Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139.
Amsterdam Brain and Cognition Centre, University of Amsterdam, 1018 WS Amsterdam, The Netherlands.
eNeuro. 2017 Mar 1;4(1). doi: 10.1523/ENEURO.0007-17.2017. eCollection 2017 Jan-Feb.
Perceiving the geometry of surrounding space is a multisensory process, crucial to contextualizing object perception and guiding navigation behavior. Humans can make judgments about surrounding spaces from reverberation cues, caused by sounds reflecting off multiple interior surfaces. However, it remains unclear how the brain represents reverberant spaces separately from sound sources. Here, we report separable neural signatures of auditory space and source perception during magnetoencephalography (MEG) recording as subjects listened to brief sounds convolved with monaural room impulse responses (RIRs). The decoding signature of sound sources began at 57 ms after stimulus onset and peaked at 130 ms, while space decoding started at 138 ms and peaked at 386 ms. Importantly, these neuromagnetic responses were readily dissociable in form and time: while sound source decoding exhibited an early and transient response, the neural signature of space was sustained and independent of the original source that produced it. The reverberant space response was robust to variations in sound source, and vice versa, indicating a generalized response not tied to specific source-space combinations. These results provide the first neuromagnetic evidence for robust, dissociable auditory source and reverberant space representations in the human brain and reveal the temporal dynamics of how auditory scene analysis extracts percepts from complex naturalistic auditory signals.
感知周围空间的几何形状是一个多感官的过程，对于上下文感知物体和引导导航行为至关重要。人类可以通过声音在多个内部表面上反射产生的混响线索来判断周围的空间。然而，大脑如何将混响空间与声源分开表示仍不清楚。在这里，我们在磁共振脑磁图（MEG）记录中报告了听觉空间和声源感知的可分离神经特征，因为受试者听了与单耳房间脉冲响应（RIR）卷积的短暂声音。声源的解码特征在刺激开始后 57 毫秒开始，并在 130 毫秒时达到峰值，而空间解码在 138 毫秒开始，并在 386 毫秒时达到峰值。重要的是，这些神经磁响应在形式和时间上是容易区分的：虽然声源解码表现出早期和瞬态响应，但空间的神经特征是持续的，与产生它的原始声源无关。混响空间响应对声源的变化具有鲁棒性，反之亦然，这表明一种普遍的响应，而不是与特定的源-空间组合相关联。这些结果提供了人类大脑中强大的、可分离的听觉声源和混响空间表示的第一个神经磁证据，并揭示了听觉场景分析如何从复杂的自然听觉信号中提取感知的时间动态。
