What the Heart Remembers | Psychology Today Ireland

On March 11, 2021, Kristy Sidlar woke up with a new heart. After a life-saving transplant, the 52-year-old was groggy and faded in and out of consciousness. Once she was cogent, her first thoughts were about her donor: “I said to my husband, ‘I feel like I have the heart of a mid-30s woman. She had a rough life. She came from a rural area and had a tough upbringing.”

It was a sudden thought, and Sidlar moved on. Despite the arduous challenges of recovery, the process went well. Soon she was walking, then running—living the life she’d desperately desired before her transplant. Several months later, she called the procurement organization. Could they tell her anything about her donor? Yes: She was a 37-year-old woman. Sidlar’s instinct had been correct.

Why did that thought pop into Sidlar’s head? Is it possible for biographical or other information—a favorite food, a musical taste, a unique phobia, a memory of a traumatic, even fatal, injury—to be transferred from one individual to another through the heart? It seems inconceivable. Yet this phenomenon may well occur. Documented cases are both extremely rare and utterly shocking. And one possible interpretation of these stories involves scientists questioning the conventional wisdom about how memories are created and retained.

Astounding Anecdotes

Perhaps the best-known example of a transplant recipient undergoing a personality change is that of Claire Sylvia. In 1988, Sylvia received the first heart-lung transplant in New England, at Yale-New Haven Hospital, from an 18-year-old man. When she emerged from the haze of the procedure, she found herself craving a beer, so much so that when a reporter asked what she wanted more than anything else, Sylvia responded, “Actually, I’m dying for a beer right now.” As soon as the words came out of her mouth, she was mortified. And surprised—she had never liked beer before.

But that wasn’t the only change. Sylvia’s food preferences shifted; she craved both green peppers, which she had hated before and would remove from any salad, and chicken nuggets, which she got for her first meal after leaving the hospital. Her gait changed; her daughter noticed that she had more of a lumbering stride. Her personality shifted, too; she craved speed and action, became more assertive, and felt less lonely.

Sylvia’s recovery encompassed both tremendous challenge and tremendous relief, health, and success. Yet she sometimes felt the organ was a foreign entity that she was struggling to integrate. She knew (from accidentally overhearing it) that her donor was an 18-year-old man who died in a motorcycle crash. A long time after the procedure, Sylvia had a dream. She recorded it in her memoir, A Change of Heart:

“I’m in an open outdoor place with grass all around. It’s summer. With me is a young man who is tall, thin, and wiry, with sandy-colored hair. His name is Tim—I think it’s Tim Leighton, but I’m not sure. I think of him as Tim L. We’re in a playful relationship, and we’re good friends.

“It’s time for me to leave, to join a performing group of acrobats. I start to walk away from him, but I suddenly feel that something remains unfinished between us. I turn around and go back to him to say goodbye. Tim is standing there watching me, and he seems happy when I return.

“Then we kiss. And as we kiss, I inhale him into me. It feels like the deepest breath I’ve ever taken, and I know that Tim will be with me forever.”

Sylvia woke up both exhilarated and relieved. This man, she felt, was her donor, and his two organs finally felt like her own.

Years later, Sylvia found her donor’s obituary in the newspaper—his name was Tim Lamirande. She eventually met Tim’s family. She asked if he liked green peppers; maybe that would explain her unusual cravings. “Are you kidding? He loved them,” Tim’s sister replied. “But what he really loved was chicken nuggets.”

Stories like Sylvia’s are rare but persistent; they’ve been around almost as long as the first heart transplant, which took place in 1967. “Ever since I got into transplant surgery, I’ve heard stories—dreams convinced patients of something from their donor, some activity they started liking, new types of foods. It’s not infrequent,” says Joshua Mezrich, a transplant surgeon and professor at the University of Wisconsin-Madison.

The phenomenon has been examined in studies that are small given the rarity of organ transplants and especially of subsequent reported changes. (About 3,500 heart transplants are performed in the United States each year.) In 1992, a study of recipients in Vienna, Austria, found that three out of 47 participants reported a distinct change of personality; others reported no personality changes or only ones that they attributed to the stress of their illness and surgery.

In 2000, neuropsychologist Paul Pearsall and his colleagues published a study documenting 10 heart transplant recipients whose personality changes appeared to align with their donor’s personality. In 2004, researchers in Israel published a study of 35 transplant recipients, among which one-third entertained the possibility that they had acquired qualities of their donor. These studies are small and can suffer from significant methodological weaknesses. Yet the phenomenon, as reported by some transplant patients, does seem to exist.

