He is a molecular biologist. He used single-cell organisms from which he extracted the DNA from the cell and realized that the cell operated normally. And then he asked, if DNA was controlling behavior, why is this cell working normally (except reproduction of course). So he quickly realized that DNA doesn't control behavior but it's the other way around. And then he built up from there, studying anomalies where DNA should do this and that (and didn't) or where the environment or person's attitude was more of a causal factor.
Btw, I've experimented myself with the electrode neural stimulation in the past and one thing I noticed was extreme reaction to stimuli. Say a mosquito flies near your ear and then you react quicker and more violently. Have you noticed something similar? (It's possible I've activated some weird neural cluster with the points I was touching the electrodes)
I haven't noticed any reactions like that, but I have not delved very far outside of the more mainstream placements. I am working right now to develop unbiased tests for these placements and I hope to test some of the other placements soon.