scholarly journals Functional architecture of the aging brain

2021 ◽  
Author(s):  
Roni Setton ◽  
Laetitia Mwilambwe-Tshilobo ◽  
Manesh Girn ◽  
Amber W. Lockrow ◽  
Giulia Baracchini ◽  
...  
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Cognitive Aging ◽  
Brain Aging ◽  
Connectivity Pattern ◽  
Aging Brain ◽  
Functional Architecture ◽  
Older Adulthood ◽  
Methodological Challenges ◽  
The Brain

The intrinsic network architecture of the brain is continuously shaped by biological and behavioral factors from younger to older adulthood. Differences in functional networks can reveal how a lifetime of learning and lived experience can alter large-scale neurophysiological dynamics, offering a powerful lens into brain and cognitive aging. Quantifying these differences has been hampered by significant methodological challenges. Here, we use multi-echo fMRI and multi-echo ICA processing, individualized cortical parcellation methods, and multivariate (gradient and edge-level) functional connectivity analyses to provide a definitive account of the intrinsic functional architecture of the brain in older adulthood. Twenty minutes of resting-state multi-echo fMRI data were collected in younger (n=181) and older (n=120) adults. Dimensionality, the number of independent, non-noise BOLD components in the fMRI signal, was significantly reduced for older adults. Macroscale functional gradients were largely preserved. In contrast, edge-level functional connectivity was significantly altered. Within-network connections were weaker while connections between networks were stronger for older adults, and this connectivity pattern was associated with lower executive control functioning. Greater integration of sensory and motor regions with transmodal association cortices also emerged as a prominent feature of the aging connectome. These findings implicate network dedifferentiation, reflected here as reduced dimensionality within the BOLD signal and altered edge-level connectivity, as a global and putatively maladaptive feature of functional brain aging. However, greater coherence among specific networks may also signal adaptive functional reorganization in later life. By overcoming persistent and pervasive methodological challenges that have confounded previous research, the results provide a comprehensive account of the intrinsic functional architecture of the aging brain.

scholarly journals The Shifting Architecture of Cognition and Brain Function in Older Adulthood

2019 ◽  
Vol 14 (4) ◽  
pp. 523-542 ◽  
Author(s):  
R. Nathan Spreng ◽  
Gary R. Turner
Keyword(s):  
Real World ◽  
Cognitive Aging ◽  
Network Architecture ◽  
Semantic Processing ◽  
Brain Aging ◽  
Cognitive Architecture ◽  
Later Life ◽  
Integrative Model ◽  
Older Adulthood ◽  
The Brain

Cognitive aging is often described in the context of loss or decline. Emerging research suggests that the story is more complex, with older adults showing both losses and gains in cognitive ability. With increasing age, declines in controlled, or fluid, cognition occur in the context of gains in crystallized knowledge of oneself and the world. This inversion in cognitive capacities, from greater reliance on fluid abilities in young adulthood to increasingly crystallized or semanticized cognition in older adulthood, has profound implications for cognitive and real-world functioning in later life. The shift in cognitive architecture parallels changes in the functional network architecture of the brain. Observations of greater functional connectivity between lateral prefrontal brain regions, implicated in cognitive control, and the default network, implicated in memory and semantic processing, led us to propose the default-executive coupling hypothesis of aging. In this review we provide evidence that these changes in the functional architecture of the brain serve as a neural mechanism underlying the shifting cognitive architecture from younger to older adulthood. We incorporate findings spanning cognitive aging and cognitive neuroscience to present an integrative model of cognitive and brain aging, describing its antecedents, determinants, and implications for real-world functioning.

scholarly journals The shifting architecture of cognition and brain function in older adulthood

2019 ◽  
Author(s):  
R. Nathan Spreng ◽  
Gary R. Turner
Keyword(s):  
Real World ◽  
Cognitive Aging ◽  
Network Architecture ◽  
Semantic Processing ◽  
Brain Aging ◽  
Cognitive Architecture ◽  
Later Life ◽  
Integrative Model ◽  
Older Adulthood ◽  
The Brain

Cognitive aging is often described in the context of loss or decline. Emerging research suggests that the story is more complex, with older adults showing both losses and gains in cognitive ability. With increasing age, declines in controlled, or fluid, cognition occurs in the context of gains in crystalized knowledge of oneself and the world. This inversion in cognitive capacities, from greater reliance on fluid abilities in young, to increasingly crystalized or semanticized cognition in older adulthood, has profound implications for cognitive and real-world functioning in later life. This shift in cognitive architecture parallels changes in the functional network architecture of the brain. Observations of greater functional connectivity between lateral prefrontal brain regions, implicated in cognitive control, and the default network, implicated in memory and semantic processing, led us to propose the Default Executive Coupling Hypothesis of Aging (DECHA). In this review we provide evidence that these changes in the functional architecture of the brain serve as a neural mechanism underlying the shifting cognitive architecture from younger to older adulthood. We incorporate findings spanning cognitive aging and cognitive neuroscience to present an integrative model of cognitive and brain aging, describing its antecedents, determinants, and implications for real-world functioning.

