Page 19 - The 'X' Chronicles Newspaper - September 2023

Brains May Predict The Future 19

To Make Sense of the

Present, Brains May

Predict The Future

Continued from Page 18

“The most profound part of it is that it
shows us how vulnerable our mental
function is,” said Philip Corlett, a clinical
neuroscientist at the Yale School of
Medicine. Experiments in Corlett’s lab
set up new “beliefs” in healthy subjects
that encourage them to hallucinate
stimuli they previously experienced. (For

instance, in one experiment, the scientists
conditioned participants to associate a
tone with a visual pattern. The subjects
continued to hear the tone when they saw
the pattern, even when there was no
sound at all.) The researchers are trying
to unravel how those beliefs translate into
perception. Through these studies,
“we’ve got evidence suggesting that

perception and cognition are not that
separate,” Corlett said. “New beliefs can
be taught and can change what you
perceive.”

But that evidence hasn’t come close to
offering proof — until now.

Zooming in for a Better Look

“Experimental work often shows a
particular result is compatible with study, inverting left and right so that Similar findings in the parts of the brain
predictive processing, but not that it’s the turning leftward meant the mice also that macaques use to process faces were
best explanation of that result,” Sprevak experienced vision leftward. The reported around the same time. Previous
said. The theory is widely accepted in the researchers realized that they could work had already shown that neurons at
cognitive sciences, but “in the field of capitalize on the accident. They lower levels in the network code for

systems neuroscience, it’s still a bit of an monitored the brain signals that orientation-based aspects of a face — by
underdog,” said Georg Keller, a represented this visual flow and found firing at, say, any face in profile. At
neuroscientist at the Friedrich Miescher that the signals changed slowly as the higher levels, neurons represent the face
Institute for Biomedical Research in mice learned the rules of the inverted more abstractly, by paying attention to its
Switzerland. His lab is trying to change environment. “The signals looked like identity rather than its position. In the
this with harder evidence. predictions of visual flow to the left,” macaque study, the researchers trained
Keller said. If the signals had simply monkeys on pairs of faces in which one
In a 2017 study published in Neuron, been sensory representations of the face, appearing first, always predicted
Keller and his colleagues observed the mouse’s visual experience, they would something about the second one. Later,
emergence of neurons in the visual have flipped immediately in the virtual the experimenters interfered with those
system of mice that became predictive world. If they had been motor signals, expectations in specific ways, by

over time. It began with an accident, they wouldn’t have flipped at all. Instead, showing the same face from a different
when they set out to train the mice on a “it is about identifying prediction,” angle, or an entirely different face. They
video game, only to find that the virtual Keller said. “The prediction of visual found prediction errors in lower-level
world had gotten its directions mixed up. flow, given movement.” areas of the face processing network, but
Ordinarily — and up until the time of the these errors were associated not with
experiment — the mice saw their field of “The work provides a kind of evidence predictions about orientation but with
vision move to the right whenever they that didn’t exist before,” Clark said. “A predictions about identity.
turned to the left, and vice versa. But very local, cell-by-cell, layer-by-layer
someone had unintentionally flipped the demonstration that the best-fit model for (Continued on Page 20)

virtual world the researchers used in the what’s going on is predictive coding.”