Figure 4.

Overlays illustrating regional homologies between the abnormal metabolic covariance patterns identified in monkeys with experimental parkinsonism and human patients with Parkinson's disease (PD). (A) Voxel-based whole-brain spatial covariance analysis of high-resolution [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) images from a combined group of parkinsonian and healthy macaques (Cohort A). This analysis revealed a significant metabolic pattern (PC1, 48% variance accounted for) that accurately discriminated the two groups of animals (P<0.00001; Supplementary Figure 1A). (B) The topography of this pattern (PRP5) resembled that of the human PD-related covariance pattern (PDRP) described consistently in multiple PD patient cohorts (Eidelberg, 2009). Both topographies were characterized by homologous regional components of the motor cortico-striato-pallido-thalamo-cortical loop and related pathways. (Both spatial covariance patterns were displayed on standard magnetic resonance imaging brain templates. Voxels with positive loadings (metabolic increases) are color coded from red to yellow; those with negative loadings (relative metabolic reductions) are color coded from blue to green). PC, principal component; PRP, parkinsonism-related pattern.