BCBL, Basque Center on Cognition, Brain and Language, 20009, San Sebastian, Spain; Laboratoire de Cartographie Fonctionnelle du Cerveau, UNI - ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium; Laboratoire Cognition Langage et Développement, UNI - ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium.
BCBL, Basque Center on Cognition, Brain and Language, 20009, San Sebastian, Spain; Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
Neuroimage. 2020 Aug 1;216:116788. doi: 10.1016/j.neuroimage.2020.116788. Epub 2020 Apr 26.
How the human brain uses self-generated auditory information during speech production is rather unsettled. Current theories of language production consider a feedback monitoring system that monitors the auditory consequences of speech output and an internal monitoring system, which makes predictions about the auditory consequences of speech before its production. To gain novel insights into underlying neural processes, we investigated the coupling between neuromagnetic activity and the temporal envelope of the heard speech sounds (i.e., cortical tracking of speech) in a group of adults who 1) read a text aloud, 2) listened to a recording of their own speech (i.e., playback), and 3) listened to another speech recording. Reading aloud was here used as a particular form of speech production that shares various processes with natural speech. During reading aloud, the reader's brain tracked the slow temporal fluctuations of the speech output. Specifically, auditory cortices tracked phrases (<1 Hz) but to a lesser extent than during the two speech listening conditions. Also, the tracking of words (2-4 Hz) and syllables (4-8 Hz) occurred at parietal opercula during reading aloud and at auditory cortices during listening. Directionality analyses were then used to get insights into the monitoring systems involved in the processing of self-generated auditory information. Analyses revealed that the cortical tracking of speech at <1 Hz, 2-4 Hz and 4-8 Hz is dominated by speech-to-brain directional coupling during both reading aloud and listening, i.e., the cortical tracking of speech during reading aloud mainly entails auditory feedback processing. Nevertheless, brain-to-speech directional coupling at 4-8 Hz was enhanced during reading aloud compared with listening, likely reflecting the establishment of predictions about the auditory consequences of speech before production. These data bring novel insights into how auditory verbal information is tracked by the human brain during perception and self-generation of connected speech.
人类大脑在言语产生过程中如何利用自我产生的听觉信息还不太清楚。目前的语言产生理论认为存在一个反馈监测系统，该系统监测言语输出的听觉后果，以及一个内部监测系统，该系统在言语产生之前对言语的听觉后果做出预测。为了深入了解潜在的神经过程，我们研究了一组成年人在大声朗读文本、听自己的录音（即回放）和听另一段录音时，听觉皮层与听到的语音声音的时间包络之间的神经磁活动耦合（即语音的皮层跟踪）。在这里，大声朗读被用作一种特殊形式的言语产生，它与自然言语有许多共同的过程。在大声朗读时，读者的大脑会跟踪言语输出的缓慢时间波动。具体来说，听觉皮层跟踪短语（<1 Hz），但程度不如在两个言语聆听条件下那么大。此外，在大声朗读时，在顶叶脑回中跟踪单词（2-4 Hz）和音节（4-8 Hz），而在聆听时则在听觉皮层中跟踪。然后使用方向分析来深入了解参与自我产生听觉信息处理的监测系统。分析结果表明，在<1 Hz、2-4 Hz 和 4-8 Hz 处的言语皮层跟踪主要由阅读和聆听时的言语到大脑的方向耦合主导，即阅读时的言语皮层跟踪主要涉及听觉反馈处理。然而，与聆听相比，阅读时 4-8 Hz 处的大脑到言语的方向耦合增强，这可能反映了在言语产生之前对言语听觉后果的预测的建立。这些数据为人类大脑在感知和自我产生连续言语时如何跟踪听觉言语信息提供了新的见解。
