Fig. 3: Differences in cortico-STN and cortico-GPi coherence for the UCL cohort; high beta band coherence segregates to the cortico-STN network and is largely uninfluenced by dopaminergic medication.

Panels A and B are SPMs showing results of the 2x2 ANOVA with factors frequency (low beta versus high beta) and target nucleus (STN versus GPi). T-values of voxels within significant clusters are superimposed onto a T1-weighted MRI with the color bar indicating the value of the t-statistic. Contours of the SMA and primary motor cortex are shown in green and blue, respectively. A The upper panel displays regions where there was a significant interaction, such that there was greater cortical coherence with the STN than with the GPi at high rather than at low beta frequencies. The cluster encompasses the mesial primary motor cortex and the SMA. Cross-hairs are centered on the location of the peak t-statistic at 10 -46 82. In the lower panel, the cross-hairs are centered at the location of the hand area of the primary motor cortex, highlighting that the interaction effect was centered medially. B Two clusters displaying a significant simple main effect of the band for the STN. The clusters include SMA and the mesial primary motor cortex. In the upper panel, the cross-hairs are centered on the location of the peak t-statistic within the posterior cluster at MNI coordinates 2 -48 72. In the lower panel cross-hairs are centered on the location of the peak t-statistic within the anterior cluster at MNI coordinates 20 -14 72. Panels C shows results of the 2 × 2 ANOVA with factors frequency (low beta versus high beta) and medication state (ON versus OFF) for the STN UCL cohort. There was a significant main effect of frequency such that the SMA exhibited higher coherence with the STN at high rather than at low beta frequencies (peak t-statistic at MNI coordinates 16 12 70). D and E show group mean (with standard errors) and individual coherence spectra computed between the STN/GPi and cortical locations of the peak t-statistic of the simple main effect of the band for the STN (these correspond to the anterior and posterior clusters in C which are located in the SMA and in the mesial primary motor cortex (M1)).