scholarly journals Does Hemispheric Asymmetry Reduction in Older Adults (HAROLD) in motor cortex reflect compensation?

2021 ◽  
Author(s):  
Ethan Knights ◽  
Alexa Morcom ◽  
Richard N Henson ◽  
Keyword(s):  
Older Adults ◽  
Motor Cortex ◽  
Hemispheric Asymmetry ◽  
Activity Patterns ◽  
Compensatory Mechanism ◽  
Adult Lifespan ◽  
Additional Information ◽  
Age Related ◽  
Alternative Hypotheses ◽  
Neural Efficiency

Older adults tend to display greater brain activation in the non-dominant hemisphere during even basic sensorimotor responses. It is debated whether this Hemispheric Asymmetry Reduction in Older Adults (HAROLD) reflects a compensatory mechanism. Across two independent fMRI experiments involving an adult-lifespan human sample (N = 586 and N = 81; approximately half female) who performed right hand finger responses, we distinguished between these hypotheses using behavioural and multivariate Bayes (MVB) decoding approaches. Standard univariate analyses replicated a HAROLD pattern in motor cortex, but in- and out-of-scanner behavioural results both demonstrated evidence against a compensatory relationship, in that reaction time measures of task performance in older adults did not relate to ipsilateral motor activity. Likewise, MVB showed that this increased ipsilateral activity in older adults did not carry additional information, and if anything, combining ipsilateral with contralateral activity patterns reduced action decoding in older adults (at least in Experiment 1). These results contradict the hypothesis that HAROLD is compensatory, and instead suggest that the age-related, ipsilateral hyper-activation is non-specific, in line with alternative hypotheses about age-related reductions in neural efficiency/differentiation or inter-hemispheric inhibition.

scholarly journals Neural pattern similarity differentially affects memory performance of younger and older adults: Age differences in neural similarity and memory

2019 ◽  
Author(s):  
Verena R. Sommer ◽  
Yana Fandakova ◽  
Thomas H. Grandy ◽  
Yee Lee Shing ◽  
Markus Werkle-Bergner ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Memory Performance ◽  
Activity Patterns ◽  
Quality Of Information ◽  
Neural Representations ◽  
Age Related ◽  
Pattern Similarity ◽  
The Brain

AbstractAge-related memory decline is associated with changes in neural functioning but little is known about how aging affects the quality of information representation in the brain. Whereas a long-standing hypothesis of the aging literature links cognitive impairments to less distinct neural representations in old age, memory studies have shown that high similarity between activity patterns benefits memory performance for the respective stimuli. Here, we addressed this apparent conflict by investigating between-item representational similarity in 50 younger (19–27 years old) and 63 older (63–75 years old) human adults (male and female) who studied scene-word associations using a mnemonic imagery strategy while electroencephalography was recorded. We compared the similarity of spatiotemporal frequency patterns elicited during encoding of items with different subsequent memory fate. Compared to younger adults, older adults’ memory representations were more similar to each other but items that elicited the most similar activity patterns early in the encoding trial were those that were best remembered by older adults. In contrast, young adults’ memory performance benefited from decreased similarity between earlier and later periods in the encoding trials, which might reflect their better success in forming unique memorable mental images of the joint picture–word pair. Our results advance the understanding of the representational properties that give rise to memory quality as well as how these properties change in the course of aging.Significance statementDeclining memory abilities are one of the most evident limitations for humans when growing older. Despite recent advances of our understanding of how the brain represents and stores information in distributed activation patterns, little is known about how the quality of information representation changes during aging and thus affects memory performance. We investigated how the similarity between neural representations relates to subsequent memory quality in younger and older adults. We present novel evidence that the interaction of pattern similarity and memory performance differs between age groups: Older adults benefited from increased similarity during early encoding whereas young adults benefited from decreased similarity between early and later encoding. These results provide insights into the nature of memory and age-related memory deficits.

scholarly journals Asymmetric thinning of the cerebral cortex across the adult lifespan is accelerated in Alzheimer’s Disease

2020 ◽  
Author(s):  
James M. Roe ◽  
Didac Vidal-Piñeiro ◽  
Øystein Sørensen ◽  
Andreas M. Brandmaier ◽  
Sandra Düzel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Hemispheric Asymmetry ◽  
Temporal Dynamics ◽  
Brain Aging ◽  
Hemispheric Specialization ◽  
Adult Life ◽  
Adult Lifespan ◽  
Age Related ◽  
Cortical Asymmetry

