Humans spend much of their lives engaging with their internal train of thoughts. Traditionally, research focused on whether or not these thoughts are related to ongoing tasks, and has identified reliable and distinct behavioral and neural correlates of task-unrelated and task-related thought. A recent theoretical framework highlighted a different aspect of thinking—how it dynamically moves between topics. However, the neural correlates of such thought dynamics are unknown. The current study aimed to determine the electrophysiological signatures of these dynamics by recording electroencephalogram (EEG) while participants performed an attention task and periodically answered thought-sampling questions about whether their thoughts were 1) task-unrelated, 2) freely moving, 3) deliberately constrained, and 4) automatically constrained. We examined three EEG measures across different time windows as a function of each thought type: stimulus-evoked P3 event-related potentials and non–stimulus-evoked alpha power and variability. Parietal P3 was larger for task-related relative to task-unrelated thoughts, whereas frontal P3 was increased for deliberately constrained compared with unconstrained thoughts. Frontal electrodes showed enhanced alpha power for freely moving thoughts relative to non-freely moving thoughts. Alpha-power variability was increased for task-unrelated, freely moving, and unconstrained thoughts. Our findings indicate distinct electrophysiological patterns associated with task-unrelated and dynamic thoughts, suggesting these neural measures capture the heterogeneity of our ongoing thoughts.

人类一生中的大部分时间都在与他们的内部思路打交道。传统上，研究的重点是这些想法是否与正在进行的任务相关，并且已经确定了与任务无关和任务相关的想法的可靠和独特的行为和神经相关性。最近的一个理论框架强调了思维的一个不同方面——它如何在主题之间动态移动。然而，这种思维动态的神经相关性是未知的。目前的研究旨在通过记录脑电图 (EEG) 来确定这些动态的电生理特征，同时参与者执行注意力任务并定期回答关于他们的想法是否是 1) 与任务无关、2) 自由移动、3) 故意的思想抽样问题约束，和 4) 自动约束。我们根据每种思维类型检查了不同时间窗口的三种 EEG 测量值：刺激诱发的 P3 事件相关电位和非刺激诱发的 α 功率和变异性。与任务无关的想法相比，与任务相关的想法的顶叶 P3 较大，而与不受限制的想法相比，故意限制的想法的额叶 P3 增加。相对于非自由移动的想法，正面电极显示出增强的自由移动想法的阿尔法功率。对于与任务无关、自由移动和不受约束的想法，阿尔法功率变异性有所增加。我们的研究结果表明与任务无关和动态思维相关的不同电生理模式，表明这些神经测量捕捉了我们正在进行的思维的异质性。