Interesting. An important question is why our brains don't function this way naturally. Either natural selection has yet to optimize up to that point, or it has optimized down from that point. Of course, it could be completely unrelated to optimization for mental performance; the brain, if it did this naturally, would probably demand a much greater calorie intake per day. It might simply be that we don't do this naturally because the power requirements are too great and we'd have to consume more food than is/was practical.
On the other hand, lightning victims tend to have neurological disorders including decreased cognitive ability, memory loss, and even alterations to their proficiency at certain tasks (though I have heard unconfirmed reports that it can "fix" things too, such as a blind man being able to see after getting struck). There's a big difference between lightning and a 9-volt battery, but I'd still want to know the long-term effects before trying this. Very hard to replace wetware if it's damaged from overclocking, and I doubt that neurons are optimized to handle anything other than the type and strength of signal that the brain produces naturally.