The left frontal aslant tract (FAT) has been proposed to be relevant for language, and specifically for spontaneous speech fluency. However, there is missing causal evidence that stimulation of the FAT affects spontaneous speech, and not language production in general. We present a series of 12 neurosurgical cases with awake language mapping of the cortex near the left FAT. Tasks for language mapping included the commonly used action picture naming, and sentence completion, tapping more specifically into spontaneous speech. A task dissociation was found in 10 participants: while being stimulated on specific sites, they were able to name a picture but could not complete a sentence. Overlaying of these sites on preoperative white-matter tract reconstructions revealed that in each individual case they were located on cortical terminations of the FAT. This corroborates the language functional specificity of the left FAT as a tract underlying fluent spontaneous speech.

中文翻译：

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自发语言流畅的左额斜束的功能语言特异性：来自术中语言映射的证据

左额叶斜束 (FAT) 已被提议与语言相关，特别是与自发的语言流畅性相关。然而，缺少因果证据表明 FAT 的刺激会影响自发的言语，而不是一般的语言产生。我们展示了一系列 12 个神经外科病例，其中包含左侧 FAT 附近皮层的清醒语言映射。语言映射的任务包括常用的动作图片命名和句子完成，更具体地挖掘自发语音。在 10 名参与者中发现了任务分离：在特定站点受到刺激时，他们能够命名图片但无法完成一个句子。将这些部位叠加在术前白质束重建上显示，在每个病例中，它们都位于 FAT 的皮质末端。