Frontal EEG Theta/beta Ratio During Mind Wandering Episodes

Background: In resting-state EEG, the ratio between frontal power in the slow theta frequency band and the fast beta frequency band (the theta/beta ratio, TBR) has previously been negatively related to attentional control. Also, increased theta and reduced beta power were observed during mind wandering (MW) compared to episodes of focused attention. Thus, increased resting-state frontal TBR could be related to MW, suggesting that previously observed relationships between TBR and attentional control could reflect MW episodes increasing the average resting state TBR in people with low attentional control.

Goals: To replicate and extend the previous theta and beta MW effects for frontal TBR recordings and test if MW related changes in frontal TBR are related to attentional control.

Method: Twenty-six healthy participants performed a 40-minute breath-counting task, after a baseline EEG recording, while EEG was measured and participants indicated MW episodes with button presses.

Results: Frontal TBR was significantly higher during MW episodes than during on-task periods. However, no relation between frontal TBR and attentional control was found.

Conclusions: This confirms that frontal TBR varies with MW, which is thought to reflect, among other things, a state of reduced top-down attentional control over thoughts.