School of Psychology, The University of Queensland, Australia.
School of Psychology, The University of Queensland, Australia.
Cortex. 2024 Sep;178:249-268. doi: 10.1016/j.cortex.2024.06.017. Epub 2024 Jul 10.
Mind wandering is a common phenomenon in our daily lives and can have both an adaptive and detrimental impact. Recently, a dynamic framework has been proposed to characterise the heterogeneity of internal thoughts, suggesting there are three distinct thought types which can change over time - freely moving, deliberately constrained, and automatically constrained (thoughts). There is currently very little evidence on how different types of dynamic thought are represented in the brain. Previous research has applied non-invasive transcranial direct current stimulation (tDCS) to causally implicate the prefrontal cortex and inferior parietal lobule in mind wandering. However, a more recently developed and nuanced technique, high-definition tDCS (HD-tDCS), delivers more focal stimulation able to target specific brain regions. Therefore, the current study investigated the effect of anodal HD-tDCS applied to the left prefrontal and right inferior parietal cortices (with the occipital cortex included as an active control) on mind wandering, and specifically, the causal neural substrates of the three internal dynamic thought types. This was a single session study using a novel task which allows investigation into how dynamic thoughts are associated with behavioural variability and the recruitment of executive control operations across the three brain regions. There was no evidence to support our hypothesised effect of stimulation reducing task unrelated thought. Furthermore, the hypothesis driven analyses found no evidence of stimulation affecting the dynamic thought types, nor any evidence for our hypothesised effects of stimulation reducing behavioural variability and increasing randomness. There was only evidence for a relationship between these two measures of performance when participants thoughts were freely moving. However, there was evidence from our exploratory analyses that anodal stimulation to the prefrontal cortex decreased freely moving thought and anodal stimulation to the parietal lobule decreased deliberately constrained thought, relative to the sham conditions. The exploratory analyses also suggested stimulation may increase freely moving thought in the occipital cortex. Overall, these findings suggest stimulation does not affect the dynamic thought types, however there is preliminary evidence to support the heterogenous nature of mind wandering, whereby different brain regions may be causally implicated in distinct dynamic thought types.
思维漫游是我们日常生活中的一种常见现象，它既有适应性的影响，也有有害的影响。最近，人们提出了一个动态框架来描述内部思维的异质性，表明有三种不同的思维类型可以随时间变化——自由移动、故意约束和自动约束（思维）。目前，关于不同类型的动态思维在大脑中是如何表现的，几乎没有什么证据。以前的研究应用非侵入性经颅直流电刺激（tDCS）来因果地暗示前额叶皮层和下顶叶在思维漫游中的作用。然而，一种最近开发的、更细致的技术——高清晰度 tDCS（HD-tDCS），提供了更集中的刺激，能够针对特定的大脑区域。因此，目前的研究调查了左前额叶和右下顶叶施加阳极 HD-tDCS（同时将枕叶皮层作为活动对照）对思维漫游的影响，特别是三种内部动态思维类型的因果神经基础。这是一项单次会议研究，使用了一种新的任务，该任务允许研究动态思维与行为变异性的关联，以及三个大脑区域的执行控制操作的招募情况。没有证据支持我们假设的刺激减少与任务无关的思维的效果。此外，假设驱动的分析没有发现刺激影响动态思维类型的证据，也没有发现刺激减少行为变异性和增加随机性的证据。只有当参与者的思维自由移动时，这两个测量结果之间才有证据表明存在关系。然而，我们的探索性分析有证据表明，与假刺激相比，刺激前额叶会减少自由移动的思维，刺激顶叶会减少故意约束的思维。探索性分析还表明，刺激可能会增加枕叶皮层中自由移动的思维。总的来说，这些发现表明刺激不会影响动态思维类型，但有初步证据支持思维漫游的异质性，即不同的大脑区域可能在不同的动态思维类型中具有因果关系。
