Ten Oever Sanne, Schroeder Charles E, Poeppel David, van Atteveldt Nienke, Mehta Ashesh D, Mégevand Pierre, Groppe David M, Zion-Golumbic Elana
Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, The Netherlands.
Departments of Psychiatry and Neurology, Columbia University Medical Center, New York, New York 10032.
J Neurosci. 2017 May 10;37(19):4903-4912. doi: 10.1523/JNEUROSCI.3658-16.2017. Epub 2017 Apr 14.
Many environmental stimuli contain temporal regularities, a feature that can help predict forthcoming input. Phase locking (entrainment) of ongoing low-frequency neuronal oscillations to rhythmic stimuli is proposed as a potential mechanism for enhancing neuronal responses and perceptual sensitivity, by aligning high-excitability phases to events within a stimulus stream. Previous experiments show that rhythmic structure has a behavioral benefit even when the rhythm itself is below perceptual detection thresholds (ten Oever et al., 2014). It is not known whether this "inaudible" rhythmic sound stream also induces entrainment. Here we tested this hypothesis using magnetoencephalography and electrocorticography in humans to record changes in neuronal activity as subthreshold rhythmic stimuli gradually became audible. We found that significant phase locking to the rhythmic sounds preceded participants' detection of them. Moreover, no significant auditory-evoked responses accompanied this prethreshold entrainment. These auditory-evoked responses, distinguished by robust, broad-band increases in intertrial coherence, only appeared after sounds were reported as audible. Taken together with the reduced perceptual thresholds observed for rhythmic sequences, these findings support the proposition that entrainment of low-frequency oscillations serves a mechanistic role in enhancing perceptual sensitivity for temporally predictive sounds. This framework has broad implications for understanding the neural mechanisms involved in generating temporal predictions and their relevance for perception, attention, and awareness. The environment is full of rhythmically structured signals that the nervous system can exploit for information processing. Thus, it is important to understand how the brain processes such temporally structured, regular features of external stimuli. Here we report the alignment of slowly fluctuating oscillatory brain activity to external rhythmic structure before its behavioral detection. These results indicate that phase alignment is a general mechanism of the brain to process rhythmic structure and can occur without the perceptual detection of this temporal structure.
许多环境刺激包含时间规律，这一特征有助于预测即将到来的输入。有观点认为，正在进行的低频神经元振荡与节律性刺激的锁相（夹带）是一种潜在机制，可通过将高兴奋性相位与刺激流中的事件对齐来增强神经元反应和感知敏感性。先前的实验表明，即使节律本身低于感知检测阈值，节律结构也具有行为益处（ten Oever等人，2014年）。尚不清楚这种“听不见的”节律性声流是否也会诱发夹带。在这里，我们使用脑磁图和皮层脑电图对人类进行测试，以记录随着阈下节律性刺激逐渐变得可闻时神经元活动的变化。我们发现，在参与者检测到节律性声音之前，就已出现了对这些声音的显著锁相。此外，这种阈下夹带并未伴随明显的听觉诱发反应。这些听觉诱发反应的特征是试验间相关性出现强烈的宽带增加，且仅在声音被报告为可闻之后才出现。结合对节律序列观察到的感知阈值降低情况，这些发现支持了以下观点：低频振荡的夹带在增强对具有时间预测性声音的感知敏感性方面发挥着机制性作用。这一框架对于理解生成时间预测所涉及的神经机制及其与感知、注意力和意识的相关性具有广泛意义。环境中充满了神经系统可用于信息处理的节律性结构信号。因此，了解大脑如何处理外部刺激的这种时间结构化的规则特征非常重要。在这里，我们报告了在行为检测之前，缓慢波动的振荡脑活动与外部节律结构的对齐情况。这些结果表明，相位对齐是大脑处理节律结构的一种普遍机制，并且可以在没有对这种时间结构进行感知检测的情况下发生。
