Advances in functional imaging of the human cerebellum

A quarter century of functional neuroimaging has provided a number of insights into the function of the human cerebellum. However, progress has been relatively slow, partly because cerebellar imaging poses a number of unique challenges for functional magnetic resonance imaging (fMRI). This review provides a guide to problems and recent solutions in the design, analysis and interpretation of neuroimaging studies of the human cerebellum.One major problem in the interpretation of functional imaging studies is that it is still unclear what type of neural activity is reflected in the cerebellar blood-oxygenation-level-dependent signal. We summarize recent work that has provided partly contradictory insights. We then highlight some technical challenges, specifically the susceptibility to physiological artifacts, and recently developed techniques to account for them. Furthermore, the small size and functional heterogeneity of the cerebellum poses a challenge for normalization and atlas methods, which demands different analysis techniques than those used in the neocortex. Finally, we highlight some novel results assessing anatomical and functional connectivity with the neocortex.Although these results clearly show the limitations of current approaches, they also show the potential of anatomical and functional MRI for the study of the human cerebellum.