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 typicallyremember 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 Iwas, 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
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 typicallyremember 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 Iwas, 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
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