Poster C37, Sunday, March 25, 1:00-3:00 pm, Exhibit Hall C
Frontoparietal EEG phase coupling reflects the maintenance and successful memory encoding of constructed objects in visual working memory
Patrick H. Khader1,2, Satu Palva3, Frank Rösler4, Julia A. Ewerdwalbesloh2; 1Brandenburg Medical School, Neuruppin, Germany, 2Ludwig-Maximilians-Universität Munich, Germany, 3University of Helsinki, Finland, 4University of Hamburg, Germany
How are mental images that have been constructed from their constituting elements maintained as a coherent representation in visual working memory (vWM)? Participants maintained visual objects that they either had to construct from single features or that were presented to them as complete objects. Increased fronto-parietal-occipital EEG phase coupling was found during the maintenance of constructed objects in the theta, alpha, and gamma frequency bands. A similar pattern was found for an increase in vWM load (2 vs. 4 features) for non-constructed objects. Under increased construction load (2 vs. 4 features for constructed objects), the pattern was restricted to fronto-parietal couplings, suggesting that the fronto-parietal attention network is coping with the higher attentional demands involved in maintaining constructed images, but without increasing the communication with the occipital visual buffer in which the visual representations are assumed to be stored. In a subsequent study, we investigated whether fronto-parietal phase coupling during maintenance promotes encoding into more permanent memory traces. Overall, the maintenance of later remembered in comparison to non-remembered objects was associated with increased fronto-parietal coupling across frequency bands. Importantly, for alpha and beta, this effect dissociated topographically for constructed vs. non-constructed objects, suggesting specific contributions to encoding depending on the kind of elaborative processing in vWM. We conclude from these findings that fronto-parietal phase coupling could be a neural implementation of an attentional control process the serves to keep object elements together as a coherent vWM representation, and, in so doing, promotes memory encoding of these representations.
Topic Area: EXECUTIVE PROCESSES: Working memory