Abstract
BackgroundThe default-mode network (DMN) is characterised by coherent very low frequency (VLF) brain oscillations. The cognitive significance of this VLF profile remains unclear, partly because of the temporally constrained nature of the blood oxygen-level dependent (BOLD) signal. Previously we have identified a VLF EEG network of scalp locations that shares many features of the DMN. Here we explore the intracranial sources of VLF EEG and examine their overlap with the DMN in adults with high and low ADHD ratings.Methodology/Principal FindingsDC-EEG was recorded using an equidistant 66 channel electrode montage in 25 adult participants with high- and 25 participants with low-ratings of ADHD symptoms during a rest condition and an attention demanding Eriksen task. VLF EEG power was calculated in the VLF band (0.02 to 0.2 Hz) for the rest and task condition and compared for high and low ADHD participants. sLORETA was used to identify brain sources associated with the attention-induced deactivation of VLF EEG power, and to examine these sources in relation to ADHD symptoms. There was significant deactivation of VLF EEG power between the rest and task condition for the whole sample. Using s-LORETA the sources of this deactivation were localised to medial prefrontal regions, posterior cingulate cortex/precuneus and temporal regions. However, deactivation sources were different for high and low ADHD groups: In the low ADHD group attention-induced VLF EEG deactivation was most significant in medial prefrontal regions while for the high ADHD group this deactivation was predominantly localised to the temporal lobes.Conclusions/SignificanceAttention-induced VLF EEG deactivations have intracranial sources that appear to overlap with those of the DMN. Furthermore, these seem to be related to ADHD symptom status, with high ADHD adults failing to significantly deactivate medial prefrontal regions while at the same time showing significant attenuation of VLF EEG power in temporal lobes.
Highlights
In the last decade, studies of the functional properties of the resting brain have identified a network of connected brain regions that are active during rest, but which deactivate during the onset of goal-directed performance [1,2,3,4]
More errors of commission and increased mean reaction time (MRT) were recorded for neutral compared with congruent stimuli, and incongruent compared with neutral stimuli
The very low frequency (VLF) signature of default-mode network (DMN) activity has been hypothesised to play a role in periodic attentional lapses. functional magnetic resonance imaging (fMRI) is poorly positioned to test the validity of this hypothesis
Summary
Studies of the functional properties of the resting brain have identified a network of connected brain regions that are active during rest, but which deactivate during the onset of goal-directed performance [1,2,3,4] This network includes medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC)/ precuneus and medial, lateral and inferior parietal cortex [5,6,7,8,9,10,11]. Resting activity within this network is thought to represent a neurophysiological baseline and has, been termed the default-mode network [DMN, 12]. We explore the intracranial sources of VLF EEG and examine their overlap with the DMN in adults with high and low ADHD ratings
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