1,721,235 research outputs found
Alterations of hand sensorimotor function and cortical motor representations over the adult lifespan
No full textUsing a cross sectional design, we aimed to identify the effect of aging on sensorimotor function and cortical motor representations of two intrinsic hand muscles, as well as the course and timing of those changes. Furthermore, the link between cortical motor representations, sensorimotor function, and intracortical inhibition and facilitation was investigated. Seventy-seven participants over the full adult lifespan were enrolled. For the first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscle, cortical motor representations, GABAA-mediated short-interval intracortical inhibition (SICI), and glutamate-mediated intracortical facilitation (ICF) were assessed using transcranial magnetic stimulation over the dominant primary motor cortex. Additionally, participants' dexterity and force were measured. Linear, polynomial, and piecewise linear regression analyses were conducted to identify the course and timing of age-related differences. Our results demonstrated variation in sensorimotor function over the lifespan, with a marked decline starting around the mid-thirties. Furthermore, an age-related reduction in cortical motor representation volume and maximal MEP of the FDI, but not for ADM, was observed, occurring mainly until the mid-forties. Area of the cortical motor representation did not change with advancing age. Furthermore, cortical motor representations, sensorimotor function, and measures of intracortical inhibition and facilitation were not interrelated.sponsorship: This work was supported by the Research Fund KU Leuven (C16/15/070), the Research Foundation Flanders grant (G089818N), the Excellence of Science grant (EOS 30446199, MEMODYN) and the Hercules fund AUHL/11/01 (R-3987) and I005018N. The authors declare no competing financial interests. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. (Research Fund KU Leuven|C16/15/070, Research Foundation Flanders|G089818N, Excellence of Science grant (MEMODYN)|EOS 30446199, Hercules fund|AUHL/11/01 (R-3987), Hercules fund|I005018N)status: Publishe
Age-related changes in TMS-based gamma-aminobutyric acid (GABA) modulation during a unimanual simple and choice reaction time task.
No full textNo evidence for a difference in lateralization and distinctiveness level of transcranial magnetic stimulation-derived cortical motor representations over the adult lifespan
No full textThis 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.sponsorship: Fonds Wetenschappelijk Onderzoek|11F6921N, KU Leuven|C16/15/070, Fonds Wetenschappelijk Onderzoek|EOS 30446199, MEMODYN, Fonds Wetenschappelijk Onderzoek|11L9322N, Fonds Wetenschappelijk Onderzoek|AUHL/11/01 (R-3987), Fonds Wetenschappelijk Onderzoek|G039821N, Fonds Wetenschappelijk Onderzoek|I005018Nstatus: Published onlin
Are age-related changes in cortical motor representations linked with facilitation/inhibition in the primary motor cortex?
No full textHemispheric asymmetries in goal-directed hand movements are independent of hand preference
No full textAsymmetries in the kinematics and neural substrates of voluntary right and left eye-hand coordinated movements have been accredited to differential hemispheric specialization. An alternative explanation for between-hand movement differences could result from hand-preference related effects. To test both assumptions, an experiment was conducted with left- and right-handers performing goal-directed movements with either hand paced by a metronome. Spatiotemporal accuracy was comparable between hands, whereas hand peak velocity was reached earlier when moving with the left compared to the right hand. The underlying brain activation patterns showed that both left- and right-handers activated more areas involved in visuomotor attention and saccadic control when using their left compared to the right hand. Altogether, these results confirm a unique perceptuomotor processing specialization of the left brain/right hand system that is independent of hand preference.sponsorship: Werner Helsen and Ann Lavrysen acknowledge the KU Leuven Research Council for their support of this research project (OT/00/40). The authors also wish to thank Ir. Marc Beirinckx and Ir. Paul Meugens for providing invaluable guidance in designing the research equipment and the electronics. (KU Leuven Research Council|OT/00/40)status: Publishe
Age-related differences in task-related modulation of cerebellar brain inhibition
