Cognitive Neuroimaging Unit, NeuroSpin, INSERM, CEA, CNRS, Université Paris-Saclay, France.
Translational Neuromodeling Unit (TNU), Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Switzerland.
Cortex. 2022 Apr;149:226-245. doi: 10.1016/j.cortex.2022.02.001. Epub 2022 Feb 11.
The human brain efficiently extracts the temporal statistics of sensory environments and automatically generates expectations about future events. An influential Hypothesis holds that these expectations can find their implementation in neural oscillations, notably in the delta band (.5-3 Hz). Rhythmic fluctuations of cortical excitement are thought to align and match up in phase to the temporal structure of the sensory environment. This alignment is thought to result in the more excitable phase range of neural oscillations to overlap with the predicted onset of sensory events which in turn results in more efficient processing of sensory input, especially so in audition. An unresolved issue concerns whether such phase-aligned rhythmic brain activity is driven exclusively by the exogenous temporal structure of the input, or whether it also reflects phase re-alignment due to endogenous expectations based on stimulus probability and task relevance. In a seminal study, Stefanics et al. (2010) presented stimuli in a rhythmic stream and observed that delta phase consistency across trials was modulated by endogenous target onset expectations: delta phase consistency was higher prior to more probable (strongly expected) compared to less probable (weakly expected) target onsets. The present study replicates Experiment II of the original study, most importantly the modulation of delta phase consistency by endogenous expectations, and underlines a direct relationship between phase locking and behaviour. Our additional analyses locate the sources of the delta phase-alignment to motor, pre-motor, parietal, and temporal areas, and provide evidence for an ongoing delta oscillation, in line with the interpretation of oscillatory phase alignment rather than a transient evoked response. Importantly, this work shows that the phase of delta oscillations can be modulated by top-down control, and hence qualifies as a potential mechanism for the neural implementation of (rhythmic) temporal predictions.
人类大脑能够有效地提取感官环境的时间统计信息，并自动生成对未来事件的预期。一个有影响力的假说认为，这些预期可以在神经振荡中找到实现方式，特别是在 delta 波段（0.5-3 Hz）。皮质兴奋的节律性波动被认为与感官环境的时间结构对齐并匹配。这种对齐被认为导致神经振荡的更易兴奋相位范围与感官事件的预测起始相重叠，从而使感官输入的处理更加高效，尤其是在听觉方面。一个悬而未决的问题是，这种相位对齐的节律性脑活动是否仅由输入的外源性时间结构驱动，或者它是否也反映了由于基于刺激概率和任务相关性的内源性预期而导致的相位重新对齐。在一项开创性的研究中，Stefanics 等人（2010 年）在有节奏的信息流中呈现刺激，并观察到跨试验的 delta 相位一致性受到内源性目标起始预期的调制：与不太可能（弱预期）相比，在更可能（强预期）的目标起始之前，delta 相位一致性更高。本研究复制了原始研究的实验 II，最重要的是内源性预期对 delta 相位一致性的调制，并强调了相位锁定与行为之间的直接关系。我们的额外分析将 delta 相位对齐的源定位到运动、前运动、顶叶和颞叶区域，并提供了持续 delta 振荡的证据，与振荡相位对齐的解释一致，而不是瞬态诱发反应。重要的是，这项工作表明 delta 振荡的相位可以通过自上而下的控制来调制，因此可以作为（节奏）时间预测的神经实现的潜在机制。
