Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, Heidelberg,Germany.
Cereb Cortex. 2010 Dec;20(12):2863-73. doi: 10.1093/cercor/bhq037. Epub 2010 Mar 17.
Streaming is a perceptual mechanism by which the brain segregates information from multiple sound sources in our environment and assigns them to distinct auditory streams. Examples for streaming cues are differences in frequency spectrum, pitch, or space, and potential neural correlates for streaming based on spectral and pitch cues have been identified in the auditory cortex. Here, magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) were used to evaluate if response enhancement in auditory cortex associated with streaming represents a general pattern that is independent of the stimulus cue. Interaural time differences (ITDs) were used as a spatial streaming cue and were compared with streaming based on fundamental frequency (f(0)) differences. The MEG results showed enhancement of the P(1)m after 60-90 ms that was similar during streaming based on ITD and pitch. Sustained fMRI activity was enhanced at identical sites in Heschl's gyrus and planum temporale for both cues; no topographical specificity for space or pitch was found for the streaming-associated enhancement. These results support the hypothesis of an early convergence of the neural representation for auditory streams that is independent of the acoustic cue that the streaming is based on.
流分离是一种感知机制，大脑通过这种机制将来自环境中多个声源的信息分离出来，并将它们分配到不同的听觉流中。流分离线索的例子包括频谱、音高或空间的差异，并且已经在听觉皮层中确定了基于频谱和音高线索的流分离的潜在神经相关性。在这里，使用脑磁图 (MEG) 和功能磁共振成像 (fMRI) 来评估与流分离相关的听觉皮层中的反应增强是否代表一种与刺激线索无关的通用模式。耳间时间差 (ITD) 被用作空间流分离线索，并与基于基频 (f(0)) 差异的流分离进行比较。MEG 结果显示，在基于 ITD 和音高的流分离后 60-90 毫秒时，P(1)m 增强，这与两种线索的情况相似。在 Heschl 回和颞平面上，与流分离相关的增强在相同的位置增强了持续的 fMRI 活动；没有发现空间或音高的拓扑特异性用于流分离相关的增强。这些结果支持了听觉流的神经表示早期融合的假设，该融合与流分离所基于的声线索无关。