A Review and Reappraisal of the Default Network in Normal Aging and Dementia

2019 ◽  
Author(s):  
Jessica R. Andrews-Hanna ◽  
Matthew D. Grilli ◽  
Muireann Irish
Keyword(s):  
Older Adults ◽  
Cognitive Function ◽  
Brain Aging ◽  
Strong Support ◽  
Well Being ◽  
Normal Aging ◽  
Aging Brain ◽  
Default Network ◽  
Pathological Aging ◽  
Age Related

The brain’s default network (DN) has received considerable interest in the context of so-called “normal” and pathological aging. Findings have generally been couched in support of a pessimistic view of brain aging, marked by substantial loss of structural brain integrity accompanied by a host of impairments in brain and cognitive function. A critical look at the literature, however, reveals that the standard loss of integrity, loss of function (LILF) view in normal aging may not necessarily hold with respect to the DN and the internally guided functions it supports. Many internally guided processes subserved by the DN are preserved or enhanced in cognitively healthy older adults. Moreover, differences in motivational, contextual, and physiological factors between young and older adults likely influence the extant neuroimaging and cognitive findings. Accordingly, normal aging can be viewed as a series of possibly adaptive cognitive and DN-related alterations that bolster cognitive function and promote socioemotional well-being and stability in a stage of life noted for change. On the other hand, the available evidence reveals strong support for the LILF view of the DN in neurodegenerative disorders, whereby syndromes such as Alzheimer’s disease (AD) and semantic dementia (SD), characterized by progressive atrophy to distinct DN subsystems, display distinct aberrations in autobiographical and semantic cognition. Taken together, these findings call for more naturalistic, age-appropriate, and longitudinal paradigms when investigating neurocognitive changes in aging and to adequately assess and control for differences in non-neural factors that may obscure “true” effects of normal and pathological aging. A shift in the framework with which age-related alterations in internally guided cognition are interpreted may shed important light on the neurocognitive mechanisms differentiating healthy and pathological aging, leading to a more complete picture of the aging brain in all its complexity.

scholarly journals Span, CRUNCH, and Beyond: Working Memory Capacity and the Aging Brain

2010 ◽  
Vol 22 (4) ◽  
pp. 655-669 ◽  
Author(s):  
Nils J. Schneider-Garces ◽  
Brian A. Gordon ◽  
Carrie R. Brumback-Peltz ◽  
Eunsam Shin ◽  
Yukyung Lee ◽  
...  
Keyword(s):  
Older Adults ◽  
Working Memory ◽  
Neural Circuits ◽  
Memory Span ◽  
Brain Activity ◽  
Memory Search ◽  
Brain Activation ◽  
Aging Brain ◽  
Younger Adults ◽  
The Brain

Neuroimaging data emphasize that older adults often show greater extent of brain activation than younger adults for similar objective levels of difficulty. A possible interpretation of this finding is that older adults need to recruit neuronal resources at lower loads than younger adults, leaving no resources for higher loads, and thus leading to performance decrements [Compensation-Related Utilization of Neural Circuits Hypothesis; e.g., Reuter-Lorenz, P. A., & Cappell, K. A. Neurocognitive aging and the compensation hypothesis. Current Directions in Psychological Science, 17, 177–182, 2008]. The Compensation-Related Utilization of Neural Circuits Hypothesis leads to the prediction that activation differences between younger and older adults should disappear when task difficulty is made subjectively comparable. In a Sternberg memory search task, this can be achieved by assessing brain activity as a function of load relative to the individual's memory span, which declines with age. Specifically, we hypothesized a nonlinear relationship between load and both performance and brain activity and predicted that asymptotes in the brain activation function should correlate with performance asymptotes (corresponding to working memory span). The results suggest that age differences in brain activation can be largely attributed to individual variations in working memory span. Interestingly, the brain activation data show a sigmoid relationship with load. Results are discussed in terms of Cowan's [Cowan, N. The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24, 87–114, 2001] model of working memory and theories of impaired inhibitory processes in aging.

scholarly journals Evidence for Bias of Genetic Ancestry in Resting State Functional MRI

2018 ◽  
Author(s):  
Andre Altmann ◽  
Janaina Mourao-Miranda
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
High Performance ◽  
Imaging Modality ◽  
Genetic Ancestry ◽  
Connectivity Pattern ◽  
Functional Magnetic Resonance ◽  
Performance Area ◽  
The Brain ◽  
Very High

