Cognitive Neuroimaging Unit, NeuroSpin, CEA, INSERM, CNRS, Université Paris-Saclay, 91191, Gif/Yvette, France.
Sci Rep. 2023 Jul 7;13(1):11031. doi: 10.1038/s41598-023-37514-1.
Rhythmic activity in the delta frequency range (0.5-3 Hz) is a prominent feature of brain dynamics. Here, we examined whether spontaneous delta oscillations, as found in invasive recordings in awake animals, can be observed in non-invasive recordings performed in humans with magnetoencephalography (MEG). In humans, delta activity is commonly reported when processing rhythmic sensory inputs, with direct relationships to behaviour. However, rhythmic brain dynamics observed during rhythmic sensory stimulation cannot be interpreted as an endogenous oscillation. To test for endogenous delta oscillations we analysed human MEG data during rest. For comparison, we additionally analysed two conditions in which participants engaged in spontaneous finger tapping and silent counting, arguing that internally rhythmic behaviours could incite an otherwise silent neural oscillator. A novel set of analysis steps allowed us to show narrow spectral peaks in the delta frequency range in rest, and during overt and covert rhythmic activity. Additional analyses in the time domain revealed that only the resting state condition warranted an interpretation of these peaks as endogenously periodic neural dynamics. In sum, this work shows that using advanced signal processing techniques, it is possible to observe endogenous delta oscillations in non-invasive recordings of human brain dynamics.
δ 频带（0.5-3 Hz）的节律性活动是大脑动力学的一个突出特征。在这里，我们研究了在清醒动物的侵入性记录中发现的自发性 δ 振荡是否可以在使用脑磁图（MEG）进行的非侵入性记录中观察到。在人类中，当处理有节奏的感觉输入时，通常会报告 δ 活动，并且与行为直接相关。然而，在有节奏的感觉刺激期间观察到的有节奏的大脑动力学不能被解释为内源性振荡。为了测试内源性 δ 振荡，我们分析了人类 MEG 数据在休息时的情况。为了进行比较，我们还分析了参与者进行自发手指敲击和无声计数的两种情况，认为内部有节奏的行为可能会激发原本沉默的神经振荡器。一组新的分析步骤使我们能够在休息时以及在明显和隐蔽的节律性活动中显示出 δ 频带中的窄谱峰。在时域中的额外分析表明，只有在休息状态条件下，这些峰值才有理由被解释为内源性周期性神经动力学。总之，这项工作表明，使用先进的信号处理技术，有可能在人类大脑动力学的非侵入性记录中观察到内源性 δ 振荡。
