Center for Adaptive Systems, Boston University, 677 Beacon Street, Boston, Massachusetts 02215, USA.
J Acoust Soc Am. 2011 Jul;130(1):440-60. doi: 10.1121/1.3589258.
How are laminar circuits of neocortex organized to generate conscious speech and language percepts? How does the brain restore information that is occluded by noise, or absent from an acoustic signal, by integrating contextual information over many milliseconds to disambiguate noise-occluded acoustical signals? How are speech and language heard in the correct temporal order, despite the influence of contexts that may occur many milliseconds before or after each perceived word? A neural model describes key mechanisms in forming conscious speech percepts, and quantitatively simulates a critical example of contextual disambiguation of speech and language; namely, phonemic restoration. Here, a phoneme deleted from a speech stream is perceptually restored when it is replaced by broadband noise, even when the disambiguating context occurs after the phoneme was presented. The model describes how the laminar circuits within a hierarchy of cortical processing stages may interact to generate a conscious speech percept that is embodied by a resonant wave of activation that occurs between acoustic features, acoustic item chunks, and list chunks. Chunk-mediated gating allows speech to be heard in the correct temporal order, even when what is heard depends upon future context.
大脑中分层的神经回路是如何组织起来产生有意识的言语和语言知觉的？大脑如何通过整合多个毫秒的上下文信息来恢复被噪声掩盖或缺失的信息，从而对被噪声掩盖的声学信号进行去模糊处理？尽管上下文可能出现在每个感知单词之前或之后的许多毫秒，但言语和语言是如何按照正确的时间顺序被听到的？一个神经模型描述了形成有意识的言语知觉的关键机制，并定量模拟了言语和语言上下文去模糊处理的一个关键示例，即音位恢复。在这里，当从语音流中删除的音位被宽带噪声取代时，即使在音位呈现后出现了去模糊处理的上下文，该音位也会被感知到。该模型描述了在皮质处理阶段的层次结构内的层状回路如何相互作用，以产生一种有意识的言语知觉，这种知觉由在声学特征、声学项目块和列表块之间发生的共振激活波体现。块介导的门控允许即使所听到的内容取决于未来的上下文，也能按照正确的时间顺序听到言语。
