Brain is such a complex mechanism. Over last few centuries the science went so far that we could go explore the depth of universe, understand the initial big-bang event, analyze the black-hole and many more wonders spanning billions of light years. After the Cambrian explosion, some 500 million years ago, [invention of photosynthesis by the Cyanobacteria]https://heyhido.com/posts/beginning-of-oxygen/ led to the sudden blossoming of complex forms.
From unicellular organisms to us with central nervous system, the development requires a more sophisticated ways of thinking to understand - memory, imagination, processing science and so forth. However, we have a very limited understanding of how the brain works. I read an article about the Split-brain that opened up my curiosity and after some reading here are my thoughts.
Epilepsy is a complex neurological condition characterized by recurrent, unprovoked seizures. It is suggested that the seizures can be initiated by various factors, including circadian changes in hormones and neuromodulators, which may trigger seizures at certain times of the day in individuals with an underlying state of increased excitability. It is likely that the groups of neurons become hyperexcitable and prone to abnormal discharges during the epileptic seizures. The exact cause of the epilepsy is not fully understood, but the includes the electrical basis of the transmembrane potential, action potential, and mechanisms governing synaptic transmission.
According to a famous research, in 1979 a surgery was done an epilepsy patient called Vicki. The surgery later got a famous name in neuroscience field - Corpus callosotomy. The corpus callosum, the only known neural bridge between left and right brain hemispheres get partially or completely severed. After the cut, left and right hemispheres stop the direct communication with one another. That should result into a big change, right?! Brain is such a marvelous thing. After the surgery, patients with severed corpus callosum did not have any significantly impaired or different function than people with intact corpus callosum, except now they did not have epileptic seizures anymore.
Each hemisphere of the brain is responsible for movement and vision on the opposite side of the body, so the right hemisphere was responsible for the left eye and vice versa. Roger Sperry used this behavior of hemispheres to run studies on cats, monkeys and on humans to understand what the impact of the corpus callosotomy is. According to his and many other scientists’ research, the left and right hemisphere can act independently. They can do the same task on their own without the need of other hemisphere.
The left hemisphere is generally associated with language processing, analytical thinking, and logical reasoning, while the right hemisphere is linked to spatial awareness, face recognition, and processing of music and emotions. An interesting finding of Sperry was that the left hemisphere was responsible not only for articulating language, but also for understanding and remembering it, while the right hemisphere could only recognize words, but was not able to articulate them. Although the right hemisphere has also skill of language recognition, but it is not able to articulate speech, so the person cannot express what the right hemisphere is processing.
The split-brain condition challenges traditional notions of self and identity, prompting questions about the nature of consciousness and whether a unified self is an illusion. If both hemispheres are able to process events and entities separately and independently, and come up with the unified explanation which is expressed by the left hemisphere, how can we ensure that it is the reality, and not just a simplification or modification done by the left hemisphere?