As an EE, I was pretty sure I could disprove this, with a quick look at conductivities of bone vs muscle. My theory being that most of the electric current would travel through the scalp, and not pass through the skull to the brain.
I found this link, however, which is pretty interesting, that shows conductivities of various tissue types, if anybody is interested. It looks like the skull is not much of an electrical barrier.
If the skull was an insulator it'd make EEG really hard. Not saying EEG is easy, but if you can record brain signals (which are very small) I'd think that dc could be having some effect.
From Wikipedia about EEG:
> A typical adult human EEG signal is about 10µV to 100 µV in amplitude when measured from the scalp and is about 10–20 mV when measured from subdural electrodes.
I found this link, however, which is pretty interesting, that shows conductivities of various tissue types, if anybody is interested. It looks like the skull is not much of an electrical barrier.
http://iopscience.iop.org/0031-9155/54/16/002/pdf/0031-9155_...