In Iron Man 3, Killian shows Pepper a live feed of his brain . He then claims to show her evidence that the human brain hasn't finished evolving--there is a clear gap present , a gap which, when filled, would provide the subject with extraordinary powers and healing capabilities. The "next step in human evolution." This is what Extremis does--it allows the brain to access that missing gap and take the next step.
Extremis enhances the user's physiology by rewriting their DNA. It harnessed bio-electricity in the body and used to activate parts of the brain that governed repair and recode it chemically.
Clearly, at this point in the movie, Killian has already been "extremified." We see that he has a much better grasp on his powers in that he is the only character we see breathe fire  and it is hinted that his miraculous physical transformation is the result of Extremis, and not, as he claims, "5 years of physical therapy".
After curing himself of his disability through Maya Hansen's research of Extremis, he conducted many illegal experiments, of which several resulted in the explosions of his test subjects.
So here is my question. If that look into his brain was truly a live feed (which we can see as the hologram responds to Pepper pinching him) , why does he still have a gap in his brain? Why has it not been filled, given that he has already been on Extremis for a long time? Does the activation not actually fill in the gap? What was even the point of showing the gap if so?
I guess I'm still a little confused as to how Extremis functions. Does anyone have any thoughts on this?