Department of Psychology, K.U. Leuven, Tiensestraat 102, bus 3715, 3000, Leuven, Belgium.
Exp Brain Res. 2008 May;187(2):275-81. doi: 10.1007/s00221-008-1302-3. Epub 2008 Feb 14.
In older adults, cognitive resources play a key role in maintaining postural stability. In the present study, we evaluated whether increasing postural instability using sway referencing induces changes in resource allocation in dual-task performance leading older adults to prioritize the more age-salient posture task over a cognitive task. Young and older adults participated in the study which comprised two sessions. In the first session, three posture tasks (stable, sway reference visual, sway reference somatosensory) and a working memory task (n-back) were examined. In the second session, single- and dual-task performance of posture and memory were assessed. Postural stability improved with session. Participants were more unstable in the sway reference conditions, and pronounced age differences were observed in the somatosensory sway reference condition. In dual-task performance on the stable surface, older adults showed an almost 40% increase in instability compared to single-task. However, in the sway reference somatosensory condition, stability was the same in single- and dual-task performance, whereas pronounced (15%) costs emerged for cognition. These results show that during dual-tasking while standing on a stable surface, older adults have the flexibility to allow an increase in instability to accommodate cognitive task performance. However, when instability increases by means of compromising somatosensory information, levels of postural control are kept similar in single- and dual-task, by utilizing resources otherwise allocated to the cognitive task. This evidence emphasizes the flexible nature of resource allocation, developed over the life-span to compensate for age-related decline in sensorimotor and cognitive processing.
在老年人中，认知资源在维持姿势稳定性方面起着关键作用。在本研究中，我们评估了使用摇摆参照来增加姿势不稳定性是否会导致在双重任务表现中资源分配发生变化，从而使老年人优先考虑更具年龄显著性的姿势任务而不是认知任务。年轻和老年参与者参加了本研究，该研究包括两个阶段。在第一阶段，检查了三种姿势任务（稳定、摇摆参考视觉、摇摆参考躯体感觉）和一项工作记忆任务（n-back）。在第二阶段，评估了姿势和记忆的单任务和双任务表现。随着阶段的进展，姿势稳定性得到了提高。参与者在摇摆参照条件下更不稳定，并且在躯体感觉摇摆参照条件下观察到明显的年龄差异。在稳定表面的双重任务表现中，与单任务相比，老年人的不稳定性增加了近 40%。然而，在摇摆参照躯体感觉条件下，单任务和双任务表现的稳定性相同，而认知的成本明显增加（15%）。这些结果表明，在站立于稳定表面的双重任务中，老年人具有灵活性，可以允许不稳定性增加以适应认知任务表现。然而，当通过损害躯体感觉信息来增加不稳定性时，通过将资源分配给认知任务，在单任务和双任务中保持相似的姿势控制水平。这一证据强调了资源分配的灵活性，这种灵活性是在整个生命周期中发展起来的，以补偿与年龄相关的感觉运动和认知加工下降。