AbstractNormal aging and Alzheimer’s Disease (AD) are accompanied by large-scale alterations in brain organization that undermine brain function. Although hemispheric asymmetry is a global organizing feature of cortex thought to promote brain efficiency, current descriptions of cortical thinning in aging and AD have largely overlooked cortical asymmetry. Consequently, the foundational question of whether and where the cerebral hemispheres change at different rates in aging and AD remains open. First, applying vertex-wise data-driven clustering in a longitudinal discovery sample (aged 20-89; 2577 observations; 1851 longitudinal) we identified cortical regions exhibiting similar age-trajectories of asymmetry across the adult lifespan. Next, we sought replication in 4 independent longitudinal aging cohorts. We show that higher-order regions of cortex that exhibit pronounced asymmetry at age ~20 also show asymmetry change in aging. Results revealed that both leftward and rightward asymmetry is progressively lost on a similar time-scale across adult life. Hence, faster thinning of the (previously) thicker homotopic hemisphere is a feature of aging. This simple organizational principle showed high consistency across multiple aging cohorts in the Lifebrain consortium, and both the topological patterns and temporal dynamics of asymmetry-loss were markedly similar across replicating samples. Finally, we show that regions exhibiting gradual asymmetry-loss over healthy adult life exhibit faster asymmetry-change in AD.Overall, our results suggest a system-wide breakdown in the adaptive asymmetric organization of cortex across adult life which is further accelerated in AD, and may implicate thickness asymmetry as a viable marker for declining hemispheric specialization in aging and AD.SignificanceThe brain becomes progressively disorganized with age, and brain alterations accelerated in Alzheimer’s disease may occur gradually over the lifespan. Although hemispheric asymmetry aids efficient network organization, efforts to identify structural markers of age-related decline have largely overlooked cortical asymmetry. Here we show the hemisphere that is thicker when younger, thins faster. This leads to progressive system-wide loss of regional thickness asymmetry across life. In multiple aging cohorts, asymmetry-loss showed high reproducibility topologically across cortex and similar timing-of-change in aging. Asymmetry-change was further accelerated in AD. Our findings uncover a new principle of brain aging – thicker homotopic cortex thins faster – and suggest we may have unveiled a structural marker for a widely-hypothesized decline in hemispheric specialization in aging and AD.

scholarly journals Neural Generators Underlying Temporal Envelope Processing Show Altered Responses and Hemispheric Asymmetry Across Age

2020 ◽  
Vol 12 ◽  
Author(s):  
Ehsan Darestani Farahani ◽  
Jan Wouters ◽  
Astrid van Wieringen
Keyword(s):  
Older Adults ◽  
Temporal Processing ◽  
Hemispheric Asymmetry ◽  
Phase Locking ◽  
Response Strength ◽  
Speech Understanding ◽  
Temporal Envelope ◽  
Age Related ◽  
Envelope Processing ◽  
Age Related Changes

Speech understanding problems are highly prevalent in the aging population, even when hearing sensitivity is clinically normal. These difficulties are attributed to changes in central temporal processing with age and can potentially be captured by age-related changes in neural generators. The aim of this study is to investigate age-related changes in a wide range of neural generators during temporal processing in middle-aged and older persons with normal audiometric thresholds. A minimum-norm imaging technique is employed to reconstruct cortical and subcortical neural generators of temporal processing for different acoustic modulations. The results indicate that for relatively slow modulations (<50 Hz), the response strength of neural sources is higher in older adults than in younger ones, while the phase-locking does not change. For faster modulations (80 Hz), both the response strength and the phase-locking of neural sources are reduced in older adults compared to younger ones. These age-related changes in temporal envelope processing of slow and fast acoustic modulations are possibly due to loss of functional inhibition, which is accompanied by aging. Both cortical (primary and non-primary) and subcortical neural generators demonstrate similar age-related changes in response strength and phase-locking. Hemispheric asymmetry is also altered in older adults compared to younger ones. Alterations depend on the modulation frequency and side of stimulation. The current findings at source level could have important implications for the understanding of age-related changes in auditory temporal processing and for developing advanced rehabilitation strategies to address speech understanding difficulties in the aging population.

