, University of Ottawa, Ottawa, Ontario, Canada
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Callow DD, Kommula Y, Stark CEL, Smith JC. Acute cycling exercise and hippocampal subfield function and microstructure in healthy older adults. Hippocampus 2023; 33:1123-1138. [PMID: 37526119 PMCID: PMC10543457 DOI: 10.1002/hipo.23571] [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: 06/07/2023] [Revised: 07/04/2023] [Accepted: 07/10/2023] [Indexed: 08/02/2023]
Abstract
Aging is associated with deterioration in dentate gyrus (DG) and CA3, both crucial hippocampal subfields for age susceptible memory processes such as mnemonic discrimination (MD). Meanwhile, a single aerobic exercise session alters DG/CA3 function and neural activity in both rats and younger adults and can elicit short-term microstructural alterations in the hippocampus of older adults. However, our understanding of the effects of acute exercise on hippocampal subfield integrity via function and microstructure in older adults is limited. Thus, a within subject-design was employed to determine if 20-min of moderate to vigorous aerobic exercise alters bilateral hippocampal subfield function and microstructure using high-resolution functional magnetic resonance imaging (fMRI) during an MD task (n = 35) and high angular resolution multi-shell diffusion imaging (n = 31), in healthy older adults, compared to seated rest. Following the exercise condition, participants exhibited poorer MD performance, particularly when their perception of effort was higher. Exercise was also related to lower MD-related activity within the DG/CA3 but not CA1 subfield. Finally, after controlling for whole brain gray matter diffusion, exercise was associated with lower neurite density index (NDI) within the DG/CA3. However, exercise-related differences in DG/CA3 activity and NDI were not associated with differences in MD performance. Our results suggest moderate to vigorous aerobic exercise may temporarily inhibit MD performance, and suppress DG/CA3 MD-related activity and NDI, potentially through neuroinflammatory/glial processes. However, additional studies are needed to confirm whether these short-term changes in behavior and hippocampal subfield neurophysiology are beneficial and how they might relate to long-term exercise habits.
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Affiliation(s)
- Daniel D. Callow
- Department of Kinesiology, University of Maryland, College Park, MD, USA
- Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
| | - Yash Kommula
- Department of Kinesiology, University of Maryland, College Park, MD, USA
- Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
| | - Craig E. L. Stark
- Department of Neurobiology and Behavior, University of California, Irvine, CA, USA
| | - J. Carson Smith
- Department of Kinesiology, University of Maryland, College Park, MD, USA
- Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
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12
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Ballard HK, Jackson TB, Symm AC, Hicks TH, Bernard JA. Age-related differences in functional network segregation in the context of sex and reproductive stage. Hum Brain Mapp 2022; 44:1949-1963. [PMID: 36541480 PMCID: PMC9980887 DOI: 10.1002/hbm.26184] [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: 08/16/2022] [Revised: 11/10/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Age is accompanied by differences in the organization of functional brain networks, which impact behavior in adulthood. Functional networks become less segregated and more integrated with age. However, sex differences in network segregation declines with age are not well-understood. Further, network segregation in the context of female reproductive stage is relatively understudied, though unmasking such relationships would be informative for elucidating biological mechanisms that contribute to sex-specific differences in aging. In the current work, we used data from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) repository to evaluate differences in resting-state network segregation as a product of sex and reproductive stage. Reproductive stage was categorized using the Stages of Reproductive Aging Workshop (STRAW+10) criteria. Replicating prior work, we investigated the following functional networks: auditory, cerebellar-basal ganglia, cingulo-opercular task control, default mode, dorsal attention, fronto-parietal task control, salience, sensory somatomotor mouth, sensory somatomotor hand, ventral attention, and visual. First, our results mirror findings from previous work indicating that network segregation is lower with increasing age. Second, when analyzing associations between network segregation and age within each sex separately, we find qualitative differences between females and males. Finally, we report significant effects of reproductive stage on network segregation, though these findings are likely driven by age. Broadly, our results suggest that impacts of sex may be important to evaluate when investigating network segregation differences across adulthood, though further work is needed to determine the unique role of menopause and sex hormones on the organization of functional brain networks within aging females.
