Cassidy Wolfe¹ (), Edward Ester¹; ¹University of Nevada, Reno

Spatially organized neural oscillations –or traveling waves– are a key mechanism for guiding the propagation of neural activity and computational processes across the brain. In a recent EEG working memory (WM) study, we documented a feedforward traveling wave propagating from posterior occipitoparietal electrode sites to frontocentral electrode sites that emerged right before the initiation of a working-memory-guided behavioral response and whose the peak latency predicted intra- and inter-individual differences in response times. Our working hypothesis is that this wave indexes the transfer of mnemonic content from storage sites in occipitoparietal cortex to motor sites responsible for producing task-relevant behaviors, but an alternative (but non-exclusive) hypothesis is that this wave is instead related to the planning of an upcoming behavior. Participants performed two versions of a visuomotor WM task in which they memorized the orientations of two bars, then recalled the orientation of a retrospectively probed bar as precisely as possible. During the “predictable recall” task, participants recalled the orientation of the retrospectively probed bar by adjusting the orientation of a recall stimulus that always started with a vertical orientation. Thus, in this condition, participants could anticipate how much (or for how long) they would have to rotate the recall stimulus before beginning their response. Conversely, during the “random recall” task, on each trial the recall stimulus was assigned a random starting orientation knowable to participants only after they began their response, obviating advance planning. The onset, timing, and peak latency of the feedforward traveling wave during the predictable recall task was identical to values observed in prior studies, however, the feedforward traveling wave was altogether eliminated during the random recall task. From this, we speculate that the feedforward traveling wave we identified in our prior research indexes a sensory-to-motor transformation that guides the precise recall of stimuli under predictable conditions.