Mind-wandering: mechanistic insights from lesion, tDCS, and iEEG

fMRI evidence has convincingly implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Less is known about which subregions in these networks are necessary, and how they facilitate mind-wandering. A growing number of studies use the lesion and transcranial direct current stimulation (tDCS) approaches to establish the causal link between DMN and FPCN subregions and mind-wandering. They have also identified the mechanistic role of intra-DMN connectivity in this phenomenon. Intracranial EEG studies have revealed the neurophysiological mechanism underlying mind-wandering and its preferred frequencies in the theta and high-frequency band for communication within and across large-scale neural networks. To achieve an in-depth understanding of the where, when, and how mind-wandering is implemented in the brain requires a shift away from the predominant reliance on one method toward an integration of complementary methodological approaches. Cognitive neuroscience has witnessed a surge of interest in investigating the neural correlates of the mind when it drifts away from an ongoing task and the external environment. To that end, functional neuroimaging research has consistently implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Yet, it remains unknown which subregions within these networks are necessary and how they facilitate mind-wandering. In this review, we synthesize evidence from lesion, transcranial direct current stimulation (tDCS), and intracranial electroencephalogram (iEEG) studies demonstrating the causal relevance of brain regions, and providing insights into the neuronal mechanism underlying mind-wandering. We propose that the integration of complementary approaches is the optimal strategy to establish a comprehensive understanding of the neural basis of mind-wandering. Cognitive neuroscience has witnessed a surge of interest in investigating the neural correlates of the mind when it drifts away from an ongoing task and the external environment. To that end, functional neuroimaging research has consistently implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Yet, it remains unknown which subregions within these networks are necessary and how they facilitate mind-wandering. In this review, we synthesize evidence from lesion, transcranial direct current stimulation (tDCS), and intracranial electroencephalogram (iEEG) studies demonstrating the causal relevance of brain regions, and providing insights into the neuronal mechanism underlying mind-wandering. We propose that the integration of complementary approaches is the optimal strategy to establish a comprehensive understanding of the neural basis of mind-wandering. a neurological disorder characterized by recurrent and unpredictable seizures during which brain activity and behavior become abnormal. Many individuals’ epilepsy can be treated by medication. However, if various types of medication fail, individuals who have a well-defined source may undergo surgery to determine the precise location of their seizures to be subsequently resected. by tracking behavioral changes resulting from the stimulation of electrodes implanted in the brains of epilepsy patients, clinicians can define the regions important for critical language and motor functions. This approach also enables researchers to infer causality by mapping brain structure with millimeter precision to behavioral, cognitive, and neural changes. an umbrella term that encapsulates a variety of phenomenological experiences. The most widely used definition – task-unrelated thought – is narrowly characterized in contrast to an ongoing task. A broader definition is stimulus-independent thought, or internal attention, which characterizes thoughts that are not focused on the external environment. a form of thought sampling that asks participants to report on multiple dimensions of their ongoing phenomenological experience. In mind-wandering studies, this often includes the task-focus, detailedness, temporal focus, and valence of thoughts, among others. the PFC is situated in the frontal part of the cerebral cortex and plays a central role in high-level cognitive functions. It can be divided into numerous subregions, associated with distinct functional roles. This review primarily discusses the ventromedial PFC as part of the DMN, and the dorsolateral PFC as part of the FPCN. the resting state is often characterized by periods of time when participants are asked to simply do nothing and think about whatever comes to mind. Given the lack of task constraints and experimentally relevant external inputs during rest, attention is presumed and shown to be preoccupied by internally focused thoughts unrelated to their immediate environment. question prompts embedded during a task in the laboratory (or in real life) that ask participants to describe their ongoing mental experience; this circumvents issues of retrospective bias. In mind-wandering studies, participants are typically asked whether they were paying attention to the task or not, among other phenomenological aspects of the mind-wandering experience. an emerging noninvasive brain-stimulation technique that modulates neuronal activity by way of low-intensity acoustic pressure waves. This neuromodulation modality is uniquely characterized by its superior focality (on the order of millimeters) and capacity to target deep brain circuits. this technique involves inducing a pulsed magnetic field that creates brief electrical currents to pass in the brain to temporarily excite or inhibit a focal brain area (on the order of centimeters) below the magnetic coil.