Lise Meitner Research Group Cognition and Plasticity, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Department of Psychology, University of Lübeck, Lübeck, Germany.
Hum Brain Mapp. 2021 Jan;42(1):110-127. doi: 10.1002/hbm.25208. Epub 2020 Sep 22.
When speech intelligibility is reduced, listeners exploit constraints posed by semantic context to facilitate comprehension. The left angular gyrus (AG) has been argued to drive this semantic predictability gain. Taking a network perspective, we ask how the connectivity within language-specific and domain-general networks flexibly adapts to the predictability and intelligibility of speech. During continuous functional magnetic resonance imaging (fMRI), participants repeated sentences, which varied in semantic predictability of the final word and in acoustic intelligibility. At the neural level, highly predictable sentences led to stronger activation of left-hemispheric semantic regions including subregions of the AG (PGa, PGp) and posterior middle temporal gyrus when speech became more intelligible. The behavioural predictability gain of single participants mapped onto the same regions but was complemented by increased activity in frontal and medial regions. Effective connectivity from PGa to PGp increased for more intelligible sentences. In contrast, inhibitory influence from pre-supplementary motor area to left insula was strongest when predictability and intelligibility of sentences were either lowest or highest. This interactive effect was negatively correlated with the behavioural predictability gain. Together, these results suggest that successful comprehension in noisy listening conditions relies on an interplay of semantic regions and concurrent inhibition of cognitive control regions when semantic cues are available.
当言语可懂度降低时，听者会利用语义语境的约束来促进理解。左角回（AG）被认为可以驱动这种语义可预测性的提高。从网络的角度来看，我们想问语言特异性和非语言特异性网络内的连接如何灵活地适应言语的可预测性和可懂度。在连续功能磁共振成像（fMRI）期间，参与者重复了句子，这些句子在最后一个单词的语义可预测性和声学可懂度方面有所不同。在神经水平上，当言语变得更加清晰时，高度可预测的句子会导致左侧半球语义区域（包括 AG 的亚区（PGa、PGp）和后颞中回）的激活增强。单个参与者的行为可预测性增益映射到相同的区域，但在前额和内侧区域的活动增加得到了补充。对于更清晰的句子，从 PGa 到 PGp 的有效连接增加。相比之下，当句子的可预测性和可懂度最低或最高时，来自预备运动区的抑制性影响最强。这种交互作用与行为可预测性增益呈负相关。总之，这些结果表明，在嘈杂的听力条件下成功理解依赖于语义区域的相互作用和认知控制区域的同时抑制，当存在语义线索时。
