Abstract
The cerebellar and cerebral cortices are powerfully connected via reciprocal, crossed projections which mediate their coordination in motor, cognitive and affective processes. In the present paper we demonstrate non-invasive imaging of crossed cerebro-cerebellar connectivity by means of wavelet coherence. In a sample of six healthy adult subjects, we recorded EEG and the electro-cerebellogram (ECeG) with a 10% cerebellar extension montage during voluntary left and right index finger movements. EMG was also recorded from finger extensors and flexors and was used to generate triggers for movement related averaging (-2000 to + 2000 ms). Consistent with prior observations of movement related changes in delta/theta power, we observed significant movement related change in delta/theta-band EEG-ECeG coherence between cerebral and cerebellar leads. Of particular note, when lateralised seeds were selected (F1 vs. F2 and SO11 vs. SO12) the low-frequency coherence was distributed contralaterally and frontally for cerebellar seeds, likely reflecting the underlying crossed cerebro-cerebellar projections, as well as the cerebral contralateral somatosensory representation. For the F1/F2 seeds the movement related change in delta/theta-band EEG-ECeG coherence was more bilateral but with right-hemisphere dominance. The cerebral frontally seeded coherence further demonstrated strong cortico-cortical delta/theta coherence with bilateral posterior parietal and temporal cortex, as well as beta/gamma coherence with primary sensory-motor cortex for the hands. These preliminary findings further support the value of recording cerebellar ECeG and demonstrate its potential to contribute to the understanding of cerebro-cerebellar function and dysfunction.