The study analysed brain activity recordings from 128 typically developing children aged 6 to 19. Using electroencephalography (EEG), the researchers examined how electrical signals fluctuate when the brain is at rest, and how closely different brain regions operate near this optimal balance. They found that children with higher IQ scores showed brain activity closer to this balanced state, particularly in brain regions involved in planning and complex thinking. “We wanted to understand whether brain signals relate to intelligence in healthy children,” Cristian explains. “This could be very important to understand what goes wrong in neurodevelopmental conditions such as autism or ADHD.”
A balanced brain is a more efficient brain
Neurons communicate through electrical signals, and healthy brain function depends on a careful balance between activity and inhibition. Too much excitation can be harmful, while too much inhibition can dampen information processing. You can think of it as the brain’s accelerator and brake. If there is no brake, the brain can lose control, as in epilepsy. If there is too much braking, information doesn’t flow efficiently.
Cristian and her colleagues focused on EEG-based measures that capture this balance across large-scale brain networks. They found that children with higher IQ scores showed signals closer to an optimal balance, especially in association areas of the brain, such as frontal and temporal regions, which support planning and higher-order cognition.
“What we see is that brain activity reflecting balance is concentrated in regions responsible for planning and complex cognition,” Cristian says. “And this relationship becomes particularly clear during adolescence.”
Why adolescence matters
The findings were strongest in teenagers, a period when the frontal brain regions are still maturing. “This was the most fascinating part of the study for me,” says Gianina Cristian. “The brain is incredibly complex. Although different regions can sometimes take over each other’s functions after injury, there is still strong evidence that certain areas are functionally specialised. Regions involved in basic functions like seeing or responding to the environment mature early, while areas responsible for planning and higher‑order thinking, such as frontal and temporal regions, develop later. That difference in timing is important, because it helps us understand how brain development relates to intelligence.”
Looking ahead
Importantly, the researchers stress that the findings do not mean intelligence can be easily increased or manipulated. At this stage, the research is about understanding mechanisms, not making predictions or interventions. Within this study they observed associations, not causes.
In the long term, the work could help establish reference values for healthy brain development and improve understanding of neurodevelopmental disorders. “If we understand how a healthy brain develops optimal balance,” Cristian says, “we’re better equipped to identify when development diverges, and why that matters for cognition.”