Adventures in Memory. Hilde østby
strange. I thought it would be difficult, but it looks as though I’ve done it rather well,” he said, astounded.
Brenda Milner was also astounded. She’d made a crucial discovery about long-term memory: that it consists of different, separate storage areas. In learning tasks that are not based on conscious memories, but rather on procedural memories (the body’s memory of how to do something), the hippocampus is not involved. If it were, Henry wouldn’t have done so well.
IN LATER YEARS, Suzanne Corkin, a student of Brenda Milner’s who became a neuroscientist, took over the work of researching Henry Molaison’s memory. Corkin and Henry’s partnership lasted for more than forty years, and in a way continued past his death. But though the two saw each other frequently, and to her he was like an old friend, she was new to him every time they met. When she asked him if he knew who she was, he replied that there was something familiar about her. He would guess that she was perhaps an old schoolmate. He may have wanted to be polite, but perhaps there was a remnant of something like a memory in his brain, which gave him a feeling of recognition, without knowing where it came from.
Henry reaffirmed that we possess a short-term memory, something he still had, and a long-term memory, which he had only half of—the part involving unconscious learning, otherwise known as procedural memory. What he was missing was the ability to store memories that can be consciously recalled: facts about the world and himself, called semantic memories, and all the experiences that would normally become part of his personal memory album, called episodic memories.
The modern theory of memory—based in part on Henry Molaison—suggests that previously stored memories are separate from new memories waiting to be let in. Henry did have memories from before his surgery. He remembered who he was and where he came from. He remembered events from his childhood and youth. But the three years leading up to the surgery were completely gone. This meant that memories could not be stored in the hippocampus, or at least not only there. Anyway, it is unlikely that there could be room for all of life’s experiences in such a tiny, fragile structure deep inside our brain. The role of the hippocampus must be to hold on to memories while they are maturing, before they are properly stored elsewhere in the brain—in the cerebral cortex, the outer layer enveloping the brain. It’s logical to think this process may take about three years, since Henry couldn’t remember the three years prior to his unfortunate surgery.
As Henry was living life from one minute to the next, in the safety of his mother’s house, the continual experiments turned him into something of a memory celebrity. Fortunately, researchers kept his identity hidden until after his death. If they hadn’t, he would have been vulnerable to overenthusiastic researchers and journalists. He was known only by his initials, and to this day, memory researchers around the world refer to him only as H.M.
Henry contributed his life to research—or at least the memories of his life. He took part in one experiment after the other, so researchers could document how memory works. Although he remembered very little after the surgery, he had memories of conversations with his doctor from several years prior to the surgery. This meant he understood that something had gone wrong—maybe with the surgery. This is why he repeatedly told the researchers that he wanted to help prevent the same thing from happening to others. “It’s a funny thing—you just live and learn. I’m living, and you’re learning,” he said.
Another important consequence of the research on Henry was that no one was ever operated on in the same way again. Scoville quit removing both hippocampi from his patients, whether they suffered from epilepsy or schizophrenia. Surgery to cure epilepsy did continue, however, and is still carried out today. If a patient has a certain type of epilepsy, originating in the area of the hippocampus, it can sometimes be remedied by removing one of the seahorses. The other one is left intact, so new memories still have at least one entrance into long-term memory.
For those of us whose brains are pretty much intact, it’s easy to take memory for granted. It’s easy to think, “I’m sure I’ll remember this, I won’t need to write it down.” All the special moments in our lives will remain with us as memories, won’t they? We like to imagine memory as a hard drive filled with film clips from our lives that we can watch whenever we want to. That’s not how it works, though. When we’re driving to the store or sitting around the dinner table with good friends and family, how can we be sure those precise moments will be remembered? Will those memories be useful or important in the future? Our memories do take good care of certain moments, of course: birthdays, weddings, a first kiss, the first time we score in soccer. But all the other moments—what happens to them? We spring-clean our brains now and then, throw out the clutter, and keep some things for safekeeping. This is a good thing, because if we had to remember every single moment of our lives, we wouldn’t be able to do much more than reminisce. When would we have time to live?
Some of us, however, store more than others: meet Solomon, the man who was unable to forget anything at all!
Solomon Shereshevsky worked as a Russian newspaper journalist in the 1920s. There, he annoyed his editor by never taking notes when he was given an assignment. The editor distributed the stories for the day, and while the other reporters eagerly wrote down what they needed to know to get to work, Solomon just sat there, as if he couldn’t care less.
“Haven’t you got anything of what I said?” the chief editor would ask.
But Solomon had gotten all of it: every address mentioned, every name, what the issue was. He could repeat it all back to his editor, every last detail. “Isn’t this the way it is for everyone?” he thought. He found it odd that others had to take notes. To him, it was natural that everything he heard, he remembered. Solomon’s editor sent him to see an expert. In the office of neuropsychologist Alexander Luria, Solomon was—like Henry Molaison—exposed to a battery of tests. How much was it possible for a human being to remember?
An almost limitless amount, as it turned out. At least it was difficult to find limits for Solomon’s memory. The psychologist showed him long lists of nonsense words and he could regurgitate them in perfect order, even backward and diagonally. He memorized poetry in other languages, tables of numbers, and advanced math in the blink of an eye. When Solomon met Luria again, seventeen years later, he could still repeat the same lists he had seen that time many years ago.
Solomon eventually quit his job at the newspaper and launched a new career as a mnemonist, a memory artist. He appeared onstage and memorized endless lists of numbers or words provided by the audience. Then he repeated them perfectly, to everyone’s amazement. But contrary to what you may think, an amazing memory—the kind so good we dream of having it ourselves—didn’t make Solomon rich, nor did it make him powerful or particularly happy. He jumped from job to job and finally died alone in 1958, without friends or family by his side.
Solomon Shereshevsky’s astonishing memory was partly due to something called synesthesia. This is a condition in which all sensations are accompanied by another sensation, such as sight, sound, smell, or taste. Solomon suffered from an extreme form of synesthesia. Everything he experienced was accompanied by impressions of bright colors, strong tastes, or special images. Hearing certain words would conjure distinct pictures, even tastes and smells. Certain voices evoked strong visual impressions. Once, when he was buying an ice cream at a kiosk, he recoiled in disgust because the seller’s voice made him see a billowing storm of black coal and ashes. These profound sensations made his memories latch on far stronger than a regular person’s. It was said that he couldn’t get rid of a memory—not even a meaningless list of numbers—unless he made a conscious effort to remove it.
Solomon was special. Almost no one remembers things as well as he did. Compared with his, the memory of an average person is a mere joke. But would you really want to be able to remember not only your parents’ phone number and the bus schedule from elementary school, but all phone numbers and bus schedules you have ever encountered?
Exactly fifty years after Solomon passed away, eighty-two-year-old Henry Molaison also died. The difference between these two exceptional men is not only that one of them had a vast trove of memories while the other couldn’t remember a thing. The fifty years between them also made a difference in terms of how