Geva Sharon, Schneider Letitia M, Roberts Sophie, Green David W, Price Cathy J
Wellcome Centre for Human Neuroimaging, University College London, London, United Kingdom.
Department of Cognition, Emotion and Methods in Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria.
Front Hum Neurosci. 2021 May 20;15:664650. doi: 10.3389/fnhum.2021.664650. eCollection 2021.
Functional imaging studies of neurologically intact adults have demonstrated that the right posterior cerebellum is activated during verb generation, semantic processing, sentence processing, and verbal fluency. Studies of patients with cerebellar damage converge to show that the cerebellum supports sentence processing and verbal fluency. However, to date there are no patient studies that investigated the specific importance of the right posterior cerebellum in language processing, because: (i) case studies presented patients with lesions affecting the anterior cerebellum (with or without damage to the posterior cerebellum), and (ii) group studies combined patients with lesions to different cerebellar regions, without specifically reporting the effects of right posterior cerebellar damage. Here we investigated whether damage to the right posterior cerebellum is critical for sentence processing and verbal fluency in four patients with focal stroke damage to different parts of the right posterior cerebellum (all involving Crus II, and lobules VII and VIII). We examined detailed lesion location by going beyond common anatomical definitions of cerebellar anatomy (i.e., according to lobules or vascular territory), and employed a recently proposed functional parcellation of the cerebellum. All four patients experienced language difficulties that persisted for at least a month after stroke but three performed in the normal range within a year. In contrast, one patient with more damage to lobule IX than the other patients had profound long-lasting impairments in the comprehension and repetition of sentences, and the production of spoken sentences during picture description. Spoken and written word comprehension and visual recognition memory were also impaired, however, verbal fluency was within the normal range, together with object naming, visual perception and verbal short-term memory. This is the first study to show that focal damage to the right posterior cerebellum leads to language difficulties after stroke; and that processing impairments persisted in the case with most damage to lobule IX. We discuss these results in relation to current theories of cerebellar contribution to language processing. Overall, our study highlights the need for longitudinal studies of language function in patients with focal damage to different cerebellar regions, with functional imaging to understand the mechanisms that support recovery.
对神经功能正常的成年人进行的功能成像研究表明，在动词生成、语义处理、句子处理和言语流畅性任务中，右侧小脑后部会被激活。对小脑损伤患者的研究一致表明，小脑支持句子处理和言语流畅性。然而，迄今为止，尚无患者研究调查右侧小脑后部在语言处理中的具体重要性，原因如下：（i）病例研究中的患者病变影响了小脑前部（无论后部小脑是否受损）；（ii）分组研究将不同小脑区域有病变的患者合并在一起，未具体报告右侧小脑后部损伤的影响。在此，我们调查了4例右侧小脑后部不同部位发生局灶性中风损伤（均累及小脑 Crus II 以及小叶 VII 和 VIII）的患者，右侧小脑后部损伤对句子处理和言语流畅性是否至关重要。我们超越了小脑解剖结构的常见解剖学定义（即根据小叶或血管区域）来检查详细的病变位置，并采用了最近提出的小脑功能分区。所有4例患者均经历了语言困难，中风后持续至少1个月，但其中3例在1年内表现恢复至正常范围。相比之下，1例小叶IX损伤比其他患者更严重的患者在句子理解和复述以及图片描述过程中口语句子生成方面存在严重的长期损伤。口语和书面单词理解以及视觉识别记忆也受损，然而，言语流畅性、物体命名、视觉感知和言语短期记忆均在正常范围内。这是第一项表明右侧小脑后部局灶性损伤会导致中风后语言困难的研究；并且在小叶IX损伤最严重的病例中，处理障碍持续存在。我们结合当前关于小脑对语言处理贡献的理论来讨论这些结果。总体而言，我们的研究强调了对不同小脑区域发生局灶性损伤的患者进行语言功能纵向研究的必要性，并通过功能成像来了解支持恢复的机制。