In a 2020 study published in the journal Medical Hypotheses, University of Colorado psychiatrist Mitchell Liester reviewed cases of personality changes in the literature. He examined the extent to which heart transplant recipients may take on tastes, preferences, fears, memories, and components of identity, all of which bore a similarity to their donors.

Liester’s interest in this subject was piqued by a patient who sought his help for an unusual situation. “She said, ‘I need to find out if you think I’m crazy or not,’” Liester recalls. She explained that she’d started having memories of things that hadn’t happened to her, predominantly the memory of being hit by a car. She said she didn’t just remember it, but she actually felt the impact on the left side of her torso. He asked if she had been hit by a car. No. He asked if she had any other medical trauma. The only medical event was a heart transplant a year or two before. She was actually going to meet the donor family soon, and Liester said to report back.

When she returned, she told him what she’d learned: Her donor was a young boy who was playing tag when he ran into an alley and was hit by a car on his left side. The parents’ description matched the new memories with which she’d been struggling. After learning this, she felt a sense of resolution.

Liester’s examination of the scientific literature turned up similar cases of memories that seemed to come out of nowhere. One 5-year-old boy, after his transplant, was asked what he thought about his donor. The boy said, “He’s just a little kid. He’s like a little brother, about half my age. He got hurt bad when he fell down. He likes Power Rangers a lot, I think, just like I used to. I don’t like them anymore though.” His donor was a 3-year-old boy who had fallen from an apartment window while trying to reach a Power Ranger toy on a window ledge. No one had told the recipient the donor’s age or the cause of death.

One 9-year-old boy received the heart of a 3-year-old girl. He loved water before the transplant but suddenly feared it afterward. He also experienced new emotions that he attributed to his donor: “She seems very sad. She is very afraid. I tell her it’s okay, but she is very afraid. She says she wishes that parents wouldn’t throw away their children. I don’t know why she would say that.” The recipient’s mother told researchers, “He doesn’t know who his donor was or how she died. We do. She drowned at her mother’s boyfriend’s house. Her mother and her boyfriend had left her with a teenage babysitter who was on the phone when it happened.”

One 47-year-old man received the heart of a 17-year-old killed in a drive-by shooting. The recipient described how he used to hate classical music, but after his transplant, he loved it and would play it all the time. It turned out that his donor had been shot as he walked to music class. He had loved playing and listening to classical music and had died hugging his violin case.

Searching for Answers

These anecdotes, and the concept of an organ transferring memories from one person to another, invite a high degree of skepticism. They’re dismissed in most medical and academic circles. There’s seemingly no pathway for such transmission to occur. And there are so many confounding variables: intense medication regimen post-transplant; psychological consequences of a tremendous medical event; new physical capacities due to the new healthy organ; and plain old coincidence.

Medication side effects are a key element. Following the procedure, transplant recipients take numerous immunosuppressants and other drugs that can come with difficult side effects. The steroid prednisone is particularly challenging and can make people angry, aggressive, and impulsive. “They’re taking a whole bunch of powerful medicines. Patients can have hallucinations, increased energy, insomnia, and that’s all combined with being really ill. This can be mind-
altering, especially early after transplant,” Mezrich says. Medications can also mess with a person’s taste buds and digestive system, which could contribute to new food and drink preferences. However, dietary and other changes tend to endure after patients have been tapered off their medication.

Physical health is another factor. If an ill 60-year-old receives the heart of a healthy 20-year-old, that heart might imbue them with energy and vigor; they might feel more energetic than before, more healthy, and pick up related hobbies like jogging or yoga. Their personality didn’t change; it expanded due to new physical capacities.

Yet another factor is that recipients have undergone an enormously challenging, potentially traumatic, medical event. They likely lived with a devastating disease, confronted their own death, underwent extensive surgery, and then labored to recover and reintegrate into the world. This trajectory could alter their identity in countless ways. Perhaps they become more assertive because life is short and who has time to tiptoe around? Perhaps they become more easygoing because the little things don’t seem to matter anymore. “I used to be more stoic, and now I’m more emotional. I attribute that change to the magnitude of my gift,” Sidlar says.

Some may also wonder if the medical team talks about the donor during or around surgery, and the recipient processes that information subconsciously. In fact, this isn’t a possibility because neither the medical team nor the recipient knows the donor’s name or information.

These are valid points. But something about these anecdotes eludes explanation: the precision. Intuiting a donor’s name, age, or cause of death, for instance, doesn’t seem to fall under the umbrella of a side effect of immunosuppressants, a physical feat, or a new perspective. “The thing that was striking to me from the anecdotal reports, assuming they’re accurate, was the specificity,” says Samuel Gershman, a professor of psychology at Harvard University. “You can’t chalk this up to some kind of randomness in the data. The likelihood that this happens by random chance is infinitesimally small.”

