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Bañuelos C, Kittleson JR, LaNasa KH, Galiano CS, Roth SM, Perez EJ, Long JM, Roberts MT, Fong S, Rapp PR. Cognitive Aging and the Primate Basal Forebrain Revisited: Disproportionate GABAergic Vulnerability Revealed. J Neurosci 2023; 43:8425-8441. [PMID: 37798131 PMCID: PMC10711728 DOI: 10.1523/jneurosci.0456-23.2023] [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: 03/13/2023] [Revised: 09/22/2023] [Accepted: 09/23/2023] [Indexed: 10/07/2023] Open
Abstract
Basal forebrain (BF) projections to the hippocampus and cortex are anatomically positioned to influence a broad range of cognitive capacities that are known to decline in normal aging, including executive function and memory. Although a long history of research on neurocognitive aging has focused on the role of the cholinergic basal forebrain system, intermingled GABAergic cells are numerically as prominent and well positioned to regulate the activity of their cortical projection targets, including the hippocampus and prefrontal cortex. The effects of aging on noncholinergic BF neurons in primates, however, are largely unknown. In this study, we conducted quantitative morphometric analyses in brains from young adult (6 females, 2 males) and aged (11 females, 5 males) rhesus monkeys (Macaca mulatta) that displayed significant impairment on standard tests that require the prefrontal cortex and hippocampus. Cholinergic (ChAT+) and GABAergic (GAD67+) neurons were quantified through the full rostrocaudal extent of the BF. Total BF immunopositive neuron number (ChAT+ plus GAD67+) was significantly lower in aged monkeys compared with young, largely because of fewer GAD67+ cells. Additionally, GAD67+ neuron volume was greater selectively in aged monkeys without cognitive impairment compared with young monkeys. These findings indicate that the GABAergic component of the primate BF is disproportionally vulnerable to aging, implying a loss of inhibitory drive to cortical circuitry. Moreover, adaptive reorganization of the GABAergic circuitry may contribute to successful neurocognitive outcomes.SIGNIFICANCE STATEMENT A long history of research has confirmed the role of the basal forebrain in cognitive aging. The majority of that work has focused on BF cholinergic neurons that innervate the cortical mantle. Codistributed BF GABAergic populations are also well positioned to influence cognitive function, yet little is known about this prominent neuronal population in the aged brain. In this unprecedented quantitative comparison of both cholinergic and GABAergic BF neurons in young and aged rhesus macaques, we found that neuron number is significantly reduced in the aged BF compared with young, and that this reduction is disproportionately because of a loss of GABAergic neurons. Together, our findings encourage a new perspective on the functional organization of the primate BF in neurocognitive aging.
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Affiliation(s)
- Cristina Bañuelos
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Joshua R Kittleson
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Katherine H LaNasa
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Christina S Galiano
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Stephanie M Roth
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Evelyn J Perez
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Jeffrey M Long
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
| | - Mary T Roberts
- California National Primate Research Center, University of California, Davis, Davis, California 95616
| | - Sania Fong
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
- California National Primate Research Center, University of California, Davis, Davis, California 95616
| | - Peter R Rapp
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, Maryland 21224
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Baxter MG, Roberts MT, Roberts JA, Rapp PR. Neuropsychology of cognitive aging in rhesus monkeys. Neurobiol Aging 2023; 130:40-49. [PMID: 37453251 PMCID: PMC10530179 DOI: 10.1016/j.neurobiolaging.2023.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023]
Abstract
Aged rhesus monkeys, like aged humans, show declines in cognitive function. We present cognitive test data from a large sample of male and female rhesus monkeys, 34 young (aged 3.5-13.6 years) and 71 aged (aged 19.9-32.5 years at the start of cognitive testing). Monkeys were tested on spatiotemporal working memory (delayed response), visual recognition memory (delayed nonmatching to sample), and stimulus-reward association learning (object discrimination), tasks with an extensive evidence base in nonhuman primate neuropsychology. On average, aged monkeys performed worse than young on all 3 tasks. Acquisition of delayed response and delayed nonmatching to sample was more variable in aged monkeys than in young. Performance scores on delayed nonmatching to sample and object discrimination were associated with each other, but neither was associated with performance on delayed response. Sex and chronological age were not reliable predictors of individual differences in cognitive outcome among the aged monkeys. These data establish population norms for multiple cognitive tests in young and aged rhesus monkeys in the largest sample reported to date. They also illustrate independence of cognitive aging in task domains dependent on the prefrontal cortex and medial temporal lobe.
