Locus coeruleus integrity is related to an exploitation-based decision-making bias in older adulthood.

Optimal decision-making balances exploration for new information against exploitation of known rewards, a process mediated by the locus coeruleus and its norepinephrine projections. We predicted that an exploitation-bias that emerges in older adulthood would be associated with lower microstructural integrity of the locus coeruleus. Leveraging in vivo histological methods from quantitative MRI-magnetic transfer saturation-we provide evidence that older age is associated with lower locus coeruleus integrity. Critically, we demonstrate that an exploitation bias in older adulthood, assessed with a foraging task, is sensitive and specific to lower locus coeruleus integrity. Because the locus coeruleus is uniquely vulnerable to Alzheimer's disease pathology, our findings suggest that aging, and a presymptomatic trajectory of Alzheimer's related decline, may fundamentally alter decision-making abilities in later life.

Structure-Function Interactions in the Hippocampus and Prefrontal Cortex Are Associated with Episodic Memory in Healthy Aging.

Aging comes with declines in episodic memory. Memory decline is accompanied by structural and functional alterations within key brain regions, including the hippocampus and lateral prefrontal cortex, as well as their affiliated default and frontoparietal control networks. Most studies have examined how structural or functional differences relate to memory independently. Here we implemented a multimodal, multivariate approach to investigate how interactions between individual differences in structural integrity and functional connectivity relate to episodic memory performance in healthy aging. In a sample of younger (N = 111; mean age, 22.11 years) and older (N = 78; mean age, 67.29 years) adults, we analyzed structural MRI and multiecho resting-state fMRI data. Participants completed measures of list recall (free recall of words from a list), associative memory (cued recall of paired words), and source memory (cued recall of the trial type, or the sensory modality in which a word was presented). The findings revealed that greater structural integrity of the posterior hippocampus and middle frontal gyrus were linked with a pattern of increased within-network connectivity, which together were related to better associative and source memory in older adulthood. Critically, older adults displayed better memory performance in the context of decreased hippocampal volumes when structural differences were accompanied by functional reorganization. This functional reorganization was characterized by a pruning of connections between the hippocampus and the limbic and frontoparietal control networks. Our work provides insight into the neural mechanisms that underlie age-related compensation, revealing that the functional architecture associated with better memory performance in healthy aging is tied to the structural integrity of the hippocampus and prefrontal cortex.

Iron Deposition and Distribution Across the Hippocampus Is Associated with Pattern Separation and Pattern Completion in Older Adults at Risk for Alzheimer's Disease.

Elevated iron deposition in the brain has been observed in older adult humans and persons with Alzheimer's disease (AD), and has been associated with lower cognitive performance. We investigated the impact of iron deposition, and its topographical distribution across hippocampal subfields and segments (anterior, posterior) measured along its longitudinal axis, on episodic memory in a sample of cognitively unimpaired older adults at elevated familial risk for AD (N = 172, 120 females, 52 males; mean age = 68.8 ± 5.4 years). MRI-based quantitative susceptibility maps were acquired to derive estimates of hippocampal iron deposition. The Mnemonic Similarity Task was used to measure pattern separation and pattern completion, two hippocampally mediated episodic memory processes. Greater hippocampal iron load was associated with lower pattern separation and higher pattern completion scores, both indicators of poorer episodic memory. Examination of iron levels within hippocampal subfields across its long axis revealed topographic specificity. Among the subfields and segments investigated here, iron deposition in the posterior hippocampal CA1 was the most robustly and negatively associated with the fidelity memory representations. This association remained after controlling for hippocampal volume and was observed in the context of normal performance on standard neuropsychological memory measures. These findings reveal that the impact of iron load on episodic memory performance is not uniform across the hippocampus. Both iron deposition levels as well as its spatial distribution, must be taken into account when examining the relationship between hippocampal iron and episodic memory in older adults at elevated risk for AD.

Taking stock of the past: A psychometric evaluation of the Autobiographical Interview.

Autobiographical memory (AM) involves a rich phenomenological re-experiencing of a spatio-temporal event from the past, which is challenging to objectively quantify. The Autobiographical Interview (AI; Levine et al. Psychology and Aging, 17(4), 677-689, 2002) is a manualized performance-based assessment designed to quantify episodic (internal) and semantic (external) features of recalled and verbally conveyed prior experiences. The AI has been widely adopted, yet has not undergone a comprehensive psychometric validation. We investigated the reliability, validity, association to individual differences measures, and factor structure in healthy younger and older adults (N = 352). Evidence for the AI's reliability was strong: the subjective scoring protocol showed high inter-rater reliability and previously identified age effects were replicated. Internal consistency across timepoints was robust, suggesting stability in recollection. Central to our validation, internal AI scores were positively correlated with standard, performance-based measures of episodic memory, demonstrating convergent validity. The two-factor structure for the AI was not well supported by confirmatory factor analysis. Adjusting internal and external detail scores for the number of words spoken (detail density) improved trait estimation of AM performance. Overall, the AI demonstrated sound psychometric properties for inquiry into the qualities of autobiographical remembering.

