MacGregor Lucy J, Gilbert Rebecca A, Balewski Zuzanna, Mitchell Daniel J, Erzinçlioğlu Sharon W, Rodd Jennifer M, Duncan John, Fedorenko Evelina, Davis Matthew H
MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK.
Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA.
Neurobiol Lang (Camb). 2022 Dec 16;3(4):665-698. doi: 10.1162/nol_a_00081. eCollection 2022.
Listening to spoken language engages domain-general multiple demand (MD; frontoparietal) regions of the human brain, in addition to domain-selective (frontotemporal) language regions, particularly when comprehension is challenging. However, there is limited evidence that the MD network makes a functional contribution to core aspects of understanding language. In a behavioural study of volunteers ( = 19) with chronic brain lesions, but without aphasia, we assessed the causal role of these networks in perceiving, comprehending, and adapting to spoken sentences made more challenging by acoustic-degradation or lexico-semantic ambiguity. We measured perception of and adaptation to acoustically degraded (noise-vocoded) sentences with a word report task before and after training. Participants with greater damage to MD but not language regions required more vocoder channels to achieve 50% word report, indicating impaired perception. Perception improved following training, reflecting adaptation to acoustic degradation, but adaptation was unrelated to lesion location or extent. Comprehension of spoken sentences with semantically ambiguous words was measured with a sentence coherence judgement task. Accuracy was high and unaffected by lesion location or extent. Adaptation to semantic ambiguity was measured in a subsequent word association task, which showed that availability of lower-frequency meanings of ambiguous words increased following their comprehension (word-meaning priming). Word-meaning priming was reduced for participants with greater damage to language but not MD regions. Language and MD networks make dissociable contributions to challenging speech comprehension: Using recent experience to update word meaning preferences depends on language-selective regions, whereas the domain-general MD network plays a causal role in reporting words from degraded speech.
听口语不仅会激活大脑中领域选择性的（额颞叶）语言区域，还会激活领域通用的多需求（MD；额顶叶）区域，尤其是在理解具有挑战性的时候。然而，仅有有限的证据表明MD网络对语言理解的核心方面有功能贡献。在一项针对19名患有慢性脑损伤但无失语症的志愿者的行为研究中，我们评估了这些网络在感知、理解以及适应因声学退化或词汇语义模糊而变得更具挑战性的口语句子方面的因果作用。我们在训练前后通过单词报告任务测量了对声学退化（噪声声码）句子的感知和适应情况。MD区域而非语言区域受损更严重的参与者需要更多的声码通道才能达到50%的单词报告率，这表明其感知能力受损。训练后感知能力有所改善，这反映了对声学退化的适应，但适应情况与损伤位置或程度无关。我们通过句子连贯性判断任务测量了对含有语义模糊单词的口语句子的理解。准确率很高，且不受损伤位置或程度的影响。我们在随后的单词联想任务中测量了对语义模糊的适应情况，结果表明，在理解了模糊单词后，其低频含义的可用性增加了（词义启动）。对于语言区域而非MD区域受损更严重的参与者，词义启动有所减少。语言网络和MD网络在具有挑战性的言语理解中发挥着可分离的作用：利用最近的经验更新词义偏好取决于语言选择性区域，而领域通用的MD网络在报告退化语音中的单词时起因果作用。
