Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802;
Institute for Computational and Data Sciences, The Pennsylvania State University, University Park, PA 16802.
Proc Natl Acad Sci U S A. 2021 Nov 23;118(47). doi: 10.1073/pnas.2105395118.
The resting brain consumes enormous energy and shows highly organized spontaneous activity. To investigate how this activity is manifest among single neurons, we analyzed spiking discharges of ∼10,000 isolated cells recorded from multiple cortical and subcortical regions of the mouse brain during immobile rest. We found that firing of a significant proportion (∼70%) of neurons conformed to a ubiquitous, temporally sequenced cascade of spiking that was synchronized with global events and elapsed over timescales of 5 to 10 s. Across the brain, two intermixed populations of neurons supported orthogonal cascades. The relative phases of these cascades determined, at each moment, the response magnitude evoked by an external visual stimulus. Furthermore, the spiking of individual neurons embedded in these cascades was time locked to physiological indicators of arousal, including local field potential power, pupil diameter, and hippocampal ripples. These findings demonstrate that the large-scale coordination of low-frequency spontaneous activity, which is commonly observed in brain imaging and linked to arousal, sensory processing, and memory, is underpinned by sequential, large-scale temporal cascades of neuronal spiking across the brain.
静息状态的大脑消耗大量能量，并表现出高度组织化的自发性活动。为了研究这种活动在单个神经元中是如何表现的，我们分析了在小鼠大脑的多个皮层和皮层下区域在静止休息期间记录的约 10000 个分离细胞的尖峰放电。我们发现，相当一部分（约 70%）神经元的放电符合一种普遍存在的、时间上有序的尖峰级联，这种级联与全局事件同步，并在 5 到 10 秒的时间尺度上进行。在整个大脑中，两种混合的神经元群体支持正交级联。这些级联的相对相位在每个时刻决定了外部视觉刺激引起的反应幅度。此外，嵌入这些级联中的单个神经元的放电与觉醒的生理指标（包括局部场电位功率、瞳孔直径和海马回波）时间锁定。这些发现表明，低频自发活动的大规模协调，这在脑成像中很常见，并与觉醒、感觉处理和记忆有关，是由整个大脑中神经元放电的顺序、大规模时间级联来支持的。
