In “Bridging the Gap” (Caltech, 10/10/11), we learn: “Caltech Neuroscientists Find Normal Brain Communication in People Who Lack Connections Between Right and Left Hemispheres.” Not in itself a new sort of find, by any means.
PASADENA, Calif.—Like a bridge that spans a river to connect two major metropolises, the corpus callosum is the main conduit for information flowing between the left and right hemispheres of our brains. Now, neuroscientists at the California Institute of Technology (Caltech) have found that people who are born without that link—a condition called agenesis of the corpus callosum, or AgCC—still show remarkably normal communication across the gap between the two halves of their brains.
Many have heard about Roger Sperry’s work with people whose brains were split to control life-threatening epilepsy, whose left hand really didn’t know that their right hand was doing. But the Caltech researchers studied people who had never had a functional corpus callosum, from the time of embryogenesis:
“This was a real surprise,” says Tyszka. “We expected to see a lot less coupling between the left and right brain in this group—after all, they are missing about 200 million connections that would normally be there. How do they manage to have normal communication between the left and right sides of the brain without the corpus callosum?”
What may have happened is that, never having been able to connect via the CC, the two halves of the brain simply use existing communication channels more intensely to stay connected. By contrast, Sperry’s split-brain subjects brains had adapted to communicating through the CC, but then it was severed. There is a practical side to this research:
“We are now examining AgCC subjects who are also on the autism spectrum, in order to gain insights about the role of brain connectivity in autism, as well as in healthy social interactions,” says Tyszka. “About a third of people with AgCC also have autism, and altered connectivity in the corpus callosum has been found in autism. The remarkable compensation in brain functional networks that we found here may thus have important implications also for understanding the function of the brains of people with autism.”
See also: Researchers “very shocked” by recent new genes that form distinctly human brain
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