When the Brain Takes a Break: A Model-Based Analysis of Mind Wandering

Abstract

Mind wandering is an ubiquitous phenomenon in everyday life. In the cognitive neurosciences, mind wandering has been associated with several distinct neural processes, most notably increased activity in the default mode network (DMN), suppressed activity within the anti-correlated (task-positive) network (ACN), and changes in neuromodulation. By using an integrative multimodal approach combining machine-learning techniques with modeling of latent cognitive processes, we show that mind wandering in humans is characterized by inefficiencies in executive control (task-monitoring) processes. This failure is predicted by a single-trial signature of (co)activations in the DMN, ACN, and neuromodulation, and accompanied by a decreased rate of evidence accumulation and response thresholds in the cognitive model.

A Neural Model of Mind Wandering

“…Our model links an active state of mind wandering to reduced activation in the PCC/mPFC and poor task performance (Table 1), which would explain these finger-tapping findings. In contrast, studies that found a positive correlation between mind wandering and PCC/mPFC activity used sustained attention tasks where mind wandering was sampled with thought-probes [2][3][4]13]. In such a setting, it is likely that episodes of mind wandering are relatively sparse and most thought probes where participants indicated they were off-task likely mirrored the state we described as off-focus (exploratory) in this model.…”

“…This operationalization is based on correlations between simultaneously recorded neural activity and pupil diameter [18], and although this link has been somewhat speculative [21,22] the relationship between LC-NE system activity and pupil diameter was recently substantiated with electrophysiological measures in non-human primates [23]. In addition, several studies have investigated pupil diameter in a mind-wandering context: An increase in tonic pupil diameter precedes mind wandering-related errors [14], and a decrease in the phasic pupil response to stimulation is observed during episodes of mind wandering [4]. These findings have been taken as evidence for a role of the LC-NE system in mind wandering.…”

“…Simultaneously, a second neural system -the locus coeruleus norepinephrine (LC-NE) system -has also been studied as a potential neural modulator of mind wandering [4,14,15].…”

“…This allows mind wandering to be conceived as a neural state or process -as outlined in this Opinion -that affects the latent components of cognitive process models, which in turn affects observed behavior. To date, only one study has taken the first step toward an integrated model-based cognitive neuroscience of mind wandering ( [4], Figure II). The general approach in this study can be extended to empirically test the tripartite neural model of mind wandering proposed in the main text.…”

“…Image taken with permission from [55]. [4]. Neural data (fMRI, pupil diameter) were preprocessed to extract theoretically relevant features for use in a machine learning classifier.…”