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Affiliation(s)
- Mark G Baxter
- Section on Comparative Medicine, Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
| | - Mary T Roberts
- California National Primate Research Center, University of California, Davis, Davis, CA, USA
| | - Jeffrey A Roberts
- California National Primate Research Center, University of California, Davis, Davis, CA, USA
| | - Peter R Rapp
- Laboratory of Behavioral Neuroscience, Neurocognitive Aging Section, National Institute on Aging, Baltimore, MD, USA.
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3
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Ibañez S, Sengupta N, Luebke JI, Wimmer K, Weaver CM. Myelin dystrophy in the aging prefrontal cortex leads to impaired signal transmission and working memory decline: a multiscale computational study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.30.555476. [PMID: 37693412 PMCID: PMC10491254 DOI: 10.1101/2023.08.30.555476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Normal aging leads to myelin alternations in the rhesus monkey dorsolateral prefrontal cortex (dlPFC), which are often correlated with cognitive impairment. It is hypothesized that remyelination with shorter and thinner myelin sheaths partially compensates for myelin degradation, but computational modeling has not yet explored these two phenomena together systematically. Here, we used a two-pronged modeling approach to determine how age-related myelin changes affect a core cognitive function: spatial working memory. First we built a multicompartment pyramidal neuron model fit to monkey dlPFC data, with axon including myelinated segments having paranodes, juxtaparanodes, internodes, and tight junctions, to quantify conduction velocity (CV) changes and action potential (AP) failures after demyelination and subsequent remyelination in a population of neurons. Lasso regression identified distinctive parameter sets likely to modulate an axon's susceptibility to CV changes following demyelination versus remyelination. Next we incorporated the single neuron results into a spiking neural network model of working memory. While complete remyelination nearly recovered axonal transmission and network function to unperturbed levels, our models predict that biologically plausible levels of myelin dystrophy, if uncompensated by other factors, can account for substantial working memory impairment with aging. The present computational study unites empirical data from electron microscopy up to behavior on aging, and has broader implications for many demyelinating conditions, such as multiple sclerosis or schizophrenia.
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Affiliation(s)
- Sara Ibañez
- Department of Anatomy & Neurobiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA USA 02118
- Centre de Recerca Matemàtica, Edifici C, Campus Bellaterra, 08193 Bellaterra, Spain
| | - Nilapratim Sengupta
- Department of Anatomy & Neurobiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA USA 02118
- Department of Mathematics, Franklin and Marshall College, Lancaster, PA, USA 17604
| | - Jennifer I Luebke
- Department of Anatomy & Neurobiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA USA 02118
| | - Klaus Wimmer
- Centre de Recerca Matemàtica, Edifici C, Campus Bellaterra, 08193 Bellaterra, Spain
| | - Christina M Weaver
- Department of Mathematics, Franklin and Marshall College, Lancaster, PA, USA 17604
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4
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Loyant L, Waller BM, Micheletta J, Meunier H, Ballesta S, Joly M. Tolerant macaque species are less impulsive and reactive. Anim Cogn 2023; 26:1453-1466. [PMID: 37245190 PMCID: PMC10442267 DOI: 10.1007/s10071-023-01789-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/26/2023] [Accepted: 05/18/2023] [Indexed: 05/29/2023]
Abstract
Inhibitory control, the inhibition of impulsive behaviours, is believed to be key in navigating a complex social environment. Species characterised by higher social tolerance, living in more complex groups, with more diverse relationships, face higher uncertainty regarding the outcome of social interactions and, therefore, would benefit from employing more inhibitory strategies. To date, little is known about the selective forces that favour the evolution of inhibitory control. In this study, we compared inhibitory control skills in three closely related macaque species which differ in their social tolerance style. We tested 66 macaques from two institutions (Macaca mulatta, low tolerance; M. fascicularis, medium tolerance; and M. tonkeana, high tolerance) using a battery of validated inhibitory control touchscreen tasks. Higher social tolerance was associated with enhanced inhibitory control performances. More tolerant species were less impulsive and less distracted by pictures of unknown conspecifics. Interestingly, we did not find evidence that social tolerance degree was associated with performance in reversal learning. Overall, our results support the hypothesis that evolution has promoted the development of socio-cognitive skills to cope with the demands related to the complexity of the social environment.
