For a very long time, the human brain has been perceived as one big computer that controls the body. Many people including most scientists believed that if one part of the brain is unable to do its work, it will lead to dysfunctional of the whole brain just as it is the case with the computer. The split-brain experiment proved this theory wrong and indicated that the human brain acts like many computers connected together through cables. The brain is made up of two main parts; the right and the left hemisphere which are joined together by network cables. These cables which include the corpus callosum, the anterior commissure, and the hippocampal commissure are tasked with the transfer of information between these two hemispheres (Schechter, 2015). Each of the brain hemispheres works separately from the other, but they require the corpus callosum to interact with each other to enable smooth flow of commands from the brain the other parts of the body.
Split Brain
Split brain refers to a process where communication between the right hemisphere and the left hemisphere is disconnected. The split is done through a brain operation which is referred to as split-brain surgery or corpus calloscotomy (Gazzaniga, 2015). The surgery is usually carried out to alleviate epileptic seizures to epilepsy patients by preventing sporadic electrical storms from moving from one side of the brain to the other through the corpus callosum. Epileptic seizures are usually caused strokes, brain tumors, or even abnormal blood vessels in the brain. Seizures occur when the neurons are firing off electrical impulse too rapidly and not letting the body and the brain respond in a timely fashion thus causing a sporadic electrical storm which strike the brain which can cause some parts not to perform as expected. Previously, the surgery involved cutting off the corpus callosum completely which disconnected the communication between the two hemispheres completely. Due to complications caused by the lack of communication between the right and the left hemisphere, currently, split-brain surgery disconnects the corpus callosum partially to allow a bit of communication between the two sides of the brain.
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Even though the two hemispheres work independently, each has dominance to particular roles. The left hemisphere mostly controls speech and language computation while the right hemisphere specializes mostly in visual-spatial processing and facial recognition (Gazzaniga, 2015). These tasks are not solely processed in the specified hemispheres but require communication between the two sides, and that’s lead to a perfect coordination of the body which we refer to as the normal behavior of a human. Michael Gazzaniga who is a cognitive neuroscientist at the University of California, and who is also referred to as the godfather of split-brain science, explained that a healthy brain looks like two distinctly different machines which are cabled together exchanging a torrent of data (Gazzaniga, 2015). He also described that the even when the connection between the two hemisphere is completely cut, both hemispheres will continue operating normally but the only difference is that they will not be able to communicate with each other. Therefore, a patient who have undergone split-brain surgery will likely act as he or she is using two different minds at the same time.
Each hemisphere can control the body by its own in the absence of the other by enhancing the operations that were dominated by the other hemisphere, therefore, a person can continue leaving with one hemisphere if the other completely damaged although he or she may have some issues in accomplishing some tasks. When the corpus callosum is completely cut, it leads the two hemispheres to operate independently unaware of what the other is thinking. This usually causes chaos in the patient’s life because both sides may be thinking differently and giving contradicting order towards the same task, and this results to abnormal behavior which affects the patient as well as those close to him or her. Since each side control a particular part of the body, the patient will have a hard time accomplishing a task because of different orders from the brain where, for example, the right hand is doing the opposite of what the left hand is doing thus causing confusion.
The Right Hemisphere of the Brain
The right brain hemisphere controls the left side of the body; therefore, the actions of our left legs and hands are controlled by the right side of the brain, but the coordination between the two arms is caused by the communication between the two sides of the brain. Information relays from the right hemisphere to the left side of the body and from that part of the body back to the right hemisphere. Apart from this role, the right hemisphere also excels in understanding spatial relationships, visual perception, recognizing patterns, music, emotion expression, creativity, among others (Schechter, 2015). This side performs highly in making inferences. When availed with several characters, the right hemisphere can draw a quick inference of what they mean. For example, when this side is primed with words such as “foot,” “glass” and “cry” it is able to combine these words and quickly relate them to “cut” which may take the left hemisphere a longer time to decipher such information. Therefore, the right hemisphere is able to process information as a whole. It also let people perceive the sense of self. Sometimes, people with the lesion in the right side of the brain experience difficulty recognizing themselves in the mirror. In general, the right hemisphere has more abilities in recognizing faces, expressing emotions, understanding music and color, reading emotions, imagination, intuition, and creativity.
The Left Hemisphere of the Brain
The left-brain hemisphere is tasked with controlling the right side of the body. It sends and receives signals from the right side of the body thus being in charge of giving commands to that section of the body. The left hemisphere is also tasked with responsibilities such as speaking, writing, arithmetic reasoning and understanding, and reasoning in general (Schechter, 2015). The study shows there is an activity increase in the left hemisphere when people speak or engage in logic or arithmetic calculations. Even though both sides of the brain are able to decipher an object, the right side can only explain it through drawing the object, but for the left side, it understands it and express it through speech. Therefore, the left hemisphere is responsible for giving a speech, it understands logic about something and solves problems through reasoning. Due to these abilities, the left hemisphere tends to process information sequentially, one at a time, unlike the right hemisphere which process it as a whole.
