A new study published in Communications Biology suggests that individuals who score higher on intelligence tests may have brains that communicate more flexibly across distant regions. The findings show that a greater diversity of connections between key brain areas, along with more complex patterns of activity over time, are associated with higher intelligence levels.
Scientists have long tried to uncover the biological roots of intelligence. Early research often focused on pinpointing specific brain regions linked to higher cognitive abilities, with the frontal and parietal lobes frequently associated with reasoning, problem-solving, and complex decision-making. More recent theories, however, suggest that intelligence may also depend on how flexibly brain networks shift between different activity patterns when tackling problems.
In the new study, led by Jonas A. Thiele from the University of Würzburg in Germany, researchers set out to test these ideas more directly. Their goal was to provide the first empirical evidence for the Multilayer Processing Theory (MLPT), which proposes that human intelligence arises from processes operating across multiple spatial and temporal scales.
Rather than analyzing brain activity during rest or simple tasks, the team examined how the brain functions while participants completed Raven’s Progressive Matrices, a well-known intelligence test. In this task, individuals are shown patterns of shapes and must identify the missing piece that correctly completes the sequence.
To investigate these multi-scale brain processes, the researchers analyzed two separate datasets collected in different laboratories. In the first, brain activity from 67 participants (26 women, average age 23) was recorded using functional magnetic resonance imaging (fMRI) as they completed the intelligence test. This technique measures changes in blood flow, enabling scientists to observe how different brain regions interact across networks during task performance.
The fMRI findings revealed an important detail: people who scored higher on the intelligence test did not simply show stronger overall brain connectivity. Instead, they displayed more diverse communication between regions in the frontal and parietal areas. These regions appeared to function as highly efficient “connector hubs,” linking different brain networks to coordinate information during complex problem-solving.
Meanwhile, EEG analysis showed that individuals with higher intelligence scores had greater signal complexity at longer (coarser) timescales, pointing to richer and more flexible large-scale brain activity. At the same time, there was a weaker, non-significant trend toward lower complexity at very short (finer) timescales, which may indicate simpler and more efficient processing within smaller, local brain circuits.
Taken together, the findings suggest that intelligence does not stem from a single brain region, but from how efficiently different areas coordinate and interact across multiple spatial and temporal scales.
Jonas A. Thiele and his colleagues concluded that their results provide the first empirical support for the Multilayer Processing Theory (MLPT), which proposes that higher intelligence arises from flexible, long-range brain processes operating over broader timescales, working in tandem with simpler, short-range processes at finer scales.
However, the researchers note several limitations. The fMRI and EEG data were collected from different groups of participants, making direct comparisons difficult. In addition, the sample sizes were relatively small, which may affect statistical reliability, and all participants were young adults, meaning the findings may not fully apply to children or older populations.
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