The Brain, the Split Brain and the Split Brain Patient

The case of split brain patients is not all that new, its certainly not unheard of. Neuroscience has always had an obsession with the brain, the ultimate goal? To understand the human brain. For a while now we have been aware of six main sections of the brain (the central nervous system), these being the four lobes of the cerebrum (frontal, temporal, parietal and occipital) plus the cerebellum (mini brain) and the brain stem, all of which for different reasons are essential for human survival. Of course the structure of the brain is far more complex, for example I could explain about the forebrain, hindbrain, and go into details of the age of brain sections (for example the cerebral cortex is the most recent addition to the brain.) Such facts would be unnecessary to this article.

More necessary is to know about something called the 'Corpus Callosum' a giant fissure in the middle of the brain which seperates the right and the left hemisphere of the human brain. It is the job of the corpus callosum to send communications between the two hemispheres, according to their specialities. I shall start this section by saying that most people are left hemisphere dominant. The left and the right hemisphere have different purposes, and the picture to the left illustrates this perfectly. The right hemisphere (green) is the 'disorganised' hemisphere, the one we use for less organised things, arts and crafts, communication. However it is the left (blue) hemisphere that we use to organise our speech, to identify an object and to do most of our day to day tasks. As one can see in the above picture, the corpus callosum is represented by a big gap with bridges for communication, this essentially is what it is.

However, the brain is a little more complex. It helps us see, hear and use all of our sensr information as well as processing this information and storing it correctly in our long term or working memory dependent on need. Damage to any area of the brain can cause loss of one or multiple brain processes.

For the sake of this article I wish to focus on eyes alone, and how they join to the brain. Some of you will know that what we see through the left eye is sent to the right hemisphere and what is seen through the right eye to the left. (Shown in the picture.) and so the information is then processed through the corpus callosum and sent for processing. Yet science gets more interesting when we add a labotomy to the scene. I do not sugest labotomising and do not agree with such procedures, however the effects which have happened in the past have been astonishing.When the first study was done on cats who had their corpus callosum severed, it was found that the cats acted as though they had two seperate brains and that the two hemipsheres took on their own roles. Now when testing has been done on humans (all of whom have had serious brain conditions which has led to the treatment being necassary) the same has happened, and they have found they can read two things at once, do two things at once and multitask successfully, taking in all information and retaining it (this would be useful for college students.)The optic fields of split brain patients has simply changed to seeing information from the right eye being sent to the right hemisphere, the same with the left. More fascinating results were found. In the case of HM, a man who in the sixties was suffering from serious and devastating epileptic ciezures went for a labotomy of the hippocampal area, and so his hippocampus (a part of the brain vital for memory) was removed, leaving HM unable to use his long term memory.This devastating case allowed psychologists to study the effects of such a tragedy and to ask HM to carry out a drawing task in which he traed a star on a piece of paper using a mirror for reflection. HM did several trials of this and each time he improved dispite having no memory of ever doing this, meaning he was able to improve dispite being classed as a split brain patient.The effects of split brain are still deeply unknown and with every benefit we find a problem, however this area of psychology and neuroscience ceases to amaze me. I hope it also amazes you.