If there is one thing that all human beings seem to have in common, it is the fear of losing their memories. After all, memory shapes our personality, determines how we see ourselves, and contributes to shared experiences on multiple levels. Losing one’s memory is akin to losing an entire life history.
The 21st century offers various technologies that keep us from forgetting the little things, such as phone numbers, which are now a touch away on our smartphones. But could mobile phones actually contribute to one’s forgetfulness? Is age to blame for memory loss? Genetics? Or maybe a combination of all of the above?
Recently, a team of scientists working under Prof. Rafi Malach of the Department of Neurobiology at the Weizmann Institute of Science published the findings of a breakthrough study on this topic, in collaboration with neurosurgeon Ashesh D. Mehta and his team at the Feinstein Institute for Medical Research in the United States.
Titled, “Hippocampal sharp-wave ripples linked to visual episodic recollection in humans,” the article was published in August in Science Magazine, the peer-reviewed academic journal of the American Association for the Advancement of Science, which is considered one of the top academic journals in the world.
The study showed that within the hippocampus — a major part of the human brain that plays an important role in the consolidation of information from short-term memory to long-term memory — large groups of nerve cells experience what can be described as rapid and powerful “electrical flare-ups” that characterize both the creation of memories and their retrieval.
Neurobiology doctoral candidate Yitzhak Norman, who co-authored the article, said the anxiety associated with memory loss is more than understandable.
“Memory is one of the cornerstones of one’s personality. You depend on memory very intimately — it determines how you perceive yourself and what you remember about yourself. That’s why any memory impairment is so frightening to us. The disintegration of memory is akin to the disintegration of the self. And what scares us the most is that this process can happen to us without us knowing it’s taking place,” Norman told Zman Yisrael, the Hebrew sister site of The Times of Israel.
According to Norman, the scientific findings coincide with seemingly random experiences we all share, such as finding it difficult to remember names or the answer to a simple trivia question.
“One of the things that happen in the hippocampus is context coding — the context of where a particular experience is experienced, when, and under what circumstances. It is believed that the hippocampus is the one that associates experiences with a particular context,” Norman explained.
“When you try to remember something, you use your ‘episodic’ imagination and memory system to do a little time traveling and go back to the point where the memory was created. When you manage to reimagine the point in time when the memory was created, there’s a good chance you’ll be able to retrieve it,” Norman said.
A beautiful mind
According to Norman, one of the key challenges in brain research is that when scientists study the brain of an animal, such as a rat, it can’t relay back to the researchers what it is experiencing mentally. “To investigate complex neurological processes that occur deep in the human brain we need invasive measures, meaning we have to insert electrodes into the brain to directly measure the electrical activity of the nerve cells,” said Norman.
Such experiments with humans are not done routinely. In fact, the only group currently participating in such an experiment comprises people suffering from severe epilepsy, who experience multiple, debilitating seizures a week.
“This is a very serious illness and these patients are initially offered medication, but if that fails to reduce the seizures, modern medicine has nothing to offer them except invasive neurosurgical treatments,” Norman said, explaining that these procedures include inserting electrodes into epilepsy patients’ brains and monitoring their brain activity around the clock, for a period of between seven and 10 days.
This allows researchers to identify where an epileptic seizure begins in the brain and which area of the brain was first involved in it. The neurons suspected of triggering seizures are then cauterized off.
“The success rate of this treatment is very high,” he said. “About 60 percent of epilepsy patients that undergo this treatment will no longer experience seizures. That’s remarkable.”
The brain as a computer
According to Norman, in an experiment that involved 15 epilepsy patients conducted over four years, participants had electrodes inserted into their brain and were monitored as they memorized a list of famous people and places from photos. After a short diversion, the subjects were asked to recall what they saw as the researchers monitored the areas in the brain responsible for recollection.
The results showed nothing less than a party by the neurons in the hippocampus.