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Affiliation(s)
- Louise Loyant
- Centre for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, King Henry I Street, King Henry Building, Portsmouth, PO1 2DY, UK.
| | - Bridget M Waller
- Department of Psychology, Nottingham Trent University, Nottingham, UK
| | - Jérôme Micheletta
- Centre for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, King Henry I Street, King Henry Building, Portsmouth, PO1 2DY, UK
| | - Hélène Meunier
- UMR (7364), Laboratoire de Neurosciences Cognitives et Adaptatives, CNRS and Université de Strasbourg, Strasbourg, France
| | - Sébastien Ballesta
- UMR (7364), Laboratoire de Neurosciences Cognitives et Adaptatives, CNRS and Université de Strasbourg, Strasbourg, France
| | - Marine Joly
- Centre for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, King Henry I Street, King Henry Building, Portsmouth, PO1 2DY, UK
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5
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Baxter MG, Roberts MT, Roberts JA, Rapp PR. Neuropsychology of cognitive aging in rhesus monkeys. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542956. [PMID: 37398407 PMCID: PMC10312569 DOI: 10.1101/2023.05.30.542956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Aged rhesus monkeys, like aged humans, show declines in cognitive function. We present cognitive test data from a large sample of male and female rhesus monkeys, 34 young (3.5-13.6 years) and 71 aged (19.9-32.5 years of age at the start of cognitive testing). Monkeys were tested on spatiotemporal working memory (delayed response), visual recognition memory (delayed nonmatching-to-sample), and stimulus-reward association learning (object discrimination), tasks with an extensive evidence base in nonhuman primate neuropsychology. On average, aged monkeys performed worse than young on all three tasks. Acquisition of delayed response and delayed nonmatching-to-sample was more variable in aged monkeys than in young. Performance scores on delayed nonmatching-to-sample and object discrimination were associated with each other, but neither was associated with performance on delayed response. Sex and chronological age were not reliable predictors of individual differences in cognitive outcome among the aged monkeys. These data establish population norms for cognitive tests in young and aged rhesus monkeys in the largest sample reported to date. They also illustrate independence of cognitive aging in task domains dependent on the prefrontal cortex and medial temporal lobe. (181 words).
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Affiliation(s)
- Mark G. Baxter
- Section on Comparative Medicine, Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Mary T. Roberts
- California National Primate Research Center, University of California, Davis, Davis, CA 95616
| | - Jeffrey A. Roberts
- California National Primate Research Center, University of California, Davis, Davis, CA 95616
| | - Peter R. Rapp
- Laboratory of Behavioral Neuroscience, Neurocognitive Aging Section, National Institute on Aging, Baltimore, MD, USA
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6
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Gray DT, Khattab S, Meltzer J, McDermott K, Schwyhart R, Sinakevitch I, Härtig W, Barnes CA. Retrosplenial cortex microglia and perineuronal net densities are associated with memory impairment in aged rhesus macaques. Cereb Cortex 2023; 33:4626-4644. [PMID: 36169578 PMCID: PMC10110451 DOI: 10.1093/cercor/bhac366] [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: 05/06/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Synapse loss and altered plasticity are significant contributors to memory loss in aged individuals. Microglia, the innate immune cells of the brain, play critical roles in maintaining synapse function, including through a recently identified role in regulating the brain extracellular matrix. This study sought to determine the relationship between age, microglia, and extracellular matrix structure densities in the macaque retrosplenial cortex. Twenty-nine macaques ranging in age from young adult to aged were behaviorally characterized on 3 distinct memory tasks. Microglia, parvalbumin (PV)-expressing interneurons and extracellular matrix structures, known as perineuronal nets (PNNs), were immuno- and histochemically labeled. Our results indicate that microglia densities increase in the retrosplenial cortex of aged monkeys, while the proportion of PV neurons surrounded by PNNs decreases. Aged monkeys with more microglia had fewer PNN-associated PV neurons and displayed slower learning and poorer performance on an object recognition task. Stepwise regression models using age and the total density of aggrecan, a chondroitin sulfate proteoglycan of PNNs, better predicted memory performance than did age alone. Together, these findings indicate that elevated microglial activity in aged brains negatively impacts cognition in part through mechanisms that alter PNN assembly in memory-associated brain regions.
