The role of transcranial magnetic stimulation in the study of cerebellar cognitive function.

Transcranial magnetic stimulation (TMS) allows non-invasive stimulation of brain structures. This technique can be used either for stimulating the motor cortex, recording motor evoked potentials from peripheral muscles, or for modulating the excitability of other non-motor areas in order to establish their necessity for a given task. TMS of the cerebellum can give interesting insights on the cerebellar functions. Paired-TMS techniques, delivering stimuli over the cerebellum followed at various interstimulus intervals by stimuli over the motor cortex, allow studying the pattern of connectivity between the cerebellum and the contralateral motor cortex in physiological as well as in pathological conditions. Repetitive TMS, delivering trains of stimuli at different frequencies, allows interfering with the function of cerebellar circuits during the execution of cognitive tasks. This application complements neuropsychological and neuroimaging studies in the study of the cerebellar involvement in a number of cognitive operations, ranging from procedural memory, working memory and learning through observation.