New and converging fields of study point to another potential mechanism, and in so doing, call into question core questions about how memory really works.

Peter Arkle / Used with permission

The New Science of Memory

For decades, the dominant theory of memory has been that memories are stored in synapses between neurons; memories persist due to the creation and strengthening of synaptic connections. But some scientists have begun to question this paradigm.

“The story we all learned in school, that finely tuned synapses are the only way to store memories, has a lot of cracks in it,” says Michael Levin, a professor of biology at Tufts University. It is now understood that some forms of memory can exist in single-celled organisms, can endure when synapses disappear, or can live outside of the brain entirely.

In thinking about memory existing in cells throughout the body—so-called cellular memory—it’s helpful to consider a few examples. Immune cells can “remember” foreign invaders years after they’ve left the body. “The immune system determines what’s self and what’s other and remembers that. If you get strep, you can fight off the infection later,” Liester says. Epigenetic memory offers another illustrative example—genes can be turned on or off based on environmental changes. These are forms of memory that scientists continue to explore.

Levin’s research uses creatures called planarians—tiny flatworms that have the capacity to regenerate. He and his colleagues trained planarians to seek food in a specific quadrant of a petri dish. They had to traverse a bumpy texture to do so. Levin then decapitated the worms. Since planarians’ rudimentary brains can regenerate, they began to grow new heads. He then introduced them to the same petri dish. Planarians whose tails had previously learned to cross the unpleasant texture to get food did so immediately or quickly re-learned to. The others didn’t. The worms’ brain had been removed—yet the memory was somehow stored elsewhere in the body.

David Glanzman, a neurobiologist at the University of California Los Angeles, studies memory in sea slugs. He and his colleagues gave slugs a drug to erase the synaptic connections that had formed as a result of electric shocks. Yet the ability to reinstate the memory indicated that traces of it still existed—suggesting that the memory was stored in the cell bodies of neurons rather than in synapses. “Even though the synaptic connections had been reset, the memory persisted,” Glanzman says. “It hadn’t been erased.”

If the memory wasn’t in the synapses, where was it? Glanzman and his colleagues coalesced around a hypothesis: memory may be encoded in a cell’s RNA. Testing this led to another key study, in 2018, in which the team ostensibly transferred a “memory” from one slug to another. The researchers shocked the slugs, which led them to become sensitized to a subsequent touch. Glanzman and his colleagues then extracted RNA from the sensitized slugs and injected it into new slugs. These slugs were sensitized to the touch even though they had never encountered the shock. The “memory” was transferred from one organism to another.

The experiments above don’t represent all of the research questioning the synaptic model. But they and others signal that the old story can’t be the full picture. “A lot of research now has questioned the synaptic theory of memory, and the focus is shifting to cellular memory,” says Thomas Verny, a psychiatrist and the author of The Embodied Mind: Understanding the Mysteries of Cellular Memory, Consciousness, and Our Bodies. “Studies suggest memories in all animals are stored in cells, including cardiac cells, and not in synapses as was long believed.”

“Synaptic strengthening is important for retrieval but not storage of information itself,” says Tomás Ryan, an associate professor at Trinity College Dublin. “If I disconnect a computer and no longer see a Word document, it doesn’t mean the information is gone. But that’s the logic we’ve been using in neuroscience for a long time.”

Questioning the synaptic model has led researchers to pursue different hypotheses. Some hypothesize that synapses are involved in some forms of memory storage but not others, some posit that memories are stored molecularly within cells, some suggest memories are retained in the brain’s network of neural pathways, and some propose memories may be stored in the brain’s electric field.

“I’m convinced that memories are encoded molecularly,” Glanzman says. “I think in the nucleus memories are encoded by epigenetic changes, or even by genomic changes, but I don’t think they’re encoded at synapses. I do believe synapses grow during learning, and growth of new synaptic connections temporarily holds memory while the nuclear memory develops. But you can erase those synaptic connections, and the memory persists.”

These scientists aren’t the only ones conducting research into novel mechanisms of memory storage. But it’s certainly not a huge club—the work is controversial, and most of the field believes the synaptic model prevails over all else. “My peers don’t accept this idea,” Glanzman says. “Part of it is because the synaptic model is very well established.”

When it comes to the phenomenon of post-transplant changes, Glanzman believes the strongest hypothesis is that noncoding RNA may be released outside the cells, in small vesicles, travel through the blood, and be taken up by target cells in the brain. Glanzman stresses that this exploration is early and would benefit from an animal model for further study. “We should be open to these possibilities and not dismiss them out of hand as I did when I first read about this. I thought it was nuts,” Glanzman says. “Then I thought about it for a bit. And I realized it might be possible.”

