The Split-Brain experiment that broke neuroscience
In 1939 neuroscientists began cutting living human brains in two in order to treat certain types of epileptic seizures. Subsequent experiments on those patients gave science an unnerving window into the nature of human consciousness. It turns out that there might be more versions inside of your own brain than you might be comfortable with.
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✦ Splitting human brains in half upended our understanding of consciousness
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- The surgeries cured epilepsy
- Experiments after the surgeries suggest multiple ‘yous’ in your brain
✦ Studying how the two halves of the human brain operate independently
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- Each eye connects directly to the opposite hemisphere
- When the corpus callosum is cut, the half brain must process information on its own
- The left hemisphere contains the language center and connects to the right eye
- The right hemisphere can only communicate with gestures and writing
- In an experiment, each half of the brain received different information about the environment
✦ Split-brain patients have two separate experiences and can exhibit conflicting responses.
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- Experiments with split-brain patients show that the two hemispheres of the brain can have different experiences and respond differently to stimuli.
- The language-using side of the brain can make up stories to explain unfamiliar pictures, rather than admitting that the brain is having two separate experiences.
✦ The human brain isn’t one integrated complete self, but multiple potential cells depending on how much of the brain is active at one particular moment.
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- The experiment has been repeated on dozens of people with split brains over the years and it’s always the same.
- There’s a neurological step in human consciousness that recombines disparate data into a sense of a unified self.
✦ Our experiences shape our biology and personality, and vice versa.
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- Experiences shape our personalities and biologies through hormonal signals and neurotransmitter releases.
- Our biology can also affect our personality, as seen in cases of leaky gut or chronic anxiety.
✦ We are part of a great living ecosystem and consciousness is mostly just context.
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- Living ecosystem works on scales as large as tectonic shifts and as small as microorganisms.
- Our unique perspectives on the world are just one link in a continuous chain of subjective experience.
✦ We are all connected in the great project of consciousness.
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- Experiencing someone alters the way our neurons fire and creates an imprint of them in our physical tissue.
- Commenting on a video alters the sense of self of the person who made it, showing how we are all connected.
✦ Split brain research needs new scientific approaches
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- Questions remain about communication between hemispheres
- Unified consciousness can alter internal biology and immune system
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