Increased theta coherence during Chinese reading.

EEG coherence has been used extensively in the investigation of language processing of English words. In contrast, relatively less is known about the EEG coherence pattern in the language processing of Chinese characters. Given the involvement of distinct and overlapping regions in the brain during English and Chinese reading, and activation in the left and right hemisphere found in functional magnetic resonance imaging (fMRI) studies on Chinese reading, the present study aimed to investigate the EEG coherence pattern associated with Chinese reading, and to determine if higher interhemispheric coherence was found in Chinese reading. EEG coherence of 32 healthy normal participants during a resting condition, English, and Chinese reading were computed and compared. The results revealed that Chinese reading was generally associated with higher theta coherence than the resting condition and English reading. Specifically, theta coherence during Chinese reading showed an increased intrahemispheric connection in the left hemisphere and interhemispheric connections over the temporal, central and parietal/occipital regions, compared to English reading. These results suggest that interhemispheric cooperation between neuronal substrates in these regions is associated with Chinese reading, and that both hemispheres are involved in Chinese reading.