Investigating the impact of executive function on complex motor control strategies

多年来，步态主要被认为是一种很少有认知输入的自动运动任务，直到最近我们才意识到认知功能对运动控制的影响。事实上，我们的大部分日常活动都需要中枢神经系统协调我们的运动动作，同时处理有关我们环境和周围环境的外部信息。例如，考虑穿过一条繁忙的街道，这需要我们观察交通流量，并根据周围的环境调整我们的运动模式。这一系列任务实际上需要高水平的认知参与，称为执行功能；此外，我们在执行这些复杂的运动模式的同时也在进行思考任务，例如生成购物清单。这些运动-认知互动可以被描述为双重任务表现。新出现的证据还表明，执行功能在控制其他复杂运动任务中的重要性，例如中枢神经系统在外部扰动后产生反应性恢复步骤。考虑到多任务处理在我们的日常生活活动中变得越来越普遍（例如边走边讲手机），双任务范式为理解复杂运动任务的注意力需求提供了一个有趣的视角。由于次优表现可能对我们的稳定性构成严重威胁，因此我们有理由问，是否可以通过练习提高双任务表现；然而，直到最近，人们对提高复杂运动任务并发表现的有效练习策略的构成知之甚少。因此，我研究的长期目标是促进我们对视觉运动控制背后机制的理解，以及认知资源在执行用于维持动态稳定性的自适应控制策略中所起的作用。未来五年的短期目标是：(i)发现避障运动任务的最佳练习次数并评估改善双任务表现的保留（研究一），（ii）探索该运动任务的新双任务练习模式（研究二）；（iii）确定反应性步进任务的有效双任务练习策略（研究iii），以及（iv）发现最佳练习次数并评估反应性步进任务中改进的双任务表现的保留情况（研究iv）。本研究具有重要的理论意义和现实意义；这将有助于阐明认知注意的竞争理论，并确定提高高要求运动和认知任务并发表现的策略。

For many years, gait was primarily thought of as an automatic motor task with little cognitive input, it is only recently that have we come to realize the impact of cognitive function on locomotor control. In fact, most of our daily activities require our central nervous system to coordinate our motor actions while simultaneously processing external information about our environment and surroundings.For example, consider crossing a busy street, which requires us to observe the traffic flow, and adjust our locomotion patterns to the surrounding environment. This series of tasks actually requires a high level of cognitive involvement, termed executive function; in addition, we routinely execute these complex movement patterns while also performing a thinking task, e.g. generation of a shopping list. These locomotorcognitive interactions can be described as dual-task performance. Emerging evidence has also suggested the importance of executive function in the control of other complex motor tasks, such the generation of reactive recovery steps by the central nervous system following an external perturbation. Given that multi-tasking is becoming increasingly more common in our activities of daily living (e.g. talking on cell phone while walking) dual-task paradigms offer an interesting perspective towards understanding attentional demands of complex motor tasks. As sub-optimal performance can present serious threats to our stability, it is logical to ask if dual-task performance can be improved with practice; until recently however, little was known about what constitutes an effective practice strategy to improve concurrent performance of complex motor tasks. Thus the long term objective of my research is to advance our understanding of the mechanisms behind visuomotor control and the role that cognitive resources play in the execution of adaptive control strategies used to maintain dynamic stability. The short term objectives over the next five years are to: (i) discover the optimal number of practice sessions and assess the retention of improved dual-task performance for an obstacle avoidance motor task (Study I), (ii) explore novel dual-task practice modalities for this motor task (Study II); (iii) ascertain effective dual-task practice strategies for a reactive stepping task (Study III), and (iv) discover the optimal number of practice sessions and assess the retention of improved dual-task performance for a reactive stepping task (Study IV).This research has both theoretical and practical importance; it will help elucidate competing theories of cognitive attention and identify strategies to improve concurrent performance of demanding motor and cognitive tasks.