"The Terminal Man" by Michael Crichton

Another Crichton. This one is already quite old, published in 1972. The theme is human-machine interfaces and mind control. At the time of publication this was probably a hot topic, given that personal computers were just about to take off. From today's perspective it is not very impressive, but still makes for a somewhat entertaining read. The story is this: A man with epileptic seizures is chosen as a test subject for a neuro-surgical procedure that links the affected brain regions to a computer interface. The wires protruding from the brain can be used to stimulate different parts of the brain, some of which might cause seizures to seize.
The patient, however, is somewhat paranoid, believing that machines are going to take over control. After the operation, he manages to escape, while the machine attached to his brain continues to give stimulating impulses with a different effect than intended. He becomes uncontrollably violent and his doctors find themselves in a race against time to find and fix him.
The book broaches some interesting philosophical topics related to psychiatric procedures. One example would be the notion of 'mind-control' that the public might be afraid of when imposed by doctors, while at the same time parents exert much greater mind control over their children with sometimes catastrophic effects.

All in all a good read, albeit outdated in its technical details. A movie was made based on this book which I haven't seen.