Examining the Role of Frontal and Posterior Oscillatory electroencephalography Activity in Distractor Suppression

Abstract

Our visual environment is filled with more input than our cognitive system can process at any point in our day. Because of these cognitive limitations on visual processing, researchers have sought to understand how we learn to attend to important aspects of our environment, while filtering out information that is not specific to our goals. The electroencephalogram (EEG) allows us to analyse how different correlates of brain activity respond to these limitations on attention. The mid-frontal theta band (MFT) (4hz-7hz) is one of these correlates, it is measured from frontal central electrode sites and has been implicated in the allocation of cognitive control. The Posterior Alpha (PA) band (8hz-14hz) is found in posterior-occipital sites and is thought to be involved in the suppression of goal irrelevant information. Conversely, the posterior lower beta band (PB) (15hz-20hz) measured at the same sites as PA, is thought to be involved in the active engagement of attentional mechanisms. The current study looked at developing the understanding of these bands by examining the role they played in distractor suppression. High-density EEG was used to measure the timing and power of these bands while participants under took a visual search task. In this task they responded to the orientation of a target letter, while ignoring a distractor of varying predictability. Our data showed that mid-frontal theta bands and PB bands provided more power when a distractor was novel compared to when a distractor was predictable. However, our findings on PA remained inconclusive. A complementary source analysis also revealed a strong link to MFT being generated in the dorsolateral pre-frontal cortex, as well as providing functional links to PB and PA enacting on early posterior and visual cortices. Our study provided support for the notion that mid-frontal theta allocates cognitive control, and PB increases available attentive processes during distractor suppression.