Differences in the content and coherence of autobiographical memories between younger and older adults: Insights from text analysis.

Several studies have shown that older adults generate autobiographical memories with fewer specific details than younger adults, a pattern typically attributed to age-relate declines in episodic memory. A relatively unexplored question is how aging affects the content used to represent and recall these memories. We recently proposed that older adults may predominately represent and recall autobiographical memories at the gist level. Emerging from this proposal is the hypothesis that older adults represent memories with a wider array of content topics and recall memories with a distinct narrative style when compared to younger adults. We tested this hypothesis by applying natural language processing approaches to a data set of autobiographical memories described by healthy younger and older adults. We used topic modeling to estimate the distribution (i.e., diversity) of content topics used to represent a memory, and sentence embedding to derive an internal similarity score to estimate the shifts in content when narrating a memory. First, we found that older adults referenced a wider array of content topics (higher content diversity) than younger adults when recalling their autobiographical memories. Second, we found older adults were included more content shifts when narrating their memories than younger adults, suggesting a reduced reliance on choronology to form a coherent memory. Third, we found that the content diversity measures were positively related to specific detail generation for older adults, potentially reflecting age-related compensation for episodic memory difficulties. We discuss how our results shed light on how younger and older adults differ in the way they remember and describe the past. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Exploration versus exploitation decisions in the human brain: A systematic review of functional neuroimaging and neuropsychological studies.

Thoughts and actions are often driven by a decision to either explore new avenues with unknown outcomes, or to exploit known options with predictable outcomes. Yet, the neural mechanisms underlying this exploration-exploitation trade-off in humans remain poorly understood. This is attributable to variability in the operationalization of exploration and exploitation as psychological constructs, as well as the heterogeneity of experimental protocols and paradigms used to study these choice behaviours. To address this gap, here we present a comprehensive review of the literature to investigate the neural basis of explore-exploit decision-making in humans. We first conducted a systematic review of functional magnetic resonance imaging (fMRI) studies of exploration-versus exploitation-based decision-making in healthy adult humans during foraging, reinforcement learning, and information search. Eleven fMRI studies met inclusion criterion for this review. Adopting a network neuroscience framework, synthesis of the findings across these studies revealed that exploration-based choice was associated with the engagement of attentional, control, and salience networks. In contrast, exploitation-based choice was associated with engagement of default network brain regions. We interpret these results in the context of a network architecture that supports the flexible switching between externally and internally directed cognitive processes, necessary for adaptive, goal-directed behaviour. To further investigate potential neural mechanisms underlying the exploration-exploitation trade-off we next surveyed studies involving neurodevelopmental, neuropsychological, and neuropsychiatric disorders, as well as lifespan development, and neurodegenerative diseases. We observed striking differences in patterns of explore-exploit decision-making across these populations, again suggesting that these two decision-making modes are supported by independent neural circuits. Taken together, our review highlights the need for precision-mapping of the neural circuitry and behavioural correlates associated with exploration and exploitation in humans. Characterizing exploration versus exploitation decision-making biases may offer a novel, trans-diagnostic approach to assessment, surveillance, and intervention for cognitive decline and dysfunction in normal development and clinical populations.

The biological role of local and global fMRI BOLD signal variability in human brain organization.

Variability drives the organization and behavior of complex systems, including the human brain. Understanding the variability of brain signals is thus necessary to broaden our window into brain function and behavior. Few empirical investigations of macroscale brain signal variability have yet been undertaken, given the difficulty in separating biological sources of variance from artefactual noise. Here, we characterize the temporal variability of the most predominant macroscale brain signal, the fMRI BOLD signal, and systematically investigate its statistical, topographical and neurobiological properties. We contrast fMRI acquisition protocols, and integrate across histology, microstructure, transcriptomics, neurotransmitter receptor and metabolic data, fMRI static connectivity, and empirical and simulated magnetoencephalography data. We show that BOLD signal variability represents a spatially heterogeneous, central property of multi-scale multi-modal brain organization, distinct from noise. Our work establishes the biological relevance of BOLD signal variability and provides a lens on brain stochasticity across spatial and temporal scales.

