Alterations of hand sensorimotor function and cortical motor representations over the adult lifespan

Hehl, Melina; Swinnen, Stephan P.; Cuypers, Koen

doi:10.18632/aging.102925

Cited by 11 publications

(17 citation statements)

References 91 publications

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“…This fits with literature showing that the excitability of the corticospinal tract is reduced in older than younger adults, evidenced by a higher M1 threshold for eliciting MEPs and smaller MEPs elicited by suprathreshold stimuli (specifically, 120% resting motor threshold) in older than younger adults (Oliviero et al, 2006;Pitcher et al, 2003). Furthermore, this finding fits with previous TMS mapping studies systematically stimulating a grid of sites over M1, which have shown reduced volume of the first dorsal interosseous representation in M1 in older than younger adults (Hehl et al, 2020;McGregor et al, 2012). The reduced excitability of the corticospinal tract in older than younger adults is thought to be due to corticospinal neurons becoming less synchronous with advancing age, leading to fewer corticospinal neurons being recruited (Eisen et al, 1996).…”

Section: Higher Si 1mv Intensity Required In Older Than Younger Adultssupporting

confidence: 91%

Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS

Rurak

Rodrigues

Power

et al. 2021

Eur J of Neuroscience

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With advancing age comes a decline in voluntary movement control. Growing evidence suggests that an age-related decline in effective connectivity between the supplementary motor area and primary motor cortex (SMA-M1) might play a role in an age-related decline of bilateral motor control. Dual-site transcranial magnetic stimulation (TMS) can be used to measure SMA-M1 effective connectivity. In the current study, we aimed to (1) replicate previous dual-site TMS research showing reduced SMA-M1 connectivity in older than younger adults and (2) examine whether SMA-M1 connectivity is associated with bilateral motor control in independent samples of younger (n = 30) and older adults (n = 30). SMA-M1 connectivity was measured using dual-site TMS with interstimulus intervals of 6, 7 and 8 ms, and bilateral motor control was measured using the Purdue Pegboard, Four Square Step Test and the Timed Up and Go task. Findings from this study showed that SMA-M1 connectivity was reduced in older than in younger adults, suggesting that the direct excitatory connections between SMA and M1 had reduced efficacy in older than younger adults. Furthermore, greater SMA-M1 connectivity was associated with better bimanual motor control in older adults. Thus, SMA-M1 connectivity in older adults might underpin, in part, the age-related decline in bilateral motor control. These findings contribute to our understanding of age-related declines in motor control and provide a physiological basis for the development of interventions to improve bimanual and bilateral motor control.

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Section: Higher Si 1mv Intensity Required In Older Than Younger Adultssupporting

confidence: 91%

Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS

Rurak

Rodrigues

Power

et al. 2021

Eur J of Neuroscience

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“…Bernard and Seidler (2012) found a larger cortical motor representation for the FDI with advancing age, irrespective of the investigated hemisphere, which they interpreted as a sign of dedifferentiation in the aging brain. In contrast, other studies found no spatial alterations of the FDI representation in the dominant M1 with age (Hehl et al, 2020) or even a decline in the extent of the dominant, but not non-dominant, abductor pollicis brevis (APB) representation (Coppi et al, 2014). For the abductor digiti minimi (ADM), a hand muscle less involved in fine motor tasks, no age-related differences in the spatial extent of the M1 representation have been reported for the dominant (Hehl et al, 2020) or both hemispheres (Coppi et al, 2014).…”

Section: Introductionmentioning

confidence: 94%

No evidence for a difference in lateralization and distinctiveness level of transcranial magnetic stimulation-derived cortical motor representations over the adult lifespan

Hehl

Swinnen

Malderen

et al. 2022

Front. Aging Neurosci.

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This study aimed to investigate the presence and patterns of age-related differences in TMS-based measures of lateralization and distinctiveness of the cortical motor representations of two different hand muscles. In a sample of seventy-three right-handed healthy participants over the adult lifespan, the first dorsal interosseus (FDI) and abductor digiti minimi (ADM) cortical motor representations of both hemispheres were acquired using transcranial magnetic stimulation (TMS). In addition, dexterity and maximum force levels were measured. Lateralization quotients were calculated for homolog behavioral and TMS measures, whereas the distinctiveness between the FDI and ADM representation within one hemisphere was quantified by the center of gravity (CoG) distance and cosine similarity. The presence and patterns of age-related changes were examined using linear, polynomial, and piecewise linear regression. No age-related differences could be identified for the lateralization quotient of behavior or cortical motor representations of both intrinsic hand muscles. Furthermore, no evidence for a change in the distinctiveness of the FDI and ADM representation with advancing age was found. In conclusion this work showed that lateralization and distinctiveness of cortical motor representations, as determined by means of TMS-based measures, remain stable over the adult lifespan.

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“…a Effective age range: 18-37 years (young adults), 60-85 years (older adults). b Age-specific versions were used for older and young adults [53]. The scale "work" ("household") applies to young adults (older adults) only.…”

Section: Figure 1 the Bimanual Tracking Task (Btt) (A)mentioning

confidence: 99%

Cognition and action: a latent variable approach to study contributions of executive functions to motor control in older adults

Seer

Sidlauskaite

Lange

et al. 2021

Aging

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Aging is associated with profound alterations in motor control that may be exacerbated by age-related executive functioning decline. Executive functions span multiple facets including inhibition (suppressing unwanted response tendencies), shifting (switching between cognitive operations), and updating (managing working memory content). However, comprehensive studies regarding the contributions of single facets of executive functioning to movement control in older adults are still lacking. A battery of nine neuropsychological tasks was administered to n = 92 older adults in order to derive latent factors for inhibition, shifting, and updating by structural equation modeling. A bimanual task was used to assess complex motor control. A sample of n = 26 young adults served as a control group to verify age-related performance differences. In older adults, structural equation models revealed that performance on the most challenging condition of the complex motor task was best predicted by the updating factor and by general executive functioning performance. These data suggest a central role for working memory updating in complex motor performance and contribute to our understanding of how individual differences in executive functioning relate to movement control in older adults.

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Alterations of hand sensorimotor function and cortical motor representations over the adult lifespan

Cited by 11 publications

References 91 publications

Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS

Reduced SMA‐M1 connectivity in older than younger adults measured using dual‐site TMS

No evidence for a difference in lateralization and distinctiveness level of transcranial magnetic stimulation-derived cortical motor representations over the adult lifespan

Cognition and action: a latent variable approach to study contributions of executive functions to motor control in older adults

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