Resting-state electroencephalogram in learning-disabled children: power and connectivity analyses.

The neurophysiological underpinnings of learning disabilities remain unknown. In this clinical study, we recorded electroencephalograms for a large sample of children with learning disabilities (LD) and healthy control children (n=216) during resting states in which the eyes were either open or closed. We calculated the power and lagged phase coherence in six main frequency bands (delta, theta, lower and upper alpha, and lower and upper beta) to re-evaluate the question of whether children with LD show frontal theta power increases and posterior alpha band decreases on the basis of patterns of electroencephalogram oscillation, which could then be considered as evidence for the so-called 'maturational delay hypothesis.' We identified a general (not restricted to frontal electrodes) power increase in the theta band and no accompanying concomitant alpha band decrease at the posterior electrode position. In addition, we observed increased beta band power at frontal electrodes for LD children. With respect to lagged phase coherence, which is a coherence measure not influenced by volume conduction, we identified decreased coherence for children with LD in the upper alpha band during the eyes closed condition. We interpret this LD-specific resting-state activation pattern as indicating a suboptimally functioning neural resting-state network that provides a detrimental 'starting point' for task-specific brain activations.