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Affiliation(s)
- Daniel T Gray
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
| | - Salma Khattab
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
| | - Jeri Meltzer
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
| | - Kelsey McDermott
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
| | - Rachel Schwyhart
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig 04103, Germany
| | - Irina Sinakevitch
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig 04103, Germany
| | - Carol A Barnes
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, United States
- Departments of Psychology, Neurology and Neuroscience, University of Arizona, Tucson, AZ 85721, United States
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7
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Chen G, Ma S, Gong Q, Xie X, Wu P, Guo W, Kang L, Li M, Zhang H, Zhou E, Zhang Y, Rong J, Duan H, Jin L, Xu S, Zhang N, Sun S, Li R, Yao L, Xiang D, Bu L, Liu Z. Assessment of brain imaging and cognitive function in a modified rhesus monkey model of depression. Behav Brain Res 2023; 445:114382. [PMID: 36871905 DOI: 10.1016/j.bbr.2023.114382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 03/07/2023]
Abstract
Depression incurs a huge personal and societal burden, impairing cognitive and social functioning and affecting millions of people worldwide. A better understanding of the biological basis of depression could facilitate the development of new and improved therapies. Rodent models have limitations and do not fully recapitulate human disease, hampering clinical translation. Primate models of depression help to bridge this translational gap and facilitate research into the pathophysiology of depression. Here we optimized a protocol for administering unpredictable chronic mild stress (UCMS) to non-human primates and evaluated the influence of UCMS on cognition using the classical Wisconsin General Test Apparatus (WGTA) method. We used resting-state functional MRI to explore changes in amplitude of low-frequency fluctuations and regional homogeneity in rhesus monkeys. Our work highlights that the UCMS paradigm effectively induces behavioral and neurophysiological (functional MRI) changes in monkeys but without significantly impacting cognition. The UCMS protocol requires further optimization in non-human primates to authentically simulate changes in cognition associated with depression.
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Affiliation(s)
- Guopeng Chen
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Simeng Ma
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Qian Gong
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Xinhui Xie
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Peng Wu
- Hubei Topgene Xinsheng Technology Co., Ltd, Wuhan 430000, China
| | - Wenbi Guo
- Department of Rehabilitation Medicine, Central Theater General Hospital, Wuhan 430070, China
| | - Lijun Kang
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Meng Li
- PET-CT/MRI Center and Molecular Imaging Center, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Honghan Zhang
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Enqi Zhou
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Yuhui Zhang
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Jingtong Rong
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Hao Duan
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Liuyin Jin
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Shuxian Xu
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Nan Zhang
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Siqi Sun
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Ruiling Li
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Lihua Yao
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Dan Xiang
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Lihong Bu
- PET-CT/MRI Center and Molecular Imaging Center, Renmin Hospital of Wuhan University, Wuhan 430060, China.
| | - Zhongchun Liu
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan 430060, China; Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan 430071, China.
