Here is a video showing how the technique of inserting a remote-controlled electrode into the brain of a bull could control the bull's behavior. The bull stops it's aggressive advance the moment the remote switch is pressed.http://www.youtube.com/watch?v=23pXqY3X6c8
The scientist was Dr. Jose Delgado. He was of Spanish origin. This was done in 1961. I saw this video clip when I was in psychology class in college. His work was funded by the CIA.
The following article in Wikipedia states that he was doing it in human beings (reference 4):