How we got Split-Brain Studies

One more cringe worthy surgery to contemplate might be Split-Brain surgery. A process by which neurosurgeons cut the corpus callosum, that then stops nerve fibres carrying messages from one side of the brain to the other. In epileptic people, quickened activity between both sides of the brain causes epileptic fits, and therefore, separating them, reduces the rate of epileptic seizures. (Calson, 2010)

The first research in this field was done by Bykov in the early 1900’s, where he worked in animals in Pavlov’s laboratory. By 1924 he had discovered that sectioning the corpus callosum in dogs prevented the contralateral skin related conditioning of salivary reflexes. (Glickstein & Sperry, 1960)

Corpus Callosum

The Corpus Callosum. Source: Psych Web

The first human case was reported in 1940 by Van Wagenen and Heeren, when the callosum was split as an attempt to cure epilepsy. The procedure was successful both in controlling epilepsy, and in finding new research on the corpus callosum. (North Dakota State University)

Years later, scientist Roger Sperry, and colleagues, performed further research in to split brained patients. They found that, although in day to day life, their behaviour seemed practically normal, that the cut off communication meant that the two half brains were actually operating independently of one another. Their work on animals showed that each half of the brain could be taught contradictory activities, with no perceivable mental conflict (Sperry, 1975).

The same behaviour is exhibited in humans. Post split-brain surgery patients have reported that their left hand seems to have a mind of its own. They may find themselves interestedly reading a book, yet then spontaneously, and through no conscious choice of their own, put it down. (Calson, 2010)

The different experiments performed, assessing responses to stimuli, opened up a whole new dimension of research, examining the brain in a new, not previously obtainable situation. The studies revealed where both sides of the brain are specialised. Sperry was awarded the Nobel Prize in Physiology or Medicine in 1981 (Horowitz, 1981).

What impresses me here is how a potentially controversial operation endured through the ages, to be not only acceptable, but also incredibly useful both in controlling epilepsy and understanding mind. If the idea were suggested today, ethical alarm bells might ring, yet through a century long research process, we now have scientifically grounded theories on the callosum and the two sides of the brain.

Is this a game that we have to play in order for research to gain widespread favour? Is that the way it should be? How much control do we have over what science achieves for humanity? It’s as if science itself is alive and kicking, an intelligence in its own right, with whom we work, that we might progress.


Carlson, N. R., (2010), Introduction. In N. R. Carlson, Physiology of Behaviour (pp. 2-27). Boston, MA: Allyn & Bacon.


4 thoughts on “How we got Split-Brain Studies

  1. I think that the split-brain studies are an excellent way to prevent epileptics from having fits. However, I also believe that more research should be done into the side effects: no conscious choices, and any other underlying side effects that may not have yet been discovered. It can then be discussed with the patients whether the side effects overweight the problem/s themselves: the fits.

    Science can, does and will continue to achieve a lot for humanity, not only will it find ways to help, it will and also find out things that it once thought would be for the better are in fact for the worse (electric shock therapy). Due to the fact that scientific theories and findings always change, and can sometimes be proven to improve peoples mental state, they can be proven wrong in the future resulting to lots of mishaps. This is the reason why I believe that things should be tried and tested for a set amount of time before they can actually be used on humans, due to the fact that more findings can prove the original findings wrong.

    Loved your blog btw, it was very informational and informative 🙂

  2. Whilst reading, my intrinsic ethical bells surely rang; with the seemingly perpetual quantity of consequences that may ensue from, for example, simply snipping a milimetre off the intended portion of the Corpus Callosum – ‘risky’ procedure would be an understatement. From what you convey with evidence, the aforementioned procedure was suprinsingly “successful” and hence, perpetuated and applied to the extent it was. Research most certainly must make the necessary sacrifices and play the, as you stated, ‘game’ with vigour; in order to allow the progression of science and psychology, tredding on the boundary of ethics is necessary, yet for majority of circumstances, not ‘the way it should be’. Upon viewing a substantial amount of videos relevant to corps callosmy, the primary side effect of the limitations of the hemispheres is one I personally would not prefer to be subject to (as opposed to fits associated with chronic epilepsy, that may be maintained even slightly with pertinent medication). In accordance with your post, I do agree, and as well, I am not accustomed to it’s prevalence. It does, however, depend on the individual and their circumstance, or the one they wish to be modified for their preference (i.e. undertaking the procedure). The procedure of labotomy is one of equally alarming proportions, serving as a prevalent psychosurgical procedure within established asylums and clinics. Until the introduction of chlorpromazine, many were left within a non-responsive, zombie esque state, while others unfortunately suffered and died at the hands of the psychiatrists, physicians, or relevant staff. In comparison with corpus callosmy, labotomy served little therupuetic value. Despite it’s atrocities and euphemistically stated, ‘rough patches’, science (specifically psychosurgery) would be hindered to an extent unimaginable. The ‘game’ must be played, with points won for humanity in the process. Irrespective, quite an interesting blog, written in a manner that eases one despite it’s cringe-worthy content. Thank you.


  3. Didn’t really find the blog cringe worthy at all, I found it really interesting and informative. I’ll be honest, although I’d heard of split-brain surgery I’d never really looked into it and didn’t have a clue what uses it had. Reading this blog has made me much wiser to the subject… And at the same time I’m curious, how would the world have reacted if split-brain research had started now rather than 1924?
    Would any of the advancements and positive discoveries have been made? What would actually be different? And is the worlds current ethical views actually limiting how we can advance in the realm of science?

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