Page 18 - The 'X' Chronicles Newspaper - September 2023

18 Brains May Predict The Future

To Make Sense of the

Present, Brains May

Predict The Future

Continued from Page 17

Enter predictive coding theory, which
offers specific formulations of how
brains can be Bayesian. Predictive coding
gets its name from a technique for
transmitting telecommunications signals
more efficiently: Because video files
contain a lot of redundancy from one
frame to the next, it’s inefficient to

encode every pixel in every image when internal model that gets adjusted; with emotions and moods can be formulated in
compressing the data. Instead, it makes motor control, it’s the actual predictive coding terms: Emotions could
more sense to encode the differences environment. (For the latter, imagine that be states the brain represents to minimize
between adjacent frames and then work you want to raise your hand. If your hand prediction error about internal signals
backward to interpret the entire video. is not already raised, that discrepancy such as body temperature, heart rate or

generates a large prediction error — blood pressure. If the brain recognizes
In 1982, scientists found that this idea has which can be minimized if you simply that it’s agitated, for instance, then it
a neat application in neuroscience — move your hand.) knows all those factors are going up.
because it appears to explain how Perhaps that’s also how the concept of

neurons in the retina encode information Experiments in perception and motor selfhood can emerge.
about a visual stimulus and transmit it control have so far provided the strongest
along the optic nerve. It’s also been evidence for predictive coding theory. In Most of the work being done in this vein
cemented as a principle of how the a 2018 paper published in the Journal of focuses on how predictive coding might
brain’s reward system functions: Neuroscience, for example, explain neuropsychiatric and
Dopamine neurons encode the magnitude experimenters had subjects read the word developmental disorders. “The idea,”
of the mismatch between an expected “kick” on a screen, then had them listen Friston said, “is that if the brain is an
reward and the actual reward that’s to a distorted recording of the word inference machine, an organ of statistics,
received. These prediction errors, “pick” that sounded like a loud whisper. then when it goes wrong, it’ll make the
researchers say, help animals update their Many heard “kick” instead, and fMRI same sorts of mistakes a statistician will
future expectations and drive decision- scans revealed that the brain represented make.” That is, it will make the wrong

making. the initial “k” or “p” sound most strongly inferences by placing too much or too
— the sound that correlated to a little emphasis on either predictions or
But despite these examples, scientists prediction error. If the brain were simply prediction errors.
mostly saw predictive coding as a process representing its perceptual experience,
specific to certain networks. Functional the strongest signal should have Aspects of autism, for instance, might be
magnetic resonance imaging tests and corresponded to “ick” instead (because characterized by an inability to ignore
other types of experiments have begun to that was represented both on screen and prediction errors relating to sensory
change that. in the audio). signals at the lowest levels of the brain’s

processing hierarchy. That could lead to a
A Universal Framework But efforts are also ongoing to widen preoccupation with sensations, a need for
predictive coding’s relevance beyond repetition and predictability, sensitivity to
Part of what makes the predictive coding perception and motion — to establish it certain illusions, and other effects. The
hypothesis so compelling is its incredible as the common currency of everything reverse might be true in conditions that
explanatory power. “What I find going on in the brain. “It’s like having are associated with hallucinations, like
convincing is how so many things all get building blocks with which different schizophrenia: The brain may pay too

accounted for under this story,” said strategies can be built,” Clark said. much attention to its own predictions
Andy Clark, a professor of logic and Different brain regions simply trade in about what is going on and not enough to
metaphysics at the University of different kinds of prediction. sensory information that contradicts
Edinburgh and an expert on the theory. those predictions. (Experts are quick to
Friston, among others, claims this applies caution, however, that autism and
First, it unifies perception and motor to higher cognitive processes including schizophrenia are much too complicated
control under a single computational attention and decision-making. Recent to be reduced to a single explanation or
process. The two are essentially opposite computational work on the prefrontal mechanism.)
sides of the same coin: In each case, the cortex has implicated predictive coding

brain minimizes prediction errors, but in in working memory and goal-directed (Continued on Page 19)
different ways. With perception, it’s the behaviors. Some researchers theorize that