Bonnefond & Jensen, 2012, Alpha oscillations serve to protect working memory maintenance against anticipated distracters, Curr Biol
When studying the impact of distraction on working memory (WM), it is often desirable to make the distractor unpredictable. Here, the goal is precisely the opposite: how does the brain handle WM distraction when it knows exactly when it will occur.
Participants perform a simple 4-item Sternberg recognition task, and in both of two conditions a distractor is presented within the delay period. The distractor of the main condition matches the WM target stimuli (a letter), while the control condition is an unrelated symbol (curly bracket). In both conditions, the timing of the distractor was 100% reliable and therefore predictable (at 1.1 secs into the delay period). To further predictability of distractor type, conditions were blocked.
The behavioral impact of distraction is null on accuracy, but slows reaction times a bit (just 29 ms, but significantly).
There is more alpha power in occipital regions prior to distraction in the (strong) distractor condition, suggesting alpha power is increased in preparation of the distractor. Crucially, the alpha increase seems to be behaviorally relevant; They bin the reaction times within each distractor condition into high and low (excluding middle and outer RTs) and find that slowed reaction times are associated with increased alpha power within the strong distractor condition.
Perhaps the most interesting result is that alpha oscillations are phase-shifted to account for the timing of the oncoming distractor. This finding is interesting in a variety of ways; first of all by showing that in predictable situations, the brain can shift its oscilllatory activity in preparation to short time-scale events, and that it argues further for the functional relationship between alpha oscillations and protection against distraction.
I agree with their proposal that “[i]n future research, it would be of interest to investigate whether these frontal regions are involved in exercising a top-down drive that adjusts the alpha activity in posterior regions”
Another individual differences analysis further argues that “that individuals with a better ability to modulate their alpha activity are less impaired by strong distracters.”