Review by Walter Cummins
One of the frequent plaints that emerges when two or more people of my age get together is lamentation over what we’ve been forgetting, primarily names of people and objects, resorting to the fillers of whosis and whatsis, relieved when minutes or even hours later the actual term pops into our memory. The fear—usually laughed off in public—is that a vanished word signals the first stage of Alzheimer’s.
Scott A. Small, who has made that cognitive disaster his medical specialty as the director of the Alzheimer’s Disease Research Center at Columbia University, opens Forgetting’s first chapter with the example of a patient named Karl who shows up in his office with that concern. An attorney with great pride of his excellent memory, he has begun to forget the names of new clients. Fortunately for Karl, he’s just experiencing age-related memory loss, the shrinking of the dendrite protrusions from the neurons that store memory. When Karl was a patient, Small didn’t have the tools to make a clear visual distinction between aging and Alzheimer’s. Now an fMRI he devised can detect neuronal sickness in each region of the hippocampus and provide visual evidence of the clear distinction between aging and Alzheimer’s hippocampi.
The memory loss of aging brains may seem a contradiction to the focus of Small’s title, though he clarifies: “Only by observing the painful consequences of pathological forgetting in patients does normal forgetting emerge in sharp relief.”
There’s no benefit to Karl forgetting a client’s name, but in the larger context of all human functioning, not just that of elderly attorneys, it’s a positive to forget, even essential. Too much information can glut our minds with a plethora of excessive details: “We now know that forgetting is not just normal but beneficial to our cognitive and creative abilities, to our emotional well-being, and even to societal health.”
Small credits Jorge Luis Borges’ story ““Funes, the Memorious,” with dramatizing this crucial insight before neuroscientists made the discovery. After he is thrown from a horse, Funes’s inflamed brain stores everything he encounters. With his mind “overloaded with the day’s minutiae,” he has lost the ability to see patterns and connections, in effect comprehending the way the world works.
Humans, therefore, must go through constant pruning to rid their memories of the nonessential. To lead normal lives, we must navigate between the extremes of a literally photographic memory and the abyss of final-stage Alzheimer’s.
Small considers three variations of a memory trap. He explains how those with severe autism are traumatized by the encounter with a change in a familiar pattern of behavior. In effect, rigid memory is a crutch for their coping with the world around them, an escape from having to integrate new information and confront change.
In contrast, those suffering PSTD are haunted by emotionally paralyzing memories of cataclysmic events they are unable to escape. Small himself shares first-hand knowledge of his involvement in a bloody battle while a soldier in the Israeli army. He later participated in a study to determine why he and others escaped the emotional haunting that others did not, theorizing that those who mocked the event and escaped in comradeship alcohol and pot were able to free themselves from a future of disabling nightmares.
Beyond the emotional pains of individuals directly involved in a disaster are the happenings that affect whole societies for generations, even centuries. Much of the world’s tensions are shaped by historical memories and legends of what afflicted ancestors beyond directly experienced sufferings. The example Small uses, however, relates to one man’s ability to overcome the painful legacy of the Holocaust. Eric Kandel, now a Nobel-winning memory researcher, and his family, as Jews, were forced out of Austria in time to escape concentration camps yet merge their experience with that of family, friends, and millions who perished, to harbor deep anger and resentments against all Austrians. Yet Kandel was able to free himself from those memories and become a participant in that country’s attempt to heal from the crimes of World War II. Small suggests, “If personal memory flexibility requires, as we have seen, active forgetting, then so does communal memory.”
Small also describes how from their skyscraper office in northern Manhattan, he and others in his office witnessed the collapse of the twin towers on 9/11. Their immediate reaction was “rageful xenophobia.” Yet though participating in communal memorials within days they were able to calm their cries for revenge: “But letting go of seething resentments is required for forgiveness—the noblest example of the benefits of a forgetful mind.”
While memories are central to these three categories, they are very specific and essentially unforgettable. The Funes-like memories are of a different nature. They embody literally everything that the person encounters, a clogging accumulation of endless specifics that overwhelms the capability to function in the world. Of course, such people are very rare, just painful case studies. Almost everyone else is capable of pruning away the vast excess to retain only what matters. People must forget the great majority of all that they encounter on a typical day. Luckily, humans possess a mechanism for this pruning:
New insight in the past few years has uncovered a completely separate set of molecules involved with normal forgetting, a molecular toolbox distinct from growing spines. When this “forgetting toolbox” is opened, its tools carefully disassemble spines, shrinking their size.
Francis Crick, the 1962 Nobel laureate for deciphering the structure of DNA, theorized that nightly dreaming plays a central role in cleansing our memory bank: “We dream in order to forget.” While we sleep, all the excessive memory spines wilt. Small explains the process:
After a good night’s sleep, we might expect to see some pockets of newly grown spines, now stabilized into a memory. But the net effect, comparing the cortex at the day’s end and the morning after, would be spine shrinkage—that is, the net effect of sleeping is forgetting.
Sleep induced forgetting is essential to the flexibility that allows memory interactions to be “loose and playful.” Ultimately, two types of memory frustrate this need. Personal and historical memories can bind us with knots of obsessive reliving. But, in addition, an excessive store of experiences could paralyze us with useless distractions. Forgetting is essential for a functional life.