Remember: The Science of Memory and the Art of Forgetting

by Lisa Genova

Memory is the sum of what we remember and what we forget, and there is an art and science to both.

Alzheimer’s disease begins its rampage in the hippocampus.

With an impaired hippocampus, people with Alzheimer’s have trouble creating new memories.

Memory is stored throughout your brain in the pattern of neural activity that was stimulated when the event or information was first experienced.

Whenever we remember something, we are reactivating the various elements of the information we experienced, woven together as a single unit.

If we want to remember something, above all else, we need to notice what is going on. Noticing requires two things: perception (seeing, hearing, smelling, feeling) and attention.

You find what you look for. If you look for magic every day, if you pay attention to the moments of joy and awe, you can then capture these moments and consolidate them into memory. Over time, your life’s narrative will be populated with memories that make you smile.

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

While semantic and episodic memories are consolidated via the hippocampus, muscle memories are bound together by a part of the brain called the basal ganglia.

The stuff you know, so-called semantic memory, is memory for the knowledge you’ve learned, the facts you know about your life and the world—the Wikipedia of your brain. And you can recall this information without remembering the details of learning it. Semantic memory is knowledge disconnected from any personal when and where. It is data unattached to any specific life experience.

Memories for what happened, for information that is attached to a where and when are called episodic. You remember episodic memories. “Remember when we went to Budapest.” Semantic memories, on the other hand, feel more like information that you just know. “Budapest is the capital of Hungary.” Episodic is personal and always about the past. Semantic memory is about information and is timeless. Just the facts, ma’am.

Repeated testing beats repeated studying.

Your brain isn’t interested in knowing what’s boring or unimportant. If you want to know more stuff, make the information meaningful to you.

Episodic memory, your memory for what happened in your life, is the history of you remembered by you.

Life events infused with emotion are what we tend to remember long term—triumphs,

Emotion and surprise activate a part of your brain called the amygdala, which, when stimulated, sends powerful signals to your hippocampus that basically communicate this: Hey, what’s going on right now is super important.

most of life’s episodic memories are likely to be clustered between the ages of fifteen and thirty. Called the reminiscence bump, these episodes are what we remember most in life.

Prospective memory is your memory for what you need to do later.

The number one archenemy of the memories you’ve created and stored is time.

Unless you actively do something to remember some piece of information, your brain will automatically forget it.

Episodic memory recall also decreases normally as we age. We forget more of what happened, but what we can recall is as accurate (and inaccurate) as younger people’s recollections.

Processing speeds normally begin diminishing in our thirties, which means it takes longer to learn new information and longer to retrieve stored information.

In the beginning stages of Alzheimer’s, dementia results from a molecular war in the neural synapses involved in consolidating and retrieving memories, rendering those connections impassible. In later stages of the disease, forgetting is caused by the death and loss of the neurons themselves.

Alzheimer’s begins in the hippocampus, which by now you know is a brain structure essential for the formation of new, consciously held memories.

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. If

Alzheimer’s will also compromise neural circuits in the prefrontal and frontal cortices—the most newly developed parts of the brain. With these regions affected, individuals experience impairments in logical thinking, decision-making, planning, and problem-solving.

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.

Alzheimer’s also invades the circuitry that houses your muscle memories. When this happens, people with Alzheimer’s forget how to do the things they learned how to do.

Progression from the first symptoms of forgetting to end-stage Alzheimer’s takes an average of eight to ten years.

Forgetting due to Alzheimer’s is pervasive, catastrophic, tragic, and not normal.

Memory retrieval is far easier, faster, and more likely to be fully summoned when the context of recall matches the context that was present when the memory was formed.

Matching the context you’re in for recall with the conditions you were in when you learned the information improves recall. Mismatched conditions impair recall.

When chronic stress continually alerts your amygdala, you’ll be spending too much time and energy in your primitive, emotional brain and not in your thinking brain.

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

if you’re under constant stress, you’ll start losing neurons in your hippocampus.

a study of perceived stress levels in eleven hundred women aged thirty-eight to sixty over thirty-five years, women who reported experiencing chronic stress had a 65 percent increased risk of Alzheimer’s.

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 puts you at a higher risk for heart disease, cancer, infection, mental illness, Alzheimer’s, and memory impairment.

Many studies show that people become increasingly worse at learning new things as the day wears on. Unless they nap.

it can take fifteen to twenty years of amyloid plaque accumulation before we become symptomatic for Alzheimer’s—we

People with low vitamin D are twice as likely to develop Alzheimer’s as are folks with normal vitamin D levels.

Older adults with a single copy of APOE4, a gene variant associated with an increased risk of Alzheimer’s, had a 3 percent decrease in hippocampus size over 1.5 years—but only if they were sedentary. If they exercised, they showed no hippocampal shrinkage. The more you sit, the smaller your hippocampus.

Building an Alzheimer’s-resistant brain through cognitive stimulation means learning to play piano, meeting new friends, traveling to a new city, or reading this book.

People do not consist of memory alone. They have feelings, will, sensibility, moral being. It is here you may touch them and see profound change. —Alexander Luria