We could clearly see how a second before he remembered something, his hippocampus experienced significant electrical activity
“The first person we tested in this experiment, an American guy in his 30s, showed the clearest activity in the hippocampus,” Norman recalled. “We heard him talk and simultaneously monitored the electrical activity in his brain. We could clearly see how a second before he remembered something, his hippocampus experienced significant electrical activity.”
When the subject had difficulty remembering something and recalled it a few seconds later, “You could see the electrical activity [in his brain] hovering around zero and then there would be a very significant uptick in electrical activity, meaning a second before he remembered the answer, the hippocampus ‘lit up’ and sends a major output to the cerebral cortex,” Norman said.
“The nature of exactly what the hippocampus ‘says’ is unclear, but we think that what it does is create some sort of index of memories, and when activated, it sends a retrieval command to the place [in the brain] where the full details of that memory are stored, making you remember,” he explained.
The brain has often been described as a computer, so the question remains if brain research becomes substantially more comprehensive — spanning hundreds of thousands of subjects — and is able to further glean how the brain stores and retrieves information, would mankind be able to deal with the issue of memory loss?
Over the last 20 years there has been a leap in our understanding of memory mechanisms. But it’s a very complex process
The safest answer, it seems, is maybe.
“That’s a very big question,” Norman said. “As someone who’s been following this field closely, making sure to follow the literature and new studies that are published, I can say that over the last 20 years there has been a leap in our understanding of memory mechanisms. But it’s a very complex process.”
Norman came to brain research from the study of cognition and philosophy at the Hebrew University of Jerusalem. He was so intrigued that he decided to investigate the workings of the human psyche.
“I wanted to understand consciousness. How it knows things in the world. How it perceives things that exist within our inner world,” he said.
But comparing the brain to a computer does not necessarily mean that researchers deal with the “hardware” as opposed to the “software” as the two are not only connected — they may be one and the same.
“They may be two sides of the same coin: One side that reveals itself as neuron activity when you look at it from a material aspect, and another side that requires us to look inward, and manifests as ‘information’ or ‘mental representation.’ To figure the latter out we need people to tell us about it. What this study allows us to do is get the most direct, highest-resolution look at the human-thought-memory process, and simultaneously see the cerebral process happening,” Norman said.
According to Norman, hippocampal flare-ups can be used to significantly improve memory.
“Using an electrode, you can stimulate the hippocampus with light or electrically and artificially extend the memory-related brainwave, providing that you recognize the process on time,” he said.
Science, not fiction
The possibility that one day people could be fitted with a helmet that stimulates the memory centers in their brains, thus ridding them of any memory problem, may seem like something out of a science-fiction movie — but in reality, it’s not.
“This is already happening, albeit only in rats,” Norman said. “[The researchers] took a rat, identified when it experienced these flare-ups and amplified them using electrodes. What they saw was that every time they amplified the flare-ups, the rat learned faster and had a better memory.
“It had to find its way through a maze, and you could see that its ability to navigate the maze was greatly improved. This indicated an improvement in its spatial perception memory, which is the main purpose of the memory in rats. After all, what do they do? Navigate through burrows,” he said.
According to Norman, one of the questions researchers are trying to answer is whether the human memory mechanism can actually be trained.
“It really opens a door for endless research questions. For example, let’s detect a pattern of brain activity, say, while you’re sleeping, and strengthen it in a way that it leads to an increase in neuron activity related to hippocampal memory encoding and retrieval. That’s a question several teams in Israel and around the world are currently researching,” Norman said.
But what about awakening forgotten memories? Researchers have long found that keeping records — such as a journal or photos — can help us preserve memories that otherwise would be buried in our minds.
We no longer look at our brains just as something that’s inside the skull. The brain today delegates powers to everyday devices that are all around us
“There’s a saying, ‘A short pencil is better than a long memory.’ We see it more and more today, thanks to technology. Today, the smartphone functions as an extension of our memory,” said Norman.
