Hemispheric asymmetry reduction in older adults: The HAROLD model.

2002 ◽  
Vol 17 (1) ◽  
pp. 85-100 ◽  
Author(s):  
Roberto Cabeza
Keyword(s):  
Older Adults ◽  
Hemispheric Asymmetry

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

2021 ◽  
pp. JN-RM-1111-21
Author(s):  
Ethan Knights ◽  
Alexa Morcom ◽  
Richard N. Henson
Keyword(s):  
Older Adults ◽  
Motor Cortex ◽  
Hemispheric Asymmetry

scholarly journals Hemispheric Asymmetry in Comprehension of Novel and Conventional Metaphors by Older Adults

2013 ◽  
Vol 94 ◽  
pp. 92-93
Author(s):  
N. Mashal ◽  
R. Gavrieli ◽  
G. Kavé
Keyword(s):  
Older Adults ◽  
Hemispheric Asymmetry

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 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.

Training-induced plasticity in older adults: Effects of training on hemispheric asymmetry

2007 ◽  
Vol 28 (2) ◽  
pp. 272-283 ◽  
Author(s):  
Kirk I. Erickson ◽  
Stanley J. Colcombe ◽  
Ruchika Wadhwa ◽  
Louis Bherer ◽  
Matthew S. Peterson ◽  
...  
Keyword(s):  
Older Adults ◽  
Hemispheric Asymmetry

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.

scholarly journals Age-Associated Reduction of Asymmetry in Human Central Auditory Function: A 1H-Magnetic Resonance Spectroscopy Study

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xianming Chen ◽  
Yonghui Liang ◽  
Yihong Deng ◽  
Jianzhong Li ◽  
Shiyan Chen ◽  
...  
Keyword(s):  
Older Adults ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Auditory Cortex ◽  
Pure Tone ◽  
Hemispheric Asymmetry ◽  
Young Group ◽  
Resonance Spectroscopy ◽  
1H Magnetic Resonance Spectroscopy ◽  
Left And Right

The aim of this study was to investigate the effects of age on hemispheric asymmetry in the auditory cortex after pure tone stimulation. Ten young and 8 older healthy volunteers took part in this study. Two-dimensional multivoxel 1H-magnetic resonance spectroscopy scans were performed before and after stimulation. The ratios of N-acetylaspartate (NAA), glutamate/glutamine (Glx), andγ-amino butyric acid (GABA) to creatine (Cr) were determined and compared between the two groups. The distribution of metabolites between the left and right auditory cortex was also determined. Before stimulation, left and right side NAA/Cr and right side GABA/Cr were significantly lower, whereas right side Glx/Cr was significantly higher in the older group compared with the young group. After stimulation, left and right side NAA/Cr and GABA/Cr were significantly lower, whereas left side Glx/Cr was significantly higher in the older group compared with the young group. There was obvious asymmetry in right side Glx/Cr and left side GABA/Cr after stimulation in young group, but not in older group. In summary, there is marked hemispheric asymmetry in auditory cortical metabolites following pure tone stimulation in young, but not older adults. This reduced asymmetry in older adults may at least in part underlie the speech perception difficulties/presbycusis experienced by aging adults.

Hemispheric Asymmetry for Differentiating Cognitive Functioning Among Older Adults

2008 ◽  
Author(s):  
Carissa N. Balderas ◽  
Steven A. Rogers
Keyword(s):  
Older Adults ◽  
Cognitive Functioning ◽  
Hemispheric Asymmetry
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