RESUMO
Several recent studies have reported a frequency-dependent directional information flow loop in resting-state networks by phase transfer entropy, comprising an anterior-to-posterior information flow in the theta band and a posterior-to-anterior information flow in the alpha band. However, the functional roles of this information flow loop remain unclear. In the current study, we compared information flow patterns in four different brain states using electroencephalography: resting-state, fixation, working memory (WM) encoding and WM maintenance. An auditory (pure tones) WM span task was carried out. A consistent anterior-to-posterior information flow in the theta band and an opposite pattern in the alpha band were found in all four segments. Flows in both patterns were enhanced during WM encoding. In contrast, a prefrontal-to-central information flow in the alpha band was dominant during the resting-state. In addition, enhanced information flows from right temporal to other brain regions in the theta band were found during WM processing (WM encoding and maintenance). Comparison of the consistency and dynamical changes of information flows in these four brain states indicated their functional roles in central executive processes, internal attention, WM information maintenance, and the right-hemisphere advantage in pure tone processing.