@Cyracuz,
If you didn't watch the original video that brought this up, you can view it here:
http://www.youtube.com/watch?v=x5QObhuLxso
As pertaining to the first part of your post, I suggest you jump to 22:05 and view until 22:42. As far as your mind, the mind is limited by the workings of the brain and the various portions of that. This is proven with various cases of brain damage (examples used in the film were Phineas Gage and Charles Whitman). With an unharmed, fully functioning brain, our mind would be able to "move freely" within the confines of those boundaries (as in the neurochemical interactions in the brain). As stated in the video, different portions of the brain and different neurochemicals within the brain influence our behaviors, these are the "barriers" that I was referring to. Now those barriers aren't immovable, but the stronger they are, the more they confine us and the harder they are to move. Our minds are never confined to the point where there's no free will or no "movement". With the case of Charles Whitman, he was "forced" into that agression and that fear, but he wasn't forced into climbing that tower in the middle of that campus and start murdering people. He could have gone to a local grocery store, sorting event, or even just left it at killing his wife and mother and then offing himself. There were many different options within those "confines", but that fact that he was "confined"reduces his responsibility for those actions.
As far as the second part of your post try viewing 22:50 to 23:46 (or longer if you prefer) in the video. There are different options other than just drugs, in which help deal with the root of the problem and is actually like a guide to push back those "barriers" and gives more "space" in to help influence people to make better choices and help to lessen or remove those influences. The reason I commented more on the drug aspect is because that seems to be where Arella Mae seemed confused and I also wanted to keep things shorted and more simplified without branching off into everything else that their is.
Your comment on my analogy means that you didn't understand it. I wasn't referring to the what, but the why. You used the analogy of the dandelion and the root, which is the same thing I was doing. I like how you just assume that I'm ignorant. I may not be knowledgable as to all the specifics with the particular field but I do know a great amount about the brain and mind. I majored in psychology and college and have studied the brain as a hobby extensively because I have epilepsy and the interworkings of the brain fascinates me. It's not the exact same thing, but there is a great amount of overlapping with the two.