Investigating a dual-pathway framework for praxis

项目总结 熟练的动作依赖于两种基本能力：模仿动作以快速学习新知识 行为，并使用工具更有效地操纵我们的环境。模仿和工具使用是至关重要的 用于日常生活的许多活动；在肢体失用的临床障碍中，这些能力的丧失，经常 在包括~50%的左半球中风患者在内的许多神经系统疾病中观察到的是 最强的预测因素是对照顾者的依赖增加和中风后康复不良。尽管公认的 尽管这些能力的重要性，但模仿和工具使用背后的加工机制仍不清楚，在 这在很大程度上是因为与研究它们相关的挑战。模仿和使用工具都涉及到翻译 概念性认知目标(即，知道如何发球)分为错综复杂的运动指令集(即， 用球拍准确地击打网球)。因此，对模仿和工具使用的研究需要将许多 认知科学和运动神经科学的概念。这项提案旨在通过以下方式弥合这种认知-运动分歧 发展一种支持模仿和工具使用的共同机制的新理论，解释如何 概念性目标实际上变成了运动指令。 提出的理论建立在我们之前的研究基础上，假设了两条相互作用的加工路线：(1)A 根据末端执行器的轨迹指定动作的路线(例如，写信)，提供 以抽象(与身体无关)的方式定义所需工具或手部动作的有效手段，以及(2)A 根据主体配置指定动作的路线，提供了更详细但仍在计算上的 对整个肢体(和工具)在整个动作中的位置的易于处理的描述。而这两条路线 通常在一起工作，由于任务需求(例如，专注于球拍)，他们可能会在不同程度上参与进来 在网球发球时的轨迹或肩-肘-腕位置)，或者当不同的大脑区域 支持这些不同的处理路线被打乱了。因此，这两条路线的证据将是 通过在健康个体中建立新的任务切换范例，测量行为障碍 由于使用经颅磁刺激或通过量化相关大脑区域的一过性干扰 左半球中风患者的慢性缺陷。我们将应用新的严格的运动学分析来 评估行为，将患者的损害与失用的临床测量相关联，并使用最近开发的 多变量病变-症状图方法以确定这些入路的神经解剖学基础。 总而言之，这些努力将确定和表征轨迹和车身配置规划如何支持 模仿和工具使用行为的产生和感知。结果不仅会增进我们对 失用症，强调可能作为康复治疗目标的替代代偿途径，但 作为更广泛地研究认知-运动相互作用的模型。

PROJECT SUMMARY Performing skilled actions relies on two fundamental abilities: imitating movements to quickly learn new behaviors, and using tools to more efficiently manipulate our environments. Imitation and tool use are critical for many activities of daily living; loss of these abilities in the clinical disorder of limb apraxia, frequently observed in many neurological disorders including in ~50% of individuals with left-hemisphere stroke, is the strongest predictor of increased caregiver dependence and poor post-stroke recovery. Despite the recognized importance of these abilities, the processing mechanisms underlying imitation and tool use remain unclear, in large part due to the challenges associated with studying them. Imitation and tool use both involve translating conceptual cognitive goals (i.e., knowing how to serve a tennis ball) into intricate sets of motor commands (i.e., accurately hitting a tennis ball with a racket). Hence, the study of imitation and tool use requires merging many concepts from cognitive and motor neuroscience. This proposal aims to bridge this cognitive-motor divide by developing a new theory of the common mechanisms supporting imitation and tool use that explains how conceptual goals are actually turned into motor commands. The proposed theory builds on our prior research by hypothesizing two interacting processing routes: (1) A route that specifies actions in terms of the trajectory of the end-effector (e.g., writing letters), affording an efficient means of defining desired tool or hand motion in an abstract (body-independent) manner, and (2) A route that specifies actions in terms of body configurations, providing a more detailed but still computationally tractable description of the positioning of the entire limb (and tool) throughout an action. While these two routes typically work together, they may be engaged to different extents due to task demands (e.g., focusing on racket trajectories or shoulder-elbow-wrist positions during a tennis serve) or when the different brain regions supporting these distinct processing routes become disrupted. Thus, evidence of these two routes will be established through novel task-switching paradigms in healthy individuals, measuring behavioral impairments due to transient disruptions of relevant brain regions using transcranial magnetic stimulation, or by quantifying chronic deficits in patients with left-hemisphere strokes. We will apply novel rigorous kinematic analyses to assess behavior, correlate patient impairments with clinical measures of apraxia, and use recently-developed multivariate lesion-symptom mapping approaches to confirm the neuroanatomical bases of these routes. Together, such efforts will identify and characterize how trajectory and body-configuration planning support the production and perception of imitation and tool use actions. Results will not only advance our understanding of apraxia, highlighting alternative compensatory pathways that might be targeted for rehabilitation treatment, but serves as a model for studying cognitive-motor interactions more broadly.