Cerebellar asymmetries.

Abstract

The cerebellum is a subcortical structure tucked underneath the cerebrum that contains the majority of neurons in the brain, despite its small size. While it has received less attention in the study of brain asymmetries than the cerebrum, structural asymmetries in the cerebellum have been found in cerebellar volume that mirror cerebral asymmetries. Larger cerebellar structures have been reported on the right compared to the left, either for the whole cerebellar hemisphere or the anterior part of the cerebellum, with the latter accompanied by a left increase in the posterior cerebellum. Cerebellar asymmetries are considered evolutionary recent and have been observed prenatally and in early development. Both asymmetries in anterior-posterior divisions and specific lobules have been linked to handedness and cognitive abilities, in particular language. Functional lateralization in the cerebellum varies across motor and cognitive functions, with language activation predominantly localized in the right hemisphere, contralateral to cerebral activation. Meanwhile, working memory and executive functions are not lateralized to one hemisphere. New neuroimaging methods and resources, including a symmetric functional atlas of the cerebellum that enables precision mapping, open novel avenues for exploring cerebellar asymmetries and answering questions about the developmental timeline, relationships to behavior, and clinical relevance.