Editor’s note: Pre-order The Immortal Mind, by Michael Egnor and Denyse O’Leary, and get a sneak peek exclusive excerpt from the book as well as the full digital book anthology Minding the Brain.

Epilepsy is a common and potentially dangerous disorder of the brain, so it has been the object of extensive scientific study over the past couple of centuries. It has many aspects but the main one is that people with epilepsy have seizures.

Different types, causes, and treatments can be effective. But one thing that is fascinating — even astonishing — about the seizures is what they don’t do to a person. And that tells us something very important about the mind and the brain.

First, Let Me Offer a Brief Description of Epilepsy…

Knowing what it does will help us appreciate the significance of what it doesn’t do.

Epilepsy is the fourth most common brain disease in the United States, behind migraines, stroke, and Alzheimer’s disease. Each year, 150,000 Americans are newly diagnosed with epilepsy. That might not seem like a lot at first. But over a lifetime, 1 in 26 Americans will be diagnosed with it. Thus, 12.5 million Americans living today will have epilepsy at some point in their lives. Around the world, 65 million people have active epilepsy, which means that they have seizures that require medical treatment.

The brain is an electrical organ and epilepsy is caused by sudden unpredictable electrical discharges. Sometimes they remain localized in a group of neurons and sometimes they spread chaotically throughout the brain. They typically begin in the cerebral cortex, along the surface of the brain hemispheres, but they can originate in deeper parts of the brain.

Seizures affect the body or the mind — for example, they might produce shaking of the muscles, tingling on the skin, odd, stereotyped behaviors, strange odors, strong emotions, and so on.

Types of seizures include:

1. Absence seizures, which are brief seizures in which patients blank out with a period of inattention, staring, and fluttering of the eyelids.
2. Atonic seizures, which are seizures in which patients suddenly lose muscle tone and may fall.
3. Clonic seizures, in which patients (often babies) experience uncontrolled twitching of the muscles.
4. Simple partial seizures, in which patients are fully awake and alert and may have muscle twitching on one side of the body, intense sensations such as skin tingling, and intense unexplained emotions. 
5. Complex partial seizures, in which patients lose awareness and can have a variety of experiences. They can include random activities such as lip smacking, picking at objects, walking, removing clothing, repeating meaningless words, and occasionally doing complex activities such as operating machinery, etc.
6. Generalized tonic-clonic seizures, in which patients lose consciousness and have a period of stiffening of body followed by rhythmic jerking of muscles.
7. Gelastic or dacrystic seizures, a rare form of seizure in which patients laugh uncontrollably or cry uncontrollably.

That’s What Seizures Do. Now Here’s What They Don’t Do

In the mid 20th century, pioneering neurosurgeon Wilder Penfield (1891–1976) noted something remarkable about epileptic seizures — they never evoke abstract thought. Seizures only evoke one or more of five kinds of brain activity — basic physiological reactions (fast heart rate, rapid breathing, etc.), movement of muscles, sensations such as tingling, flashes of light, etc., strong emotions, and (rarely) memories.

He observed that seizures never evoke what he called “mind” activity. By that, he meant abstract thought, concepts, reasoning, judgments, etc. He was astonished by this and drew the obvious conclusion: perhaps abstract thought isn’t generated by the brain.

I have noticed the same thing Penfield noticed (I’m a neurosurgeon and have treated thousands of patients with seizures). There are no intellectual seizures. There are no arithmetic seizures, no calculus seizures, no logic seizures, no philosophy or history or politics seizures. The remarkable fact is that there is a whole class of mental activity — abstract conceptual thought — that is never evoked by epileptic seizures.

Why is this so? Why do the ordinary activities of our minds — thinking abstractly — never get activated when the brain seizes, although a broad spectrum of other activities occurs during seizures?

What About Forced Thinking Seizures?

Some neuroscientists argue that a rare kind of epilepsy called forced thinking seizures does indeed involve abstract thought. But they are mistaken. Forced thinking seizures involve compulsive thinking about particular objects and activities with strong emotions. They never have abstract content. In some ways, these seizures resemble obsessive-compulsive behavior.

Is Abstract Thought Just Too Complex to Be Evoked by Seizures?

Some neuroscientists also argue that abstract thought is never evoked by seizures because abstract thought is so complex that random sparking of neurons doesn’t give rise to these kinds of thoughts. But that is a misunderstanding as well. Many abstract thoughts which are never evoked by seizures are quite simple — one plus one is two, dogs are better than cats, mercy is better than justice, snow is great for skiing, and so on. On the other hand, many complex partial seizures involve quite complex activity, such as undressing, walking around, operating machinery, etc.

Abstract Thought Is Not Generated by the Brain

I think that Penfield was right: the remarkable fact that epileptic seizures never evoke abstract thought is best explained by the theory that abstract thought is not generated by the brain.

At first, this explanation is shocking. We are led to believe that all of our mental activity is wholly caused by brain processes. But that’s not what the evidence really suggests. It’s fair to say that brain activity is ordinarily necessary for abstract thought (alcohol or a whack to the head will impair our ability to think abstractly for a while). But brain activity is not sufficient for abstract thought.

Classical philosophers and theologians such as Aristotle (384–322 BC) and Thomas Aquinas (1225–1274) made powerful philosophical arguments that our intellect — our capacity for thinking of concepts, for reasoning, and for making judgments — is not a material power of the body but is an immaterial power of the spiritual soul. The remarkable fact that brain activation caused by epileptic seizures never activates abstract thought implies that they were right.

Cross-posted at Mind Matters News.