ABSTRACTResting state functional magnetic resonance imaging (rs-fMRI) is a popular imaging modality for mapping the functional connectivity of the brain. Rs-fMRI is, just like other neuroimaging modalities, subject to a series of technical and subject level biases that change the inferred connectivity pattern. In this work we predicted genetic ancestry from rs-fMRI connectivity data at very high performance (area under the ROC curve of 0.93). Thereby, we demonstrated that genetic ancestry is encoded in the functional connectivity pattern of the brain at rest. Consequently, genetic ancestry constitutes a bias that should be accounted for in the analysis of rs-fMRI data.

scholarly journals Impaired Mitophagy in Neurons and Glial Cells during Aging and Age-Related Disorders

2021 ◽  
Vol 22 (19) ◽  
pp. 10251
Author(s):  
Vladimir Sukhorukov ◽  
Dmitry Voronkov ◽  
Tatiana Baranich ◽  
Natalia Mudzhiri ◽  
Alina Magnaeva ◽  
...  
Keyword(s):  
Glial Cells ◽  
Brain Aging ◽  
Cellular Level ◽  
Aging Brain ◽  
The Past ◽  
Age Related ◽  
Accumulation Of Damage ◽  
Quantity Control ◽  
The Brain

Aging is associated with a decline in cognitive function, which can partly be explained by the accumulation of damage to the brain cells over time. Neurons and glia undergo morphological and ultrastructure changes during aging. Over the past several years, it has become evident that at the cellular level, various hallmarks of an aging brain are closely related to mitophagy. The importance of mitochondria quality and quantity control through mitophagy is highlighted by the contribution that defects in mitochondria–autophagy crosstalk make to aging and age-related diseases. In this review, we analyze some of the more recent findings regarding the study of brain aging and neurodegeneration in the context of mitophagy. We discuss the data on the dynamics of selective autophagy in neurons and glial cells during aging and in the course of neurodegeneration, focusing on three mechanisms of mitophagy: non-receptor-mediated mitophagy, receptor-mediated mitophagy, and transcellular mitophagy. We review the role of mitophagy in neuronal/glial homeostasis and in the molecular pathogenesis of neurodegenerative disorders, such as Parkinson’s disease, Alzheimer’s disease, and other disorders. Common mechanisms of aging and neurodegeneration that are related to different mitophagy pathways provide a number of promising targets for potential therapeutic agents.

scholarly journals Sex differences in the relationship between cardiorespiratory fitness and brain function in older adulthood

2019 ◽  
Vol 126 (4) ◽  
pp. 1032-1041 ◽  
Author(s):  
Christina J. Dimech ◽  
John A. E. Anderson ◽  
Amber W. Lockrow ◽  
R. Nathan Spreng ◽  
Gary R. Turner
Keyword(s):  
Older Adults ◽  
Sex Differences ◽  
Functional Connectivity ◽  
Cardiorespiratory Fitness ◽  
Resting State ◽  
Brain Function ◽  
Network Integration ◽  
Resting State Functional Connectivity ◽  
Older Adulthood ◽  
Fitness Level

We investigated sex differences in the association between a measure of physical health, cardiorespiratory fitness (CRF), and brain function using resting-state functional connectivity fMRI. We examined these sex differences in the default, frontoparietal control, and cingulo-opercular networks, assemblies of functionally connected brain regions known to be impacted by both age and fitness level. Healthy older adults ( n = 49; 29 women) were scanned to obtain measures of intrinsic connectivity within and across these 3 networks. We calculated global efficiency (a measure of network integration) and local efficiency (a measure of network specialization) using graph theoretical methods. Across all three networks combined, local efficiency was positively associated with CRF, and this was more robust in male versus female older adults. Furthermore, global efficiency was negatively associated with CRF, but only in males. Our findings suggest that in older adults, associations between brain network integrity and physical health are sex-dependent. These results underscore the importance of considering sex differences when examining associations between fitness and brain function in older adulthood. NEW & NOTEWORTHY We examined the association between cardiorespiratory fitness and resting state functional connectivity in several brain networks known to be impacted by age and fitness level. We found significant associations between fitness and measures of network integration and network specialization, but in a sex-dependent manner, highlighting the interplay between sex differences, fitness, and aging brain health. Our findings underscore the importance of considering sex differences when examining associations between fitness and brain function in older adulthood.

scholarly journals Functional Connectivity within and beyond the Face Network Is Related to Reduced Discrimination of Degraded Faces in Young and Older Adults

