Task-specific and task-unspecific long term effects of cognitive-motormultitask training

人类的多任务处理能力是有限的。然而，有充分的证据表明，通过特定的单任务训练可以显著提高各种认知和运动任务的成绩(SPP的可塑性观点)，这种训练也可能转移到多任务情景中。此外，研究表明，与单任务训练相比，多任务训练甚至可能导致已练习任务和迁移到未练习任务的更大的成绩增量。在双重任务中，训练可能导致加工结构的三种变化：a)减少至少一个任务的加工需求，b)智能整合独立的信息加工流，c)增加加工资源量。我们将重点研究这些问题，重点是运动认知双重任务训练，即涉及足够复杂的连续运动任务的情况，如行走或其他姿势任务。这种类型的培训被广泛应用于老年人预防跌倒的背景下，并受到了具体调查。它还受到了一些关注，因为它可能会对认知表现产生有益影响。然而，这些训练效果背后的机制还没有最终确定。在训练过程中，不同任务流的加工如何介入和招募资源是影响训练效果的关键因素。在第一个资助期，我们观察到与更具挑战性的力量追踪任务相比，自动化行走任务在训练和转移任务中的表现以及训练诱导的加工结构变化的水平上具有不同的效果。在第二个资助期，我们将更深入地调查这些任务引发的加工结构。我们将使用探测-反应时间技术来揭示受试者在多大程度上参与了在不同时刻对每项任务的加工。我们将这项工作与进一步的训练研究相结合，在这些研究中，受试者练习选定的运动-认知双重任务组合，时间为数周。基于这些研究中收集的数据，我们将回顾现有的解释性概念，这些概念可以分为假设固定限制和灵活限制在多任务中的加工。根据第一种方法，改进只能通过更有效地处理至少一个任务来解释，或者通过处理流的智能集成来解释。因此，长期训练效果应仅限于至少涉及其中一项练习任务的情况。灵活限制的概念允许在某些情况下更有力地招募加工资源，因此看到了长期增加的可能性。在更广泛的转移情况下，这种可塑性应在绩效效益中观察到。

Multi-tasking capacity of humans is limited. Nonetheless, there is ample evidence that perfor-mance in a variety of cognitive and motor tasks can significantly be improved (plasticity perspective of the SPP) by specific single-task training that might also transfer to multi-task situations. Moreo-ver, studies have demonstrated that multi-task training, compared to single-task training, may even lead to larger performance increments in the practiced tasks as well as in transfer to unpracticed tasks. Three possible training-induced transformations of the processing structure in dual tasks are conceivable: a) Reduction of processing demands of at least one of the tasks involved, b) smart integration of separate information processing streams, and c) increased quantity of processing resources.We will study these questions with a focus on motor-cognitive dual-task training, that is, situations in which a sufficiently complex continuous motor task is involved, like walking or other postural tasks. This type of training is widely applied in in the context of fall prevention in elderly and has been subject to specific investigations. It has also received some attention with respect to possible beneficial effects on cognitive performance. However, the mechanisms underlying these training effects have not been identified conclusively.A crucial factor for any resulting training effect is how processing streams of the different tasks in-terfere and recruit resources during practice. In the first funding period, we observed different effects for an "automatized" walking task compared to a more challenging force-tracking task at the level of the resulting performances in practiced and transfer tasks, and the training-induced altera-tions of the processing structure. In the second funding period, we will investigate the processing structure induced by these tasks in more depth. We will use a probe-reaction time technique to reveal, to which extent subjects are engaged in processing of each of the tasks at different moments in time. We combine this work with further training studies where subjects practice selected motor-cognitive dual-task combinations for several weeks. Based on the data collected in these studies, we will review existing explanatory concepts, which can be categorized as either assuming fixed-limit or flexible-limit processing during multitasking. According to the first, improvements can only be explained by more effective processing of at least one of the tasks, or by a smart integration of the processing streams. Accordingly, long-term training effects should be restricted to situations where at least one of the practiced tasks is involved. Flexible-limit concepts allow stronger recruitment of processing resources in certain contexts and, thus, see the possibility of long-term increases. This plasticity should then be observable in performance benefits in a broader range of transfer situations.