by Su Meck
Left to right: my brother Rob, Mom, my sister Diane, me, and my sister Barb, Mentor, Ohio, Easter 1968
That episode, a visceral combination of sight, sound, and powerful emotion, is part of the shared heritage that binds the members of the Miller family—my family—together. It endures as a rich, nearly palpable memory within the minds of both Miller parents and each of their children, remote in time and space but instantly accessible to any Miller at the mere utterance of a simple prompt: Remember when Su ran out into the street at Niagara Falls?
Brain scientists call these “episodic memories”—recollections of specific events from one’s lived experience. Episodic memory is thought to be a distinctly human trait, one of the few things that set us apart from the other animals, and perhaps the most important quality that defines each of us as individuals.
But I have no memory of that episode at Niagara Falls. In fact, I have no lingering episodic memory, not a stitch, from the first twenty-two years of my life. My sense of who I am, and my relationship with the other Millers, is entirely based on the events of the last twenty years.
For most people, episodic memory is synonymous with memory itself. But it is only one of at least three different kinds of memory, along with “semantic memory” and “procedural memory.” Each has a different purpose, and each resides in different places within the human brain.
Procedural memory is the remembered ability to perform tasks. We never forget how to ride a bike (or to walk, or to talk, or to swing a bat) because of the fundamental strength of our procedural memories. Semantic memory is the recollection of facts: names, concepts, and even specific events, but not events we recall as scenes from our own life. Most people have semantic memories of Woodstock; those who attended have episodic memories as well. All of my memories from childhood are semantic memories; stories that have been told to me and stories that I can recite, but that don’t feel like any real experiences I have lived. Anyone who has studied psychology in school will also remember the concept of short-term and long-term memories. Short-term memories are disposable, lasting only seconds or minutes: Post-its from our brain. We use short-term memory to recall the digits of a telephone number to be dialed once, the location of a coconut we just spotted in a tree, and other facts useful for our immediate survival but trivial in the broader course of life. Long-term memory is reserved for information useful beyond the present moment: the directions to our house; the phone numbers of loved ones; our blood type; our first date with a spouse.
Repetition—learning—consolidates short-term memories into long-term ones. The consolidation process can be voluntary, as in studying for an exam, or involuntary, as in those conditioning experiments with animals that used electric shocks and treats to “teach” the rat to find the pellet. Long-term memories can endure for weeks or years or decades. The human brain is forever sifting through memories, preserving the ones that matter for our survival and discarding those that don’t. Memories are Darwinian: Only the ones the brain deems most vital to our survival will, themselves, survive.
That was news to me. Jim remembers a dog-walk conversation that we had less than ten years ago when he first realized how I thought my memory was supposed to work. For most of my life I thought that other adults remembered every fact, every image, every scene they had ever lived, recording memories like a twenty-four-hour security camera. But I guess it makes sense: Who could possibly handle that much memory?
Our brain’s anatomy plays a role in memory; the recall of a memory is thought to involve several areas of the brain. Different regions record sights and sounds, numbers and names, motor skills and three-dimensional spaces. To recall a whole memory, the medial temporal lobe, a section at the brain’s inner core, must fetch each individual component from different places in the brain. The medial temporal lobe is also thought to help us consolidate short-term episodic and semantic memories into long-term ones, although it does not control formation of procedural memories. The frontal lobe, behind the forehead, seems to help us understand episodic memories by helping the brain place them in context, so that they make sense as a coherent whole. Without a functioning frontal lobe, we might remember the Air and Space Museum as semantic, factual knowledge but forget the childhood visit that is the source of that memory.
Most people who suffer amnesia through injury, such as a football tackle or car accident, forget the things that happened shortly before the traumatic event, a mild form of what is called “retrograde” amnesia. The presumed reason is that the injury disrupts the memory-making process, erasing short-term memories before they can become long-term ones. Thus, a driver who hits a tree might never remember whatever he was doing or thinking in the minutes before the impact, because the collision interrupted the conversion of those items into enduring memories. In more serious cases, such as people with profound dementia or Alzheimer’s disease, the oldest memories tend to be the safest. This is called Ribot’s law, after the nineteenth-century French psychologist who first described this pattern. The destruction of memory “advances progressively from the unstable to the stable,” from new memories to old, Ribot wrote.
Even people with severe cases of retrograde amnesia typically remember their earliest memories. But not everyone. Daniel Schacter, a Harvard psychologist, studied a man named Gene who, following a motorcycle accident, was “unable to recall a single specific episode from any time in his life.” Gene suffered damage to both his frontal and temporal lobes. He can neither create new memories nor retrieve old ones. His brain does not obey Ribot’s law.
Of all the amnesia victims studied by scientists, Gene’s case may be the most like mine. I have what is called “complete retrograde amnesia.” The injury knocked out not just my episodic memory but also most of my semantic memory, my knowledge of the world. According to Jim, after the injury, my factual knowledge base was effectively empty: I didn’t know who I was and couldn’t recall that I had a husband or children or the identities of my parents or siblings. I didn’t know what a house was or that I lived in one. I didn’t know the purpose of school, or that I had ever attended one. I didn’t know what a city was; the name Fort Worth did not register, nor did the terms Texas, United States, and Earth. I didn’t know what a president was, and the name Ronald Reagan held no special significance for me.
