Fig. 3
From: Pure akinesia with gait freezing: a clinicopathologic study
Schematic diagram of the cortical-basal ganglia-thalamocortical loop. The areas of greatest neurodegeneration in PAGF caused by PSP and PNLA are shown in red. The hyperdirect pathway (cortex-STN-GPi), direct pathway (cortex-striatum-GPi) and indirect pathways (cortex-striatum-GPe-STN-GPi) are all interrupted by pathology, thereby precluding modulation of the thalamus and midbrain locomotor region (MLR), which includes the pedunculopontine and cuneiform nuclei. GPe: globus pallidus externa, GPi: globus pallidus interna, SNc: substantia nigra pars compacta, SNr: substantia nigra pars reticulata, STN: subthalamic nucleus