Changes in Phase Synchronization of EEG During Development of Symbolic Communication Systems

To identify neural synchrony changes during the establishment of symbolic communication systems, we analyzed Phase Locking Value, a phase synchronization index reflective of the cognitive process of finding meaning in visual stimuli. Hyper-scanning electroencephalograms were recorded during a symbolic communication task. Good and bad performance pairs were studied to find features of phase synchronization during the establishment of a communication system. During the initial phase of the establishment process, the good performance pair showed synchronization in the 150-300-ms and 450-750-ms latency periods and desynchronization at 300-450 ms in the gamma band after receipt of the partner's message. The synchronization at around 500 ms strengthened and lasted longer during the last phase when a shared communication system was established. This pattern was not observed in the bad pair. These results suggest that phase synchrony around 500 ms and later is involved in the cognitive process of finding meaning in symbolic messages.