Cutting the cables: The split brain

Epilepsy is a serious neurological disorder often characterized by recurrent episodes of increased and abnormal activity in the brain. Epilepsy can occur due to gene mutation, trauma, tumors, infections, or even from the brain being exposed to toxic substances however, the cause is usually unknown.

The Surgery

While there are a couple of methods of treatment, the more severe cases of epilepsy in patients can be treated by performing a rare surgery that cuts the corpus callosum called corpus callosotomy.

It is a risky and invasive treatment option because the corpus callosum will not heal therefore is left as last alternative. As you may know, the main responsibility of the corpus callosum  is allowing communication between the two hemispheres. It is the reason why even though each hemisphere is specialized for certain tasks it never feels as if two people are sharing one body. Severing the corpus callosum works because it stops the epileptic seizures from crossing into the other hemisphere and therefore shorten the time the seizures last as well. Sometimes if the surge of electrical activity cannot "ping" back and forth, a seizure will not even develop! 

Aftermath

You may be thinking, "this sounds great, no more seizures!" however, any surgery has risks associated with it and this is no exception. People who have undergone corpus callosotomy are often referred to as split-brain people who although maintain motor and intellectual abilities have difficulty performing tasks that are not familiar to them. Severing the corpus callosum affects what split -brain people can see; if an object is presented to them in one hemisphere, the other will not see it. One benefit found in split-brain people is they can use their two hands independently in a way non split-brain people cannot. What do I mean by this? They have the ability of simultaneously moving the left hand and right hand in different directions. They are able to do this because they can plan two actions at once since each hemisphere process information independently. Eventually conflicts between the two hemispheres will diminish as the brain begins to adapt and use smaller connections between the hemispheres.

Hemisphere Specialization 

Studies have shown people suffering damage to a certain hemisphere lose specific abilities and functions which leads to the concept of lateralization. Lateralization is division of labor between the two hemispheres such as the left hemisphere to be involved in language and logical thinking with the right mainly specialized in emotions and creative thinking.

Patients with damage to the left hemisphere are more apt at recognizing and understanding gestures and facial expression because the right hemisphere is better at perceiving emotions, recognizing humor and sarcasm, as well as spatial relations. With the left hemisphere "out of the way", the right hemisphere is able to do what it does best, recognizing emotions. Need clarification? Here is a video that further explains the concept of lateralization and split-brain theory.

In conclusion...

References:

Kalat, J. (2012). Biological psychology. Cengage Learning.

http://www.nature.com/news/the-split-brain-a-tale-of-two-halves-1.10213