Intelligence is shaped by how the brain functions as an integrated system rather than by activity in any single region or cognitive network, according to a study that lends support to theNetwork Neuroscience Theory.
Researchers from the University of Notre Dame in the United States analysed brain imaging and cognitive data from 831 adults participating in the Human Connectome Project, which maps links between brain structure, function and behaviour. Findings were validated using an independent dataset of 145 adults.
The theory proposes that intelligence reflects the brain’s ability to coordinate and adapt networks to solve a wide range of problems encountered in daily life, rather than being tied to isolated cognitive functions.
“We found evidence for system-wide coordination in the brain that is both robust and adaptable. This coordination does not carry out cognition itself, but determines the range of cognitive operations the system can support,” said Ramsey Wilcox, a graduate student at the University of Notre Dame and lead author of the study published in Nature Communications.
Wilcox explained that under this framework, the brain is modelled as a network governed by global properties such as efficiency, flexibility and integration. “Once the question shifts from where intelligence is to how the system is organised, the empirical targets change,” he said.
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The study found that effective intelligence depends on integration and long-range communication across multiple brain networks, enabling distributed processing of information. These system-level properties were consistently associated with individual differences in general intelligence across both datasets.
Aron Barbey, professor of psychology at the University of Notre Dame, said the brain relies on “a large and complex system of connections that serve as ‘shortcuts’ linking distant brain regions and integrating information across the networks.”
Barbey added that general intelligence depends on the brain’s ability to balance local specialisation with global integration. The brain functions most efficiently when tightly connected local clusters communicate effectively while remaining linked to distant regions through short communication paths, enabling optimal problem-solving.
Across both datasets, the researchers found that no single brain region or discrete “intelligence network” accounted for differences in intelligence. Instead, intelligence emerged when cognition was coordinated across the system.
“General intelligence becomes visible when cognition is coordinated, when many processes must work together under system-level constraints,” Barbey said.
The authors concluded that general intelligence engages multiple networks, relies on weak long-range connections for efficient global coordination, recruits regions that orchestrate network interactions, and depends on a small-world architecture that supports system-wide communication.
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