Age differences in functional brain networks associated with loneliness and empathy.

Loneliness is associated with differences in resting-state functional connectivity (RSFC) within and between large-scale networks in early- and middle-aged adult cohorts. However, age-related changes in associations between sociality and brain function into late adulthood are not well understood. Here, we examined age differences in the association between two dimensions of sociality-loneliness and empathic responding-and RSFC of the cerebral cortex. Self-report measures of loneliness and empathy were inversely related across the entire sample of younger (mean age = 22.6y, n = 128) and older (mean age = 69.0y, n = 92) adults. Using multivariate analyses of multi-echo fMRI RSFC, we identified distinct functional connectivity patterns for individual and age group differences associated with loneliness and empathic responding. Loneliness in young and empathy in both age groups was related to greater visual network integration with association networks (e.g., default, fronto-parietal control). In contrast, loneliness was positively related to within- and between-network integration of association networks for older adults. These results extend our previous findings in early- and middle-aged cohorts, demonstrating that brain systems associated with loneliness, as well as empathy, differ in older age. Further, the findings suggest that these two aspects of social experience engage different neurocognitive processes across human life-span development.

Facial Trustworthiness Perception Across the Adult Life Span.

OBJECTIVES: Trust is crucial for successful social interaction across the life span. Perceiver age, facial age, and facial emotion have been shown to influence trustworthiness perception, but the complex interplay between these perceiver and facial characteristics has not been examined. METHOD: Adopting an adult life-span developmental approach, 199 adults (aged 22-78 years) rated the trustworthiness of faces that systematically varied in age (young, middle-aged, and older) and emotion (neutral, happy, sad, fearful, angry, and disgusted) from the FACES Lifespan Database. RESULTS: The study yielded three key results. First, on an aggregated level, facial trustworthiness perception did not differ by perceiver age. Second, all perceivers rated young faces as the most trustworthy, and middle-aged and older (but not young) perceivers rated older faces as least trustworthy. Third, facial emotions signaling threat (fear, anger, and disgust) relative to neutral, happy, and sad expressions moderated age effects on facial trustworthiness perception. DISCUSSION: Findings from this study highlight the impact of perceiver and facial characteristics on facial trustworthiness perception in adulthood and aging and have potential to inform first impression formation, with effects on trait attributions and behavior. This publication also provides normative data on perceived facial trustworthiness for the FACES Lifespan Database.

Hippocampus and temporal pole functional connectivity is associated with age and individual differences in autobiographical memory.

Recollection of one's personal past, or autobiographical memory (AM), varies across individuals and across the life span. This manifests in the amount of episodic content recalled during AM, which may reflect differences in associated functional brain networks. We take an individual differences approach to examine resting-state functional connectivity of temporal lobe regions known to coordinate AM content retrieval with the default network (anterior and posterior hippocampus, temporal pole) and test for associations with AM. Multiecho resting-state functional magnetic resonance imaging (fMRI) and autobiographical interviews were collected for 158 younger and 105 older healthy adults. Interviews were scored for internal (episodic) and external (semantic) details. Age group differences in connectivity profiles revealed that older adults had lower connectivity within anterior hippocampus, posterior hippocampus, and temporal pole but greater connectivity with regions across the default network compared with younger adults. This pattern was positively related to posterior hippocampal volumes in older adults, which were smaller than younger adult volumes. Connectivity associations with AM showed two significant patterns. The first dissociated connectivity related to internal vs. external AM across participants. Internal AM was related to anterior hippocampus and temporal pole connectivity with orbitofrontal cortex and connectivity within posterior hippocampus. External AM was related to temporal pole connectivity with regions across the lateral temporal cortex. In the second pattern, younger adults displayed temporal pole connectivity with regions throughout the default network associated with more detailed AMs overall. Our findings provide evidence for discrete ensembles of brain regions that scale with systematic variation in recollective styles across the healthy adult life span.

Neurocognitive aging data release with behavioral, structural and multi-echo functional MRI measures.

Central to understanding human behavior is a comprehensive mapping of brain-behavior relations within the context of lifespan development. Reproducible discoveries depend upon well-powered samples of reliable data. We provide to the scientific community two, 10-minute, multi-echo functional MRI (ME-fMRI) runs, and structural MRI (T1-MPRAGE), from 181 healthy younger (ages 18-34 y) and 120 older adults (ages 60-89 y). T2-FLAIR MRIs and behavioral assessments are available in a majority subset of over 250 participants. Behavioral assessments include fluid and crystallized cognition, self-reported measures of personality, and socioemotional functioning. Initial quality control and validation of these data is provided. This dataset will be of value to scientists interested in BOLD signal specifically isolated from ME-fMRI, individual differences in brain-behavioral associations, and cross-sectional aging effects in healthy adults. Demographic and behavioral data are available within the Open Science Framework project "Goal-Directed Cognition in Older and Younger Adults" ( http://osf.io/yhzxe/ ), which will be augmented over time; neuroimaging data are available on OpenNeuro ( https://openneuro.org/datasets/ds003592 ).

