Previous studies have demonstrated that the enhanced PAC at rest derived from ECoG recordings of patients with PD is localized in motor regions, including the premotor cortex (PMC) and the primary motor cortex (M1). In our previous paper (10), we have reported that enhanced PAC can also be detected in somatosensory areas, namely, the primary somatosensory cortex (BA3) and the primary somatosensory complex (BA1&2), via EEG source localization techniques. These four brain regions have also been reported to be involved in motor control (26, 27). Here, we report our analyses of oscillatory EEG activity in these regions during different types of voluntary repetitive movement tasks in patients with PD. Certain tasks were chosen specifically to elicit the cardinal motor signs employed in clinical examination of PD. Our results challenge the view that bradykinesia is merely a consequence of the strength of cross-frequency coupling. Rather, they suggest that bradykinesia might be better understood as a deficit of the dynamic regulation of that coupling.
