The Cerebellum and Grammatical Agreement in Bilinguals: Evidence from Grammaticality Judgments Using fMRI

The cerebellum is linked to all the key regions of the language control network. Currently, the cerebellum is recognized to be involved in the networks that handle grammatical aspects. Clinical and neuroimaging studies have confirmed cerebellar contributions to grammar processing. The present study intended to investigate the activity of the cerebellum in alternating L1-L2 processing in balanced bilinguals. We selected 35 Turkish-Persian bilinguals (21 women) who had learned their second language at the age of 7. Based on the Bilingual Dominance Scale, there was no significant difference between the high proficiency levels of the participants in L1 (Turkish) and L2 (Persian). Participants carried out an auditory grammaticality judgment task in an alternative language-switching paradigm while fMRI images were acquired using a standard protocol. Combining a whole-brain and regions-of-interest (ROIs) approach, we examined event-related fMRI during syntactic processing. Following the identification of the activity of the bilateral cerebellum at the whole-brain level according to the Harvard-Oxford Atlas in FSL, percent signal change was extracted per participant as an intensity measure in the cerebellar region and statistically analyzed in SPSS. The results indicate a right hemispheric superiority in bilingual language processing, confirming that the right cerebellum is more involved in language control. Furthermore, bilinguals have shown stronger activation for L1 as compared to L2 in the cerebellum, substantiating the reversed language dominance effects.