Bad Odors Stick Better Than Good Ones

2009 ◽  
Vol 56 (6) ◽  
pp. 375-380 ◽  
Author(s):  
Maria Larsson ◽  
Christina Öberg-Blåvarg ◽  
Fredrik U. Jönsson
Keyword(s):  
Older Adults ◽  
High Intensity ◽  
Sensory System ◽  
Olfactory Memory ◽  
Old Adults ◽  
Adult Lifespan ◽  
Olfactory Information ◽  
Age Related ◽  
Young Old ◽  
Better Than

The influences of perceived odor qualities on the retention of olfactory information across the adult lifespan were examined. Young (19–36 years), young-old (60–74 years), and old (75–91 years) adults (n = 202) rated a set of unfamiliar odors across a series of perceptual dimensions (i.e., pleasantness, intensity, and irritability) at encoding. The overall results indicated that memory for unpleasant olfactory information was better than that for pleasant odors across the lifespan. Also, participants showed better retention for odors perceived with high intensity and irritability than for odors rated with low or medium scores. Interestingly, the old adults showed selective beneficial memory effects for odors rated as highly irritable. To the extent that perceptions of high irritability reflect an activation of the trigeminal sensory system, this finding suggests that older adults may use trigeminal components in odor information to compensate for age-related impairments in olfactory memory.

scholarly journals Long-interval intracortical inhibition is asymmetric in young but not older adults

2017 ◽  
Vol 118 (3) ◽  
pp. 1581-1590 ◽  
Author(s):  
A.-M. Vallence ◽  
E. Smalley ◽  
P. D. Drummond ◽  
G. R. Hammond
Keyword(s):  
Older Adults ◽  
Hemispheric Asymmetry ◽  
Intracortical Inhibition ◽  
Manual Dexterity ◽  
Hand Movements ◽  
Dominant Hand ◽  
Dominant Hemisphere ◽  
Younger Adults ◽  
Inhibitory Circuits ◽  
Age Related

Aging is typically accompanied by a decline in manual dexterity and handedness; the dominant hand executes tasks of manual dexterity more quickly and accurately than the nondominant hand in younger adults, but this advantage typically declines with age. Age-related changes in intracortical inhibitory processes might play a role in the age-related decline in manual dexterity. Long-interval intracortical inhibition (LICI) is asymmetric in young adults, with more sensitive and more powerful LICI circuits in the dominant hemisphere than in the nondominant hemisphere. Here we investigated whether the hemispheric asymmetry in LICI in younger adults persists in healthy older adults. Paired-pulse transcranial magnetic stimulation was used to measure LICI in the dominant and nondominant hemispheres of younger and older adults; LICI stimulus-response curves were obtained by varying conditioning stimulus intensity at two different interstimulus intervals [100 ms (LICI100) and 150 ms]. We have replicated the finding that LICI100 circuits are more sensitive and more powerful in the dominant than the nondominant hemisphere of young adults and extend this finding to show that the hemispheric asymmetry in LICI100 is lost with age. In the context of behavioral observations showing that dominant hand movements in younger adults are more fluent than nondominant hand movements in younger adults and dominant hand movements in older adults, we speculate a role of LICI100 in the age-related decline in manual dexterity. NEW & NOTEWORTHY In younger adults, more sensitive and more powerful long-interval intracortical inhibitory circuits are evident in the hemisphere controlling the more dexterous hand; this is not the case in older adults, for whom long-interval intracortical inhibitory circuits are symmetric and more variable than in younger adults. We speculate that the highly sensitive and powerful long-interval intracortical inhibition circuits in the dominant hemisphere play a role in manual dexterity.

Consideration of Age-Related Changes in Behavior Trends in Older Adults in Assessing Risks of Environmental Exposures

2012 ◽  
Vol 25 (2) ◽  
pp. 243-273 ◽  
Author(s):  
Lauren Tuttle ◽  
Qingyu Meng ◽  
Jacqueline Moya ◽  
Douglas O. Johns
Keyword(s):  
Older Adults ◽  
Health Risk ◽  
Older Adult ◽  
Activity Pattern ◽  
Activity Patterns ◽  
Human Health Risk ◽  
Risk Assessments ◽  
Susceptible Population ◽  
Age Related ◽  
Adult Exposure

Objectives: To explore age-related behavior differences between older and younger adults, and to review how older adult activity patterns are considered in evaluating the potential risk of exposure to environmental pollutants. Methods: Activity pattern data and their use in risk assessments were analyzed using the U.S. EPA Exposure Factors Handbook (EFH), U.S. EPA Consolidated Human Activity Pattern Database (CHAD), and peer-reviewed literature describing human health risk assessments. Results: The characterization by age of some factors likely to impact older adults’ exposures remains limited. We demonstrate that age-related behavior trends vary between younger and older adults, and these differences are rarely explicitly considered in environmental health risk assessment for older adults. Discussion: Incorporating older adult exposure factors into risk assessments may be challenging because of data gaps and difficulty in defining and appropriately binning older adults. Additional data related to older adult exposure factors are warranted for evaluating risk among this susceptible population.

