Our brain is divided into two hemisphere, the right hemisphere and the left hemisphere. The thing connecting the left and right hemisphere is called the corpus callosum. When you write with your left hand the right hemisphere is working, and if you write with your right hand the left hemisphere is working, and the two hemispheres can send signals to each other. The reason that they can send signals is the corpus callosum. Some people have to have the corpus callosum removed from their brain. The reason some people have to get it removed is because they have a lot of seizures and getting it removed stops the spread of seizures from hemisphere to hemisphere, however it also stops the two hemispheres form sending signals to each other. For example if you cover your left eye and look at a pencil with your right eye, you can write the what you saw with your left hand, because your left hemisphere can tell your right hemisphere what it saw. But if you have your corpus callosum removed and cover your left eye and look at a pencil with your right eye, you can’t write what you saw with your left hand, because the two hemispheres have no way to connect without your corpus callosum. If you have any questions about this topic please leave a comment!