Cerebellar activity and functional connectivity in subacute subcortical aphasia: Association with language recovery

Loss of language function (aphasia) is a common complication after stroke, and post-stroke recovery remains highly unpredictable due to the absence of reliable neurobiomarkers. Growing evidence points to involvement of the cerebellum in language processing; however, it is unclear if abnormal cerebellar activity and altered functional connectivity (FC) to language-related regions of cerebral cortex are underlying neural mechanisms for subcortical aphasia. In this longitudinal observational study, we used resting-state functional magnetic resonance imaging to examine potential abnormalities in spontaneous cerebellar activity and resting-state (rs)FC with language networks among post-stroke patients with subacute subcortical aphasia (n = 19) compared to healthy controls (HCs, n = 18). In addition, correlations between rsFC variables and language performance metrics were examined at post-stroke baseline and at follow-up. Compared to HCs, patients with subacute subcortical aphasia exhibited significantly reduced fractional amplitude of low frequency fluctuations, a measure of spontaneous activity, in the right cerebellar Crus II (rCrus II) region and reduced rsFC between rCrus II and left inferior frontal gyrus (LIFG), left angular gyrus (LAG), and left middle temporal gyrus (LMTG). Both rCrus II-LAG and rCrus II-LMTG rsFC values were positively correlated with Aphasia Battery of Chinese scores at baseline. Baseline rCrus II-LIFG rsFC was also positively correlated with spontaneous speech and naming scores at follow-up. A stronger baseline rCrus II-LIFG rsFC predicted superior recovery of language function post-stroke. We conclude that the right cerebellum may be an effective therapeutic target for subcortical aphasia.