We know our brains are made up of two halves, called hemispheres: the left hemisphere and the right hemisphere. These two hemispheres are connected by a bundle of nerve fibers called the corpus callosum. This connection allows the two sides to communicate and work together. What happens if the corpus callosum is cut off?
Cutting Off the Connection
In some cases, doctors might decide to cut the corpus callosum in a procedure called corpus callosotomy. This is usually done to treat severe epilepsy, a condition where abnormal electrical activity in the brain causes uncontrollable seizures. When medications don’t help, cutting the corpus callosum can reduce the severity of seizures.
Won’t they die?
Since each hemisphere can operate independently, patients can still survive and function, even after the disconnection. The two hemispheres can still manage most of the body’s essential functions on their own. But, as the two hemispheres can no longer share information, it can lead to some strange effects.
Real human brain obtained after an autopsy:
Vision
We know the two halves of the brain control the opposite halves of our body. So, the left brain cannot see what’s visible to the left eye. Since language skills are located in the left brain, split-brain persons cannot verbally describe the things seen by the left eye.
This problem is demonstrated in season 4 episode 24 of the series House M.D. The doctors show the word ‘candle’ only to the left eye of a split-brain patient and ask him to pronounce the word. He can’t say the word since it didn’t reach his left brain. Then, the doctors ask him to draw a picture of what the word might be. The patient correctly draws a candle. So the word has reached his right brain where it is recognised but not the left brain where it can be pronounced, proving that the connection is cut off.
Alien Hand Syndrome
This is another problem experienced by some split-brain patients. Here, one hand seems to act on its own, without the person’s conscious control. For instance, the left hand might pick up an object or throw something without their control. This happens because the right hemisphere, which controls the left hand, can initiate actions independently of the left hemisphere, which is responsible for conscious thought and awareness.
Confabulation
In some cases, actions initiated by the right brain can lead to confusion. When the right brain initiates an action, the left brain is unaware of why they are doing that action. If you ask them about why they are doing it, they will tell you some unrelated reason to explain their action. This is because the left brain is responsible for logical reasoning, but it doesn’t know the real reason for the action. So it makes up an imaginary reason to explain it. It doesn’t mean the patient is lying. Their left brain creates the reason without their conscious control. This is called confabulation.
This is also demonstrated in the same scene in House M.D. The doctors show the word ‘stand up’ only to the patient’s left eye. The right brain processes it and he stands up. When the doctors ask him why he’s standing up, he says it’s because he feels chilly and he wants to go to his room to get a sweater.
Coordination Problems
Another problem split-brain patients face is the difficulty in performing tasks that require coordination between both hands. For example, tying shoelaces or using a knife and fork together can become challenging. Additionally, patients might struggle with tasks that need both hemispheres to work together, like solving complex puzzles.
Life of Split-Brain People
Despite these challenges, many split-brain patients can lead normal lives. Mainly because the left hemisphere remains in control of daily activities, handling most of the conscious actions like speaking, reading, and logical thinking. Note that this is not the same as the split-personality disorder shown in movies. Over time, patients adapt to their new way of thinking and acting, finding strategies to cope with their unique situation.
Think About
Our brain is our identity. If the brain is split into two, is it like two different people in a single body?
Reference Links:
https://my.clevelandclinic.org/health/treatments/11546-corpus-callosotomy
https://en.wikipedia.org/wiki/Split-brain
https://www.webmd.com/brain/what-is-alien-hand-syndrome