Reorganized functional connectivity of language centers as a possible compensatory mechanism for basal ganglia aphasia

Primary Object: To investigate the functional connectivity (FC) of cortical language centers in patients who have regained fluent speech after basal ganglia aphasia and identify the possible compensatory mechanism. Methods & Procedures: A retrospective cohort of 12 patients and 17 healthy controls were studied using resting-state functional MRI (rs-fMRI). All patients suffered from an ischemic stroke with lesions confined to the basal ganglia and showed impaired language functions at admission. Seven patients had lesions in the left basal ganglia, three in the right, and two in both sides. The rs-fMRI was performed after the patients regained fluent speech. Broca's area, Wernicke's area, and their contralateral homologues were selected as the region-of-interest (ROI) for both voxel-wise and ROI-wise FC studies. Results: We discovered that the interhemispheric FC of the language centers (i.e. Broca's area and Wernicke's area) decreased and the intrahemispheric FC of the language centers increased in these patients who regained fluent speech after basal ganglia aphasia. Conclusions: We speculated that damages to the basal ganglia disrupted the cortico-subcortical circuits that facilitated the transhemispheric communications of language functions, resulting in decreased interhemispheric FC. Consequently, the intrahemispheric FC increased as a possible compensatory mechanism to restore the language functions.