Posterior default mode network activity underlies distracted interoceptive attention and provides an objective basis for low mindfulness & depression

Abstract

Abstract Interoceptive attention to internal sensory signals is fundamental to mindfulness. However, it is difficult to measure objectively, and the vast majority of investigations of the neural correlates of mindfulness-based attention rely on subjective and retrospective measures of distraction. In this study, we measured consistency of response times on a breath-monitoring task (instruction to respond every two breath cycles) to objectively measure interoceptive attention in individuals across the lifespan (15–91 years of age, n = 324). Consistently timed responses were indicative of on-task attention, whereas variable delayed responses indicated distraction or mind-wandering. Signifying the importance of interoceptive attention consistency, we observed that this measure was positively correlated across subjects with performance across several exteroceptive cognitive tasks. Electroencephalographic (EEG) source reconstruction demonstrated that distraction on the eyes-closed task was associated with elevated alpha band (8–12 Hz) brain activity particularly in posterior default mode network (pDMN) brain regions. The neural data revealed four important findings: 1) pDMN brain activity was inversely linked with functional connectivity to the fronto-parietal network (FPN), suggesting that pDMN-FPN interactions play a key role in the regulation of pDMN activity during interoceptive attention. 2) pDMN activity on distracted trials was inversely correlated with trait level mindfulness. 3) A key hub of the pDMN, the isthmus region of the posterior cingulate cortex (ICC), showed elevated activity on distracted trials in individuals with self-reported depressive symptoms. And 4) in an independent second experiment, pDMN activity was adaptively modulated by task difficulty that invoked different levels of distraction. These results identify an EEG-based neurophysiological marker (elevated pDMN alpha activity) underlying interoceptive distraction, which is correlated with subjective markers of mindfulness and depression and that can be adaptively modulated. Our findings, thus, provide a direct link between a neurophysiological substrate of interoceptive attention, and subjective ratings of mindfulness and depressed mood.