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Age-Related Learning and Working Memory Impairment in the Common Marmoset. J Neurosci 2022; 42:8870-8880. [PMID: 36257687 PMCID: PMC9698676 DOI: 10.1523/jneurosci.0985-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 12/29/2022] Open
Abstract
Aging is the greatest risk factor for the development of neurodegenerative diseases, yet we still do not understand how the aging process leads to pathologic vulnerability. The research community has relied heavily on mouse models, but the considerable anatomic, physiological, and cognitive differences between mice and humans limit their translational relevance. Ultimately, these barriers necessitate the development of novel aging models. As a nonhuman primate (NHP), the common marmoset (Callithrix jacchus) shares many features in common with humans and yet has a significantly shorter lifespan (10 years) than other primates, making it ideally suited to longitudinal studies of aging. Our objective was to evaluate the marmoset as a model of age-related cognitive impairment. To do this, we used the Delayed Recognition Span Task (DRST) to characterize age-related changes in working memory capacity in a cohort of sixteen marmosets, of both sexes, varying in age from young adult to geriatric. These monkeys performed thousands of trials over periods of time ranging up to 50% of their adult lifespan. To our knowledge, this represents the most thorough cognitive profiling of any marmoset aging study conducted to date. By analyzing individual learning curves, we found that aged animals exhibited delayed onset of learning, slowed learning rate after onset, and decreased asymptotic working memory performance. These findings are not accounted for by age-related impairments in motor speed and motivation. This work firmly establishes the marmoset as a model of age-related cognitive impairment.SIGNIFICANCE STATEMENT Understanding the normal aging process is fundamental to identifying therapeutics for neurodegenerative diseases for which aging is the biggest risk factor. Historically, the aging field has relied on animal models that differ markedly from humans, constraining translatability. Here, we firmly establish a short-lived nonhuman primate (NHP), the common marmoset, as a key model of age-related cognitive impairment. We demonstrate, through continuous testing over a substantial portion of the adult marmoset lifespan, that aging is associated with both impaired learning and working memory capacity, unaccounted for by age-related changes in motor speed and motivation. Characterizing individual cognitive aging trajectories reveals inherent heterogeneity, which could lead to earlier identification of the onset of impairment, and extended timelines during which therapeutics are effective.
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9
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Upright NA, Baxter MG. Prefrontal cortex and cognitive aging in macaque monkeys. Am J Primatol 2021; 83:e23250. [PMID: 33687098 DOI: 10.1002/ajp.23250] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 02/17/2021] [Accepted: 02/21/2021] [Indexed: 11/11/2022]
Abstract
Cognitive impairments that accompany aging, even in the absence of neurodegenerative diseases, include deficits in executive function and memory mediated by the prefrontal cortex. Because of the unique differentiation and expansion of the prefrontal cortex in primates, investigations of the neurobiological basis of cognitive aging in nonhuman primates have been particularly informative about the potential basis for age-related cognitive decline in humans. We review the cognitive functions mediated by specific subregions of prefrontal cortex, and their corresponding connections, as well as the evidence for age-related alterations in specific regions of prefrontal cortex. We also discuss evidence for similarities and differences in the effects of aging on prefrontal cortex across species.
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Affiliation(s)
- Nicholas A Upright
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Mark G Baxter
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Gray DT, De La Peña NM, Umapathy L, Burke SN, Engle JR, Trouard TP, Barnes CA. Auditory and Visual System White Matter Is Differentially Impacted by Normative Aging in Macaques. J Neurosci 2020; 40:8913-8923. [PMID: 33051354 PMCID: PMC7659446 DOI: 10.1523/jneurosci.1163-20.2020] [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: 05/08/2020] [Revised: 08/06/2020] [Accepted: 10/04/2020] [Indexed: 11/21/2022] Open
Abstract
Deficits in auditory and visual processing are commonly encountered by older individuals. In addition to the relatively well described age-associated pathologies that reduce sensory processing at the level of the cochlea and eye, multiple changes occur along the ascending auditory and visual pathways that further reduce sensory function in each domain. One fundamental question that remains to be directly addressed is whether the structure and function of the central auditory and visual systems follow similar trajectories across the lifespan or sustain the impacts of brain aging independently. The present study used diffusion magnetic resonance imaging and electrophysiological assessments of auditory and visual system function in adult and aged macaques to better understand how age-related changes in white matter connectivity at multiple levels of each sensory system might impact auditory and visual function. In particular, the fractional anisotropy (FA) of auditory and visual system thalamocortical and interhemispheric corticocortical connections was estimated using probabilistic tractography analyses. Sensory processing and sensory system FA were both reduced in older animals compared with younger adults. Corticocortical FA was significantly reduced only in white matter of the auditory system of aged monkeys, while thalamocortical FA was lower only in visual system white matter of the same animals. Importantly, these structural alterations were significantly associated with sensory function within each domain. Together, these results indicate that age-associated deficits in auditory and visual processing emerge in part from microstructural alterations to specific sensory white matter tracts, and not from general differences in white matter condition across the aging brain.SIGNIFICANCE STATEMENT Age-associated deficits in sensory processing arise from structural and functional alterations to both peripheral sensory organs and central brain regions. It remains unclear whether different sensory systems undergo similar or distinct trajectories in function across the lifespan. To provide novel insights into this question, this study combines electrophysiological assessments of auditory and visual function with diffusion MRI in aged macaques. The results suggest that age-related sensory processing deficits in part result from factors that impact the condition of specific white matter tracts, and not from general decreases in connectivity between sensory brain regions. Such anatomic specificity argues for a framework aimed at understanding vulnerabilities with relatively local influence and brain region specificity.
