Previous psychophysical and neurophysiological studies in young healthy adults have provided evidence that audiovisual speech integration occurs with a large degree of temporal tolerance around true simultaneity. To further determine whether audiovisual speech asynchrony modulates auditory cortical processing and neural binding in young healthy adults, N1/P2 auditory evoked responses were compared using an additive model during a syllable categorization task, without or with an audiovisual asynchrony ranging from 240 ms visual lead to 240 ms auditory lead. Consistent with previous psychophysical findings, the observed results converge in favor of an asymmetric temporal integration window. Three main findings were observed: 1) predictive temporal and phonetic cues from pre-phonatory visual movements before the acoustic onset appeared essential for neural binding to occur, 2) audiovisual synchrony, with visual pre-phonatory movements predictive of the onset of the acoustic signal, was a prerequisite for N1 latency facilitation, and 3) P2 amplitude suppression and latency facilitation occurred even when visual pre-phonatory movements were not predictive of the acoustic onset but the syllable to come. Taken together, these findings help further clarify how audiovisual speech integration partly operates through two stages of visually-based temporal and phonetic predictions.

中文翻译：

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视听语音异步不对称调节神经结合

先前针对年轻健康成年人的心理物理学和神经生理学研究提供了证据，表明视听语音整合在真实同时性周围存在很大程度的时间耐受性。为了进一步确定视听语音异步是否调节年轻健康成年人的听觉皮层处理和神经结合，在音节分类任务期间使用加法模型比较 N1/P2 听觉诱发反应，不使用或使用视听异步范围从 240 毫秒视觉导联到240 毫秒听觉导联。与之前的心理物理学发现一致，观察到的结果趋于支持不对称时间积分窗口。观察到三个主要发现：1）发声前视觉运动的预测时间和语音线索对于神经结合的发生至关重要，2）视听同步，视觉发声前运动预测声信号的出现，是 N1 潜伏期促进的先决条件，并且 3）即使视觉发声前运动不能预测声学开始，而是预测即将到来的音节，P2 幅度抑制和潜伏期促进也会发生。总而言之，这些发现有助于进一步阐明视听语音整合如何部分地通过基于视觉的时间和语音预测的两个阶段进行操作。