Default network and frontoparietal control network theta connectivity supports internal attention.

Attending to our inner world is a fundamental cognitive phenomenon, yet its neural underpinnings remain largely unknown. Neuroimaging evidence implicates the default network (DN) and frontoparietal control network (FPCN); however, the electrophysiological basis for the interaction between these networks is unclear. Here we recorded intracranial electroencephalogram from DN and FPCN electrodes implanted in individuals undergoing presurgical monitoring for refractory epilepsy. Subjects performed an attention task during which they attended to tones (that is, externally directed attention) or ignored the tones and thought about whatever came to mind (that is, internally directed attention). Given the emerging role of theta band connectivity in attentional processes, we examined the theta power correlation between DN and two subsystems of the FPCN as a function of attention states. We found increased connectivity between DN and FPCN during internally directed attention compared to externally directed attention, which positively correlated with attention ratings. There was no statistically significant difference between attention states in the connectivity between DN and FPCN. Our results indicate that enhanced theta band connectivity between the DN and FPCN is a core electrophysiological mechanism that underlies internally directed attention.