hmm. tDCS and DBS are certainly really interesting technologies, but i still don't see them having any recreational mechanism. in the case that they can act as monoamine releasing agents, the absolute best case is that you can make a meth-band.
the second study is completely irrelevant to the point you were trying to make. not trying to be mean but i just don't understand how a study about the efficacy of tDCS in studies is related to possible recreational effects from tDCS/DBS.