Wavelet variance coefficients of children and adolescents with and without ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that often persists into adulthood. One hallmark in the characterization of pathological processing in ADHD is that attention skills are not impaired per se but more inconsistent and with higher variability compared to typically developing children (TDC). Increased variability in ADHD patients has been found in reaction times, as well as resting-state fMRI (rs-fMRI) brain signals. High variability has been assumed to reflect occasional lapses in attention, linked to intrusions of distracting activity during task performance and/or reduced anti-correlation between regions in the DMN and attention networks. Therefore, Dajani et al. (2019) concluded that it is more likely the dynamics between and within neural networks [i.e., the variability of network processing across time- and frequency-scales], that are affected in ADHD, than functional connectivity [in terms of one coefficient describing the (averaged) co..., MRI data acquisition: Scanning was performed on a 3 Tesla TIM Trio Scanner at the Institute for Diagnostical and Interventional Neuroradiology at the University Hospital Wuerzburg and on a 3 Tesla PRISMA Scanner (Siemens, Erlangen, Germany) at the Department of Diagnostic and Interventional Radiology at the University Hospital Duesseldorf. Whole-brain T2*-weighted BOLD images were recorded with a simultaneous multi-slice echo-planar imaging sequence (repetition time=800ms, echo time=37ms, 72 slices, 2mm thickness, flip angle=52°, rs-fMRI: 6:58min, 512volumes, task-fMRI: 14.5min, 1069 volumes).
We determined wavelet variance (wVar) at rest and under task in fMRI timeseries of the DMN and the FPN in three different frequency bands: 0.02 to 0.04Hz, 0.04 to 0.08Hz, and 0.08-0.16Hz in children and adolescents with and without ADHD. WVar was determined from fMRI timeseries in regions defined from CONN’s ICA analyses of the HCP dataset (497 subjects) including the default mode network (DMN) an...,