Inserm U960 - École Normale Supérieure, Paris, France.
Nat Neurosci. 2011 Jun;14(6):797-801. doi: 10.1038/nn.2810. Epub 2011 May 8.
According to the predictive coding theory, top-down predictions are conveyed by backward connections and prediction errors are propagated forward across the cortical hierarchy. Using MEG in humans, we show that violating multisensory predictions causes a fundamental and qualitative change in both the frequency and spatial distribution of cortical activity. When visual speech input correctly predicted auditory speech signals, a slow delta regime (3-4 Hz) developed in higher-order speech areas. In contrast, when auditory signals invalidated predictions inferred from vision, a low-beta (14-15 Hz) / high-gamma (60-80 Hz) coupling regime appeared locally in a multisensory area (area STS). This frequency shift in oscillatory responses scaled with the degree of audio-visual congruence and was accompanied by increased gamma activity in lower sensory regions. These findings are consistent with the notion that bottom-up prediction errors are communicated in predominantly high (gamma) frequency ranges, whereas top-down predictions are mediated by slower (beta) frequencies.
根据预测编码理论，自上而下的预测通过反向连接来传递，预测误差沿皮质层次结构向前传播。我们使用人类的 MEG 证明，违反多感觉预测会导致皮质活动的频率和空间分布发生根本的、定性的变化。当视觉语音输入正确预测了听觉语音信号时，在高级语音区域中会出现一个缓慢的 delta 节律（3-4 Hz）。相反，当听觉信号否定了从视觉推断出的预测时，一个低β（14-15 Hz）/高γ（60-80 Hz）的耦合节律在一个多感觉区域（STS 区域）局部出现。这种振荡反应的频率变化与视听一致性的程度成正比，并且伴随着较低感觉区域中γ活动的增加。这些发现与以下观点一致，即自下而上的预测误差主要通过较高（γ）频率范围进行传递，而自上而下的预测则通过较慢（β）频率进行介导。
