scholarly journals Age-Related Neural Dedifferentiation and Cognition

2019 ◽  
Author(s):  
Joshua Koen ◽  
Sabina Srokova ◽  
Michael Rugg
Keyword(s):  
Episodic Memory ◽  
Brain Regions ◽  
Functional Specificity ◽  
Neural Representations ◽  
Age Related ◽  
Functional Brain Networks ◽  
Age Related Cognitive Decline ◽  
Neural Selectivity ◽  
Invariant Relationship ◽  
Existing Data

This review focuses on possible contributions of neural dedifferentiation to age-related cognitive decline. Neural dedifferentiation is held to reflect a breakdown in the functional specificity of brain regions and networks that compromises the fidelity of neural representations supporting episodic memory and related cognitive functions. The evidence for age-related dedifferentiation is robust when it is operationalized as neural selectivity for different categories of perceptual stimuli or as decreased segregation or modularity of resting-state functional brain networks. Neural dedifferentiation for perceptual categories appears to demonstrate a negative, age-invariant relationship with performance on tests of memory and fluid processing. Whether this pattern extends to network-level measures of dedifferentiation cannot currently be determined due to insufficient evidence. The existing data highlight the importance of further examination of neural dedifferentiation as a factor contributing to episodic memory and to cognitive performance more generally.

scholarly journals The relationship between age, neural differentiation, and memory performance

2018 ◽  
Author(s):  
Joshua D. Koen ◽  
Nedra Hauck ◽  
Michael D. Rugg
Keyword(s):  
Episodic Memory ◽  
Neural Differentiation ◽  
Memory Performance ◽  
Younger Adults ◽  
Age Related ◽  
Cortical Regions ◽  
Age Related Cognitive Decline ◽  
Neural Selectivity ◽  
The Relationship ◽  
Differentiation Index

AbstractHealthy aging is associated with decreased neural selectivity (dedifferentiation) in category-selective cortical regions. This finding has prompted the suggestion that dedifferentiation contributes to age-related cognitive decline. Consistent with this possibility, dedifferentiation has been reported to negatively correlate with fluid intelligence in older adults. Here, we examined whether dedifferentiation is associated with performance in another cognitive domain – episodic memory – that is also highly vulnerable to aging. Given the proposed role of differentiation in age-related cognitive decline, we predicted there would be a stronger link between dedifferentiation and episodic memory performance in older than in younger adults. Young (18-30 yrs) and older (64-75 yrs) male and female humans underwent fMRI scanning while viewing images of objects and scenes prior to a subsequent recognition memory test. We computed a differentiation index in two regions-of-interest (ROIs): parahippocampal place area (PPA) and lateral occipital complex (LOC). This index quantified the selectivity of the BOLD response to an ROI’s preferred versus non-preferred category (scenes for PPA, objects for LOC). The differentiation index in the PPA, but not the LOC, was lower in older than in younger adults. Additionally, the PPA differentiation index predicted recognition memory performance for the studied items. This relationship was independent of and not moderated by age. The PPA differentiation index also predicted performance on a latent ‘fluency’ factor derived from a neuropsychological test battery; this relationship was also age invariant. These findings suggest that two independent factors, one associated with age, and the other with cognitive performance, drive neural differentiation.Significance StatementAging is associated with neural dedifferentiation – reduced neural selectivity in ‘category selective’ cortical brain regions – which has been proposed to mediate cognitive aging. Here, we examined whether neural differentiation is predictive of episodic memory performance, and whether the relationship is moderated by age. A neural differentiation index was estimated for scene-(PPA) and object-(LOC) selective cortical regions while participants studied images for a subsequent memory test. Age related reductions were observed for the PPA, but not the LOC, differentiation index. Importantly, the PPA differentiation index demonstrated age invariant correlations with subsequent memory performance and a fluency factor derived from a neuropsychological battery. Together, these findings suggest that neural differentiation is associated with two independent factors: age and cognitive performance.

scholarly journals Age-related declines in neural distinctiveness correlate across brain areas and result from both decreased reliability and increased confusability

