Department of Neuromotor Behavior and Exercise, Institute of Sport and Exercise Sciences, University of Münster, Münster, Germany.
J Gerontol A Biol Sci Med Sci. 2024 Oct 1;79(10). doi: 10.1093/gerona/glae137.
During role-differentiated bimanual movements (RDBM), an object is typically stabilized with 1 hand and manipulated with the other. RDBM require coupling both hands for coordinated action (achieved through interhemispheric connections), but also inhibition of crosstalk to avoid involuntary movements in the stabilizing hand. We investigated how healthy cognitive aging and mild cognitive impairments (MCI) affect force stabilization during an RDBM in a cohort sequential study design with up to 4 measurement points over 32 months. In total, 132 older adults (>80 years) participated in this study, 77 were cognitively healthy individuals (CHI) and 55 presented with MCI. Participants performed a visuomotor bimanual force-tracking task. They either produced a constant force with both hands (bimanual constant) or a constant force with 1 and an alternating force with the other hand (role-differentiated). We investigated force fluctuations of constant force production using the coefficient of variation (CV), detrended fluctuation analysis (DFA), and sample entropy (SEn). Results showed higher CV and less complex variability structure (higher DFA and lower SEn) during the role-differentiated compared to the bimanual constant task. Furthermore, CHI displayed a more complex variability structure during the bimanual constant, but a less complex structure during the role-differentiated task than MCI. Interestingly, this complexity reduction was more pronounced in CHI than MCI individuals, suggesting different changes in the control mechanisms. Although understanding these changes requires further research, potential causes might be structural deteriorations leading to less efficient (intra- and interhemispheric) networks because of MCI, or an inability to appropriately divert the focus of attention.
在角色分化双手运动（RDBM）中，通常用一只手稳定物体，用另一只手操作。RDBM 需要双手协调动作（通过半球间连接实现），但也需要抑制串扰以避免稳定手的无意识运动。我们在一项队列序贯研究设计中，调查了健康认知老化和轻度认知障碍（MCI）如何影响 RDBM 期间的力稳定，该设计在 32 个月内最多有 4 个测量点。共有 132 名老年人（>80 岁）参与了这项研究，其中 77 人认知健康（CHI），55 人患有 MCI。参与者执行了一个视觉运动双手力跟踪任务。他们要么用双手产生恒定的力（双手恒定），要么用一只手产生恒定的力，用另一只手产生交替的力（角色分化）。我们使用变异系数（CV）、去趋势波动分析（DFA）和样本熵（SEn）来研究恒定力产生的力波动。结果表明，在角色分化任务中，CV 更高，变异性结构更简单（DFA 更高，SEn 更低）。此外，CHI 在双手恒定任务中表现出更复杂的变异性结构，但在角色分化任务中表现出比 MCI 更简单的结构。有趣的是，与 MCI 相比，CHI 的这种复杂性降低更为明显，表明控制机制的不同变化。虽然了解这些变化需要进一步的研究，但潜在的原因可能是由于 MCI 导致结构恶化，从而导致（半球内和半球间）网络效率降低，或者无法适当转移注意力焦点。
