[PeterisP]

Direct electric stimulation of brain (implanting electrodes) is simple only if you don't care if the subject has a risk of fatal infection, and if performing literal brain surgery is cheap and routine, as it is for mice/rats (again, because a risk of death or brain damage is acceptable).

Yes, we can do that, but that would be complicated to do it safely on humans - compared to that, a lifetime supply of drugs is cheap and simple.