Analysis of induced gamma-band activity in EEG during visual perception of Korean, English, Chinese words

The oscillation of brain activities in the gamma-band is known to be a manifestation of the formation of neuronal assemblies that jointly constitute neural correlates of feature binding and conscious awareness. Visual word perception is a task that demands a considerable amount of cognitive resources and integration of information from multiple functionally connected neuronal circuits at various scales. Thus, it is anticipated that a substantial increase in gamma-band activity (GBA) would be observed during visual word perception. The purpose of this study was to examine whether meaningful increases in GBA occur during visual word perception and to explore similarities and differences in the amount and spatiotemporal GBA patterns while native Korean subjects perceive Korean, English, and Chinese words. We also aimed at identifying relationships between GBA increase and a behavioral measure such as response time. The results of power spectrum and time-frequency analyses showed that the increases in GBA were most significant in the prefrontal, frontal, and temporal sites, which are known to be relevant to visual word perception. The GBAs in the prefrontal and temporal sites were significantly correlated with response time. The differences in spatiotemporal patterns of GBA among languages were not prominent compared to inter-individual differences.