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Affiliation(s)
- Daniel T Gray
- Division of Neural System, Memory and Aging, University of Arizona, Tucson, Arizona 85724
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
| | - Nicole M De La Peña
- Division of Neural System, Memory and Aging, University of Arizona, Tucson, Arizona 85724
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
| | - Lavanya Umapathy
- Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85724
| | - Sara N Burke
- Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, Florida 32609
| | - James R Engle
- Division of Neural System, Memory and Aging, University of Arizona, Tucson, Arizona 85724
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
| | - Theodore P Trouard
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85724
| | - Carol A Barnes
- Division of Neural System, Memory and Aging, University of Arizona, Tucson, Arizona 85724
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, Arizona 85724
- Departments of Psychology, Neurology and Neuroscience, University of Arizona, Tucson, Arizona 85724
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11
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Gray DT, Umapathy L, De La Peña NM, Burke SN, Engle JR, Trouard TP, Barnes CA. Auditory Processing Deficits Are Selectively Associated with Medial Temporal Lobe Mnemonic Function and White Matter Integrity in Aging Macaques. Cereb Cortex 2020; 30:2789-2803. [PMID: 31833551 DOI: 10.1093/cercor/bhz275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Indexed: 12/22/2022] Open
Abstract
Deficits in auditory function and cognition are hallmarks of normative aging. Recent evidence suggests that hearing-impaired individuals have greater risks of developing cognitive impairment and dementia compared to people with intact auditory function, although the neurobiological bases underlying these associations are poorly understood. Here, a colony of aging macaques completed a battery of behavioral tests designed to probe frontal and temporal lobe-dependent cognition. Auditory brainstem responses (ABRs) and visual evoked potentials were measured to assess auditory and visual system function. Structural and diffusion magnetic resonance imaging were then performed to evaluate the microstructural condition of multiple white matter tracts associated with cognition. Animals showing higher cognitive function had significantly better auditory processing capacities, and these associations were selectively observed with tasks that primarily depend on temporal lobe brain structures. Tractography analyses revealed that the fractional anisotropy (FA) of the fimbria-fornix and hippocampal commissure were associated with temporal lobe-dependent visual discrimination performance and auditory sensory function. Conversely, FA of frontal cortex-associated white matter was not associated with auditory processing. Visual sensory function was not associated with frontal or temporal lobe FA, nor with behavior. This study demonstrates significant and selective relationships between ABRs, white matter connectivity, and higher-order cognitive ability.
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Affiliation(s)
- Daniel T Gray
- Division of Neural System, Memory and Aging.,Evelyn F. McKnight Brain Institute
| | - Lavanya Umapathy
- Electrical and Computer Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Nicole M De La Peña
- Division of Neural System, Memory and Aging.,Evelyn F. McKnight Brain Institute
| | - Sara N Burke
- Evelyn F. McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - James R Engle
- Division of Neural System, Memory and Aging.,Evelyn F. McKnight Brain Institute
| | - Theodore P Trouard
- Evelyn F. McKnight Brain Institute.,Department of Biomedical Engineering
| | - Carol A Barnes
- Division of Neural System, Memory and Aging.,Evelyn F. McKnight Brain Institute.,Departments of Psychology, Neurology and Neuroscience, University of Arizona, Tucson, AZ 85721, USA
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