i just assume these researchers aren't stupid.

i've always assumed that either we were born with too few dopamine neurons or some brain injury reduced the amount we had so when the normal 1% die off/year occurred we ran out too soon. but i'm willing to deal with imperfect and take an implant that might only last 5 years.

remember dennis turner and dr. levesque and the autologous stem cell implant of his own modified cells that never went commercial? i guess the implanted cells petered out.

i think some of the foetal neuron implants done in the 90's are still working?