KIDNEY CELLS / BODY MEMORY
Cells of the body can learn like brain cells. What will we teach them?
Since 2015, when I first started teaching at NYU, I’ve seen more and more of my students — mostly freshmen and sophomores — struggle with their mental health. But I noticed another change in them, too, possibly as a consequence: they are a lot more aware of the flow of information through their brain.
Many of them, for example, take deliberate, timed breaks from cell phones or screens in general. Many anticipate their emotions in specific situations and take pre-emptive action to cope with them. Sometimes I see students create detailed rules about the use of individual apps, calibrated to maximize their daily well-being.
What surprises me about this is planning. Compared to students ten years ago, they now seem to anticipate the states of their mind far further into the future. They are not just doing what feels best in the moment — they are engaging in precise, bespoke patterning of experience, managing their mental health months, if not years ahead.
I wonder if this new way of thinking about the brain — the careful, anticipatory patterning of life in the name of future wellness — will soon expand to our body as well.
To some extent, we are already doing a lot more of it than people did in the past. We take vitamins in the morning and make sure to get enough fiber though the day, even though it doesn’t seem to have any obvious benefit right away. We go to the gym and avoid too many sweets because we want to be healthy, live long and look well, not just immediately, but years ahead. A 100 years ago, sobriety was a matter of social order — now, we do Dry Januarys to give our bodies a detox.
But it might be that even things we do on shorter timescales leave an imprint on the body, much in the same way as individual experiences can leave a lasting memory in the brain. The gap between your lunch and your dinner. The number of times you repeated your squats yesterday. The frequency with which you watch horror movies. All of those could, theoretically, have effects on the body that we cannot yet predict or anticipate.
I study cellular cognition. It is an exciting new field of biology focused on the ways in which living cells process information — how they analyze their environment, detect patterns, form memories, and communicate with each other.
Until recently, “information” in biology referred to one of two things: either genetics, or the brain.
But we now understand that all cells, even cells that have nothing to do with reproduction or with the brain, exist in a complex, information-rich environment: thousands of different chemicals — nutrients, salts, hormones — passing by, entering and exiting the cells at unpredictable times for unpredictable durations, depending on what we eat, when we sleep, which muscles we use, what medicines we take, and a myriad other tiny details of life. All these chemicals modify the behavior of each cell in infinite ways for various durations of time.
In a recent study, which I co-led with Tom Carew, we showed that non-brain cells — including cells derived from a kidney — can learn from patterns of these chemicals in much the same ways as brain cells learn when we learn to play a piano, or study for class.
This learning happens surprisingly fast, on the scale of minutes, even though non-brain cells are generally considered relatively “slow”. The effects, however, can last for days, and maybe longer.
What does it mean for everyday life? We don’t know yet. One thing it might mean is that our conscious, emotional memories —for example, trauma — reside in part outside the brain. This is the main thesis of “The Body Keeps the Score”, a controversial but influential book about trauma by the Dutch psychiatrist Bessel van der Kolk.
Published in 2014, the book was criticized for jumping ahead of the evidence. But today, the idea that memory is spread throughout the brain and the body no longer sounds as risqué as it did ten years ago. We know that the brain and the body have mutual effects on each other: a thought or an emotion can modify a cell in the gut or the liver, and that, in turn, could modify thoughts and emotions. We now understand that non-brain cells have memory, and this memory could potentially store such changes.
So there’s nothing spooky about trauma being stored, in some meaningful part, in the body.
But our bodies probably retain a lot more than such imprints of conscious experiences.
There have been studies in the past, coming from different fields of medical science, showing memory-like properties in various organs and tissues: a quick input causes a lasting change.
But until recently, no one thought of these isolated cases as literal memory — and no one considered the possibility that they might operate similarly to each other, and to the canonical, brain-based memory.
For example, cells in the pancreas respond to sugar in the blood by releasing the hormone insulin, which causes sugar to be absorbed. If you expose those cells to a large amount of sugar at once, then wait twenty minutes and do it again, the second time they will release twice as much insulin as the first time.
This makes biological sense: if you maxed out your insulin-releasing (and therefore, sugar-absorbing) capacity, you would want to ramp it up in case more sugar arrives, but you wouldn’t want it permanently elevated, or you would get hungry and fatigued too easily.
Another example: bone cells detect mechanical load, and respond to it with more bone formation. The bone becomes stronger if you repeatedly bend it.
What’s more, the bone cells respond not just to the load, but to its frequency: if you apply pressure to a rat leg once every two seconds, the bone is unaffected, but if you do it a rate of twice per second, bone growth increases as much as four-fold.[iii]
There are many other examples: in the immune system, in embryonic development, in cancer. Maybe the most obvious example, hiding in plain sight, is muscles growing in response to exercise.
This list is probably just scratching the surface. But already two things are clear about cellular memory.
One, it exists.
Two, it can depend on precise timing, sometimes down to minutes, and even seconds.
As we continue to uncover the rules of this cellular memory in the future, I suspect it might lead us to be even more sensitive to the experiences of our body than we are now, with all our fiber and vitamins.
We might develop sophisticated, ornate rules: no dumbbells for three days after eating smoked salmon, unless supplemented by mustard; five dabs of vitamin B at fifteen-second intervals before going out, but only in the summer.
What will that future world be like — a world in which we are hyper-cognizant of both our mental memory, and our “body memory”? Will it make us better, healthier versions of ourselves? Or will it just feed into our growing anxiety about the future, a compulsion to control every cell of the body to maximize success?
Time will tell — but for now, there’s no reason to do anything drastic. Until science refines the timeline, we are safe with “an apple a day keeps the doctor away”.
A version of this post was published on my Psychology Today blog.