Dynamic brain network interactions underlying human thought and spontaneous cognition

自发思维，包括自发产生的记忆、图像和叙述，是人类经验的核心。迄今为止，大多数研究都采用认知任务来检查任务外思维，或者使用功能磁共振成像扫描仪中的静息状态。然而，这两种范式都没有捕捉到我最近认为对于理解自发心理过程至关重要的思想动态（Christoff et al., 2016， NRN）。本研究就是在这一理论框架的基础上，探讨动态产生思维的特征。具体目标将是：***1。扩展我们的知识，了解不同的大脑网络如何动态相互作用，以促进不同形式的动态思维维度***2。为捕捉持续思维流的主观体验的第一人称报告开发新的范例******前两个项目将利用沉思实践者的内省专业知识。项目一旨在通过思维方式操纵揭示新发现的思想维度的神经关联——思想是如何自由运动的。在fMRI扫描期间，专业的冥想实践者会在集中注意力和开放监控冥想之间交替进行。开放式监测（相对于集中注意力）有望促进自由移动的思想，并且在默认网络（DN）的内侧颞叶部分具有更强的功能连接（FC），因为它提供自发的心理内容。项目二将通过要求冥想者评估从自发产生的想法中解脱出来的困难程度，来检查思维自动约束的神经基础。动态FC测量将用于评估导致自发产生的想法的关键大脑网络的时间模式。******我们实验室最近的行为证据表明，自由活动的思维在早上最低，中午之后最高。项目3将在一天中的不同时间（上午8点和下午1点）用功能磁共振成像扫描仪检查自由移动的思想，以了解这些昼夜周期差异背后的神经基础。我们假设，在一天中的不同时间，我们会在突出网络中看到FC的差异。最后，项目4将开发一种新的方法，可以捕捉思想随时间的动态变化。我们将把标准的经验抽样范式扩展为一种连续的抽样方法，在这种方法中，参与者报告他们的想法。******这项提议的工作将超越传统的研究自发思维的方法，以扩大我们对塑造心理体验的动态大脑网络相互作用的理解。这项研究将对教育和工作场所实践产生重要影响，因为在这些实践中，考虑的重点是非任务思维，而不是思维的动态维度。

Spontaneous thought, including spontaneously arising memories, images, and narratives, is central to human experience. Most studies to date have employed a cognitive task to examine off-task thought, or have used the resting-state in the fMRI scanner. Neither of these paradigms, however, capture the dynamics of thought that I have recently argued are essential for understanding spontaneous mental processes (Christoff et al., 2016, NRN). The proposed research builds on this theoretical framework to explore the characteristics of dynamically arising thoughts. The specific objectives will be to:***1. Expand our knowledge about how different brain networks dynamically interact to contribute to different forms of dynamic dimensions of thought***2. Develop novel paradigms for first-person reporting of subjective experience that capture ongoing thought flow******The first two projects will capitalize on the introspective expertise of contemplative practitioners. Project 1 aims to uncover the neural correlates of a newly identified dimension of thought – how freely thought moves – through a mindset manipulation. Expert contemplative practitioners will alternate between focused attention vs. open monitoring meditation during an fMRI scan. Open monitoring (vs. focused attention) is expected promote freely moving thought and be marked by stronger functional connectivity (FC) in the medial temporal lobe part of the default network (DN) because it is supplying the spontaneous mental content. Project 2 will examine the neural basis of automatic constraints on thought by asking contemplative practitioners to rate the level of difficulty in disengaging from their spontaneously arising thoughts. Dynamic FC measures will be used to assess the temporal patterns of key brain networks in leading up to a spontaneously arising thought. ******Recent behavioral evidence from our lab suggests freely moving thought is lowest in the morning and highest after noon. Project 3 will examine freely moving thoughts at different times during the day in the fMRI scanner (8AM vs. 1PM) in order to understand the neural basis underlying these differences across the diurnal cycle. We hypothesize that we will see differences in FC within the salience network across different times in the day. Finally, Project 4 will develop a new methodology that can capture the dynamic changes in thought over time. We will extend the standard experience sampling paradigm towards a continuous sampling method in which participants report their thoughts as they unfold.******The proposed work will go beyond conventional methods for investigating spontaneous thought in order to expand our understanding of dynamic brain networks interactions that shape mental experience. This research will have important implications for education and workplace practices where considerations have focused on off-task thought to the exclusion of dynamic dimensions of thought.