Examining the role of phonological and semantic mechanisms during morphological processing of sentences in 7-year-old children.

Morphology refers to the smallest difference in sound that makes a difference in meaning, such as walk versus walked. Morphological skill is a key linguistic feature that impacts language and literacy outcomes, but its neural underpinnings have mostly been examined at the word level. We examined if phonological and semantic mechanisms play a role during morphological processing in sentences in 7-year-old children using functional MRI. Using a novel functional localizer approach that correlates brain activation during sound and meaning in-scanner tasks with standardized scores for phonology and semantics, we show that morphological processing is especially reliant on phonological mechanisms given significant activation in the left dorsal inferior frontal gyrus and left posterior superior temporal gyrus. Semantic mechanisms were engaged to a lesser degree in the left ventral inferior frontal gyrus. Exploratory whole-brain analyses revealed a brain-behavior correlation in the cerebellum showing that greater activation during morphological processing was related to lower language abilities. Our results suggest that processing morphological structures in sentences relies mostly on phonemic segmentation, and that those with lower language may compensate for their lower phonological skill by engaging the cerebellum to amplify and refine those phonemic representations to aid in segmentation when listening to sentences.