Neural representations of Chinese noun and verb processing at the semantic, lexical form, and morpho-syntactic levels

Abstract

This study investigated the neural bases underlying representation of nouns and verbs at the semantic, lexical form, and morpho-syntactic levels in Mandarin Chinese, a language with little inflectional morphology. Compared with other studies employing European languages with rich inflections, examination of Chinese would allow the separation of conceptual and morpho-syntactic operations based on different stimulus formats and experimental paradigms. To deal with both the theoretical and design issues in previous studies, several additional measures were taken. First, at each cognitive level, two experiments, one receptive and one expressive, were conducted. Moreover, convergence across experiments at the same cognitive level was computed in order to search for taskindependent grammatical class effects. Second, both concrete and abstract nouns and verbs were included, and conjunction analyses across the two concreteness levels were employed to ensure the generalizability of the findings to all nouns and verbs. Results revealed greater activation for verbs in the left posterior lateral temporal gyri in experiments at both semantic and morpho-syntactic levels, and stronger responses in the prefrontal cortex, including left BA47 and the supplementary motor area, only for morpho-syntactic processing associated with nominal grammatical morphemes, namely, classifiers. No differential levels of activation for nouns and verbs were observed in tasks emphasizing word form representation. While greater activation for processing of nominal classifiers in prefrontal areas may reflect differences in computational complexity associated with selection of grammatical morphemes, the involvement of left posterior lateral temporal cortex has been interpreted as reflecting semantic processing of verbs. The nature of processes represented in each of these regions was further discussed with findings from previous relevant studies. Finally, future studies are proposed for further exploration into the neural mechanisms underlying presentation of nouns and verbs using more recently developed methods of analyses.