Can a Cell Make Decisions?

Can a Cell Make Decisions?

Jennifer Frazer

In short, stentors could confront a stimulus with one behavior, and then choose a costlier approach if the irritant persisted. At least for a short while (a period that Jennings declared difficult to determine experimentally and still unresolved), it could “remember” that it had tried one solution without success, and opt for another.

But in 1967, scientists from a different school of animal behavior repeated his experiment and failed to produce the same result. And with that, Jennings’s findings were consigned to the dustbin.

Then about 10 years ago, Jeremy Gunawardena, an associate professor of systems biology at Harvard Medical School, discovered the experiment and its defenestration and decided that it deserved another look. To his surprise, he discovered the 1967 team had not used the correct species of Stentor (being behaviorists who believed variation flowed from the environment and not genes, they might have felt the species didn’t matter). The one they had chosen, Stentor coeruleus, strongly prefers to swim, unlike Jennings’s Stentor roeselii, which prefers to chill poolside.

Gunawardena became fascinated by what replicating the experiment might reveal about what single cells are capable of...

[Laird]

I remembered reading about this (absolutely fascinating) study earlier, and tracked down the source. Turns out you'd posted a different article about it in the 2019-12-17 thread, Can a single-celled organism 'change its mind'? New study says yes

Can a Cell Make Decisions?

Jennifer Frazer

Of course, a living cell can process information objects, such as affordances, that change probabilities in their environments.  It is the tools that are being applied that jump off the page for me.

 So, the three fell back on their core expertise as quantitative biologists. They developed a method to encode the different behaviors they saw into a series of symbols, and then used statistical analyses to look for patterns.
[i]If bending and cilia alteration are insufficient, [/i]S. roeselii [i]will contract onto its holdfast, or detach and swim away. Video: Dexter et al, 2019.[/i]
Where observation failed, math triumphed. There was, indeed, a behavioral hierarchy, the analysis revealed. 

[Laird]

What Can a Cell Remember?

Claire L. Evans
July 30, 2025
Quanta Magazine

This article discusses among other things the stentor experiments (and their rediscovery and replication) described in the articles linked in the above posts, along with other experiments:

Then, in a process Kukushkin described as a tedious choreography of clockwork pipetting, they exposed the cells to precisely timed bursts of chemicals that imitated bursts of neurotransmitters in the brain. Kukushkin’s team found that the both the nerve and kidney cells could finely differentiate these patterns. A steady three-minute burst activated CRE, making the cells glow for a few hours. But the same amount of chemicals, delivered as four shorter pulses spaced 10 minutes apart, lit up the petri dish for over a day, indicating a lasting imprint — a memory.

Kukushkin’s findings suggest that nonneural cells can count and detect patterns. Even though they can’t do it at the speed of a neuron, they do remember, and they appear to remember a stimulus for longer when it is delivered at spaced intervals — a hallmark of memory formation in all animals.

It also discusses a key semantic issue:

Like all important terminology, “memory” is loaded, imprecise and defined variously by different disciplines. It means one thing to a computer scientist and another to a biologist — to say nothing of the rest of us. “When you ask a normal person what memory is, they think of it introspectively,” Kukushkin said. “They think, ‘Well, I close my eyes and I think back to yesterday, and that’s memory.’ But that’s not what we’re studying in science.”

In neuroscience, Kukushkin writes, the most common definition of memory is that it’s what remains after experience to change future behavior. This is a behavioral definition; the only way to measure it is to observe that future behavior. Think of S. roeselii snapping back into its holdfast, or a lab rat freezing up at the sight of an electrified maze it’s tangled with before. In these cases, how an organism reacts is a clue that prior experience left a lingering trace.

But is a memory only a memory when it’s associated with an external behavior? “It seems like an arbitrary thing to decide,” Kukushkin said. “I understand why it was historically decided to be that, because [behavior] is the thing you can measure easily when you’re working with an animal. I think what happened is that behavior started as something that you could measure, and then it ended up being the definition of memory.”