The brain is able to conduct all its operation by having a perfect communication between the two hemispheres in a way that it is very hard to explain which hemisphere is responsible for a certain operation. Breakdown of this communication leads to abnormal body performance. For example, if a person experience stroke of one hemisphere to the point of total destruction, it will cause the half of the patient’s body to be dysfunctional. For example, if the left hemisphere becomes dysfunctional, the patient will not be able to use his right side of the body. But if one part of the brain is unable to function at early ages in a personal growth (14 years and below) the other side has the capability of enhancing the abilities of damaged one so that his or her brain can function properly and be in a position to learn new skills that would have required both hemispheres. Although the operating hemisphere in such a case can enhance the skills of the damaged one in adults, it does not have the ability to learn new skills such as playing the piano.
Split Brain Case Study
We will use a case study of a lady called Vicki and see how split brain helped her, and how it affected her life after the surgery. Vicki was an epilepsy patient who through the aid of her neurologist decided to go through split-brain surgery after her epileptic seizures continued to be severe (Siffredi, et al, 2018). She recounts one time that she experienced a seizure and collapsed onto the bar of an old-fashioned oven which burned her back leaving her with deep scars. She underwent surgery in June 1979 in a 10-hour operation where the doctors sliced through her corpus callosum to separate her left and right hemisphere (Siffredi, et al, 2018). The surgery was meant to prevent sporadic electric storms from moving from one side of the brain to the other thus preventing severe seizures.
This procedure led to the disconnection of the two sides of the neocortex, thus separating the home of language, conscious thought, and movement control. As a consequence of this operation, Vicki’s brain stopped functioning as one but acted as if she had two separate minds. Vicki narrates the predicaments she experienced after the surgery especially when she went to the supermarket to do some shopping. She says that she took two to three hours just to pick out food for one week because of the brain conflict. Vicki explains how she could reach something she wanted with her right hand, but the left one would come in, and they’d kind fight each other (Siffredi, et al, 2018). This was caused by the two hemispheres operating separately without communication with each other.
Vicki also explained how she had a similar challenge when dressing: she says she couldn’t reconcile what she wanted to wear with what her hands were doing, and sometimes she could end up wearing three outfits at once. Neuroscientists explain that this problem was caused by a case where information is presented to one hemisphere without the other noticing it, therefore each acting differently. Vicki explains that this problem started to subdue after a year where most of the times she could do things like a normal person. Through more research, it was identified that Vickie’s right hemisphere had some capacity for language. This explains the theory that when the two hemispheres are completely disconnected, each hemisphere may try to enhance the abilities of the other so that it can perform perfectly as a complete brain.
In conclusion, the split-brain study has shown that a human brain uses two hemispheres which operate differently but communicate with each other for smooth operation. The study has shown us that each hemisphere has its specific abilities and roles within the brain and requires the help of the other to execute certain commands. The case study of Vicki shows us that if the communication between the two hemispheres is broken down, it will cause the brain to operate abnormally because each side is giving different commands without communicating with the other one. Even though split-brain surgeries have decreased due to advancement of medication that can treat epilepsy, the study of patients who have undergone the operation gave more light to how the brain works. It is through these experiments that the neuroscientists were able to prove that brain operate through two hemispheres that work independently but require sharing of information between them.
References
Gazzaniga, M. S. (2015). Tales from both sides of the brain: A life in neuroscience . Ecco/HarperCollins Publishers.
Schechter, E. (2015). The Subject in Neuropsychology: Individuating Minds in the Split ‐ Brain Case. Mind & Language , 30 (5), 501-525.
Siffredi, V., Anderson, V., McIlroy, A., Wood, A. G., Leventer, R. J., & Spencer-Smith, M. M. (2018). A neuropsychological profile for agenesis of the corpus callosum? Cognitive, academic, executive, social, and behavioral functioning in school-age children. Journal of the International Neuropsychological Society , 24 (5), 445-455.
Volz, L. J., Hillyard, S. A., Miller, M. B., & Gazzaniga, M. S. (2018). Unifying control over the body: consciousness and cross-cueing in split-brain patients. Brain , 141 (3), e15-e15.
Zhang, R., Isola, P., & Efros, A. A. (2017, July). Split-brain autoencoders: Unsupervised learning by cross-channel prediction. In CVPR (Vol. 1, No. 2, p. 5).
