Somatotopic Motor Representation in the Human Anterior Cerebellum. A High-resolution Functional MRI Study

Though somatotopic encoding of function is a prominent feature in brain structures involved in sensori-motor processing, it has not been well established for the human cerebellum. We delineated the representation of hand, foot and tongue movements in the anterior cerebellar lobe of eight healthy subjects using dynamic high-resolution MRI sensitized to changes in cerebral blood oxygenation (CBO). Activation was determined by pixel-by-pixel correlation of signal intensity time courses with the performance protocol. All subjects showed task-related signal increases in an ipsilateral region during distal limb movements. For the hand task, the centre of activation was located in the intermediate hemispheric portion of Larsell lobules H IV-V. Foot movements activated areas within the central lobule, Larsell lobules II-III, medial and anterior to the corresponding hand areas in all subjects. Responses for tongue movements were less consistent across subjects but found in areas posterior to the respective individual hand representation.