No full textAge-related reductions in cerebellar integrity predict motor impairments in older adults (OA), but the contribution of cerebro-cerebellar interactions to these impairments remains unclear. Understanding these interactions could reveal underlying mechanisms associated with age-related deficits in motor control. To explore this, twenty younger adults (YA) and twenty OA, all right-handed, participated in a dual-site transcranial magnetic stimulation protocol. Cerebellar brain inhibition (CBI) was measured at rest and during the anticipatory period of a bimanual tracking task (BTT). The results revealed that YA outperformed OA on the BTT. Both age groups demonstrated reduced CBI during the anticipatory period of the BTT compared to CBI at rest, with no differences in CBI levels between both groups. Notably, motor performance was influenced by CBI modulation, as learning progressed (early vs. slightly later short-term learning), and this influence differed between age groups. In summary, resting-state CBI and the task-related release of CBI were maintained in OA, challenging previous assumptions of reduced inhibitory function in OA. However, the modulation of CBI appears to influence short- term motor learning differently for both groups, suggesting potential functional reorganization of the cerebellar neural system.This work was supported by the Research Foundation Flanders grant (G039821N). SVM (11L9322N), MH (11F6921N), and MN (11PBG24N) are funded by a grant from the Research Foundation Flanders. SVM (BOF21INCENT15) and MN (BOF23INCENT18) are supported by the UHasselt Special Research Fund grant. RMH is supported by grants from the Belgian National Fund for Scientific Research (F.4523.23 & J.0084.21)
GABA, Glx, and GSH in the cerebellum: their role in motor performance and learning across age groups
No full textIntroduction The cerebellum is essential for motor control and learning, relying on structural and functional integrity. Age-related atrophy leads to Purkinje cell loss, but subtle neurochemical changes in GABA, Glx (glutamate + glutamine), and glutathione (GSH) may precede degeneration and contribute to motor decline.Methods 25 younger (YA) and 25 older adults (OA) were included in this study. Magnetic resonance spectroscopy (MRS), using the MEGA-PRESS sequence, was used to investigate how age affects GABA, Glx and GSH levels in the right cerebellar hemisphere, and their relationship with motor performance, measured using a visuomotor bimanual tracking task (BTT).Results In line with previous work YA outperformed OA on both the simple and complex task variants of the BTT. Furthermore, YA demonstrated faster short-term motor learning as compared to OA. On the metabolic level, no significant age group differences in cerebellar GABA, Glx or GSH levels, nor any task-related modulation of GABA or Glx were observed. Additionally, neither baseline neurometabolite levels nor their modulation predicted motor performance or learning.Discussion These results align with previous research suggesting that neurometabolic aging is region-specific, with the cerebellum potentially being more resilient due to its slower aging process. Since neither baseline nor task-related modulation of GABA, Glx, or GSH predicted motor performance or learning, cerebellar neurometabolite concentrations may not directly underlie age-related behavioral changes. Instead, volumetric decline and changes in structural and functional connectivity in the aging cerebellum may play a more significant role in motor decline as compared to neurochemical alterations. Nonetheless, it is important to consider that motor performance and learning rely on distributed brain networks-including cortical and subcortical structures-which also undergo age-related changes and may contribute to observed behavioral declines. While our findings do not support a direct role of cerebellar neurometabolite levels in age-related motor performance differences, they underscore the complexity of neurochemical aging.The author(s) declare that financial support was received for the research and/or publication of this article. This work was supported by the Research Foundation Flanders grant (G039821N). SVM (11L9322N), MH (11F6921N), and RB (1SD8323N) were funded by a grant from the Research Foundation Flanders. SVM (BOF21INCENT15) was supported by the UHasselt Special Research Fund grant. MH was supported by the KU Leuven Special Research
Fund (PDMT2/24/077)
Cortical grey matter content is associated with both age and bimanual performance, but is not observed to mediate age-related behavioural decline
No full textDeclines in both cortical grey matter and bimanual coordination performance are evident in healthy ageing. However, the relationship between ageing, bimanual performance, and grey matter loss remains unclear, particularly across the whole adult lifespan. Therefore, participants (N = 93, range 20-80 years) performed a complex Bimanual Tracking Task, and structural brain images were obtained using magnetic resonance imaging. Analyses revealed that age correlated negatively with task performance. Voxel-based morphometry analysis revealed that age was associated with grey matter declines in task-relevant cortical areas and that grey matter in these areas was negatively associated with task performance. However, no evidence for a mediating effect of grey matter in age-related bimanual performance decline was observed. We propose a new hypothesis that functional compensation may account for the observed absence of mediation, which is in line with the observed pattern of increased inter-individual variance in performance with age
Aging, brain plasticity, and motor learning
No full textMotor skill learning, the process of acquiring new motor skills, is critically important across the lifespan, from
early development through adulthood and into older age, as well as in pathological conditions (i.e., rehabilitation).
