Hertie Institute for Clinical Brain Research, University Medical Center Tübingen, Tübingen 72076, Germany.
Department of Anesthesiology and Intensive Care Medicine, University Medical Center Tübingen, Tübingen 72076, Germany.
J Neurosci. 2024 Oct 16;44(42):e0171242024. doi: 10.1523/JNEUROSCI.0171-24.2024.
Human sleep exhibits multiple, recurrent temporal regularities, ranging from circadian rhythms to sleep stage cycles and neuronal oscillations during nonrapid eye movement sleep. Moreover, recent evidence revealed a functional role of aperiodic activity, which reliably discriminates different sleep stages. Aperiodic activity is commonly defined as the spectral slope of the 1/frequency (1/f) decay function of the electrophysiological power spectrum. However, several lines of inquiry now indicate that the aperiodic component of the power spectrum might be better characterized by a superposition of several decay processes with associated timescales. Here, we determined multiple timescales, which jointly shape aperiodic activity using human intracranial electroencephalography. Across three independent studies (47 participants, 23 female), our results reveal that aperiodic activity reliably dissociated sleep stage-dependent dynamics in a regionally specific manner. A principled approach to parametrize aperiodic activity delineated several, spatially and state-specific timescales. Lastly, we employed pharmacological modulation by means of propofol anesthesia to disentangle state-invariant timescales that may reflect physical properties of the underlying neural population from state-specific timescales that likely constitute functional interactions. Collectively, these results establish the presence of multiple intrinsic timescales that define the electrophysiological power spectrum during distinct brain states.
人类睡眠表现出多种反复出现的时间规律性，从昼夜节律到非快速眼动睡眠期间的睡眠阶段周期和神经元振荡。此外，最近的证据揭示了非周期性活动的功能作用，它可靠地区分不同的睡眠阶段。非周期性活动通常被定义为电生理功率谱的 1/f（1/f）衰减函数的谱斜率。然而，现在有几条研究线索表明，功率谱的非周期性成分可能更好地用与相关时间尺度相关的几个衰减过程的叠加来描述。在这里，我们使用人类颅内脑电图确定了多个时间尺度，这些时间尺度共同塑造了非周期性活动。在三项独立的研究（47 名参与者，23 名女性）中，我们的结果表明，非周期性活动可靠地区分了以区域特异性方式依赖于睡眠阶段的动力学。一种参数化非周期性活动的原则性方法描绘了几个空间和状态特异性的时间尺度。最后，我们通过异丙酚麻醉进行药理学调节，以区分可能反映潜在神经群体物理特性的状态不变时间尺度和可能构成功能相互作用的状态特定时间尺度。总的来说，这些结果确立了存在多个内在时间尺度，这些时间尺度定义了不同大脑状态下的电生理功率谱。