“We no longer look at our brains just as something that’s inside the skull. The brain today delegates powers to everyday devices that are all around us. That’s why people today don’t know how to navigate without Waze,” he explained, referring to the popular GPS-based mobile navigation application. “The brain can allow the functions associated with memorizing routes and navigation to atrophy.”
This may weaken some aspects of one’s memory while strengthening others, as the brain diverts its memory resources to other issues, he said.
People who remember events in great detail, he noted, may simply have a larger hippocampus. This means that this part of the brain can be trained, like a muscle.
“There are all kinds of groups that are exploring how memory can be trained and strengthened. In this matter, I can share my own intuition: if you want to strengthen your memory, sit down for half an hour at the end of each day and think back about everything that happened during the day. Think of it as memory meditation,” he said.
Essentially, Norman believes that what many see as mundane small talk — asking people in your life “how was your day” and hearing the smallest details about gridlock and the line at the grocery store — plays a role in bolstering memory.
If you want to strengthen your memory, sit down for half an hour at the end of each day and think back about everything that happened during the day. Think of it as memory meditation
Even people with a good memory need to take those 30 minutes at the end of the day and process its occurrences.
“Run a conversation you had in your head, process it again, arrange it in your memory in a more coherent way. This can help [the brain] to store it better and have easier access to it in the future,” he said.
A night to remember
Norman stressed that it is important that memory training be done before you go to sleep, explaining that “sleep has a very important part in building memories and there are ample studies to support that. When we sleep, the hippocampus reactivates flashbacks of what we experienced throughout the day. It essentially recreates behavioral patterns experienced during waking hours.”
“Whether or not dreams have anything to do with it remains an open-ended question, but it probably doesn’t happen as part of REM sleep,” he continued, referring to rapid eye movement sleep — one of the two basic states of sleep, the other being quiescent sleep.
“When you sleep, [dreaming] has something to do with your experiences and some details come from real life, but not all the details and not necessarily in every dream,” Norman said.
Sleep has a very important part in building memories, and there are ample studies to support that
“It is unclear what dictates the behavior of dreams. It is precisely in this stage, that’s not a dream sleep, in the deepest sleep, that the hippocampus experiences these flare-ups once every two seconds and with it, the cerebral cortex goes through the patterns of activity that it experienced during the day. According to recent studies, this is probably the stage where the brain arranges the memories it accumulated during the day,” he said.
Multiple studies have proven the link between a good night’s sleep and good memory.
“By the way, one of the answers to the question of why we sleep in the first place is that it takes time for the brain to sort out memories and transfer them from the hippocampus to the cortex, where they can be stored more permanently,” Norman said.
The hippocampus, said Norman, is very dynamic and constantly works with new informational input and output. “The cortex is where information can be stored in a more orderly fashion. It’s very interesting to see how the brain does this during sleep, when it’s not bombarded by information all the time,” he said.
“You don’t even dream, so the brain can finally say, ‘Quiet, give me a second. Let me sort things out,'” Norman continued. “That’s why I think if you take that half hour before bed to arrange the day’s experiences it’s super important for your memory. The brain needs you to stop inserting input and let it sort out what it already has.”
Memories are made of these
Norman said that since social media came onto the scene, it seems that consumers of it are under a constant barrage of information, which overloads our brains.
“There is an inflation of information. The brain is bombarded with constant, unimportant information and it’s like it says, ‘Stop, I can’t process it all.’ Then you become a little apathetic,” he said.
While those of us who grew up in the 1970s and 1980s have to rely on our own recollection of childhood events, whatever photos we had taken and the occasional home video, today, children’s lives are constantly documented, which is likely to completely change how they remember their childhood.
There is an inflation of information. The brain is bombarded with constant, unimportant information and it’s like it says, ‘Stop, I can’t process it all.’ Then you become a little apathetic
“We don’t have the perspective to answer such questions yet,” he said. “I was born in 1985, so I’m in the transitional generation — half of my adolescence was without the internet and the smartphone, and from high school and my military service we already had internet, smartphones and social media. Somehow we were with one foot here and one foot there and a generational gap was created that is very much related to memory and self-image.”
