Your Second Brain

• Posted by sreejith s February 8, 2015 - Filed in Health - #brain  #second brain  #two halves  - 2,347 views

  Since the days of Ancient Egypt, it's been known that the human brain is made up of two halves. Joining the two halves is a network of about three hundred million nerve fibres. This network is called corpus callosum.

  
  If, for example, you cut through the corpus callosum of a cat or a monkey, you don't kill it or sent it mad. In fact, it continues to behave much as it always did. Surgeons reckoned that if they cut through the corpus callosum of an epileptic patient, it would stop the storm spreading from one half of the brain to the other. They tried it and it worked. Patients continued to behave normally. For a while this sort of surgery became quite fashionable. But then in 1950, a couple of scientists called Roger W Sperry and Michael Gazzaniga discovered something very peculiar while studying patients who had the operation.

   

  
  They found these patients couldn't read with their left eyes. They could see with their left eyes all right, but couldn't read with them. They could, however, read quite normally with their right eyes. They also found that if a patient bumped into something with his left side, he didn't notice. The right side was fine. It got more weird. If they covered each of the patient's eyes in turn they showed him a square and a circle, he'd tell you he'd just seen a square, without mentioning the circle. The experiments went on for a long time because the scientists couldn't quite believe what they'd discovered. The only thing that made sense of their findings was that the brain doesn't consist of two halves at all. Each of those halves had to be a brain in its own right and, while they looked much the same, they actually did different things.