Structural hemispheric asymmetry has long been assumed to guide functional asymmetry of the human brain, but empirical evidence for this compelling hypothesis remains scarce. Recently, it has been suggested that microstructural asymmetries may be more relevant to functional asymmetries than macrostructural asymmetries. To investigate the link between microstructure and function, we analyzed multimodal MRI data in 907 participants. We quantified structural and functional asymmetries of the planum temporale (PT), a cortical area crucial for auditory-language processing. We found associations of functional PT asymmetries and several microstructural asymmetries, such as intracortical myelin content, neurite density, and neurite orientation dispersion. The PT microstructure per se also showed hemispheric-specific coupling with PT functional activity. All these functional-structural associations are highly specific to within-PT functional activity during auditory-language processing. These results suggest that structural asymmetry guides functional lateralization of the same brain area and highlight a critical role of microstructural PT asymmetries in auditory-language processing.

Background: Hemispherotomy is an effective surgery developed to treat refractory epilepsy caused by diffuse unihemispheric pathologies. Post-surgery neuroplastic mechanisms supporting behavioral recovery after left and right hemispherotomy as well as their difference remain largely unclear. Methods: In a large cohort of 57 pediatric patients who underwent hemispherotomy, voxel-wise GMV in unaffected regions (contralesional cerebrum and bilateral cerebellum) and behavioral abilities were assessed before and after surgery. Using linear mixed models, we evaluated changes in GMV and behavioral scores, and how GMV changes correlated with improvements in behavioral scores. In addition, three machine learning regression algorithms were applied to assess whether preoperative GMV can predict postoperative behavior. Results: In the two patient groups (29 left hemispherotomy patients, age of surgery mean ± standard deviation = 3.5 ± 2.5; 28 right hemispherotomy patients, age of surgery 4.6 ± 2.5), widespread increases in the postoperative GMV in the contralateral cerebrum and ipsilateral cerebellum but decreases in the postoperative GMV in the contralateral cerebellum were consistently observed. Importantly, the decrease in GMV in the contralateral cerebellum was significantly correlated with improvement in behavioral scores in right but not left hemispherotomy patients. Moreover, the preoperative GMV around the most longitudinally changed locations significantly predicted postoperative behavioral scores in left but not right hemispherotomy patients. Conclusions: Our findings indicate an important role for the contralateral cerebellum in the recovery after right hemispherotomy, and postoperative behavioral scores can be predicted with preoperative GMV features.