Limb apraxia, a disorder of skilled action not consequent on primary motor or sensory deficits, has traditionally been defined according to errors patients make on neuropsychological tasks. Previous models of the disorder have failed to provide a unified account of patients' deficits, due to heterogeneity in the patients and tasks used. In this study we hypothesised that we may be able to map apraxic deficits onto principal components, some of which may be specific, whilst others may align with other cognitive disorders. We implemented principal component analysis (PCA) to elucidate core factors of the disorder in a preliminary cohort of 41 unselected left hemisphere chronic stroke patients who were tested on a comprehensive and validated apraxia screen. Three principal components were identified: posture selection, semantic control and multi-demand sequencing. These were submitted to a lesion symptom mapping (VBCM) analysis in a subset of 24 patients, controlled for lesion volume, age and time post-stroke. The first component revealed no significant structural correlates. The second component was related to regions in inferior frontal gyrus, primary motor area, and adjacent parietal opercular (including inferior parietal and supramarginal gyrus) areas. The third component was associated with lesions within the white matter underlying the left sensorimotor cortex, likely involving the 2nd branch of the left superior longitudinal fasciculus as well as the posterior orbitofrontal cortex (pOFC). These results highlight a significant role of common cognitive functions in apraxia, which include action selection, and sequencing, whilst more specific deficits may relate to semantic control. Moreover, they suggest that previously described ‘ideomotor’ and ‘ideational’ deficits may have a common neural basis within semantic control. Further research using this technique would help elucidate the cognitive processes underlying limb apraxia, its neural correlates and their relationship with other cognitive disorders.

肢体失用症是一种不因原发性运动或感觉障碍而导致的熟练动作障碍，传统上根据患者在神经心理学任务中所犯的错误来定义。由于患者和使用的任务的异质性，以前的疾病模型未能提供患者缺陷的统一说明。在这项研究中，我们假设我们可以将失用缺陷映射到主要成分上，其中一些可能是特定的，而另一些可能与其他认知障碍一致。我们实施了主成分分析 (PCA)，以在 41 名未经选择的左半球慢性中风患者的初步队列中阐明疾病的核心因素，这些患者在全面和经过验证的失用症筛查中进行了测试。确定了三个主要组成部分：姿势选择，语义控制和多需求排序。这些被提交给 24 名患者的一个子集进行病变症状映射 (VBCM) 分析，控制病变体积、年龄和卒中后时间。第一个组件显示没有显着的结构相关性。第二个成分与额下回、初级运动区和相邻的顶叶岛盖（包括顶下回和边缘上回）区域有关。第三个成分与左感觉运动皮层下方的白质内的病变有关，可能涉及左上纵束的第二分支以及后眶额叶皮层 (pOFC)。这些结果突出了常见认知功能在失用症中的重要作用，包括动作选择和排序，而更具体的缺陷可能与语义控制有关。此外，他们认为先前描述的“意念运动”和“意念”缺陷可能在语义控制中具有共同的神经基础。使用这种技术的进一步研究将有助于阐明肢体失用症的认知过程、其神经相关性以及它们与其他认知障碍的关系。