Temporal pole volume is associated with episodic autobiographical memory in healthy older adults.

Recollection of personal past events differs across the lifespan. Older individuals recall fewer episodic details and convey more semantic information than young. Here we examine how gray matter volumes in temporal lobe regions integral to episodic and semantic memory (hippocampus and temporal poles, respectively) are related to age differences in autobiographical recollection. Gray matter volumes were obtained in healthy young (n = 158) and old (n = 105) adults. The temporal pole was demarcated and hippocampus segmented into anterior and posterior regions to test for volume differences between age groups. The Autobiographical Interview was administered to measure episodic and semantic autobiographical memory. Volume associations with episodic and semantic autobiographical memory were then assessed. Brain volumes were smaller for older adults in the posterior hippocampus. Autobiographical memory was less episodic and more semanticized for older versus younger adults. Older adults also showed positive associations between temporal pole volumes and episodic autobiographical recall; in the young, temporal pole volume was positively associated with performance on standard laboratory measures of semantic memory. Exploratory analyses revealed that age-related episodic autobiographical memory associations with anterior hippocampal volumes depended on sex. These findings suggest that age differences in brain structures implicated in episodic and semantic memory may portend reorganization of neural circuits to support autobiographical memory in later life.

Age differences in the functional architecture of the human brain.

The intrinsic functional organization of the brain changes into older adulthood. Age differences are observed at multiple spatial scales, from global reductions in modularity and segregation of distributed brain systems, to network-specific patterns of dedifferentiation. Whether dedifferentiation reflects an inevitable, global shift in brain function with age, circumscribed, experience-dependent changes, or both, is uncertain. We employed a multimethod strategy to interrogate dedifferentiation at multiple spatial scales. Multi-echo (ME) resting-state fMRI was collected in younger (n = 181) and older (n = 120) healthy adults. Cortical parcellation sensitive to individual variation was implemented for precision functional mapping of each participant while preserving group-level parcel and network labels. ME-fMRI processing and gradient mapping identified global and macroscale network differences. Multivariate functional connectivity methods tested for microscale, edge-level differences. Older adults had lower BOLD signal dimensionality, consistent with global network dedifferentiation. Gradients were largely age-invariant. Edge-level analyses revealed discrete, network-specific dedifferentiation patterns in older adults. Visual and somatosensory regions were more integrated within the functional connectome; default and frontoparietal control network regions showed greater connectivity; and the dorsal attention network was more integrated with heteromodal regions. These findings highlight the importance of multiscale, multimethod approaches to characterize the architecture of functional brain aging.

White matter lesion load is associated with lower within- and greater between- network connectivity across older age.

White matter hyperintensities (WMH) are among the most prominent structural changes observed in older adulthood. These changes coincide with functional changes to the intrinsic network organization of the aging brain. Yet little is known about how WMH are associated with changes to the whole-brain functional connectome in normal aging. We used a lesion prediction algorithm to quantify WMH as well as resting-state multiecho functional magnetic resonance imaging to characterize resting-state functional connectivity in a cross-sectional sample of healthy older adults (N = 105, 60-83 years of age). In a multivariate analysis, we found that higher lesion load was associated with a global pattern of network dedifferentiation, marked by lower within- and greater between- network connectivity. Network specific changes included greater visual network integration and greater posterior-anterior connectivity. The relationship between WMH and resting-state functional connectivity was negatively associated with fluid IQ as well as Blood Oxygen Level Dependent signal dimensionality. Reduced functional network segregation is a widely observed pattern of age-related change. Our findings show that these functional changes are associated with the accumulation of WMH in older adulthood.

Troubled past: A critical psychometric assessment of the self-report Survey of Autobiographical Memory (SAM).

