Dataset Information

Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge.

ABSTRACT: A cognitive challenge when imposed during a low-force isometric contraction will exacerbate sex- and age-related decreases in force steadiness, but the mechanism is not known. We determined the role of oscillations in the common synaptic input to motor units on force steadiness during a muscle contraction with a concurrent cognitive challenge. Forty-nine young adults (19-30 yr; 25 women, 24 men) and 36 old adults (60-85 yr; 19 women, 17 men) performed a cognitive challenge (counting backward by 13) during an isometric elbow flexion task at 5% of maximal voluntary contraction. Single-motor units were decomposed from high-density surface EMG recordings. For a subgroup of participants, motor units were matched during control and cognitive challenge trials, so the same motor unit was analyzed across conditions. Reduced force steadiness was associated with greater oscillations in the synaptic input to motor units during both control and cognitive challenge trials ( r?=?0.45-0.47, P < 0.01). Old adults and young women showed greater oscillations in the common synaptic input to motor units and decreased force steadiness when the cognitive challenge was imposed, but young men showed no change across conditions (session?×?age?×?sex, P < 0.05). Oscillations in the common synaptic input to motor units is a potential mechanism for altered force steadiness when a cognitive challenge is imposed during low-force contractions in young women and old adults. NEW & NOTEWORTHY We found that oscillations in the common synaptic input to motor units were associated with a reduction in force steadiness when a cognitive challenge was imposed during low-force contractions of the elbow flexor muscles in young women and old men and women but not young men. Age- and sex-related muscle weakness was associated with these changes.

SUBMITTER: Pereira HM

PROVIDER: S-EPMC6485692 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Cerebrovascular reactivity (CVR), is important for determining future risk of cerebrovascular disease. It is unclear if primary aging is associated with reductions in CVR because previous studies often include participants with vascular risk factors. Additionally, the inconsistency in the literature may be due to the inherent difficulty in quantifying intracranial cerebral blood flow and CVR. To address these limitations, we determined the effect of age on CVR in the large intracranial vessels in adults with low vascular risk using state-of-the-art MRI techniques. We also determined if the effect of age on CVR was sex-specific. Young (n = 20; 25 ± 3 years) and older (n = 19; 61 ± 5 years) healthy, physically active adults participated in the study. CVR was measured in response to hypercapnia using 4D flow MRI, which allows for simultaneous angiographic and quantitative blood flow measurements in the intracranial arteries. Older adults had lower global CVR and CVR in multiple intracranial arteries [right and left internal carotid arteries (ICA), right and left middle cerebral arteries (MCA), and basilar artery (BA)] compared with young adults (p < 0.05 for all). In addition, the MCA dilated significantly in response to hypercapnia in young (p < 0.05), but not older adults. Young men demonstrated higher global CVR and CVR in multiple intracranial arteries (ICAs, MCAs, and BA) compared with young women and older men (p < 0.05 for both); however, CVR did not differ between young women and older women. Our results demonstrate that, using 4D flow MRI, primary aging is associated with lower CVR in adults with low vascular risk. In addition, the effect of age on CVR may be driven by men. The 4D flow MRI technique may provide a promising new alternative to measure cerebrovascular physiology without the limitations of commonly used techniques. Future studies could utilize this MRI technique to examine interventions to maintain CVR with advancing age. This study was registered under clinicaltrials.gov # NCT02840851.

Project description:Analysis of neural oscillations in the electroencephalogram (EEG) during cognitive tasks provides valuable information about underlying neuronal processing not accessible by other methods such as event-related potentials (ERPs) and the BOLD signal in fMRI. We investigated neural substrates of motor preparation and expectancy by analyzing neural oscillations of healthy subjects performing the AX continuous performance task (AX-CPT), a task widely used to evaluate processes such as cognitive control, motor preparation and anticipatory and sustained attention. The task consists of letters presented sequentially on a monitor, and subjects are required to respond only when they see the letter A (cue) followed by the letter X (target). In this study, to emphasize expectation and motor preparation, three versions of AX-CPT were used in which the overall propensity to respond was differentially modulated, by changing the probability of the letter sequences. Neural activity was investigated in three time windows following presentation of the cue: sensory, evaluation and preparation. Alpha power was reduced following cue onset similarly in all versions of the task in both the sensory and evaluation periods, but in the later preparation period there were task dependent modulations. Alpha was decreased when an infrequent cue increased the chance of a response, and increased when a propensity to respond had to be overcome, possibly reflecting an anticipatory attentional mechanism to gate visuo-motor processing. Beta power was modulated by task and cue in both evaluation and preparation periods. In the latter, beta power reflected the propensity to respond and correlated both with amplitude of the contingent negative variation (CNV), an ERP that reflects response preparation, and with reaction time. Some clinical populations such as patients with schizophrenia or attention-deficit disorder show specific deficits when performing the AX-CPT. These results provide a basis for investigating the differential neural underpinnings of oscillatory cognitive control deficits observed in various patient populations.

Project description:Coordinated bimanual control depends on information processing in different intra- and interhemispheric networks that differ with respect to task symmetry and laterality of execution. Aging and age-related cognitive impairments, but also sex can have detrimental effects on connectivity of these networks. We therefore expected effects of age, cognitive function and sex on bimanual force coordination. We furthermore expected these effects to depend on the characteristics of the task (i.e., difficulty and symmetry). 162 right handed participants (19 younger adults [YA], 21-30 years, 9 females; 52 cognitively healthy older adults [HOA], 80-91 years, 32 females; and 91 older adults with mild cognitive impairments [MCI] 80-91 years, 37 females) performed isometric bimanual force control tasks that required following constant or alternating (cyclic sine-wave) targets and varied in symmetry, i.e., (i) constant symmetric, asymmetric [with constant left and alternating right (ii) or vice versa (iii)], (iv) alternating in- and (v) alternating antiphase (both hands alternating with 0° or 180° relative phase, respectively). We analyzed general performance (time on target), bimanual coordination as coupling between hands (linear correlation coefficient) and structure of variability (i.e., complexity measured through detrended fluctuation analysis). Performance and coupling strongly depended on task symmetry and executing hand, with better performance in symmetric tasks and in asymmetric tasks when the left hand produced a constant and the right hand an alternating force. HOA and MCI, compared to YA, showed poorer performance (time on target) and reduced coupling in in- and antiphase tasks. Furthermore, both groups of OA displayed less complex structure in alternating force production tasks, a marker of reduced control. In addition, we found strong sex effects with females displaying reduced coupling during in- and antiphase coordination and less complex variably structure in constant force production. Results of this study revealed strong effects of age, but also sex on bimanual force control. Effects depended strongly on task symmetry and executing hand, possibly due to different requirements in interhemispheric information processing. So far, we found no clear relationship between behavioral markers of bimanual force control and age-related cognitive decline (compared to healthy aging), making further investigation necessary.

Dataset Information

Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets