In split-brain experiments, the two hemispheres are separated by cutting the corpus callosum. During experiment, it was observed that certain tasks are performed only by the left hemisphere and some by the right hemisphere.
For example, the language processing is performed by the left hemisphere. Since most people are right handed means, the left hemisphere is dominant in these people. By these observations, scientists coined a word “cerebral lateralization” or “cerebral dominance” that indicates the dominance of one hemisphere over the over.
Thus, the blank can be filled with corpus callosum.