Rudisch Julian, Müller Katrin, Kutz Dieter F, Brich Louisa, Sleimen-Malkoun Rita, Voelcker-Rehage Claudia
Institute of Human Movement Science and Health, Faculty of Behavioral and Social Sciences, Chemnitz University of Technology, Chemnitz, Germany.
Department of Neuromotor Behavior and Exercise, Institute of Sport and Exercise Sciences, University of Muenster, Muenster, Germany.
Front Physiol. 2020 Mar 27;11:245. doi: 10.3389/fphys.2020.00245. eCollection 2020.
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.
双手协调控制依赖于不同半球内和半球间网络中的信息处理，这些网络在任务对称性和执行的偏侧性方面存在差异。衰老以及与年龄相关的认知障碍，还有性别，都可能对这些网络的连通性产生不利影响。因此，我们预期年龄、认知功能和性别会对双手力量协调产生影响。我们还预期这些影响将取决于任务的特征（即难度和对称性）。162名右利手参与者（19名年轻成年人[YA]，年龄21 - 30岁，9名女性；52名认知健康的老年人[HOA]，年龄80 - 91岁，32名女性；以及91名轻度认知障碍的老年人[MCI]，年龄80 - 91岁，37名女性）进行了等长双手力量控制任务，这些任务要求跟随恒定或交替（循环正弦波）目标，并且在对称性方面有所不同，即（i）恒定对称、不对称[左手恒定且右手交替（ii）或反之（iii）]、（iv）交替同相和（v）交替反相（双手分别以0°或180°相对相位交替）。我们分析了总体表现（目标上的时间）、双手协调作为双手之间的耦合（线性相关系数）以及变异性结构（即通过去趋势波动分析测量的复杂性）。表现和耦合强烈依赖于任务对称性和执行手，在对称任务以及左手产生恒定力而右手产生交替力的不对称任务中表现更好。与YA相比，HOA和MCI在同相和反相任务中的表现（目标上的时间）较差且耦合减少。此外，两组老年人在交替力产生任务中表现出较不复杂的结构，这是控制能力下降的一个标志。此外，我们发现了强烈的性别效应，女性在同相和反相协调期间耦合减少，并且在恒定力产生中变异性结构较不复杂。这项研究的结果揭示了年龄以及性别对双手力量控制有强烈影响。这些影响强烈依赖于任务对称性和执行手，这可能是由于半球间信息处理的不同要求所致。到目前为止，我们发现双手力量控制的行为指标与年龄相关的认知衰退（与健康衰老相比）之间没有明确的关系，因此有必要进行进一步研究。
