Lesion-symptom mapping of the human cerebellum

Although the function of the cerebellum cannot be inferred from lesion data alone, it is still of major scientific and clinical interest to assess whether lesions of a given cerebellar area lead to specific behavioral deficits. The introduction of high-resolution structural brain imaging and new analysis methods has lead to significant improvement in the ability to draw such conclusions. Lesion-symptom mapping is now possible with a spatial resolution at the level of individual lobules and nuclei of the cerebellum. The investigation of patients with defined focal lesions yields the greatest potential for obtaining meaningful correlations between lesion site and behavioral deficits. In smaller groups of patients, overlay plots and subtraction analysis are good options. If larger groups of patients are available, different statistical techniques have been introduced to compare behavior and lesion site on a voxel-by-voxel basis. Although localization in degenerative cerebellar disorders is less accurate because of the diffuse nature of the disease, certain information about the supposed function of larger subdivisions of the cerebellum can be gained. This review highlights the current developments of lesion-symptom mapping in human cerebellar lesion studies. Examples are given which show that meaningful correlations between lesion site and behavioral data can be obtained both in patients with degenerative as well as focal cerebellar disorders.