Extensive research has demonstrated that motor skill acquisition in young adults is accompanied by
significant neuroplastic changes, including alterations in brain structure (gray and white matter), function (i.e.,
activity and connectivity), and neurochemistry (i.e., levels of neurotransmitters). In the aging population, motor
performance typically declines, characterized by slower and less accurate movements. However, despite these
age-related changes, older adults maintain the capacity for skill improvement through training. In this review,
we explore the extent to which the aging brain retains the ability to adapt in response to motor learning, specifically
whether skill acquisition is accompanied by neural changes. Furthermore, we discuss the associations
between inter-individual variability in brain structure and function and the potential for future learning in older
adults. Finally, we consider the use of non-invasive brain stimulation techniques aimed at optimizing motor
learning in this population. Our review provides insights into the neurobiological underpinnings of motor
learning in older adults and emphasizes strategies to enhance their motor skill acquisition.This work was supported by the Research Fund KU Leuven (C16/15/ 070), the Research Foundation Flanders grant (G089818N, G039821N), and the Excellence of Science grant (EOS 30446199, MEMODYN), awarded to S.P. Swinnen and colleagues. Melina Hehl was funded by a fellowship grant from Research Foundation Flanders (11F6921N; V434023N) and Research Fund KU Leuven (PDMT2/24/077). This work was additionally supported by grants from the KU Leuven (STG/21/018) and from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 794042, awarded to Jolien Gooijers and Caroline Seer, respectively. Additionally, Caroline Seer was funded by a postdoctoral fellowship from the Research Foundation – Flanders (179732). The authors declare no competing financial interests. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Cerebellar brain inhibition and its association with motor inhibition and reaction time in younger and older adults
No full textBackground: Motor performance declines with age, particularly affecting reaction time and proactive response inhibition. While cortical influences on age-related motor decline are well-documented, the cerebellum's role remains unclear. Cerebellar Brain Inhibition (CBI), which can be measured through dual-site transcranial magnetic stimulation (TMS), may provide insights into age-related changes in motor control.
Objectives: We aimed to (1) compare resting-state CBI between young and older adults, (2) investigate the relationship between CBI and upper limb motor performance, and (3) examine whether this relationship differs between age groups.
Methods: Using dual-site TMS, resting-state CBI was assessed in young and older adults. Motor performance was evaluated using a task battery measuring simple and choice reaction times, and response inhibition.
Results: As expected, older adults exhibited significantly longer reaction times and reduced reactive inhibition with lower accuracy compared to younger adults. No significant differences in resting CBI were observed between age groups, and no association was found between CBI and motor performance outcomes.
Conclusions: Despite clear age-related differences in motor performance, resting CBI revealed no difference between age groups and showed no association with motor control measures. These findings suggest that the effect of aging on dual-site TMS-derived cerebellar inhibition at rest and its association with motor performance might be limited. However, age-related cerebellar effects on motor control might manifest during task execution rather than at rest, highlighting the potential importance of investigating CBI modulation during motor performance in the context of aging.This work was supported by the Research Foundation Flanders grant (G039821N). SVM (11L9322N), MH (11F6921N), and MN (11PBG24N) are funded by a grant from the Research Foundation Flanders. SVM (BOF21INCENT15) and MN (BOF23INCENT18) are supported by the UHasselt Special Research Fund grant. MH is supported by the KU Leuven Special Research Fund (PDMT2/24/077)
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