"Split-Brain Syndrome"

Consciousness still remains undivided when the brain is split into two halves, by a surgical procedure called corpus callosotomy – the severing of the bridge connecting the left and right brain has captivated psychiatrists and clinical psychologists since 1950s. This radical kind of brain surgery and the last resort to treat Epilepsy has failed to produce the expected treatment results. However, the decades of research and controversial experimental studies, allowed intriguing notions to come to light that has expanded our understanding of the brain, mind and the deep neural connections within.       

As quoted by Sigmund Freud - “The mind is like an iceberg, it floats with one-seventh of its bulk above water.” 

The three pounds of tissue mass, the human brain, is a widely researched organ of the human body. In fact, most people including me are fascinated by the theory of Split Brain Syndrome. So, I am going to shed some light on this topic, together with some interesting questions as to how corpus callosotomy results in this syndrome and what were the reasons behind performing split-brain surgery.   

Let’s first get acquainted with a little bit of Neuroanatomy, involving the concept of a contra-lateral wiring of the brain. In order for easy understanding, I have devised a simple method: the left hemisphere controls your right limbs and right visual field, whereas your left limbs and left visual field are controlled by the right hemisphere. Honestly, it still seems confusing! Fortunately, the image below will provide some help.  

   

Why split-brain surgery was considered?
It was thought that severing the highway connecting the two halves of the brain will prevent the two hemispheres of the brain from communicating with each other.  Particularly in patients who are suffering from Grand Mal kind of Epileptic seizures. These are the more severe type of seizure, which results in uncontrollable electrical activity that short circuit’s the brain and eventually causes the person to convulse and result in uncontrollable jerky movements.  Despite all the research into treating seizures by surgical means, split-brain surgery was unsuccessful to a greater extent.  

What causes split-brain syndrome?
Michael Gazzaniga and Roger W. Sperry were the first to study split brains in humans, found out that the patients who have undergone complete callosotomy suffered from an impairment called, split brain syndrome. After the split brain surgery, the two hemispheres do not exchange information as efficiently as before and therefore affects the behavior and agency. For instance, the right hemisphere acts independently of the left hemisphere and the person’s ability to make rational decisions. This can give rise to a kind of split personality. 

As depicted in the above image; when the post-surgical patient is shown a card with a word written, to his right visual field, his left hemisphere processed the information and being the speech center of the brain, said it out loud. When the same card is shown to his left visual field, he couldn’t be able to speak the word as now the information is processed by the right hemisphere. Although the patient cannot share the information with the left hemisphere, his right hemisphere is able to make the left hand draw an image of that word.

Let's pause for a few seconds to allow that to sink in!
Together with these experiments, a most interesting notion, the role of consciousness came into existence. As I have mentioned in the beginning of this blog, that the consciousness remains intact even after the link between the two halves of the brain is disconnected. Isn’t it amazing! Human brain is able to do that because of the presence of millions of neurons designed to make deep electrical connections inside the brain.         

Why is the split-brain surgery considered extremely dangerous? The answer to this question lies in the fact that a great percentage of people who have undergone this irreversible procedure haven’t survived and those who have, are still suffering from epileptic seizures.    
Needless to say, this conventional treatment method has more cons than pros. Besides, with the advancements in more safer and effective pharmaceutical modes of treatment, the split-brain surgery is already going into the shadows. 

- Dr. Paras Baloch