Not to derail this further, but your description of Parkinson's disease is incorrect. Dopamine plays a role, but it isn't degeneration motor neurons themselves.

Not to derail this further, but your description of Parkinson's disease is incorrect. Dopamine plays a role, but it isn't degeneration motor neurons themselves. There are many effects, but the primary symptoms WRT motor control are caused by death of dopaminergic neurons whose cell bodies reside in the substantia nigra but innervate and regulate firing of corticostriatal pre-motor pathways. [0] I did my PhD on this [1] https://en.wikipedia.org/wiki/Parkinson%27s_disease#Pathophysiology https://en.wikipedia.org/wiki/Parkinson%27s_disease#Pathophy... [2] https://en.wikipedia.org/wiki/Nigrostriatal_pathway https://en.wikipedia.org/wiki/Nigrostriatal_pathway