The brain is divided into a right and left hemisphere, and the two halves are connected by the corpus callosum. This bundle of neural tissue features over 200 million axons by rough estimate. However, this number is only a conservative estimation. Also, this neural tissue facilitates communication between the two sides of the brain. This neural tissue is also the largest collection of white matter within the brain, and it contains a high myelin content, which facilitates quicker transmission of information. This should not be confused with grey matter. The brain uses grey matter for computation, thinking, memory storage, and more. White matter, like the corpus callosum, allows different parts of the brain to communicate with each other. Some congenital defects include a complete lack of this neural tissue. In recent history, some surgeons have surgical cut it as a means for treating epileptic seizures. By disrupting contact between the two brain hemispheres, a seizure can be isolated and kept from spreading.