I could speak, but my vocabulary extended to only maybe one hundred words. Jim tells me I couldn’t recall the names of the objects around me—the clock, the bed, the door—or their functions. I didn’t know what a utensil was, or how to use one. “And even after you figured out how to use a fork,” Jim recalls, “you gripped it in a fist, like a toddler.”
My hospital records offer some corroboration of Jim’s memories. Nurses’ logs show I struggled to answer simple “orientation” questions at times, although at other times (according to the medical records) I appear to have correctly stated who I was, where I was, and what day it was. It is possible I somehow bluffed my way through these questions, or maybe the nurses weren’t paying very close attention to my answers. I certainly got through much of my life after the hospital through a combination of those two things.
For a long time after my injury, I suffered not just retrograde amnesia but also “anterograde amnesia,” the inability to form new memories. For months (even years) afterward, I would wake up “lost” in unfamiliar places. According to Jim, I could carry on conversations with nurses and family in the hospital, but I would lose my train of thought after a few minutes, and I could manage such a conversation “only if the person stayed in sight.” Communicating was a chore. “I remember [that] a lot—I would say a majority—of our communication became nonverbal, gesture-based,” Jim recalls. “That said, I also recall a ‘word book,’ a spiral notebook one of your therapists helped you develop. She would drill you on the words and add a new word or two every day. I remember your excitement at recognizing a new word as new, and then writing it down. I remember it was an almost terrifyingly small list in the beginn
ing, and being reassured by the therapist that it would get better, so much so that your learning and vocabulary would hit a critical mass, and your vocabulary growth would take off. It did. But I also remember you writing simple letters to family and asking for your word book to help you.”
Here is a passage from a letter I wrote to my mother, shortly after the injury:
I hav to go to mor doctors be case fall lots to hitig head bad head ackes.
Like many other amnesiacs, I was lucky enough to retain some procedural memory. I didn’t completely lose the ability to speak, although my vocabulary was severely limited. I didn’t entirely forget how to sit, stand, or walk, although the partial paralysis on my left side made all those tasks much more difficult. Based on the story about my riding a bicycle on the hospital roof—albeit with help from two burly orderlies—it’s clear that I must have been relatively strong and in good physical condition, which in turn may have helped with my overall recovery.
This is one example of a letter I wrote to my grandparents about six months after my head injury.
Other physical skills were lost. For instance, one nurse noted that I was unable to brush my hair, I was unable to drink from a cup, and I had to relearn how to eat. But I proved particularly adept at mimicking the actions of others. A physical therapist discovered that I could accomplish some physical tasks while watching myself in a mirror (tasks that were beyond me without it), apparently tapping some deep muscle memory.
Like many amnesiacs, I am told I had trouble remembering that I even had a damaged memory. In the early days of my recovery, “you didn’t seem to know that memory was an issue,” Jim recalls, and I had to be frequently reminded of my deficits. “There were times when I had the sense that you knew something was terribly wrong, but that was generally, and perhaps exclusively, when you were being asked to do something that you couldn’t do, or didn’t understand what was being asked of you because you didn’t understand the words being used.”
I have been told that my case is puzzling to scientists. The scope of my memory loss places me among the most severe cases of retrograde amnesia on record. Very few amnesiacs have lost all trace of episodic memory; very few are unable to recall a single life experience. I am unusual, too, in the extent of my recovery. But the most confounding part of my story, for scientists, is the lack of visible damage to my brain. I sustained a head injury; of that there is no doubt. But the doctors who examined me after the accident found only faint evidence of palpable injury to my brain itself: on the CT scan I had in the hospital, and on an MRI of my spine that showed a sharply diminished flow of blood in the right vertebral artery, consistent with the partial paralysis on my left side. Those findings are, to this day, the sole direct evidence of physical damage to my brain.
“We always try to relate these conditions to neuroanatomy”: in other words, to trace memory loss to damage in specific areas of the brain, says Larry Squire, a memory scientist at the University of California, San Diego. “And we know what kinds of damage cause what types of conditions. But the cases that are particularly hard to relate to anatomy are head injuries,” because those injuries are random and unpredictable, and the exact location of damage can be hard to pinpoint.
According to Daniel Schacter, the Harvard scientist who studied the amnesiac Gene, damage to the medial temporal region at the inner core of my brain might have compromised my ability to form new episodic and semantic memories, and such damage might also have hindered my recall of old memories. Damage to the frontal lobe as recorded in my CT scan would affect my ability to comprehend the source of episodic memory “scenes” and my capacity to be aware of my memory loss.
But because my episodic memory was completely erased, Schacter says, “You would expect to see more evidence of brain damage” than my brain scans revealed. “It doesn’t sound like there was a detectable brain lesion.”
