The spiritual aspect of the human soul, sadly, leaves its signature in epilepsy:
As a neurosurgeon, I’ve treated thousands of seizure patients. I’ve never seen a seizure, even in “intellectual” areas of the brain, that affected free will.
In his classic book, Mystery of the Mind, (1975) epilepsy surgery pioneer Dr. Wilder Penfield, asked a significant question: “Why are there no intellectual seizures?”
Epileptic seizures can be experienced in a variety of ways—convulsions of the whole body, slight twitching of a muscle, compulsive memories, emotions, perceptions of smells or flashes of light, complex motor behaviors such as chewing or laughing or even walking, or subtle moments of inattention.
But seizures never have intellectual content. There are no intellectual seizures, which is odd, given that large regions of the brain are presumed by neuroscientists to serve intellectual thought. It is all the more remarkable when we consider that seizures commonly originate in these “intellectual” areas of the brain. Yet the outcome is never intellectual seizures.
An intellectual seizure would be a seizure that caused abstract thought, such as logic, or reasoning, or mathematics. People never have, for example, mathematics seizures—seizures in which they involuntarily do calculus or arithmetic. This observation, which is as true today as it was in Penfield’s time nearly a century ago, begs for explanation.Michael Egnor, “Why, as a neurosurgeon, I believe in free will” at Mind Matters News
Penfield concluded, quite reasonably, that this was because intellectual thought didn’t come from the brain. Intellectual thought (Penfield called it “mind”) is an immaterial human power. There is more to the mind than matter. Penfield began his career as a materialist. He ended it as a convinced dualist. There was, he noted, an aspect of mental function that wasn’t a material product of brain chemistry.
More on dualism as an approach to human psychology:
Your mind vs. your brain: Ten things to know. Although we are only beginning to understand the workings of the brain, it clearly isn’t the same thing as the mind.
Why the mind is the opposite of a computer. Matthew Cobb, a materialist, only scratches the surface when he explains why your brain is not a computer. (Michael Egnor)