TH and Parkinson disease: Some of the beneficial effects of CRT observed are motor improvement many years post-transplant and surviving tyrosine hydroxylase (TH)+ grafted cells in the PD patients’ brain post-mortem (Hallett et al., 2014; Li et al., 2016; Stoker and Barker, 2016; Yasuhara et al., 2017; Stoker et al., 2018; U.S. National Library of Medicine, 2021).