Cerebellar Asymmetry and Its Relation to Cerebral Asymmetry

26 27 Asymmetry of the human cerebellum was investigated using intrinsic functional 28 connectivity. Regions of functional asymmetry within the cerebellum were identified 29 during resting-state functional MRI (fMRI; N=500) and replicated in an independent 30 cohort (N=500). The most strongly right lateralized cerebellar regions fell within the 31 posterior lobe including Crus I and Crus II in regions estimated to link to cerebral 32 association cortex. The most strongly left lateralized cerebellar regions were located in 33 lobules VI and VIII in regions linked to distinct cerebral association networks. 34 Comparing cerebellar asymmetry with independently estimated cerebral asymmetry 35 revealed that the lateralized regions of the cerebellum belong to the same networks that 36 are strongly lateralized in the cerebrum. The degree of functional asymmetry of the 37 cerebellum across individuals was significantly correlated with cerebral asymmetry and 38 varied with handedness. In addition, cerebellar asymmetry estimated at rest predicted 39 cerebral lateralization during an active language task. These results demonstrate that 40 functional lateralization is likely a unitary feature of large-scale cerebrocerebellar 41 networks, consistent with the hypothesis that the cerebellum possesses a roughly 42 homotopic map of cerebral cortex including the prominent asymmetries of association 43 cortex. 44 45 46 47 48 49