2021 ◽  
Author(s):  
Molly Simmonite ◽  
Thad A Polk
Keyword(s):  
Neural Activity ◽  
Healthy Aging ◽  
Brain Regions ◽  
Aging Brain ◽  
Activation Patterns ◽  
Neural Representations ◽  
Age Related ◽  
Behavioural Performance ◽  
The Difference ◽  
The Brain

According to the neural dedifferentiation hypothesis, age-related reductions in the distinctiveness of neural representations contribute to sensory, cognitive, and motor declines associated with aging: neural activity associated with different stimulus categories becomes more confusable with age and behavioural performance suffers as a result. Initial studies investigated age-related dedifferentiation in the visual cortex, but subsequent research has revealed declines in other brain regions, suggesting that dedifferentiation may be a general feature of the aging brain. In the present study, we used functional magnetic resonance imaging to investigate age-related dedifferentiation in the visual, auditory, and motor cortices. Participants were 58 young adults and 79 older adults. The similarity of activation patterns across different blocks of the same condition was calculated (within-condition correlation, a measure of reliability) as was the similarity of activation patterns elicited by different conditions (between-category correlations, a measure of confusability). Neural distinctiveness was defined as the difference between the mean within- and between-condition similarity. We found age-related reductions in neural distinctiveness in the visual, auditory, and motor cortices, which were driven by both decreases in within-category similarity and increases in between-category similarity. There were significant positive cross-region correlations between neural distinctiveness in different regions. These correlations were driven by within-category similarities, a finding that indicates that declines in the reliability of neural activity appear to occur in tandem across the brain. These findings suggest that the changes in neural distinctiveness that occur in healthy aging result from changes in both the reliability and confusability of patterns of neural activity.

Contributions of representational distinctiveness and stability to memory performance and age differences

2021 ◽  
Author(s):  
Verena R. Sommer ◽  
Myriam C. Sander
Keyword(s):  
Episodic Memory ◽  
Age Differences ◽  
Cognitive Aging ◽  
Memory Performance ◽  
Activity Patterns ◽  
Stimulus Category ◽  
Neural Representations ◽  
Age Related ◽  
Pattern Similarity ◽  
Versatile Tool

Long-standing theories of cognitive aging suggest that memory decline is associated with age-related differences in the way information is represented in the brain. In the last years, these hypotheses have been substantiated by novel neuroscientific evidence that was derived from multivariate pattern similarity analyses. This approach enabled researchers to take a representational perspective on brain and cognition, and allowed them to study the properties of neural representations that support successful episodic memory. In young adults, two prominent representational properties have been identified as crucial for memory performance, namely the distinctiveness and the stability of neural representations. Distinctiveness describes the relation of neural representations to each other, i.e., how similar or dissimilar they are, while stability characterizes how much or how little representations change over time. However, researchers have only recently started to explore age differences in these representational properties and how they interact to support episodic memory in old age. Here, we review studies that used multivariate analysis tools for different neuroimaging techniques to clarify how representational distinctiveness, stability, and their interactions relate to memory performance across adulthood, and specifically during aging. While most evidence on age differences in neural representations involved how stimulus category information is represented, recent studies demonstrated that particularly item-level stability and specificity of activity patterns are positively linked to memory success and decline during aging. Overall, multivariate methods offer a promising and versatile tool for our understanding of age differences in the neural representations underlying episodic memory.

scholarly journals Functional neuroimaging studies of aging and emotion: Fronto-amygdalar differences during emotional perception and episodic memory

2009 ◽  
Vol 15 (6) ◽  
pp. 819-825 ◽  
Author(s):  
PEGGY L. ST. JACQUES ◽  
BRANDY BESSETTE-SYMONS ◽  
ROBERTO CABEZA
Keyword(s):  
Episodic Memory ◽  
Emotional Regulation ◽  
Functional Neuroimaging ◽  
Brain Regions ◽  
Consistent Finding ◽  
Emotional Perception ◽  
Emotional Processes ◽  
Frontal Brain ◽  
Age Related ◽  
Regulation Strategies

