Fig. 6

Hypothetical scheme for categorizing clusters and FOG types. Each cluster based on pedunculopontine nucleus (PPN) and cuneiform nucleus (CnF) parameters was mapped to the clinical classification of FOG [19, 20], according to differences in FOG characteristics (Fig. 3). Leg motion and effective forward motion correspond to the freezing ratio and walking distance during the first 3 s of walking, respectively. Complete akinesia: no observable motion of the legs, shuffling with small steps: FOG associated with very small shuffling steps and with minimal forward movement, trembling in place: FOG with some leg trembling but no effective forward motion