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Affiliation(s)
- Hannah K. Ballard
- Texas A&M Institute for NeuroscienceTexas A&M UniversityCollege StationTexasUSA
| | - T. Bryan Jackson
- Department of Psychological & Brain SciencesTexas A&M UniversityCollege StationTexasUSA
| | - Abigail C. Symm
- Department of Psychological & Brain SciencesTexas A&M UniversityCollege StationTexasUSA
| | - Tracey H. Hicks
- Department of Psychological & Brain SciencesTexas A&M UniversityCollege StationTexasUSA
| | - Jessica A. Bernard
- Texas A&M Institute for NeuroscienceTexas A&M UniversityCollege StationTexasUSA,Department of Psychological & Brain SciencesTexas A&M UniversityCollege StationTexasUSA
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13
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Hodges TE, Lieblich SE, Rechlin RK, Galea LAM. Sex differences in inflammation in the hippocampus and amygdala across the lifespan in rats: associations with cognitive bias. Immun Ageing 2022; 19:43. [PMID: 36203171 PMCID: PMC9535862 DOI: 10.1186/s12979-022-00299-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/19/2022] [Indexed: 11/05/2022]
Abstract
Background Cognitive symptoms of major depressive disorder, such as negative cognitive bias, are more prevalent in women than in men. Cognitive bias involves pattern separation which requires hippocampal neurogenesis and is modulated by inflammation in the brain. Previously, we found sex differences in the activation of the amygdala and the hippocampus in response to negative cognitive bias in rats that varied with age. Given the association of cognitive bias to neurogenesis and inflammation, we examined associations between cognitive bias, neurogenesis in the hippocampus, and cytokine and chemokine levels in the ventral hippocampus (HPC) and basolateral amygdala (BLA) of male and female rats across the lifespan. Results After cognitive bias testing, males had more IFN-γ, IL-1β, IL-4, IL-5, and IL-10 in the ventral HPC than females in adolescence. In young adulthood, females had more IFN-γ, IL-1β, IL-6, and IL-10 in the BLA than males. Middle-aged rats had more IL-13, TNF-α, and CXCL1 in both regions than younger groups. Adolescent male rats had higher hippocampal neurogenesis than adolescent females after cognitive bias testing and young rats that underwent cognitive bias testing had higher levels of hippocampal neurogenesis than controls. Neurogenesis in the dorsal hippocampus was negatively associated with negative cognitive bias in young adult males. Conclusions Overall, the association between negative cognitive bias, hippocampal neurogenesis, and inflammation in the brain differs by age and sex. Hippocampal neurogenesis and inflammation may play greater role in the cognitive bias of young males compared to a greater role of BLA inflammation in adult females. These findings lay the groundwork for the discovery of sex-specific novel therapeutics that target region-specific inflammation in the brain and hippocampal neurogenesis. Supplementary Information The online version contains supplementary material available at 10.1186/s12979-022-00299-4. • Adolescent male rats had more hippocampal inflammation than females after cognitive bias testing. • Adult female rats had more basolateral amygdalar inflammation than males after cognitive bias testing. • HPC neurogenesis was negatively associated to cognitive bias in young adult male rats.
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Affiliation(s)
- Travis E. Hodges
- grid.17091.3e0000 0001 2288 9830Department of Psychology, University of British Columbia, Vancouver, Canada
| | - Stephanie E. Lieblich
- grid.17091.3e0000 0001 2288 9830Department of Psychology, University of British Columbia, Vancouver, Canada ,grid.17091.3e0000 0001 2288 9830Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Rebecca K. Rechlin
- grid.17091.3e0000 0001 2288 9830Department of Psychology, University of British Columbia, Vancouver, Canada ,grid.17091.3e0000 0001 2288 9830Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Liisa A. M. Galea
- grid.17091.3e0000 0001 2288 9830Department of Psychology, University of British Columbia, Vancouver, Canada ,grid.17091.3e0000 0001 2288 9830Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada ,grid.17091.3e0000 0001 2288 9830Graduate Program in Neuroscience, University of British Columbia, Vancouver, Canada
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14
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Wang H, Sun N, Wang X, Han J, Zhang Y, Huang Y, Zhou W. A touchscreen-based paradigm to measure visual pattern separation and pattern completion in mice. Front Neurosci 2022; 16:947742. [PMID: 36090275 PMCID: PMC9449699 DOI: 10.3389/fnins.2022.947742] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/29/2022] [Indexed: 11/27/2022] Open
Abstract
Memory accuracy involves two major processes: pattern separation and pattern completion. Pattern separation refers to the ability to reduce overlap among similar inputs to avoid interference, and pattern completion refers to the ability to retrieve the whole information from partial or degraded cues. Impairments in pattern separation/pattern completion contribute to cognitive deficits in several diseases of the nervous system. Therefore, it is better to evaluate both pattern separation and pattern completion in one apparatus. However, few tools are available to assess pattern separation and pattern completion within the same apparatus for rodents. In this study, we designed a series of images with varying degrees of similarity to the correct image to evaluate pattern separation and pattern completion. First, mice were trained to discriminate between two totally different images, and once the correct percentage reached above 77% for two consecutive days, the images with different degrees of similarity were used to measure pattern separation and pattern completion. The results showed the mice performed progressively worse from S0 to S4 (increasing similarity) when discriminating similar images in pattern separation, and the mice performed progressively worse from C0 to C4 (decreasing cues information) when recalling the correct image according to partial cues in pattern completion, implying a good image similarity-dependent manner for memory accuracy evaluation. In sum, we designed a convenient, effective paradigm to evaluate pattern separation and pattern completion based on a touchscreen pairwise discrimination task, which may provide a new method for the studies of the effects and mechanisms of memory accuracy enhancing drugs.
