[Spatiotemporal analysis of event-related potentials during mind wandering]

To investigate the neural mechanism of mind wandering.

Event-related potentials (ERP) was recorded from 10 healthy college students while having a sustained attention to response task (SART), which consisted of frequent stimuli and rare stimuli with varied probability ratios. The fault response to the rare stimulus suggested the occurrence of an episode of mind wandering. The ERP of the frequent stimuli before the erroneous or correct responses of the rare stimuli were analyzed with two-way ANOVA of repeated-measurement [(wandering: yes, no)×(probability ratio: 0.1/0.9, 0.2/0.8, 0.3/0.7)].

The reaction time of the error response was shorter than that of the correct one. Significant probability effects were also found: the larger the frequent probability, the shorter its reaction time and the lower its accuracy. The sensitivity d' had no significant effect. The statistical parametric mapping of ERP suggested an interaction effect in the bilateral parietal areas (500-600 ms) and frontal areas (800-900 ms); the probability effect occurred in the left prefrontal lobe and the right parietal lobe (300-350 ms) and mind wandering effect in the bilateral occipital lobes (150-350 ms), frontal poles (250-300 ms), bilateral frontal-temporal-parietal regions (400-600 ms) and left prefrontal (800-900 ms).

During mind wandering, the activation of cognitive processing for environment information decreases and speedy responses are more common with faults. The functional failure of the executive attention system influenced by the probability structure of SART may cause the occurrence of mind wandering.