Re: The original for this tech dates from the late 1960s
Michael Crichton wrote a sci-fi novel, The Terminal Man about the same time, about this very topic. In the story, a temporal-lobe epileptic was fitted with a set of brain electrodes that stimulated the pleasure centres of his brain whenever the implanted computer detected the onset of a seizure. The problems began when the patient, called Benson, started subsconsciously triggering repeated seizures to get the pleasure rush, doing it more and more often until he entered a constant fugue state - at which point he then goes on a murderous rampage.
I remember reading this story back in the late 70s, and it had particular relevance to be because I was also diagnosed with temporal lobe epilepsy, and I wondered then if they were going to plant electrodes into my brain too, but they never did.
But it's weird seeing something from so long ago becoming current technology. I guess for me The Terminal Man joins Arthur C. Clarke's 2001: A Space Odyssey and 2010: The Year We Make Contact in the list of sci-fi books about the future, that has now passed.