to remember more. Maybe they’ll talk about the older woman, who rescued them.” Over time, more and more detail crept into the false memory: “The old lady was wearing this crazy hat”; “I had my favorite toy with me”; “My mom was so mad”.
So not only was it possible to implant false new memories in the brain, but people embraced and embellished them, unknowingly weaving fantasy into the fabric of their identity.
We’re all susceptible to this memory manipulation – even Loftus herself. As it turns out, when Elizabeth was a child, her mother had drowned in a swimming pool. Years later, a conversation with a relative brought out an extraordinary fact: that Elizabeth had been the one to find her mother’s body in the pool. That news came as a shock to her; she hadn’t known that, and in fact she didn’t believe it. But, she describes, “I went home from that birthday and I started to think: maybe I did. I started to think about other things that I did remember – like when the firemen came, they gave me oxygen. Maybe I needed the oxygen ’cause I was so upset that I found the body?” Soon, she could visualize her mother in the swimming pool.
But then her relative called to say he had made a mistake. It wasn’t the young Elizabeth after all who had found the body. It had been Elizabeth’s aunt. And that’s how Loftus had the opportunity to experience what it was like to possess her own false memory, richly detailed and deeply felt.
Our past is not a faithful record. Instead it’s a reconstruction, and sometimes it can border on mythology. When we review our life memories, we should do so with the awareness that not all the details are accurate. Some came from stories that people told us about ourselves; others were filled in with what we thought must have happened. So if your answer to who you are is based simply on your memories, that makes your identity something of a strange, ongoing, mutable narrative.
The aging brain
Today we’re living longer than at any point in human history – and this presents challenges for maintaining brain health. Diseases like Alzheimer’s and Parkinson’s attack our brain tissue, and with it, the essence of who we are.
But here’s the good news: in the same way that your environment and behavior shape your brain when you’re younger, they are just as important in your later years.
MEMORY OF THE FUTURE
Henry Molaison suffered his first major epileptic seizure on his fifteenth birthday. From there, the seizures grew more frequent. Faced with a future of violent convulsions, Henry underwent an experimental surgery – one which removed the middle part of the temporal lobe (including the hippocampus) on both sides of his brain. Henry was cured of the seizures, but with a dire side effect: for the rest of his life, he was unable to establish any new memories.
But the story doesn’t end there. Beyond his inability to form new memories, he was also unable to imagine the future.
Picture what it would be like to go to the beach tomorrow. What do you conjure up? Surfers and sandcastles? Crashing waves? Rays of sun breaking through clouds? If you were to ask Henry what he might imagine, a typical response might be, “all I can come up with is the color blue”. His misfortune reveals something about the brain mechanisms that underlie memory: their purpose is not simply to record what has gone before but to allow us to project forward into the future. To imagine tomorrow’s experience at the beach, the hippocampus, in particular, plays a key role in assembling an imagined future by recombining information from our past.
Across the US, more than 1,100 nuns, priests, and brothers have been taking part in a unique research project – The Religious Orders Study – to explore the effects of aging on the brain. In particular the study is interested in teasing out the risk factors for Alzheimer’s disease, and it includes subjects, aged sixty-five and over, who are symptom-free and don’t exhibit any measurable signs of disease.
Keeping a busy lifestyle into old age benefits the brain.
In addition to being a stable group that can be easily tracked down each year for regular tests, the religious orders share a similar lifestyle, including nutrition and living standards. This allows for fewer so-called “confounding factors”, or differences, that might arise in the wider population, like diet or socioeconomic status or education – all of which could interfere with the study results.
Data collection began in 1994. So far, Dr. David Bennett and his team at Rush University in Chicago have collected over 350 brains. Each one is carefully preserved, and examined for microscopic evidence of age-related brain diseases. And that’s only half the study: the other half involves the collection of in-depth data on each participant while they’re alive. Every year, everyone in the study undergoes a battery of tests, ranging from psychological and cognitive appraisals to medical, physical, and genetic tests.
Hundreds of nuns have donated their brains for examination after their death. Researchers were caught off guard by the results.
When the team began their research, they expected to find a clear-cut link between cognitive decline and the three diseases that are the most common causes of dementia: Alzheimer’s, stroke and Parkinson’s. Instead, here’s what they found: having brain tissue that was being riddled with the ravages of Alzheimer’s disease didn’t necessarily mean a person would experience cognitive problems. Some people were dying with a full-blown Alzheimer’s pathology without having cognitive loss. What was going on?
The team went back to their substantial data sets for clues. Bennett found that psychological and experiential factors determined whether there was loss of cognition. Specifically, cognitive exercise – that is, activity that keeps the brain active, like crosswords, reading, driving, learning new skills, and having responsibilities – was protective. So were social activity, social networks and interactions, and physical activity.
On the flip side, they found that negative psychological factors like loneliness, anxiety, depression, and proneness to psychological distress were related to more rapid cognitive decline. Positive traits like conscientiousness, purpose in life, and keeping busy were protective.
The participants with diseased neural tissue – but no cognitive symptoms – have built up what is known as “cognitive reserve”. As areas of brain tissue have degenerated, other areas have been well exercised, and therefore have compensated or taken over those functions. The more we keep our brains cognitively fit – typically by challenging them with difficult and novel tasks, including social interaction – the more the neural networks build new roadways to get from A to B.
Think of the brain like a toolbox. If it’s a good toolbox, it will contain all the tools you need to get a job done. If you need to disengage a bolt, you might fish out a ratchet; if you don’t have access to the ratchet, you’ll pull out a wrench; if the wrench is missing you might try a pair of pliers. It’s the same concept in a cognitively fit brain: even if many pathways degenerate because of disease, the brain can retrieve other solutions.
The nuns’ brains demonstrate that it’s possible to protect our brains, and to help hold on to who we are for as long as possible. We can’t stop the process of aging, but by practicing all the skills in our cognitive toolbox, we may be able to slow it down.
I am sentient
When