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Affiliation(s)
- Hao Wang
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Na Sun
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Xinyue Wang
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Jinyuan Han
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yongxiang Zhang
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Yan Huang
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
- *Correspondence: Yan Huang,
| | - Wenxia Zhou
- Beijing Institute of Pharmacology and Toxicology, Beijing, China
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
- Wenxia Zhou,
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15
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5 Hz of repetitive transcranial magnetic stimulation improves cognition and induces modifications in hippocampal neurogenesis in adult female Swiss Webster mice. Brain Res Bull 2022; 186:91-105. [PMID: 35688304 DOI: 10.1016/j.brainresbull.2022.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/23/2022] [Accepted: 06/03/2022] [Indexed: 11/22/2022]
Abstract
Adult hippocampal neurogenesis is regulated by several stimuli to promote the creation of a reserve that may facilitate coping with environmental challenges. In this regard, repetitive transcranial magnetic stimulation (rTMS), a neuromodulation therapy, came to our attention because in clinical studies it reverts behavioral and cognitive alterations related to changes in brain plasticity. Some preclinical studies emphasize the need to understand the underlying mechanism of rTMS to induce behavioral modifications. In this study, we investigated the effects of rTMS on cognition, neurogenic-associated modifications, and neuronal activation in the hippocampus of female Swiss Webster mice. We applied 5 Hz of rTMS twice a day for 14 days. Three days later, mice were exposed to the behavioral battery. Then, brains were collected and immunostained for Ki67-positive cells, doublecortin-positive (DCX+)-cells, calbindin, c-Fos and FosB/Delta-FosB in the dentate gyrus. Also, we analyzed mossy fibers and CA3 with calbindin immunostaining. Mice exposed to rTMS exhibited cognitive improvement, an increased number of proliferative cells, DCX cells, DCX cells with complex dendrite morphology, c-Fos and immunoreactivity of FosB/Delta-FosB in the granular cell layer. The volume of the granular cell layer, mossy fibers and CA3 in rTMS mice also increased. Interestingly, cognitive improvement correlated with DCX cells with complex dendrite morphology. Also, those DCX cells and calbindin immunoreactivity correlated with c-Fos in the granular cell layer. Our results suggest that 5 Hz of rTMS applied twice a day modify cell proliferation, doublecortin cells, mossy fibers and enhance cognitive behavior in healthy female Swiss Webster mice.