“How you will remember yourself in the future — your self-image today, your memory of yourself — is already intertwined with some kind of digital and virtual image that’s out there somewhere,” Norman said. “Today you’re constantly experiencing yourself through photos as well as how through you present yourself to others [on social media]. That also affects memory because others’ perception prompts profound changes in consciousness.”
In the context of social media, Norman explained that through uploading a photo of yourself or details about your personality, you are allowing multiple people to access the recorded memory, which, he said, alters your own perceptions of the memory.
“I am very aware of this experience — letting someone else into your inner world changes something essential in your consciousness. Someone else’s access instigates a profound and intimate change in your own experience, which is bound to make a profound and intimate change in the way you remember that experience,” he said.
“I have a one-year-old baby. Like all parents, we documented her first step on video and then immediately watched it with her. So she not only has the experience of taking that first step, but also the experience of watching herself take it. I can’t tell you what it does to the experience or the memory shaped from it. We didn’t experience things like that. But it’s clear to me that this is a dramatic change and that it’s too early to know what implications it will have,” Norman said.
Sniffing out a memory
The sense of smell is closely linked with memory, probably more so than any of our other senses, so for nearly everyone even a random whiff can trigger hidden memories.
Norman explains that “the sense of smell is the only sense that is directly connected to the hippocampus, which is perhaps why smells can immediately evoke memories. On the other hand, when I remember, I can’t imagine smells. It has to do with bringing the brain to the same state it was in when the memory was created. The more you are in a situation similar to the one when you memorized the information, the easier it will be for you to retrieve the memory.”
“One of the hypotheses is that if you go back to the situation where the memory was encoded, the pattern of neuron activity in the brain is more similar to the pattern which created the memory, so it is easier to retrieve it,” he said.
This explains why when we go back to our childhood home, memories come flooding back, said Norman: “You have to go back to the same context of neuron to retrieve the memory. It also says something about the cognitive strategy you can take to improve your memory.”
According to Norman, when trying to retrieve a memory in real time, people intuitively search for context — who they were with, where they were, and so on — “and the mere fact that you’re evoking memories that are related to the same context triggers more related memories. It further unveils the additional levels of the same memory layer, and makes it easier for a latent memory to be retrieved.”
But what about when you run into someone familiar but can’t remember their name or where you met before?
Norman explained that “the issue of remembering names is a little bit different because it’s a near-random label. What’s a name? A sequence of syllables. It’s very important for the memory system and our daily lives, but really, it’s something very ‘thin’ content-wise — a verbal code affixed to a place, a photo, a human face. The connection between a person and their name is random. The fact someone is called Brad Pitt is not imprinted on his face. His name is Brad Pitt because that’s the name he was given, that’s all.”
When it comes to names, you have to cut your brain a little slack. It has a ton of details to remember and it’s a wonder it manages to do it at all
Unlike with people’s names, we are unlikely to fail to recognize a dog, a cow, or a camel, something Norman said is “derived from the inherent properties of the object itself. It may be related to the very significant differences between different animals. I can’t explain exactly why. Maybe it has something to do with the fact that you learn animal names in a different context, a younger age, or different situations.”
When it comes to remembering names, said Norman, “You have to cut your brain a little slack. It has a ton of details to remember and it’s a wonder it manages to do it at all. Think about how many people you know in your life: family, friends, colleagues, athletes, historical figures – the list goes on. I don’t know if anyone has ever counted that, but we’re talking about hundreds and thousands.”
“Every human being is a unique example in and of himself and you have to remember their name. How many objects do you need to remember in the ‘kitchenware’ category? Twenty? Thirty? That’s not too many. In the ‘humans’ category, we have the most details to remember,” Norman said.
Throw your 5,000 Facebook friends into the mix and things, he said, “Can get completely out of control.”
A version of this article first appeared in Hebrew on The Times of Israel’s sister site, Zman Yisrael.