Copyright © 2007-2018 Russ Dewey
Epileptic Auras: Natural Brain Stimulation
Epilepsy has intrigued scientists for thousands of years because of the mental phenomena associated with it. Seizures involve intense activity in brain tissue. The area can be localized, in which case seizures are said to be focal.
A person with seizures of this type may have petit mal (literally "small sickness") epilepsy. This is characterized by brief periods of absence of thought, or trembling of a limb, or other symptoms.
If seizures spread to the whole brain, a person has so-called grand mal ("large sickness") seizures. Those are characterized by strong muscular convulsions and a period of unconsciousness.
Seizures beginning in motor cortex may announce themselves through a trembling of the arm or a march of activity from the fingertips up through the hand, elbow, and arm. This is called the Rolandic March.
The Rolandic March is caused by seizure activity moving along the Rolandic fissure on the cortex. This is one place where the body image or homunculus is represented on the sensory and motor cortex.
The Rolandic March is relatively rare. It occurs only if seizure activity spreads slowly through hand, elbow, and arm areas of motor cortex.
What is the Rolandic March?
Seizures beginning in visual cortex give rise to glowing dots. Seizures in the area of cortex that process complex visual pattern recognition (the inferotemporal cortex) can produce complex visual hallucinations.
In general, the symptoms produced by seizure activity depend upon the area of the brain involved. This makes seizures informative to neuropsychologists.
What is a prodrome? What are some exotic auras and some common auras?
Sometimes a distinctive feeling of some kind, known as an epileptic aura or prodrome signals the beginning of a seizure. Depending on the case, an epileptic person may be able to ward off an impending seizure by relaxing.
Occasionally patients have exotic prodromes. Horowitz, Adams and Rutkin (1968) described a patient who characteristically saw "pigs walking upright, like people" before a seizure.
One student reported that her mother's seizures always began the same way. "She said she would start hearing a song and couldn't get it out of her head."
More common auras are odors, flashing lights, feelings of dread, nausea, dizziness, and weakness in limbs. These symptoms are identical to the results of direct brain stimulation in Penfield's studies.
What is micropsia? Macropsia?
Micropsia, a common aura, is a sudden feeling that things look very far away and small, or the environment is moving away into the distance. The opposite feeling is macropsia, which occurs when things suddenly look very large, or the environment looks like it is coming closer with jerky movements.
Some students are shocked to realize this phenomenon is familiar. One asked, "Does this mean there is something wrong with me?" Probably not. Normal people experience all the common types of auras occasionally.
Deja Vu as a Brain Event
Déjà vu is a common prodrome, an eerie feeling of "having been here before." In one classroom survey I conducted, 95% of introductory students reported having déjà vu sensations occasionally.
John Hughlings Jackson (1835-1911) was a London neurologist who pioneered in the study of epilepsy. He noticed that déjà vu and similar sensations were common in epileptics. He wrote:
The state is often like that occasionally experienced by healthy people as a feeling of "reminiscence"...
It is sometimes called "dreamy feelings" or is described as "dreams mixed up with present thoughts," "double consciousness," "feeling of being somewhere else," "as if I went back to all that occurred in my childhood..." (Jackson, quoted in Penfield, 1959)
The déjà vu sensation is probably caused by a small discharge of neural activity in the temporal lobe and the limbic system. These two areas are joined by dense fiber tracts.
As Swartz (1982) puts it, limbic epileptic storms can make the mind light up with "vivid feelings, including convictions of what is real and true." Déjà vu sensations, in particular, can be triggered by direct stimulation on the top surface of the temporal lobe, during surgery.
What feelings commonly accompany limbic "storms"?
Déjà vu means, literally, "already seen." A variation of déjà vu is called déjà penseé (already thought). This occurs when one has a feeling that every detail of a current situation is familiar or that one has predicted the events of the present moment. This prediction is felt to be "real and true."
People often interpret such sensations as a memory of a recent dream that foretold the exact details of the present moment. The feeling is an illusion–it is not a dream coming true–but the illusion is very powerful. It can be difficult to convince someone in the grip of a déjà vu episode that this is an illusion, a brain stimulation event, not an episode of psychic power.
How do people commonly interpret a déjà vu sensation?
My boyfriend and I were sitting eating lunch last week, having a small conversation. I remarked that I couldn't wait for cold weather to come so we could go skiing in North Carolina.
"Yeah," he said, "And I'll clobber you in a snowball fight if you give me any hassle about not knowing how to ski." I laughed and told him that I once had to learn, too, and that Beach Mountain Ski Slope had a special place for teaching beginners.
Suddenly my boyfriend's face went white, and his eyes grew wide open. "What's the matter?" I said.
"This has happened before!" he remarked. "We have had this whole conversation before and it seems like we were right at this table and everything, everything's the same."
I knew good and well that we hadn't talked about us going skiing before. But I smiled and became excited because I knew why it seemed that we had this conversation before.
I said, "Hey, that's déjà vu. We talked about it in psychology. You really didn't have this conversation with me before, it only seems like it because déjà vu is what happens. It's only a little feedback going on in your brain..."
I proceeded to explain it to him in a proud scientific way (because I was proud of myself for knowing) but he interrupted me and said, "Forget it. I don't want to hear about all that psychology stuff, 'cause I know I'm psychic !"
I smiled and said to myself, "Sure, that's what they all say!" [Author's files]
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References:
Horowitz, M. J., Adams, J. E., & Rutkin, B. B. (1968). Visual imagery on brain stimulation. Archives of General Psychiatry, 19, 469-486.
Penfield, W. (1959). The role of the temporal cortex in recall of past experience and interpretation of the present. [Paper read at Eastern Psychological Association, Atlantic City, April, 1959].
Swartz, J. (1982, August) Brain evolution linked to concern for others. APA Monitor, p.45.
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