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16
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Lucey BP, Wisch J, Boerwinkle AH, Landsness EC, Toedebusch CD, McLeland JS, Butt OH, Hassenstab J, Morris JC, Ances BM, Holtzman DM. Sleep and longitudinal cognitive performance in preclinical and early symptomatic Alzheimer's disease. Brain 2021; 144:2852-2862. [PMID: 34668959 PMCID: PMC8536939 DOI: 10.1093/brain/awab272] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 06/13/2021] [Accepted: 07/01/2021] [Indexed: 11/12/2022] Open
Abstract
Sleep monitoring may provide markers for future Alzheimer's disease; however, the relationship between sleep and cognitive function in preclinical and early symptomatic Alzheimer's disease is not well understood. Multiple studies have associated short and long sleep times with future cognitive impairment. Since sleep and the risk of Alzheimer's disease change with age, a greater understanding of how the relationship between sleep and cognition changes over time is needed. In this study, we hypothesized that longitudinal changes in cognitive function will have a non-linear relationship with total sleep time, time spent in non-REM and REM sleep, sleep efficiency and non-REM slow wave activity. To test this hypothesis, we monitored sleep-wake activity over 4-6 nights in 100 participants who underwent standardized cognitive testing longitudinally, APOE genotyping, and measurement of Alzheimer's disease biomarkers, total tau and amyloid-β42 in the CSF. To assess cognitive function, individuals completed a neuropsychological testing battery at each clinical visit that included the Free and Cued Selective Reminding test, the Logical Memory Delayed Recall assessment, the Digit Symbol Substitution test and the Mini-Mental State Examination. Performance on each of these four tests was Z-scored within the cohort and averaged to calculate a preclinical Alzheimer cognitive composite score. We estimated the effect of cross-sectional sleep parameters on longitudinal cognitive performance using generalized additive mixed effects models. Generalized additive models allow for non-parametric and non-linear model fitting and are simply generalized linear mixed effects models; however, the linear predictors are not constant values but rather a sum of spline fits. We found that longitudinal changes in cognitive function measured by the cognitive composite decreased at low and high values of total sleep time (P < 0.001), time in non-REM (P < 0.001) and REM sleep (P < 0.001), sleep efficiency (P < 0.01) and <1 Hz and 1-4.5 Hz non-REM slow wave activity (P < 0.001) even after adjusting for age, CSF total tau/amyloid-β42 ratio, APOE ε4 carrier status, years of education and sex. Cognitive function was stable over time within a middle range of total sleep time, time in non-REM and REM sleep and <1 Hz slow wave activity, suggesting that certain levels of sleep are important for maintaining cognitive function. Although longitudinal and interventional studies are needed, diagnosing and treating sleep disturbances to optimize sleep time and slow wave activity may have a stabilizing effect on cognition in preclinical or early symptomatic Alzheimer's disease.
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Affiliation(s)
- Brendan P Lucey
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Julie Wisch
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Anna H Boerwinkle
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Eric C Landsness
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Cristina D Toedebusch
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jennifer S McLeland
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Omar H Butt
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jason Hassenstab
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
- Knight Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO 63110, USA
| | - John C Morris
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
- Knight Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Beau M Ances
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
| | - David M Holtzman
- Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA
- Knight Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, MO 63110, USA
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17
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Krotkova OA, Kuleva AY, Galkin MV, Kaverina MY, Strunina YV, Danilov GV. Memory Modulation Factors in Hippocampus Exposed to Radiation. Sovrem Tekhnologii Med 2021; 13:6-13. [PMID: 34603759 PMCID: PMC8482834 DOI: 10.17691/stm2021.13.4.01] [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: 12/03/2020] [Indexed: 11/14/2022] Open
Abstract
Although the key scene of the hippocampus in memory processes is obvious, the specificity of its participation in information processing is far from being established. Current advanced neuroimaging enables to operate with precise morphometric parameters. The aim of the study was to reveal fine memory rearrangements under mechanical impact on the hippocampus by a neoplasm and radiation exposure in the course of therapy. Materials and Methods We used a homogeneous sample of 28 patients with parasellar meningiomas adjacent to hippocampus. In 10 patients (5 with left-sided and 5 with right-sided meningiomas), the tumor was located near the hippocampus but exhibited no mechanical effect on it. In 18 patients (10 with left-sided and 8 with right-sided tumors), the neoplasm compressed the adjacent hippocampus. The control group consisted of 39 healthy subjects. All three groups were comparable in age, education, and gender characteristics. In order to control tumor growth, the patients underwent radiotherapy when the hippocampus involuntary was exposed to a dose comparable to that in the tumor (30 sessions with a single focal dose of 1.8 Gy, total dose - 54.0 Gy).Based on the literature data on hippocampus involved in mnestic processes, a special methodology to investigate memory was developed. Incorrect responses the subjects made when identifying previously memorized images were classified as neutralizing the novelty factor of an identified stimulus or as wrongly emphasizing its novelty. Results At the first observation point (before radiation therapy) all groups underwent a complete standardized neuropsychological examination and performed a battery of cognitive tests. The overall results of the tests assessing attention, memory, thinking processes, and neurodynamic indicators corresponded to standard values. A mild brain compression by the tumor without brain tissue destruction was not accompanied by focal neuropsychological symptoms and deficit manifestations in the cognitive sphere. However, as early as in the first observation point, the number of "pattern separation" errors in the clinical group was significantly higher than that in healthy subjects.The second observation point (immediately after radiotherapy) and the third observation point - 6 months after the treatment - showed that, in general, the patients' cognitive sphere condition was not deteriorating, and in a number of parameters was characterized by positive dynamics, apparently associated with some tumor reduction due to the therapy provided. However, the distribution of errors in the original method significantly changed. When previously memorized stimuli were recognized, the errors neutralizing the novelty factor of the evaluated stimulus increased, while the number of errors with overestimating the stimuli novelty decreased.All tendencies hypothetically (according to the published data) associated with the changes in functional activity of the hippocampus were more pronounced in the subgroup of patients with mechanical impact of the tumor on hippocampus. Conclusion The continuous flow of impressions any person has at any moment of his activity is most likely marked by the hippocampus in a continuum "old-similar-new". The present study has shown that mechanical impact on the hippocampus combined with radiation exposure changes the range of assessments towards the prevailing labeling "old, previously seen, already known".