AbstractEmotional processes are enhanced in aging, such that aging is characterized by superior emotional regulation. This article provides a brief review of the neural bases supporting this effect with a focus on functional neuroimaging studies of perception and episodic memory. The most consistent finding across these studies is that older adults show an alteration in the recruitment of the amygdala, but greater recruitment of the frontal cortex. These Fronto-amygdalar Age-related Differences in Emotion (FADE) may reflect emotional regulation strategies mediated by frontal brain regions that dampen emotion-related activations in the amygdala. (JINS, 2009, 15, 819–825.)

scholarly journals Selective Vulnerability of Neurons in Layer II of the Entorhinal Cortex during Aging and Alzheimer's Disease

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Alexis M. Stranahan ◽  
Mark P. Mattson
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Entorhinal Cortex ◽  
Selective Vulnerability ◽  
Brain Regions ◽  
System Level ◽  
Molecular Alterations ◽  
Age Related ◽  
Existing Data ◽  
Biochemical Features

All neurons are not created equal. Certain cell populations in specific brain regions are more susceptible to age-related changes that initiate regional and system-level dysfunction. In this respect, neurons in layer II of the entorhinal cortex are selectively vulnerable in aging and Alzheimer's disease (AD). This paper will cover several hypotheses that attempt to account for age-related alterations among this cell population. We consider whether specific developmental, anatomical, or biochemical features of neurons in layer II of the entorhinal cortex contribute to their particular sensitivity to aging and AD. The entorhinal cortex is a functionally heterogeneous environment, and we will also review data suggesting that, within the entorhinal cortex, there is subregional specificity for molecular alterations that may initiate cognitive decline. Taken together, the existing data point to a regional cascade in which entorhinal cortical alterations directly contribute to downstream changes in its primary afferent region, the hippocampus.

scholarly journals Cardiorespiratory Fitness Is Associated With Cognitive Performance in Older But Not Younger Adults

2014 ◽  
Vol 71 (3) ◽  
pp. 474-482 ◽  
Author(s):  
Scott M. Hayes ◽  
Daniel E. Forman ◽  
Mieke Verfaellie
Keyword(s):  
Executive Function ◽  
Episodic Memory ◽  
Cognitive Decline ◽  
Cardiorespiratory Fitness ◽  
Neuropsychological Testing ◽  
Memory Task ◽  
Age Related ◽  
Age Related Cognitive Decline ◽  
The Relationship ◽  
Better Than

Abstract Objectives: Aging is associated with declines in executive function and episodic memory. Cardiorespiratory fitness (CRF) has been associated with enhanced executive function in older adults (OA), but the relationship with episodic memory remains unclear. The purpose of the study was to examine the relationship between CRF and cognition in young and OA and whether CRF mitigates age-related cognitive decline. Methods: Participants completed exercise testing to evaluate CRF (peak VO 2 ) and neuropsychological testing to assess cognition. Results: In OA, peak VO 2 was positively related to executive function, as well as to accuracy on an experimental face–name memory task and visual episodic memory. In young adults (YA), a relationship between peak VO 2 and cognition was not evident. High-fit OA performed as well as YA on executive function measures. On episodic memory measures, YA performed better than high-fit OA, who in turn performed better than low-fit OA. Conclusions: CRF is positively associated with executive function and episodic memory in OA and attenuates age-related cognitive decline. We provide preliminary support for the age-dependence hypothesis, which posits that cognition and CRF relationships may be most readily observed during lifetime periods of significant neurocognitive development.

scholarly journals Age- and reserve-related increases in fronto-parietal and anterior hippocampal activity during episodic encoding predict subsequent memory

2019 ◽  
Author(s):  
Abdelhalim Elshiekh ◽  
Sivaniya Subramaniapillai ◽  
Sricharana Rajagopal ◽  
Stamatoula Pasvanis ◽  
Elizabeth Ankudowich ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Brain Activity ◽  
Activity Patterns ◽  
Brain Regions ◽  
Task Demands ◽  
Aging Brain ◽  
Older Individuals ◽  
Age Related ◽  
Brain Responses ◽  
Encoding And Retrieval

