Remember: The Science of Memory and the Art of Forgetting

by Lisa Genova

Creating a memory takes place in four basic steps: Encoding. Your brain captures the sights, sounds, information, emotion, and meaning of what you perceived and paid attention to and translates all this into neurological language. Consolidation. Your brain links the previously unrelated collection of neural activity into a single pattern of associated connections. Storage. This pattern of activity is maintained over time through persistent structural and chemical changes in those neurons. Retrieval. You can now, through the activation of these associated connections, revisit, recall, know, and recognize what you learned and experienced.

Memory is different. When we remember something, we’re not withdrawing from a “memory bank.” There is no memory bank. Long-term memories don’t reside in one particular neighborhood in your brain.

The number one reason for forgetting what you just said, a person’s name, where you left your phone, and whether you already drove over a really big bridge is lack of attention.

We have three basic types of long-term memories: memory for information, memory for what happened, and memory for how to do things.

Repetition is the key to muscle memory mastery.

Episodic memory is time-traveling to your past.

If you experience something highly unexpected and exceptionally emotional, you might create what is known as a flashbulb memory.

Flashbulbs are episodic memories for experiences that were shocking and highly significant to you and evoked big emotions—fear, rage, grief, joy, love. These stunningly unexpected, personally important, and emotionally charged experiences become memories that feel resistant to fading and can be readily recalled years later.

Strung together, your most meaningful episodic memories create your life story and are collectively called your autobiographical memory. This is your highlights reel—your

We can still remember what happened from the past couple of years pretty well, thanks to what is called the recency effect. We don’t have to brush away too many cobwebs or dig too far into the attic to find these recently created memories, and so they’re easy to grab.

The average American adult today spends almost twelve hours a day in front of some kind of screen. If you’re getting eight hours of sleep a night, that means you’re conscious for nonscreen experience for only four hours a day. If you want to have three-dimensional, richly detailed memories of what’s happening in your life, you have to get out there and live in the three-dimensional world.

Putting any sensory experience into words distorts and narrows the original memory of the experience.

This common kind of memory error is called a confabulation. Information provided by your coworker wriggled its way into your episodic memory.

One of the most common experiences of memory failure is known as blocking or tip of the tongue (TOT). You’re trying to come up with a word, most often a person’s name, a city, a movie title, or the name of a book.

Prospective memory is your memory for what you need to do later. This kind of memory is a bit like mental time travel.

More recent studies have shown that if the collection of synapses representing a memory isn’t activated over time, the connections will be physically pruned away. If dormant for too long, neurons will literally retract their anatomical, electrochemical connections with other neurons. The connections, and consequently the memory contained in those connections, will no longer exist.

Ebbinghaus’s forgetting curve for meaningless information,

But maybe you want to forget something. Let’s say your spouse cheated on you, and you got divorced. Want to forget the sordid details and the heartache you’re feeling? Stop repeating the story of what happened. Stop going over the details with your friends and in your thoughts. Don’t overlearn the experience. If you can find the discipline to leave those memories alone, they will eventually fade.

People with post-traumatic stress disorder (PTSD) can’t stop retrieving, reliving, and reconsolidating unwanted memories, and unfortunately, these individuals unwittingly strengthen these memories with every unwelcome recall.

Tell your brain, “Forget about it. Don’t keep this. Let it go”—and your brain might obey. Self-instruction can work and is thought to do so by both derailing consolidation before new memories are fully created and activating neural signaling programs that deliberately erase memories already formed.

Memory impairment due to Alzheimer’s (often called dementia, an umbrella term that includes deficits in memory, language, and cognition) isn’t caused by slower processing speeds or diminished attention.

Think of amyloid plaques as a lit match. The lit match alone doesn’t cause a problem, but at the tipping point, the match sets fire to the forest. Your brain is now ablaze with Alzheimer’s disease. And you are now experiencing significant, abnormal memory loss.

Failure to retrieve the right words is another early symptom of Alzheimer’s.