scholarly journals Stimulus Specific to Age-Related Audio-Visual Integration in Discrimination Tasks

i-Perception ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 204166952097841
Author(s):  
Yanna Ren ◽  
Zhihan Xu ◽  
Sa Lu ◽  
Tao Wang ◽  
Weiping Yang
Keyword(s):  
Older Adults ◽  
Time Window ◽  
Response Times ◽  
Race Model ◽  
Compensatory Mechanism ◽  
Younger Adults ◽  
Visual Integration ◽  
Age Related ◽  
Significant Difference ◽  
The Mean

Age-related audio-visual integration (AVI) has been investigated extensively; however, AVI ability is either enhanced or reduced with ageing, and this matter is still controversial because of the lack of systematic investigations. To remove possible variates, 26 older adults and 26 younger adults were recruited to conduct meaningless and semantic audio-visual discrimination tasks to assess the ageing effect of AVI systematically. The results for the mean response times showed a significantly faster response to the audio-visual (AV) target than that to the auditory (A) or visual (V) target and a significantly faster response to all targets by the younger adults than that by the older adults (A, V, and AV) in all conditions. In addition, a further comparison of the differences between the probability of audio-visual cumulative distributive functions (CDFs) and race model CDFs showed delayed AVI effects and a longer time window for AVI in older adults than that in younger adults in all conditions. The AVI effect was lower in older adults than that in younger adults during simple meaningless image discrimination (63.0 ms vs. 108.8 ms), but the findings were inverse during semantic image discrimination (310.3 ms vs. 127.2 ms). In addition, there was no significant difference between older and younger adults during semantic character discrimination (98.1 ms vs. 117.2 ms). These results suggested that AVI ability was impaired in older adults, but a compensatory mechanism was established for processing sematic audio-visual stimuli.

scholarly journals Pronoun production remains stable over the adult lifespan for contexts with topic continuity

2022 ◽  
Author(s):  
Madeleine Long ◽  
Hannah Rohde ◽  
Paula Rubio-Fernandez
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Perspective Taking ◽  
Referential Communication ◽  
Main Character ◽  
Younger Adults ◽  
Discourse Context ◽  
Adult Lifespan ◽  
Age Related ◽  
Referential Choice

A prevalent finding in the referential communication literature is that older adults produce more ambiguous pronouns than younger adults, likely because they have difficulty determining the prominence of referents. This finding has been widely understood to reflect a general age-related deficit in communication. However, all studies from this line of work have used materials involving topic shifts (i.e. when the to-be-named referent shifts from one character to another, which requires perspective-taking and can be cognitively costly). To determine the extent to which younger and older adults’ pronominal use diverges, we investigated whether other aspects of the discourse context influence age-related differences in referential choice, apart from topic shifts. Here we tested a large sample of adults (N=496, ages 18-82) using narrative elicitation tasks across four experiments and nine contexts of topic continuity (i.e. contexts in which the to-be-named referent remained the same). In Experiments 1 and 2, we varied the number of characters in the scene while keeping the sex/gender of the characters distinct and found that pronominal use did not differ by age for scenes with 1, 2, and 3 characters. In Experiments 3 and 4, we varied the number of characters, the sex/gender of those characters (such that they were the same or different), and the linguistic emphasis placed on the main character. Again, we found no age differences across all conditions. Taken together, our findings suggest that older adults’ difficulty with prominence estimates is not all- encompassing, but rather appears to be confined to contexts involving topic shifts.

scholarly journals Precise Slow Oscillation-Spindle Coupling Promotes Memory Consolidation in Younger and Older Adults

2018 ◽  
Author(s):  
Beate E. Muehlroth ◽  
Myriam C. Sander ◽  
Yana Fandakova ◽  
Thomas H. Grandy ◽  
Björn Rasch ◽  
...  
Keyword(s):  
Older Adults ◽  
Memory Consolidation ◽  
Associative Memories ◽  
Younger Adults ◽  
Adult Lifespan ◽  
Healthy Elderly ◽  
Human Lifespan ◽  
Source Regions ◽  
Age Related ◽  
And Shifts

AbstractMemory consolidation during sleep relies on the precisely timed interaction of rhythmic neural events. Here, we investigate differences in slow oscillations (SO) and sleep spindles (SP) and their coupling across the adult human lifespan and ask whether observed alterations relate to the ability to retain associative memories across sleep. We demonstrate that the fine-tuned SO–SP coupling that is present in younger adults diffuses with advanced age and shifts both in time and frequency. Crucially, we show that the tight precision of SO–SP coupling promotes memory consolidation in younger and older adults, and that brain integrity in source regions for the generation of SOs and SPs reinforces this beneficial SO–SP coupling in old age. Our results reveal age-related differences in SO–SP coupling in healthy elderly individuals. Furthermore, they broaden our understanding of the conditions and the functional significance of SO–SP coupling across the entire adult lifespan.

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