Robert M Watson Jr
I would consider sticking needle probes into the body exotic methods.
*Surface* electrodes, Robert.
Anyway, you wanted a 'how'...so there you go. Ponder the literature, design the protocol, get the subjects....you should have the data you want in a year or three.
Or you could just...I dunno...be empirical about it. I mean, does the exact histology really matter...or can we focus on how to whack the bejesus out someone?
If all the classic sources says 'do this, because'...and guys in the know (who can evidence these skills) say 'yeah, do that, because'....maybe I'll save myself some time not reinventing the wheel