What is the name of the structure that connects the two hemispheres of the brain?

The structure that connects the two hemispheres of the brain is the corpus callosum. It is a broad band of white-matter nerve fibers linking corresponding regions of the left and right cerebral hemispheres.

This connection allows the hemispheres to exchange sensory, motor, and higher-level information. The corpus callosum is organized into regions including the rostrum, genu, body, and splenium, which connect different areas of the cerebral cortex. Its fibers are covered largely by myelin, an insulating material that helps electrical signals travel efficiently.

Scientists learned much about its role from split-brain research. In some patients with severe epilepsy, surgeons performed a callosotomy, cutting part or all of the corpus callosum to limit seizure spread. These cases showed that the hemispheres can operate with some independence when communication between them is interrupted.

The corpus callosum is not the same as the thalamus or hypothalamus, which are deep-brain structures with different functions. Nor is it the cerebellum, which helps coordinate movement and balance. The corpus callosum is specifically the brain’s largest interhemispheric connection.