Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, United States.
Elife. 2022 May 30;11:e73693. doi: 10.7554/eLife.73693.
Current theory and empirical studies suggest that humans segment continuous experiences into events based on the mismatch between predicted and actual sensory inputs; detection of these 'event boundaries' evokes transient neural responses. However, boundaries can also occur at transitions between internal mental states, without relevant external input changes. To what extent do such 'internal boundaries' share neural response properties with externally driven boundaries? We conducted an fMRI experiment where subjects watched a series of short movies and then verbally recalled the movies, unprompted, in the order of their choosing. During recall, transitions between movies thus constituted major boundaries between internal mental contexts, generated purely by subjects' unguided thoughts. Following the offset of each recalled movie, we observed stereotyped spatial activation patterns in the default mode network, especially the posterior medial cortex, consistent across different movie contents and even across the different tasks of movie watching and recall. Surprisingly, the between-movie boundary patterns did not resemble patterns at boundaries between events within a movie. Thus, major transitions between mental contexts elicit neural phenomena shared across internal and external modes and distinct from within-context event boundary detection, potentially reflecting a cognitive state related to the flushing and reconfiguration of situation models.
目前的理论和实证研究表明，人类基于预测和实际感官输入之间的不匹配将连续的体验分割成事件；对这些“事件边界”的检测会引起短暂的神经反应。然而，边界也可能出现在内部心理状态之间的转换中，而没有相关的外部输入变化。这些“内部边界”在多大程度上与外部驱动的边界共享神经反应特性？我们进行了一项 fMRI 实验，让受试者观看一系列短片，然后在没有提示的情况下，按照自己的选择顺序口头回忆电影。在回忆过程中，电影之间的转换构成了内部心理环境之间的主要边界，完全是由受试者的无指导思维产生的。在回忆的每部电影结束后，我们观察到默认模式网络中的刻板的空间激活模式，特别是后内侧皮质，与不同的电影内容一致，甚至与观看电影和回忆的不同任务一致。令人惊讶的是，电影之间的边界模式与电影内部事件之间的边界模式并不相似。因此，心理环境之间的主要转换会引发跨内部和外部模式共享的神经现象，与内部上下文事件边界检测不同，可能反映了与情景模型刷新和重新配置相关的认知状态。
