When new information or experiences cause you to modify your existing schemes.
The answer is true.
Initially a person enjoys the physical and emotional response, as time goes on they need more of the drug just to feel "normal". They are always seeking the same feeling as the first high.
I think scientists are so interested with our brains, because our brain could be considered the most powerful thing ever, everything man-made was from our brain. Our brain can literally scare itself to death. I think they are so interested because it is so powerful.
Bones are classified by their ability to maintain the actions within a human's body. This is so because a leg for an example, is classified as a "running" ideal bone, etc. along with the rest of the bones.