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Affiliation(s)
- O A Krotkova
- Senior Researcher, Rehabilitation Unit; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - A Y Kuleva
- PhD Student; Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5A Butlerova St., Moscow, 117485, Russia
| | - M V Galkin
- Researcher, Radiotherapy Department; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - M Y Kaverina
- Junior Researcher, Rehabilitation Unit; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - Y V Strunina
- Managing Engineer; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - G V Danilov
- Scientific Secretary; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia; Associate Professor, Neurosurgery Department; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
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18
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Evidences for Adult Hippocampal Neurogenesis in Humans. J Neurosci 2021; 41:2541-2553. [PMID: 33762406 DOI: 10.1523/jneurosci.0675-20.2020] [Citation(s) in RCA: 128] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 07/20/2020] [Accepted: 09/28/2020] [Indexed: 12/16/2022] Open
Abstract
The rodent hippocampus generates new neurons throughout life. This process, named adult hippocampal neurogenesis (AHN), is a striking form of neural plasticity that occurs in the brains of numerous mammalian species. Direct evidence of adult neurogenesis in humans has remained elusive, although the occurrence of this phenomenon in the human dentate gyrus has been demonstrated in seminal studies and recent research that have applied distinct approaches to birthdate newly generated neurons and to validate markers of adult-born neurons. Our data point to the persistence of AHN until the 10th decade of human life, as well as to marked impairments in this process in patients with Alzheimer's disease. Moreover, our work demonstrates that the methods used to process and analyze postmortem human brain samples can limit the detection of various markers of AHN to the point of making them undetectable. In this Dual Perspectives article, we highlight the critical methodological aspects that should be strictly controlled in human studies and the robust evidence that supports the occurrence of AHN in humans. We also put forward reasons that may account for current discrepancies on this topic. Finally, the unresolved questions and future challenges awaiting the field are highlighted.
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Crowley EK, Grabrucker S, Long-Smith CM, Stack A, O'Gorman DM, Nolan YM. A Reduction in Behavioral Pattern Separation Is Attenuated by Dietary Supplementation with a Magnesium-Rich Marine Mineral Blend in Middle-Aged Rats. J Med Food 2021; 25:924-929. [PMID: 34185600 DOI: 10.1089/jmf.2020.0213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Middle age is increasingly accepted as a key period during which individuals are susceptible to the effect of environmental and lifestyle factors. Emerging research indicates that dietary factors play a crucial role in brain health and cognitive function, and studies in both animals and humans have demonstrated that dietary interventions can mitigate cognitive impairment. Specifically, magnesium has been shown to enhance learning and memory, and magnesium deficiency is associated with impaired hippocampal-dependent memory formation in animal studies. The aim of this study was to examine if supplementation with a magnesium-rich marine mineral blend (MMB) could alter middle-age-related cognitive impairment. Young and middle-aged rats were given access to a control diet or an experimental diet formulated with an MMB for 4 weeks before undergoing a series of behavioral assessments. Supplementation of MMB to middle-aged rats rescued a deficit in cognitive impairment, specifically a pattern separation paradigm that is sensitive to alterations in a type of brain plasticity called neurogenesis. It had no effect on general activity in the open field or performance on other hippocampal-associated tasks. Changes in cognitive function occur as a predictable consequence of aging. Research into whether modification of dietary factors, such as this MMB, may play a role in the prevention of age-related cognitive impairment warrants further investigation.
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Affiliation(s)
- Erin K Crowley
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Stefanie Grabrucker
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Alice Stack
- Marigot Ltd., Strand Farm, Currabinny, Carrigaline, Co. Cork, Ireland
| | - Denise M O'Gorman
- Marigot Ltd., Strand Farm, Currabinny, Carrigaline, Co. Cork, Ireland
| | - Yvonne M Nolan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
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