Evidence for anticipatory motor control within a cerebello-diencephalic-parietal network.

The posterior parietal cortex and the cerebellum are assumed to contribute to anticipatory motor control. Thus, it is reasonable that these areas act as a functional unit. To identify a neural signature of anticipatory motor control, 11 healthy volunteers performed a bimanual finger-tapping task with respect to isochronous (i.e., regular) and randomized (i.e., irregular) auditory pacing. Neuromagnetic activity was recorded using a 122-channel whole-head neuromagnetometer. Functional interaction between spatially distributed brain areas was determined by measures of tap-related phase synchronization. Assuming that (i) the cerebellum predicts sensory events by an internal model and (ii) the PPC maintains this prediction, we hypothesized that functional interaction between both structures varies depending on the predictability of the pacing signal. During isochronous pacing, functional connectivity within a cerebello-diencephalic-parietal network before tap onset was evident, suggesting anticipatory motor control. During randomized pacing, however, functional connectivity after tap onset was increased within a parietal-cerebellar loop, suggesting mismatch detection and update of the internal model. Data of the present study imply that anticipatory motor control is implemented in a network-like manner. Our data agree well with the hypothesis that functional connectivity in a cerebello-diencephalic-parietal loop might be crucial for anticipatory motor control, whereas parietal-cerebellar interaction might be critical for feedback processing.