We then considered the possibility that the dynamic modulation of PAC might be more directly related to the underlying pathophysiology of motor impairment than its absolute level. We first visualized dynamic PAC and EMG activity recorded from the FDI muscle, aligned with the peripheral movement onset (Fig. 4A). Alignment to movement onset confirmed that, in patients, PAC was generally reduced in all movement tasks compared with the resting state, as shown in the previous paragraph. In addition, it became evident that in controls, the PAC values in the pressing and slow movement tasks were markedly modulated along the movement cycle. In contrast, this modulation was considerably less pronounced in the resting state and during fast tapping. For pressing and slow tapping, PAC rapidly and markedly declined around movement onset after a brief peak and then rebounded again. Modulation appeared to be less marked in patients.