AbstractRemembering associations between encoded items and their contextual setting is a feature of episodic memory. Although this ability deteriorates with age in general, there is substantial variability in how older individuals perform on episodic memory tasks. This variability may stem from genetic and/or environmental factors related to reserve, allowing some individuals to compensate for age-related decline through differential recruitment of brain regions. In this fMRI study, we tested predictions related to reserve and compensation in a large adult lifespan sample (N=154). We used multivariate Behaviour Partial Least Squares (B-PLS) analysis to examine how age, retrieval accuracy, and a proxy measure of reserve, impacted brain activity patterns during spatial and temporal context encoding and retrieval. Reserve modulated age-related compensatory brain responses in ventral visual, temporal, and fronto-parietal regions during memory encoding as a function of task demands. Activity in inferior parietal, medial temporal, and ventral visual regions were strongly impacted by age at encoding and retrieval, but were also related to individual differences in reserve. Our findings are consistent with the concepts of reserve and compensation and suggest that reserve may mitigate age-related decline by modulating compensatory brain responses in the aging brain.

Activity Engagement in Cognitive Aging: A Review of the Evidence

2013 ◽  
Vol 23 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yvonne Rogalski ◽  
Muriel Quintana
Keyword(s):  
Older Adults ◽  
Cognitive Decline ◽  
Cognitive Aging ◽  
Social Activity ◽  
Current Evidence ◽  
Omega 3 ◽  
Neuroprotective Effects ◽  
Activity Engagement ◽  
Age Related ◽  
Age Related Cognitive Decline

The population of older adults is rapidly increasing, as is the number and type of products and interventions proposed to prevent or reduce the risk of age-related cognitive decline. Advocacy and prevention are part of the American Speech-Language-Hearing Association’s (ASHA’s) scope of practice documents, and speech-language pathologists must have basic awareness of the evidence contributing to healthy cognitive aging. In this article, we provide a brief overview outlining the evidence on activity engagement and its effects on cognition in older adults. We explore the current evidence around the activities of eating and drinking with a discussion on the potential benefits of omega-3 fatty acids, polyphenols, alcohol, and coffee. We investigate the evidence on the hypothesized neuroprotective effects of social activity, the evidence on computerized cognitive training, and the emerging behavioral and neuroimaging evidence on physical activity. We conclude that actively aging using a combination of several strategies may be our best line of defense against cognitive decline.

Inefficient Encoding as an Explanation for Age-Related Deficits in Recollection-Based Processing

2014 ◽  
Vol 28 (3) ◽  
pp. 148-161 ◽  
Author(s):  
David Friedman ◽  
Ray Johnson
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Cognitive Processes ◽  
Brain Activity ◽  
Memory Performance ◽  
Brain Regions ◽  
Semantic Retrieval ◽  
Age Related ◽  
The Face ◽  
Episodic Memories

A cardinal feature of aging is a decline in episodic memory (EM). Nevertheless, there is evidence that some older adults may be able to “compensate” for failures in recollection-based processing by recruiting brain regions and cognitive processes not normally recruited by the young. We review the evidence suggesting that age-related declines in EM performance and recollection-related brain activity (left-parietal EM effect; LPEM) are due to altered processing at encoding. We describe results from our laboratory on differences in encoding- and retrieval-related activity between young and older adults. We then show that, relative to the young, in older adults brain activity at encoding is reduced over a brain region believed to be crucial for successful semantic elaboration in a 400–1,400-ms interval (left inferior prefrontal cortex, LIPFC; Johnson, Nessler, & Friedman, 2013 ; Nessler, Friedman, Johnson, & Bersick, 2007 ; Nessler, Johnson, Bersick, & Friedman, 2006 ). This reduced brain activity is associated with diminished subsequent recognition-memory performance and the LPEM at retrieval. We provide evidence for this premise by demonstrating that disrupting encoding-related processes during this 400–1,400-ms interval in young adults affords causal support for the hypothesis that the reduction over LIPFC during encoding produces the hallmarks of an age-related EM deficit: normal semantic retrieval at encoding, reduced subsequent episodic recognition accuracy, free recall, and the LPEM. Finally, we show that the reduced LPEM in young adults is associated with “additional” brain activity over similar brain areas as those activated when older adults show deficient retrieval. Hence, rather than supporting the compensation hypothesis, these data are more consistent with the scaffolding hypothesis, in which the recruitment of additional cognitive processes is an adaptive response across the life span in the face of momentary increases in task demand due to poorly-encoded episodic memories.

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