Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany.
Neuroimage. 2013 Oct 1;79:111-20. doi: 10.1016/j.neuroimage.2013.04.064. Epub 2013 May 2.
Dynamic communication between functionally specialized, but spatially distributed areas of the brain is essential for effective brain functioning. A candidate mechanism for effective neuronal communication is oscillatory neuronal synchronization. Here, we used magnetoencephalography (MEG) to study the role of oscillatory neuronal synchronization in audio-visual speech perception. Subjects viewed congruent audio-visual stimuli of a speaker articulating the vowels /a/ or /o/. In addition, we presented modified, incongruent versions in which visual and auditory signals mismatched. We identified a left hemispheric network for processing congruent audio-visual speech as well as network interaction between areas: low frequency (4-12 Hz) power was suppressed for congruent stimuli at auditory onset around auditory cortex, while power in the high gamma (120-140 Hz)-band was enhanced in the Broca's area around auditory offset. In addition, beta-power (20-30 Hz) was suppressed in supramarginal gyrus for incongruent stimuli. Interestingly, coherence analysis revealed a functional coupling between auditory cortex and Broca's area for congruent stimuli demonstrated by an increase of coherence. In contrast, coherence decreased for incongruent stimuli, suggesting a decoupling of auditory cortex and Broca's area. In addition, the increase of coherence was positively correlated with the increase of high gamma-power. The results demonstrate that oscillatory power in several frequency bands correlates with the processing of matching audio-visual speech on a large spatio-temporal scale. The findings provide evidence that coupling of neuronal groups can be mediated by coherence in the theta/alpha band and that low frequency coherence and high frequency power modulations are correlated in audio-visual speech perception.
大脑中功能专业化但空间分布的区域之间的动态交流对于有效的大脑功能至关重要。有效的神经元通信的候选机制是振荡神经元同步。在这里，我们使用脑磁图（MEG）研究振荡神经元同步在视听语音感知中的作用。受试者观看说话者发出元音 /a/ 或 /o/ 的视听一致刺激。此外，我们还呈现了经过修改的不一致版本，其中视觉和听觉信号不匹配。我们确定了一个处理视听语音的左半球网络，以及区域之间的网络交互：在听觉起始时，听觉皮层周围的一致刺激抑制低频（4-12 Hz）功率，而听觉结束时布罗卡区的高伽马（120-140 Hz）带功率增强。此外，对于不一致的刺激，顶下小叶的β功率（20-30 Hz）受到抑制。有趣的是，相干分析显示，在听觉皮层和布罗卡区之间存在功能耦合，这表现为相干性的增加。相比之下，对于不一致的刺激，相干性降低，表明听觉皮层和布罗卡区的解耦。此外，相干性的增加与高伽马功率的增加呈正相关。研究结果表明，几个频带的振荡功率与大时空尺度上匹配的视听语音处理相关。这些发现提供了证据，表明神经元群的耦合可以通过θ/α频段的相干性来介导，并且低频相干性和高频功率调制在视听语音感知中是相关的。
