Resting as Knowing: A Lagged Structure Analysis of Resting State fMRI with Application to Mind Wandering during Oral Reading

Abstract

The human brain is an ongoing dynamic system not activated by experience but nudged from intrinsic activity into new network configurations during perception and learning. Ongoing neural activity during rest is assumed to reflect these intrinsic dynamics in a relatively closed system state. Traditionally, inter-regional connectivity in this system is measured by obtaining time-locked correlations in BOLD activity using fMRI. It is well documented, however, that neural activity unfolds across time and is not isolatent to some reference point.

This exploratory study is a theoretical analysis of how a lagged analysis of resting state dynamics in fMRI could represent persistent representations of knowledge in the neocortex. A novel procedure using both surface based maps and independent component analysis (ICA) is applied to a small group of 54 adolescents. The ICA methods appear to reveal lagged structures with different information than traditional resting state analysis. The group level results are symmetrical between hemispheres and may represent high level perceptual systems. 

The components obtained from this exploration are then used to attempt understand how these knowledge systems in neocortex frame mind-wandering frequency when reading aloud in a subset of 38 individuals. The results did not correlate with any known neural systems related to mind wandering, but the methods here are unique. One of the identified components shows significant difference in the lag structure of the occipital cortex as a function of mind wandering frequency during oral reading. This demonstrates that it may be worth exploring the timing in visual system to understand why individuals mind wander when reading aloud. Reverse inference is used to interpret results and suggest future approaches.