Abstract
Numerous studies have shown that visual Working Memory (vWM) resources can be flexibly re-allocated after encoding by using so-called retro-cues. In this study, we investigated the functional role of alpha oscillations for this resource re-allocation. Alpha-band power (ABP) typically increases with the number of memorized items, which has been interpreted as reflecting the stronger requirement for inhibiting task-irrelevant distraction. However, recent studies have also found evidence that ABP might be associated with attention towards the target or even with the memory representation itself. Subjects (N=39) encoded two lateralized oriented lines on each trial. Half way through the maintenance interval, a retro-cue indicated which of the two items was to be remembered. After the maintenance interval, subjects reported the target's orientation. Retro-cues improved memory precision relative to a no-cue condition, in which both items had to be maintained. This benefit was paralleled by stronger ABP after no-cues compared to retro-cues. Furthermore, the reported stimulus orientations were systematically biased towards the unreported item even on cued trials, demonstrating the distracting influence of the uncued item. Importantly, ABP lateralized while the retro-cue was presented, such that power increased ipsilateral and decreased contralateral to the cued target. This lateralization pattern provides evidence against the idea that alpha oscillations participate in representing the target in the contralateral hemisphere. Instead, alpha oscillations might be associated with the retro-cuing benefit by allocating resources towards the target or by inhibiting the irrelevant distractor. Thus, we analyzed this association by correlating alpha-band lateralization with precision of the reported target and the bias towards the irrelevant distractor, respectively. In sum, by using retro-cues and distractors that were no longer physically present, our study complements previous research on the role of ABP, in which distractors were physically present either during encoding or during the maintenance interval.
Meeting abstract presented at VSS 2018