2020 ◽  
Vol 30 (12) ◽  
pp. 6206-6223
Author(s):  
Cheryl L Grady ◽  
Jenny R Rieck ◽  
Daniel Nichol ◽  
Douglas D Garrett
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Brain Networks ◽  
Brain Network ◽  
Whole Brain ◽  
The Face ◽  
Brain Correlates ◽  
Brain And Behavior ◽  
Face Stimuli ◽  
The Brain

Abstract Degrading face stimuli reduces face discrimination in both young and older adults, but the brain correlates of this decline in performance are not fully understood. We used functional magnetic resonance imaging to examine the effects of degraded face stimuli on face and nonface brain networks and tested whether these changes would predict the linear declines seen in performance. We found decreased activity in the face network (FN) and a decrease in the similarity of functional connectivity (FC) in the FN across conditions as degradation increased but no effect of age. FC in whole-brain networks also changed with increasing degradation, including increasing FC between the visual network and cognitive control networks. Older adults showed reduced modulation of this whole-brain FC pattern. The strongest predictors of within-participant decline in accuracy were changes in whole-brain network FC and FC similarity of the FN. There was no influence of age on these brain-behavior relations. These results suggest that a systems-level approach beyond the FN is required to understand the brain correlates of performance decline when faces are obscured with noise. In addition, the association between brain and behavior changes was maintained into older age, despite the dampened FC response to face degradation seen in older adults.

scholarly journals INTEREST GROUP SESSION—EPIDEMIOLOGY OF AGING: BIOSOCIAL RESEARCH ON BRAIN AGING AND BIOLOGICAL AGING

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S348-S348
Author(s):  
Daniel W Belsky
Keyword(s):  
Life Course ◽  
Cognitive Aging ◽  
Brain Aging ◽  
Functional Decline ◽  
Biological Aging ◽  
Social Psychological ◽  
Aging Research ◽  
System Integrity ◽  
Organ Systems ◽  
The Brain

Abstract Our aging global population presents a new set of challenges for public health. Individual-disease focused models are becoming outmoded as geriatricians recognize multimorbidity and frailty as the central challenges in preserving health for older adults. Evidence from research into the biology of aging suggests that a set of common cellular-level processes underpin decline in system integrity that induces vulnerability to disease across multiple organ systems, including the brain. In parallel, research in life-course gerontology indicates that the roots of aging-related decline in system integrity extend from early life and encompass histories of social, psychological, and biochemical exposures. The research presented in this symposium aims to integrate these emerging paradigms in aging research by mapping connections among measures of aging in the brain and body and social, psychological, and nutrition exposures. Our symposium focuses on (1) links between social-psychological determinants of health and biological aging in the brain and body; and (2) social and behavioral protective factors that may buffer emerging biological risk in aging. The overarching goal of this symposium is to introduce an approach to gerontology that integrates geroscience with life-course social and psychiatric epidemiology to advance understanding of cognitive aging and functional decline, and ultimately identify novel interventions to extend healthy lifespan.

Prefrontal Engagement and Reduced Default Network Suppression Co-occur and Are Dynamically Coupled in Older Adults: The Default–Executive Coupling Hypothesis of Aging

2015 ◽  
Vol 27 (12) ◽  
pp. 2462-2476 ◽  
Author(s):  
Gary R. Turner ◽  
R. Nathan Spreng
Keyword(s):  
Older Adults ◽  
Functional Connectivity ◽  
Cognitive Control ◽  
Executive Control ◽  
Network Activity ◽  
Default Network ◽  
Cognitive Approach ◽  
Older Adulthood ◽  
Age Related ◽  
Neurocognitive Aging

Reduced executive control is a hallmark of neurocognitive aging. Poor modulation of lateral pFC activity in the context of increasing task challenge in old adults and a “failure to deactivate” the default network during cognitive control tasks have been observed. Whether these two patterns represent discrete mechanisms of neurocognitive aging or interact into older adulthood remains unknown. We examined whether altered pFC and default network dynamics co-occur during goal-directed planning over increasing levels of difficulty during performance on the Tower of London task. We used fMRI to investigate task- and age-related changes in brain activation and functional connectivity across four levels of task challenge. Frontoparietal executive control regions were activated and default network regions were suppressed during planning relative to counting performance in both groups. Older adults, unlike young, failed to modulate brain activity in executive control and default regions as planning demands increased. Critically, functional connectivity analyses revealed bilateral dorsolateral pFC coupling in young adults and dorsolateral pFC to default coupling in older adults with increased planning complexity. We propose a default–executive coupling hypothesis of aging. First, this hypothesis suggests that failure to modulate control and default network activity in response to increasing task challenge are linked in older adulthood. Second, functional brain changes involve greater coupling of lateral pFC and the default network as cognitive control demands increase in older adults. We speculate that these changes reflect an adaptive shift in cognitive approach as older adults come to rely more upon stored representations to support goal-directed task performance.

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