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This study aims to evaluate effects of word-internal variables on reading disyllabic Chinese words by manipulating (a) morphological complexity, defined as the number of morphemes and (b) structural complexity, defined as whether the two syllables relate to each other via the specifier-head-complement structure. In a visual lexical decision task, magnetoencephalography (MEG) was recorded during the reading of four types of Chinese disyllabic words: (1), disyllabic-monomorphemic (e.g., 蚯蚓 “qiu yin” earthworms), used as the control condition; (2) coordinative compounds (such as 花草 “hua cao” flower-grass: plants), which are double-headed, with meanings jointly derived from the two roots; (3) modifier-head compounds (such as 汽車 “qi che” gas-car: an automobile), which are right-headed, with the first root as the modifier; and (4) verb-object compounds (such as 開車 “kai che” operate-car: to drive a car), in which the first and second roots express an action and an object respectively. Our source analysis indicated that, at 200 m s, reading compounds revealed larger activity in left anterior temporal cortex than reading monomorphemic words, which might reflect composition of morphologically complex words during processing. From 300 to 400 m s, reading modifier-head compounds and verb-object compounds revealed larger activity in the left posterior temporal cortex than reading monomorphemic words, but there was no significant difference between reading coordinative compounds and reading monomorphemic words in this time window. These results indicate that morphological complexity and structural complexity substantially modulate activities in left temporal cortex during the reading of disyllabic words.

Brain neuroplasticity refers to anatomical changes and functional reorganization in the brain as the results of daily experience and new learning, and thus, should have profound implications for the changes in brain processing during and after bilingual learning. By using a MEG experiment of magnetic mismatch negativity (MMN)/magnetic mismatch field (MMNm) paradigm, the present study examined the brain wave patterns of beginning learners of learning Chinese as a second language (CSL), who enrolled in a short term digital learning program, and were found to have improved sensitivity in discrimination for lexical tones by developing a left lateralized dominance for processing Chinese lexical tones, just like native Mandarin speakers. In the experiment, the measurements of MMNm, with the contrast between large deviant T3/T1 and between small deviant T3/T2, were computed to index the changed patterns of brain processing before and after learning. Results of the MMNm data indicated that activation for large deviant contrast T3/T1 elicited earlier and significantly larger MMN than that of the small deviant contrast T3/T2, which is in line with previous studies done on native Chinese speakers. More importantly, in the comparison of pre-test and post-test time course, the amplitude of MMNm showed a significant increase in the left hemisphere after learning. The evidence indicated clearly a learning effect in the perception of linguistic features and a left lateralized neural network of processing Mandarin lexical tones. Moreover, in the source analysis, the left lateralized patterns of prefrontal generator (i.e., insula) and generator of auditory cortex (i.e., Heschl's Gyrus) changed after learning, which is also consistent with the native Mandarin speaker's response patterns. In sum, the present study provides neural evidence for a functional reorganization in the brains of second language learners, transforming the CSL learners to behave like native speakers in the perception of lexical tones even after just a short-term and non-specific training program.