Scary Split Brain Situations

As it is Halloween I thought I would write a bit about a spooky part of science. Now epileptic fits and seizures in a vast simplification can be described as when all the neurones in someones brain activate simulatanously. Sometimes it is necessary for very extreme cases of epilepsy to damp these rogue firings by severing the connections between the left and right hemispheres of the brain. The corpus collosum is the main connection and this process is called callosotomy although the commissures which are smaller connections are severed as well. Never letting a good opportunity go to waste scientists study the people who have undergone this treatment to see what effects it has on their life.

Since previously each half of the brain had some specialities but now they fail to communicate some interesting actions occur. If a person sits so there is a screen right down the centre of their face what there left and right can see are now partitioned from each other. Generally the left eye feeds information to the right side of the brain but language is the majority of the population is controlled with the left side of the brain. So when an image is presented in the left hand section, the person can not say what they are seeing, but in the  right hand section they can. Even stranger is when both sides are presented with two distinct images, lets say a car and a mountain, and the person is asked to pick two words from a long list that relate to these images. The person will often choose correctly such as picking a tyre and some snow but when asked the reason for there pick they will only respond talking about one image. The car is driving in the snow or the tyre is rolling down a mountain. Even more unnerving again is when the left hand side is asked to pick up an object shown on a screen. Once they have hold of it the person is asked what they are holding. Due to the lack of communication the person will either respond saying they don’t know or that they aren’t holding anything. Finally  although this is rare, the two sides of the brain can disagree on a course of action. This was most prominently displayed when a man, attempting to assault his wife with his left hand, was stopped by his intervening right hand.

The question about which brain actually represents the person is very difficult and should be considered thoroughly. Since only the left brain can talk it is certainly the one you communicate with, but emotional memories are stored in the right brain and without them would you really be who you are?


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