Most city dwellers will readily describe rats as master schemers. For example, a New Yorker once told me about watching a rat bring a slice of pizza down the subway stairs, drag it across the platform, and finally haul it into a train car where he could indulge without competition.
But attributing this sort of behavior to planning or imagination was long thought to be an unscientific inference. Rene Descartes declared in the 17th century that animals behaved like machines. Early scientists were shaped by Western religions that taught that humans, but not animals, had souls. Even when Darwin showed that we and our fellow mammals were close relatives, there was still a pervasive belief that animals lived only in the moment, unable to think back or ahead in time.
But some recent experiments using advanced technology show that rat brains have more in common with ours than we’d perhaps like to admit.
A study published in November in Science showed that rats can actively conjure up an image in their mind’s eye — a form of imagination. The work required a technology known as a brain-computer interface, by which brain activity can be translated into actions on a computer. Brain-computer interfaces with humans have shown the astonishing capacity to decode thoughts, thus promising to give voice to those who’ve lost the ability to move or speak.
With the rats, the researchers first recorded the animals’ brain activity while they navigated a virtual reality world — running on a ball-shaped treadmill took them through a series of shapes in a virtual landscape filled with rods, brick walls and domes. (The video caused my cat to paw at the screen, making me wonder whether there’s a market somewhere for a pet VR system.)
Then the scientists changed the rules so that running didn’t move the scenery, but instead the scenery would change if the rats activated the same neural patterns they did while exploring on the treadmill. It would feel like being in a car that you moved by just imagining where you wanted to go, said Albert Lee, a neuroscientist at the Howard Hughes Medical Institute and Beth Israel Deaconess Medical Center and a member of the team.
Then they set up the system so that if the rat activated a certain pattern again, a cursor would move to this goal — and the rat would get a reward. Three of four rats they trained figured out how to do this. In a variation of this experiment, they couldn’t see the cursor reach the goal with their eyes, but possibly could with their mind’s eye — as we would do if asked to picture a piece of furniture in our homes.
This was both an act of memory and an act of imagination — two functions that are intrinsically linked, said Loren Frank, a neuroscientist at the University of California, San Francisco. The main survival benefit animals get from memory is the ability to learn lessons to better navigate the future.
Frank was involved in a paper published in Cell in 2020, in which scientists monitored the brain waves of rats navigating a puzzle, eventually hitting a T intersection with a reward on one side. In all these experiments, the scientists monitored part of the brain called the hippocampus, which functions in both memory and imagination. They noted different patterns of neurons firing in various locations when the rats were exploring the maze. Later, as the rats ran toward the T, their neurons would fire with patterns that corresponded to the different paths that lay ahead — as would happen in a human planning a next move.
“[It] seems like absolute common sense that all these animals can flexibly deal with the world, draw inferences, generalise, use concepts or use internal models … [But] weirdly enough, that was far from common sense just about 100 years ago,” said neuroscientist Kenneth Kay of Columbia University, lead author on that study.
And while those New York City rats are street smart enough to know they’d starve without a chance to be alone with their pizza, in other circumstances rats have shown generosity. In one famous 2012 experiment, lab rats consistently let a trapped companion out of a cage to share some chocolate chips. And in 2016, researchers found that the physiology of empathy is similar in both humans and voles. It’s an act of imagination to be able to put yourself in someone else’s shoes — or paws.
Columbia’s Kay pondered whether scientists may shift to asking new questions — losing their obsession with proving humans are unique among animals and instead investigating how mammalian brains are different from our increasingly intelligent machines.
While we long for fellow intelligent life, we’re also afraid of it. We scan the stars for extraterrestrials, but most movies about alien encounters end in all-out existential war. Elon Musk says he’s afraid of AI, and if I’m honest, I’m nervous when I see a rat eating takeout. Maybe if humans screw things up badly enough, AI will take over, or maybe the rats will inherit everything. They may already be imagining it.
FD Flam is a Bloomberg Opinion columnist. Views do not represent the stand of this publication.
Credit: Bloomberg
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