Also, people with Alzheimer’s start to use simpler and simpler words. Bag instead of suitcase or luggage. Paper or thing instead of document. This kind of blocking is not an uncomfortable, relatable inconvenience. This is now disruptive, profound memory loss. This is dementia.

Unfortunately, Alzheimer’s doesn’t just stay put in the hippocampus. It goes on a murderous road trip, invading other regions of the brain. As it spreads to the parietal lobes, where spatial information is processed, people with Alzheimer’s start getting lost in familiar places.

People with Alzheimer’s start misplacing their keys, wallets, phones, glasses, laptops, and money.

Alzheimer’s also gunks up the amygdala and limbic system, brain regions that control mood and emotion. So grief, rage, and lust might become dysregulated and disinhibited.

Plenty of scientific evidence demonstrates that relentless, unmanaged stress is toxic for your body and brain. Chronic stress can contribute to the development of many diseases and ailments, such as type 2 diabetes, heart disease, cancer, infections, pain disorders, panic attacks, insomnia, depression, and Alzheimer’s disease.

Stress itself isn’t deadly, but excessive exposure to it creates the opportunity for many other things to kill you.

Psychological stress can be caused by a perceived lack of certainty, control, predictability, social support, or belonging. And even if the stressor you’re perceiving or anticipating never happens, you will have lived through the stress response in your brain and body by simply imagining it.

In fact, unrelenting stress is disastrous for your memory.

Stress inhibits your prefrontal cortex, impairing your ability to think.

Chronic stress inhibits neurogenesis in the hippocampus. So if you’re experiencing unrelenting, unmanaged stress, you’ll have a smaller hippocampus, which means fewer neurons available to consolidate memories, which means your ability to create new memories will be impaired. Hippocampal neurons under continual exposure to stress and cortisol also seem to be more vulnerable to damage by other insults, such as a stroke or Alzheimer’s disease.

Through yoga, meditation, a healthy diet, exercise, and practices in mindfulness, gratitude, and compassion, we can train ourselves to become less reactive, to put the brakes on the runaway stress response, to stay healthy in the face of toxic anxiety.

Insufficient sleep is likely to be a significant risk factor in the development of Alzheimer’s.

Every night, your sleep processes actively fight off heart disease, cancer, infection, and mental illness. The vitality of every organ system in your body—including your brain—is improved when you get enough sleep, but your health and ability to remember is drastically compromised when you don’t. Sleeping less than seven to nine hours a night poses a real risk to your health, both the next day and over a lifetime.

In summary, if you don’t get seven to nine hours of sleep tonight, Your frontal cortex neurons will be sluggish tomorrow, hampering your ability to pay attention and therefore to encode important new memories; You won’t as clearly and completely remember what you learned and experienced yesterday; You’ll see no improvement in your golf swing, despite yesterday’s lesson and eighteen holes; You might prematurely max out on what you can learn today; and You might be increasing your risk of developing Alzheimer’s.

In the United States, one in ten people at age sixty-five has Alzheimer’s. At eighty-five, it’s one in three, fast approaching one in two. Half of us.

Several studies have now clearly demonstrated that people who eat foods from the Mediterranean diet or the MIND diet (a combination of the Mediterranean diet and DASH [dietary approaches to stop hypertension]) cut their risk of Alzheimer’s disease by anywhere from a third to a half. Those results are significant. If I told you that the U.S. Food and Drug Administration just approved a medication that reduces your risk of Alzheimer’s by 50 percent, would you take it? You bet you would. Both the Mediterranean and the MIND diets include green leafy vegetables, brightly colored berries, nuts, olive oil, whole grains, beans, and fish (especially fish rich in omega-3 fatty acids, which our bodies don’t make on their own).

As a rule of thumb, anything that is good for your heart is good for your brain—and for preventing Alzheimer’s.

Called the superiority illusion, the idea goes like this: You are more likely to remember a detail about yourself or something that you did than you are to retain a detail about someone else or something someone else did.