Puvvada Krishna C, Simon Jonathan Z
Department of Electrical & Computer Engineering.
Department of Electrical & Computer Engineering,
J Neurosci. 2017 Sep 20;37(38):9189-9196. doi: 10.1523/JNEUROSCI.0938-17.2017. Epub 2017 Aug 18.
The ability to parse a complex auditory scene into perceptual objects is facilitated by a hierarchical auditory system. Successive stages in the hierarchy transform an auditory scene of multiple overlapping sources, from peripheral tonotopically based representations in the auditory nerve, into perceptually distinct auditory-object-based representations in the auditory cortex. Here, using magnetoencephalography recordings from men and women, we investigate how a complex acoustic scene consisting of multiple speech sources is represented in distinct hierarchical stages of the auditory cortex. Using systems-theoretic methods of stimulus reconstruction, we show that the primary-like areas in the auditory cortex contain dominantly spectrotemporal-based representations of the entire auditory scene. Here, both attended and ignored speech streams are represented with almost equal fidelity, and a global representation of the full auditory scene with all its streams is a better candidate neural representation than that of individual streams being represented separately. We also show that higher-order auditory cortical areas, by contrast, represent the attended stream separately and with significantly higher fidelity than unattended streams. Furthermore, the unattended background streams are more faithfully represented as a single unsegregated background object rather than as separated objects. Together, these findings demonstrate the progression of the representations and processing of a complex acoustic scene up through the hierarchy of the human auditory cortex. Using magnetoencephalography recordings from human listeners in a simulated cocktail party environment, we investigate how a complex acoustic scene consisting of multiple speech sources is represented in separate hierarchical stages of the auditory cortex. We show that the primary-like areas in the auditory cortex use a dominantly spectrotemporal-based representation of the entire auditory scene, with both attended and unattended speech streams represented with almost equal fidelity. We also show that higher-order auditory cortical areas, by contrast, represent an attended speech stream separately from, and with significantly higher fidelity than, unattended speech streams. Furthermore, the unattended background streams are represented as a single undivided background object rather than as distinct background objects.
分层听觉系统有助于将复杂的听觉场景解析为可感知的对象。该分层结构的连续阶段将多个重叠声源的听觉场景，从听神经中基于周边音调拓扑的表征，转变为听觉皮层中基于可感知的不同听觉对象的表征。在此，我们利用对男性和女性的脑磁图记录，研究由多个语音源组成的复杂声学场景在听觉皮层不同分层阶段是如何表征的。通过刺激重建的系统理论方法，我们表明听觉皮层中类似初级的区域主要包含基于频谱时间的整个听觉场景表征。在此，被关注和被忽略的语音流几乎以相同的保真度被表征，并且包含所有语音流的完整听觉场景的全局表征，比单独表征各个语音流更有可能是神经表征。我们还表明，相比之下，高阶听觉皮层区域分别表征被关注的语音流，且保真度明显高于未被关注的语音流。此外，未被关注的背景语音流更忠实地被表征为单个未分离的背景对象，而不是分离的对象。总之，这些发现证明了复杂声学场景的表征和处理在人类听觉皮层分层结构中的进展。利用在模拟鸡尾酒会环境中人类听众的脑磁图记录，我们研究由多个语音源组成的复杂声学场景在听觉皮层不同分层阶段是如何表征的。我们表明，听觉皮层中类似初级的区域主要使用基于频谱时间的整个听觉场景表征，被关注和未被关注的语音流几乎以相同的保真度被表征。我们还表明，相比之下，高阶听觉皮层区域将被关注的语音流与未被关注的语音流分开表征，且保真度明显更高。此外，未被关注的背景语音流被表征为单个未分割的背景对象，而不是不同的背景对象。
