Supporting these findings from human PD patients, data from rodent and non-human primate models have shown that intra-intestinal injection of alpha-synuclein fibrils triggers aggregation of phosphorylated alpha-synuclein at the dorsal motor nucleus of the vagus nerve, followed by the locus coeruleus and substantia nigra via the vagus nerve in a longitudinal follow-up [32, 46, 47]. Here, SNCA is linked to Parkinson disease.