Figure 6.

Cortical-subthalamic coupling in the β-frequency. (A) Percentage relative change of cortical-subthalamic β-coupling during gait freezing versus (effective) walking. At gait freezing start (F_START) the cortical-subthalamic coupling in the β-frequency showed a significant increase in comparison to (effective) walking selectively in the hemisphere with less striatal dopamine (H−). (B) Percentage relative change of cortical-subthalamic β-coupling during gait freezing versus successful passing through a door. The increase in β-coupling between the cortex and the STN (in H−) at gait freezing start (F_START) was similar to successful passing through a door. (C) Percentage relative change of cortical-subthalamic β-coupling during gait freezing versus voluntary stop. The increase in β-coupling between the cortex and the STN (in H−) did not differ between freezing onset and voluntary stop. Cx = cortex (i.e. SMA, M1 and PC); H = hemisphere (H+ and H− refer to the side with more and less striatal dopaminergic innervation, respectively); STN− refers to the hemisphere with less striatal dopaminergic innervation. Statistical significance is shown with a horizontal bar (P < 0.05). Of note, the statistical horizontal bars in A are not replicated in B and C, for clarity of the text.