However, Michael Yassa, a researcher at Johns Hopkins, points out that MRI technology has improved dramatically since the 1980s. He thinks it’s possible that if I got an MRI today, doctors would see some damage that wouldn’t have been visible back then. Assuming that I did, in fact, suffer an injury to my brain, there are at least three possibilities for where the damage could lie, according to Yassa. “One is, it could be a frontal lobe problem,” the area of the brain related to managing and making sense of episodic memories. “Two, it could be a hippocampus problem”; the hippocampus is an organ in the inner core of the brain that is critical to forming new episodic and semantic memories and to creating permanent memories. “Three, it could be a problem with the connection between the two.” If brain imaging shows no serious damage to either region, Yassa reasons, then the problem likely lies in that connection.
Larry Squire, at UC San Diego, says my case is particularly unusual in that I suffered “such extensive retrograde amnesia and not so much anterograde amnesia, at least not much that has persisted.” Amnesiacs with severe loss of past memories tend to also have chronic trouble making new memories. Squire suggests that I might have suffered damage to the lateral temporal cortex, the area adjacent to the medial temporal region and associated with long-term memory storage, in contrast to the medial temporal “core,” where those memories are built. “If one had a lesion that was primarily in the lateral temporal cortex, but the damage was such that it was still possible” for brain signals “to get into the medial temporal lobe,” such an injury “could approximate what’s being described,” he says.
All of these scientists are quick to note that complete retrograde amnesia is very rare—so rare that it is sometimes called “Hollywood amnesia,” existing more in movies than in real life. Yassa believes the reason for my total memory loss could be that I was relatively young at the time of my injury. He says it is possible that, at the age of twenty-two, none of my memories were fully consolidated and etched into permanent storage. Many amnesia patients are much older than twenty-two when their memory deficits appear, and their earliest memories are, at that point, several decades in the past. And scientists don’t know precisely how long it takes the brain to fully consolidate memories, to render them permanent. It’s thought to take years, at least, and possibly decades. By Yassa’s theory, my life memories might have been in a transitory state at the time of my injury: not in the memory bank, so to speak, but in the truck, on its way to the bank. The injury robbed the truck. If that’s the case, my memories are not buried somewhere within my brain, waiting for some hypnotist or surgeon to access them: They are gone. Schacter, the Harvard scientist, disagrees: At age twenty-two, he reasons, my early childhood memories would have been fully consolidated into permanent storage. That I cannot access them is exceedingly unusual, he says, but not unprecedented; remember Gene, who lost all of his life memories at thirty.
There is one other possibility, one that has always haunted me: the possibility that my memory loss could be psychological. “Functional” or “psychogenic” amnesia is memory loss caused not by brain injury or illness but by some psychological reason. The classic Hollywood case is the Hitchcock film Spellbound: A young doctor, played by Gregory Peck, has forgotten who he is and taken on another man’s identity. A glamorous therapist, Ingrid Bergman, helps him reclaim his identity by escorting him back to the place where he lost it: a mountain precipice where a friend had fallen to his death. Revisiting the site, the doctor relives the memory, and his lost identity comes flooding back.
After my release from the hospital, Jim took me to the neurologist about every two weeks. Jim says we lived for these appointments. One day, we showed up late, and were crushed when he refused to see me. At the same time, the way Jim tells it, I get the feeling that these appointments were an exercise in futility. The doctor would insist on seeing me alone, and afterward, I would have no idea of what I had said to him, or what he said to me. Then the doctor would give Jim a ninety-second generic summary and conclude with something like, “I’m not seeing any change.” He could find no physiological explanati
on for my memory loss, or for the lingering numbness in my left hand and foot. He gave me another MRI, and when the results came back, he told Jim, “I see absolutely nothing here. Her brain looks completely normal. I see no damage.” And then under his breath, “I think she’s just making all this up.”
Jim stopped taking me to the neurologist.
I get the feeling from everything I have heard that the doctors and everyone else in the medical community were maybe just as frustrated as Jim and I were. There didn’t seem to be any test or imaging that explained my symptoms. Everybody had told Jim that all of this was going to just be temporary, and when it wasn’t, it somehow became my fault. I was faking it. It was all in my head, psychological. And that makes absolutely no sense to me at all! Why would I want to be this way? Why would I—why would anyone—choose to be this way?
Happily for me, though, the facts don’t seem to bear out the possibility that it is “all in my head.” Psychogenic amnesia is “much rarer than amnesia that results from brain damage and easy to distinguish from it,” according to Larry Squire. When amnesia is psychological in origin, the damage is typically limited to past memories; the ability to form new memories is not impaired. People with psychogenic amnesia sometimes lose episodic memories of their own lives but retain semantic memories about the world. Others lose both episodic and semantic memories. Psychogenic amnesia can block the memory of a single event, a full life chapter, or a person’s entire past history. Often, psychogenic amnesia clears up in a relatively short span, and lost memories are recovered.
Squire and colleagues carried out the first study of a large group of patients with psychogenic amnesia, ten cases in all. The researchers found that almost no one in the group had trouble forming new memories. But eight of the ten had retrograde amnesia that lingered for more than a year after its onset.
