How does our brain absorb information? And why do we learn from experiences?
Throughout much of the 20th century, many researchers viewed the brain largely as a passive receiver that received and processed sensory impressions before sending them on to higher-level processing areas in the brain.
From the 1990s and 2000s onward, growing research — including work by British theorists Karl Friston and Andy Clark — undermined that view.
"Today we are quite certain that our brain is a “prediction machine”. It does not passively receive sensory impressions; it creates internal models with expectations about incoming external information," says Olgerta Asko, a researcher at RITMO Centre for Interdisciplinary Studies in Rhythm, Time and Motion, part of the University of Oslo.
Surprises Spark Brain Activity
Photo: Annica Thomsson
Even newborns show signs of innate expectations for sounds and visual patterns. As life progresses, our brain becomes increasingly refined.
In her doctoral thesis, Asko measured electrical brain activity during surprises; this activity is technically known as a "mismatch signal."
Study participants heard sounds that repeated in a pattern before the pattern suddenly broke.
"If everything matches the brain's expectations, we see almost no extra response in the electrical signal. Surprises, however, produce a clear spike in activity and serve as learning signals," she explains.
"Each time the world behaves as expected, the existing model strengthens. Each unexpected event adjusts the model."
Explaining Optical Illusions
This brain mechanism efficiently organizes experiences, Asko explains.
"It does not need to wait for new sensory input, as it actively generates expectations about how the world works and fills in missing information."
This also explains why illusions fool us:
"The brain draws on existing knowledge, but it lacks precision and fails."
The Mysterious Prefrontal Cortex
Thousands of studies examine the brain's response to surprises. Asko focused on one area: the prefrontal cortex, located just behind the forehead.
"Fully understanding the prefrontal cortex is one of the toughest challenges in neuroscience. We know it plays roles in decision-making, artistic activity, and social behavior, and it is especially large and complex in humans compared to other animals. But its exact mechanisms remain unclear."
She describes the prefrontal cortex as a "hub" connected to many other brain regions. Does it help build the expectations that lead to surprises – and learning?
Yes, according to Asko.
Weaker Signals in Damaged Brains
Researchers played sounds with surprise elements to participants while recording electrical brain activity. Some had prefrontal cortex damage, with nerve cells and their connections destroyed in a specific area; others did not.
Then they compared mismatch signals.
"Those with damage showed weaker, delayed signals, which means they have a reduced ability to prepare for potential surprises."
Asko notes that accessing patients with such brain damages is challenging, which explains the scarcity of prior research on this topic.
Practical Benefits for Patients
What does this research mean? Why does it matter which part of the brain does what?
According to Asko, the knowledge holds value in multiple ways. It tells us something fundamental about how the brain builds and updates expectations, and it may also be important for healthcare and people with prefrontal cortex damage from, for instance, strokes, tumors, or accidents.
"Other brain areas often compensate when one is damaged, but not for all functions, and the compensation is rarely 100 percent," Asko says.
"Now we know that these patients may struggle to form expectations about future events and also struggle to adapt to surprises. "
This could guide new support strategies, she explains, and adds:
"For me, the main drive is basic curiosity about how the brain works. But in the long term, these kinds of insights can also inspire better computer and AI models that have to learn from experience and deal with uncertainty, just like our brains do."
Predictions Simplify Life
Next time you wait for a bus you expected to be on time, but it is delayed, view it as a gift.
You become slightly better prepared for next time – and more delighted when it arrives precisely on schedule.
"Or perhaps you travel to a country where buses never arrive on time? Your brain models will likely update. This helps us adapt to new environments and situations, making life much easier," says Olgerta Asko.