Levin concurs that this is one of many possibilities, but he believes there may not be a single substrate for memory storage. He hypothesizes that all biological structures, including the smallest cells and organelles, may be storing and interpreting information. “Most cells, if not all, are suitable for memory encoding in one medium or another,” he argues. “Memory can exist outside the brain.”

Levin is a pioneer in the field of basal cognition, also called diverse intelligence, which explores the precursors of cognitive capacities in and outside of the brain. When caterpillars become butterflies, they retain memories of their caterpillar existence—such as what and where to eat—even though the brain is dissolved during metamorphosis. “You can train a caterpillar and recover memories in the butterfly. Where the hell is that memory? It’s not in the brain.”

Peter Arkle / Used with permission

Beyond the Heart

Could memory transfer occur in organs other than the heart? In Claire Sylvia’s memoir, she writes that the most common changes reported in her informal surveys were food preference changes after kidney transplants.
Liester recently explored this question. Earlier this year he published a paper in the journal Transplantology, comparing changes among people who received new hearts with those in people who received new kidneys, livers, or lungs.

This study has significant caveats—it was a small sample (47 people) and the data were self-reported, which can be biased. But he and his colleagues found that both groups reported similar rates of post-transplant changes. The only statistically significant difference between the two groups was for physical attributes, which may be due to the improved health and abilities a new heart provides. Still, this early evidence suggests that the heart may not be wholly unique, and changes may occur after any organ transplant.

Michaela Pyfferoen is one such recipient. Twelve years ago, at age 17, she received a liver transplant. A few hours after waking up, she asked her parents for a cheeseburger. “You want what?” her mother responded. Pyfferoen had never been particularly fond of meat, but that was her first meal post-transplant. Pyfferoen wrote the family of her donor, “CL,” several letters, and eventually received one in return from his mother.

“It’s an indescribable feeling, finding out who literally saved your life,” Pyfferoen says. She began reading. “He loved hamburgers!” she yelled out. “They were one of his favorite foods.” Over time Pyfferoen became close with CL’s mom, Lori. At their first meeting, at a Cracker Barrel in Rockford, Illinois, the two hugged, sobbed, and talked. At one point Lori exclaimed, “Oh that’s CL in her!”

The Ultimate Gift

There are still many open questions—and they may remain that way. “My skeptical self says this isn’t supposed to happen,” says heart transplant surgeon Joshua Hermsen of the University of Wisconsin-Madison. “But some things are not explainable. There’s a lot we don’t know. There’s no way to draw a line, but there’s got to be something to it.”

After her heart transplant, Sidlar, who had intuited that her donor was a woman in her mid-thirties, wrote to her donor family a few times a year. Several months ago, she received her first letter back. Angie. That was the name of the woman whose heart now beat in Sidlar’s chest. The family wrote that they missed Angie. Angie had been spunky, full of life, and didn’t let anything get to her. They wrote how glad they were that Sidlar was doing well, and to keep enjoying life. They signed the letter, “Your extended family.”

Sidlar had gotten a tattoo after the transplant. It was a triangle with her old cardiac rhythm on the left, her new one on the right, and her husband’s below. After she heard from Angie’s family, she turned the top of the triangle into an A for Angie. “Every day I thank them,” Sidlar says.“When I practice gratitude, the first is always my donor family,” Sidlar says. “You don’t really understand what gratitude can mean until someone gives you their life.”

In addition to their incredible physical gift, organ donors may have bestowed an intangible one as well—the possibility of helping understanding human memory and identity in a novel way. A new understanding of memory could have dramatic implications for science, medicine, technology, and more. A new understanding of memory could hypothetically lead to novel treatments: Could a traumatic memory be dampened for those with PTSD? Could lost connections be restored for those with Alzheimer’s disease? “That’s science fiction at the moment,” Gershman says. “But it’s a possibility we could start to think about.”

Artificial intelligence borrows from neuroscience; current models for deep learning are based on the synaptic model of learning and memory. “If [that model] isn’t the way we learn, there’s potentially a much more powerful system of AI that’s escaping these generative AI models,” says Glanzman.

“This is much bigger than just neuroscience,” Levin says. “It gets at the deep question of how cells work together in the first place. The field of diverse intelligence is critical for everything from artificial intelligence to regenerative medicine.”

The question of whether memories can transfer from one organism or being to another stands at a biological crossroads. The answer, when it arrives, will shed light on the science of memory, and may inform cutting-edge technology in the future. Until then, we can simply marvel at the mystery.

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