Apraxia, a cognitive disorder of motor control, can severely impair transitive actions (object-related) and may lead to action errors (e.g., rubbing a hammer on a nail instead of pounding it) and hand posture errors (e.g., grasping a tool in a wrong way). Here, we report a rare observation of a left-handed patient, left-lateralized for language, who developed a severe apraxia following a right brain lesion. Interestingly the patient showed a significant number of hand posture errors, while she perfectly demonstrated the actual use of tools. This case stressed the predictions made by the current theories of tool use. According to the manipulation-based approach, the hand posture errors should be associated with an impaired manipulation knowledge. According to the reasoning-based approach, the absence of action errors should be associated with spared mechanical knowledge. Moreover, to better understand the neurocognitive origins of the deficit observed in VF, we examined several potential brain lateralization of praxis functions. We initiated a systematic examination of VF's performance in several contexts of tool use allowing us to investigate which kinds of tool-use representations were potentially impaired in VF. Our investigation did not reveal any major deficit of manipulation knowledge. This can hardly account for the high frequency of hand posture errors, contrary to the predictions of the manipulation-based approach. In contrast, in line with the reasoning-based approach, mechanical knowledge was spared and can explain the absence of action errors. We also found that VF probably had a bilateral organization of praxis functions, but irrespective of the possible brain lateralization considered, none of which established a satisfactory association between manipulation knowledge and hand posture errors. Taken together, the manipulation-based approach fails to explain fully the deficit presented by this patient and should lead us to consider alternative explanations.

失用症是一种运动控制的认知障碍，会严重损害及物性动作（与对象相关），并可能导致动作错误（例如，用锤子摩擦钉子而不是敲打钉子）和手部姿势错误（例如，在错误的方式）。在这里，我们报告了一名左撇子患者的罕见观察结果，该患者语言偏左，在右脑损伤后出现严重的失用症。有趣的是，患者表现出大量的手部姿势错误，而她完美地展示了工具的实际使用。这个案例强调了当前工具使用理论所做的预测。根据基于操作的方法，手部姿势错误应该与受损的操作知识相关联。根据基于推理的方法，没有动作错误应该与备用的机械知识相关联。此外，为了更好地了解在 VF 中观察到的缺陷的神经认知起源，我们检查了几个潜在的大脑侧化实践功能。我们在工具使用的几种情况下对 VF 的性能进行了系统检查，使我们能够调查哪些类型的工具使用表示在 VF 中可能受到损害。我们的调查没有发现任何重大的操纵知识不足。这很难解释手姿势错误的高频率，这与基于操作的方法的预测相反。相比之下，与基于推理的方法一致，机械知识得以幸免，并且可以解释不存在动作错误。我们还发现 VF 可能具有双边的实践功能组织，但无论考虑到可能的大脑偏侧化，都没有在操作知识和手部姿势错误之间建立令人满意的关联。综上所述，基于操作的方法无法完全解释该患者呈现的缺陷，应引导我们考虑其他解释。