Modulation of posterior default mode network activity during interoceptive attention and relation to mindfulness

Background: Interoceptive attention to internal sensory signals, such as the breath, is fundamental to mindfulness. However, interoceptive attention can be difficult to study and the vast majority of investigations of the neural correlates of mindfulness-based attention rely on subjective and retrospective measures. Response consistency is an established method for evaluating variability of attention on exteroceptive attention tasks but has rarely been applied to interoceptive attention task. Methods: In this study, we measured consistency of response times on a breath-monitoring task in individuals across the lifespan (15-91 years of age, n=324) with simultaneous electroencephalography (EEG).  Results: We found that consistency on this breath monitoring task was positively correlated with attentive performance on an exteroceptive inhibitory control task. EEG source reconstruction showed that on-task alpha band (8-12 Hz) activity was greater than that measured at rest. Low consistency/longer breath responses were associated with elevated brain activity relative to high consistency responses particularly in posterior default mode network (pDMN) brain regions. pDMN activity was inversely linked with functional connectivity to the fronto-parietal network (FPN) and the cinguloopercular network (CON) on task but not at rest, suggesting a role for these frontal networks in on-task regulation of pDMN activity. pDMN activity was greater in subjects reporting low subjective mindfulness, and was adaptively modulated by task difficulty in an independent experiment. Conclusions: Elevated pDMN alpha activity serves as an objective neural marker for low consistency responding during interoceptive breath attention, scales with task difficulty and is associated with low subjective mindfulness.