The two hemispheres of my brain are competing?" Fred said.
"Substance D. It often causes that, functionally. This is what we expected; this is what the tests confirm. Damage having taken place in the normally dominant left hemisphere, the right hemisphere is attempting to compensate for the impairment. But the twin functions do not fuse, because this is an abnormal condition the body isn't prepared for. It should never happen. "Cross-cuing", we call it. Related to splitbrain phenomena. We could perform a right hemispherectomy, but--"
"Will this go away," Fred interrupted, "when I get off Substance D?"
"Probably," the psychologist on the left said, nodding. "It's a functional impairment."
The other man said, "It may be organic damage. It may be permanent. Time'll tell, and only after you are off Substance D for a long while. And off entirely."
"What?" Fred said. He did not understand the answer-- was it yes or no? Was he damaged forever or not? Which had they said?
-- Phillip K. Dick, A Scanner Darkly