The Survey of Autobiographical Memory (SAM) was designed as an easy-to-administer measure of self-perceived autobiographical memory (AM) recollection capacity. We provide a comprehensive psychometric evaluation of the SAM in younger and older adults. First, we evaluated the reliability of the SAM as a measure of self-perceived recollective capacity. Next, we tested whether the SAM was a valid measure of episodic and autobiographical memory performance, as assessed with widely used performance-based measures. Finally, we investigated associations between the SAM, cognitive measures and self-reported assessments of psychological functioning. The SAM demonstrated reliability as a self-report measure of perceived recollective capacity. High internal consistency was observed across subscales, with the exception of SAM-semantic. Evidence for independence among the subscales was mixed: SAM-episodic and SAM-semantic items showed poor correspondence with respective subscales. Good correspondence was observed between the future and spatial items and their SAM subscales. The SAM showed limited associations with AM performance as measured by the Autobiographical Interview (AI), yet was broadly associated with self-reported AI event vividness. SAM scores were weakly associated with performance-based memory measures and were age-invariant, inconsistent with known age effects on declarative memory. Converging evidence indicated that SAM-episodic and SAM-semantic subscales are not independent and should not be interpreted as specific measures of episodic or semantic memory. The SAM was robustly associated with self-efficacy, suggesting an association with confidence in domain general self-report abilities. We urge caution in the use and interpretation of the SAM as a measure of AM, pending revision and further psychometric validation.

Loneliness Progression Among Older Adults During the Early Phase of the COVID-19 Pandemic in the United States and Canada.

OBJECTIVES: Older adults are at high risk for complications from coronavirus disease 2019 (COVID-19). Health guidelines recommend limiting physical contact during the pandemic, drastically reducing opportunities for in-person social exchange. Older adults are also susceptible to negative consequences from loneliness, and the COVID-19 pandemic has likely exacerbated this age-related vulnerability. METHODS: In 107 community-dwelling older individuals (65-90 years, 70.5% female) from Florida, the United States, and Ontario, Canada, we examined change in loneliness over the course of the pandemic after implementation of COVID-19-related physical distancing guidelines (March-September 2020; T1-T5; biweekly concurrent self-report) using multilevel modeling. We also explored gender differences in loneliness during the early phase of the COVID-19 pandemic at both data collection sites. RESULTS: Consistent across the 2 sites, levels of loneliness remained stable over time for the full sample (T1-T5). However, our exploratory moderation analysis suggested gender differences in the trajectory of loneliness between the United States and Canada, in that older men in Florida and older women in Ontario reported an increase in loneliness over time. DISCUSSION: Leveraging a longitudinal, binational data set collected during the early phase of the COVID-19 pandemic, this study advances understanding of stability and change in loneliness among a North American sample of individuals aged 65 and older faced with the unique challenges of social isolation. These results can inform public health policy in anticipation of future pandemics and highlight the need for targeted intervention to address acute loneliness among older populations.

From exploration to exploitation: a shifting mental mode in late life development.

Changes in cognition, affect, and brain function combine to promote a shift in the nature of mentation in older adulthood, favoring exploitation of prior knowledge over exploratory search as the starting point for thought and action. Age-related exploitation biases result from the accumulation of prior knowledge, reduced cognitive control, and a shift toward affective goals. These are accompanied by changes in cortical networks, as well as attention and reward circuits. By incorporating these factors into a unified account, the exploration-to-exploitation shift offers an integrative model of cognitive, affective, and brain aging. Here, we review evidence for this model, identify determinants and consequences, and survey the challenges and opportunities posed by an exploitation-biased mental mode in later life.

Age differences in intuitive moral decision-making: Associations with inter-network neural connectivity.

Positions of power involving moral decision-making are often held by older adults (OAs). However, little is known about age differences in moral decision-making and the intrinsic organization of the aging brain. In this study, younger adults (YAs; n = 117, Mage = 22.11) and OAs (n = 82, Mage = 67.54) made decisions in hypothetical moral dilemmas and completed resting-state multi-echo functional magnetic resonance imaging (fMRI) scans. Relative to YAs, OAs were more likely to endorse deontological decisions (i.e., decisions based on adherence to a moral principle or duty), but only when the choice was immediately compelling or intuitive. By contrast, there was no difference between YAs and OAs in utilitarian decisions (i.e., decisions aimed at maximizing collective well-being) when the utilitarian choice was intuitive. Enhanced connections between the posterior medial core of the default network (pmDN) and the dorsal attention network, and overall reduced segregation of pmDN from the rest of the brain, were associated with this increased deontological-intuitive moral decision-making style in OAs. The present study contributes to our understanding of age differences in decision-making styles by taking into account the intuitiveness of the moral choice, and it offers further insights as to how age differences in intrinsic brain connectivity relate to these distinct moral decision-making styles in YAs and OAs. (PsycInfo Database Record (c) 2021 APA, all rights reserved).