The Future of the Mind Read Online Free PDF Page A

problems, such as speech and language impairment, and damage to specific regions of the brain.
    Another breakthrough took place amid the chaos of war. Throughout history, there were many religious taboos prohibiting the dissection of the human body, which severely restricted progress in medicine. In warfare, however, with tens of thousands of bleeding soldiers dying on the battlefield, it became an urgent mission for doctors to develop any medical treatment that worked. During the Prusso-Danish War in 1864, German doctor Gustav Fritsch treated many soldiers with gaping wounds to the brain and happened to notice that when he touched one hemisphere of the brain, the opposite side of the body often twitched. Later Fritsch systematically showed that, when he electrically stimulated the brain, the left hemisphere controlled the right side of the body, and vice versa. This was a stunning discovery, demonstrating that the brain was basically electrical in nature and that a particular region of the brain controlled a part on the other side of the body. (Curiously, the use of electrical probes on the brain was first recorded a couple of thousand years earlier by the Romans.In the year A.D. 43, records show that the court doctor to the emperor Claudius used electrically charged torpedo fish, which were applied to the head of a patient suffering from severe headaches.)
    The realization that there were electrical pathways connecting the brain to the body wasn’t systematically analyzed until the 1930s, when Dr. Wilder Penfield began working with epilepsy patients, who often suffered from debilitating convulsions and seizures that were potentially life-threatening. For them, the last option was to have brain surgery, which involved removing parts of the skull and exposing the brain. (Since the brain has no pain sensors, a person can be conscious during this entire procedure, so Dr. Penfield used only a local anesthetic during the operation.)
    Dr. Penfield noticed that when he stimulated certain parts of the cortex with an electrode, different parts of the body would respond. He suddenly realized that he could draw a rough one-to-one correspondence between specific regions of the cortex and the human body. His drawings were so accurate that they are still used today in almost unaltered form. They had an immediate impact on both the scientific community and the general public. In one diagram, you could see which region of the brain roughly controlled which function, and how important each function was. For example, because our hands and mouth are so vital for survival, a considerable amount ofbrain power is devoted to controlling them, while the sensors in our back hardly register at all.
    Furthermore, Penfield found that by stimulating parts of the temporal lobe, his patients suddenly relived long-forgotten memories in a crystal-clear fashion. He was shocked when a patient, in the middle of brain surgery, suddenly blurted out, “It was like … standing in the doorway at [my] high school.… I heard my mother talking on the phone, telling my aunt to come over that night.” Penfield realized that he was tapping into memories buried deep inside the brain. When he published his results in 1951, they created another transformation in our understanding of the brain.

    Figure 1 . This is the map of the motor cortex that was created by Dr. Wilder Penfield, showing which region of the brain controls which part of the body. ( illustration credit 1.1 )
    A MAP OF THE BRAIN
    By the 1950s and ’60s, it was possible to create a crude map of the brain, locating different regions and even identifying the functions of a few of them.
    In Figure 2 , we see the neocortex, which is the outer layer of the brain, divided into four lobes. It is highly developed in humans. All the lobes of the brain are devoted to processing signals from our senses, except for one: the frontal lobe, located behind the forehead. The prefrontal cortex, the foremost part of the