The Forgetting: Understanding Alzheimer’s: A Biography of a Disease. David Shenk

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       Chapter 3 THE GOD WHO FORGOT AND THE MAN WHO COULD NOT

      There could be no happiness, cheerfulness, hope, pride, immediacy, without forgetfulness. The person in whom this apparatus of suppression is damaged, so that it stops working, can be compared … to a dyspeptic; he cannot “cope” with anything.

      —FRIEDRICH NIETZSCHE

      As found in the Pyramid Texts, from 2800 B.C., Ra was the Sun God, the creator of the universe and of all other gods. From his own saliva came air and moisture. From his tears came humankind and the river Nile. He was all-powerful and, of course, immortal—but still not immune to the ravages of time: Ra, the supreme God, became old and senile. He began to lose his wits, and became easy prey for usurpers.

      Throughout recorded history, human beings have been celebrating the powers of memory and lamenting its frailties. “Worse than any loss in body,” wrote the Roman poet Juvenal in the first century A.D., “is the failing mind which forgets the names of slaves, and cannot recognize the face of the old friend who dined with him last night, nor those of the children whom he has begotten and brought up.”

      It took several thousand years, though, for anyone to figure out how memory actually worked. Plato was among the first to suggest a mechanism. His notion was of a literal impression made upon the mind. “Let us suppose,” he wrote, “that every man has in his mind a block of wax of various qualities, the gift of Memory, the mother of the Muses; and on this he receives the seal or stamp of those sensations and perceptions which he wishes to remember. That which he succeeds in stamping is remembered and known by him as long as the impression lasts; but that, of which the impression is rubbed out or imperfectly made, is forgotten, and not known.”

      Later came the ventricular theory of cognition, from Galen (129 – ca. 199 A.D.), Nemesius (fourth century), and St. Augustine (354–430). According to this notion, the three major functions of the brain—sensation, movement, and memory—were governed from three large, round fluid-filled sacs. Vital Spirit, a mysterious substance that also contained the human soul, was harbor to the swirl of memories.

      From this model came cerebral localization, the theory that the various functions of the brain were each controlled by specialized “modules.” This model of specialization turned out to be generally correct (if radically different in the details from what Galen had imagined). In the early twentieth century, it emerged that the brain wasn’t really an organ so much as a collection of organs, dozens of structures interacting with one another in dazzling complexity. Deep in the center of the brain the amygdala regulates fear while the pituitary coordinates adrenaline and other hormones. Visual stimulus is processed in the occipital lobe, toward the rear of the skull. Perception of texture is mediated by Area One of the parietal lobe near the top of the head, while, just to the rear, the adjacent Area Two differentiates between the size and shape of objects and the position of joints. The prefrontal cortex, snuggled just behind the forehead, spurs self-determination. Broca’s area, near the eyes, enables speech. Wernicke’s area, above the ears, facilitates the understanding of speech.

      The more researchers discovered about localization, though, the more they wondered about the specialized zone for memory. Where was it? If vision was in the back of the brain, texture on top, and so on, what region or regions controlled the formation of lasting impressions and the retrieval of those impressions?

      Part of the answer came in 1953, when a Harvard-trained neurosurgeon named William Beecher Scoville performed experimental surgery on a twenty-seven-year-old patient known as H.M. He had been suffering from violent epileptic seizures since childhood, and in a last-ditch effort to give him a chance at a normal life, Scoville removed a small collection of structures, including the hippocampus, from the interior portion of his brain’s two temporal lobes. The surgery was a great success in that it significantly reduced the severity of H.M.’s epilepsy. But it was also a catastrophe in that it eliminated his ability to lay down new memories. The case revolutionized the study of memory, revealing that the hippocampus is essential in consolidating immediate thoughts and impressions into longer-lasting memories (which are in turn stored elsewhere).

      Time stopped for H.M. in 1953. For the rest of his long life, he was never again able to learn a new name or face, or to remember a single new fact or thought. Many doctors, researchers, and caregivers got to know him quite well in the years that followed, but they were still forced to introduce themselves to him every time they entered his room. As far as H.M. was concerned, he was always a twenty-five-year-old man who was consulting a doctor about his epilepsy (he had also lost all memory of the two years immediately prior to the surgery). H.M. became perhaps the most important neurological subject in history and was subject to a vast number of studies, but he remembered none of the experiments once they were out of his immediate concentration. He was always in the Now.

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