Traveling waves link human visual and frontal cortex during working memory-guided behavior

Working Memory (WM) enables flexible behavior by forming a temporal bridge between recent sensory events and possible actions. Through re-analysis of published human EEG studies, we show that successful WM-guided behaviors are accompanied by bidirectional cortical traveling waves linking sensory areas implicated in WM storage with frontal areas implicated in response selection and production. We identified a feedforward (occipital-to-frontal) theta wave that emerged shortly after a response probe and whose latency predicted intra- and inter-individual differences in response initiation, and a feedback (frontal-to-occipital) beta wave that emerged after response termination. Importantly, both waveforms were only observed during an overt motor response: when participants could select task-relevant WM content and prepare but not yet execute a task-appropriate action, neither waveform was observed. Our observations suggest that cortical traveling waves play an important role in the generation and execution of WM-guided behaviors.