Someone told me about a book with the following plot: Earth was threatened by a bomb which also contained a device that demolished brain tissue. They couldn't send in a robot to dismantle the bomb as is was a rather complex one. So some scientist removed the brain of a man and replaced it with some remote control gear. The removed brain was placed in a lab and backed up by an AI that received the same sensory input as the real brain. They also equipped the man with a switch that allowed him to switch over to the backup system. The guy goes in and dismantles the bomb. A couple of years later he wants to demonstrate the use of the switch to a group of students and he is unable to switch back; the AI takes over!
Does someone know the title and author of this book?