  The primary goal of this paper is to develop a method that quantifies how
activity in one brain region can explain future activity in another region.
Here, we propose the mixed effects spectral vector-autoregressive (ME-SpecVar)
model to investigate differences in dynamics of dependence in a brain network
between healthy children and those who are diagnosed with ADHD. Specifically,
ME-SpecVar model will be used to formally test for significant connectivity
structure obtained using filtered EEG signals in delta, theta, alpha, beta, and
gamma frequency bands. The suggested model allows one-stage procedure for
deriving Granger causality in common group structure and variation of subject
specific random effects in different frequency oscillations. The model revealed
novel results and showed more significant connections in all frequency bands
and especially in slow waves in control group. In contrast, children with ADHD
shared a pattern of diminished connectivity and variability of random effects.
The results are consistent with previous findings about decreased
anterior-posterior connectivity in children with ADHD. Moreover, the novel
finding is that the most diverse subject specific effective connectivity
parameters in healthy children belong to parietal-occipital region that is
associated with conscious visual attention.
