Lateralization: The Split-Brain Experiments and Findings

One of the most interesting aspects of the brain deals with the differences between the left and right cerebral hemispheres. Although the brain may look similar in its entirety, both the left and right hemispheres perform different functions in daily life. Instead of the brain acting as a whole, it actually acts independently based on various areas of the brain. For example, we now know that the hippocampus or hippocampi (sense there are two located in the medial temporal lobe of the brain) plays a role in long-term memory, while the amygdale, another section in the medial temporal lobe, is responsible for emotional response, and memory processing, among other things. Although both are in close proximity, and are part of the same brain, they each play different roles. Similarly, the left and right hemispheres of the brain also play different roles.

After an unsuccessful speech on the possibility of lateralization of function in 1836 by Marc Dax, Paul Broca sparked interest in the topic after discovering that two of his patients with aphasia*, examed postmortem, were found to have lesions on the left-hemisphere of the brain. After more research into the subject matter, this small area near the back left side of the frontal lobe became known as Broca's area, and was the first real proof that the brain functioned, not as a whole, but as separate pieces.