The neural substrate of noun morphological inflection: A Rapid Event-related fMRI Study in Italian.

Abstract The present research investigated the neural correlates of nominal inflection and aimed at disclosing their possible link with the frequency distribution of noun inflectional features: grammatical gender, inflectional suffixes and inflectional classes. The properties of the Italian nominal system were exploited since it allows to explore exhaustively fine-grained phenomena in the inflectional processing. An event-related functional magnetic resonance imaging (fMRI) experiment was carried out where Italian masculine and feminine nouns were visually presented to 50 healthy participants in an overt inflectional task (generation of the plural from the singular and vice versa); the grammatical gender (masculine vs. feminine) and the citation form suffix of nouns (opaque vs. non-opaque with respect to gender) were manipulated in a factorial design. Functional data showed that inflectional operations for nouns activate an extensive cortical network involving the left inferior and right superior frontal gyri, the left and right middle temporal gyri, the posterior cingulate cortex and the cerebellum. Activations were variably modulated by distributional features of gender-dependent properties of nouns. Particularly, cortical activity increased during inflectional operations for small and/or scarcely consistent inflectional classes. These findings demonstrate the relevance of specific morphological (inflectional suffixes) and distributional features (size and consistency) shared by groups of words (inflectional classes) in a language, particularly when implementing fundamental cognitive operations required for language processing like the processing of morphologically complex words.