People with a higher-than-average intelligence level have brains that are "wired" in a different way, researchers say. A new study suggests that intelligence is linked with increased connectivity between some regions, and reduced interaction between others.
Researchers at Goethe University Frankfurt in Germany have been giving a lot of thought to how the brains of intelligent people function.
In previous studies, Kirsten Hilger, Christian Fiebach, and Ulrike Basten — all from Goethe University Frankfurt's Department of Psychology — have revealed that there are key differences in brain activation patterns that set intelligent people apart.
In 2015, this team published an article showing that the frontal and parietal regions of the brain are more strongly activated in people with a high IQ.
A more recent study, whose findings were reported earlier this year, added that the brain's anterior insula and anterior cingulate cortex are more actively connected with other regions in the case of intelligent individuals.
At the same time, the researchers noted that high IQ is also associated with a reduced connectivity in the temporoparietal junction, where — as the name suggests — the temporal and parietal lobes connect.
"The different topological embedding of these regions into the brain network could make it easier for smarter persons to differentiate between important and irrelevant information — which would be advantageous for many cognitive challenges," suggests Basten.
Intrigued by these findings, Hilger and colleagues went further, setting out to explore how patterns of activation and integration in the brain correlate with a higher level of intelligence.
In their new study — the results of which were recently published in the journal Scientific Reports — the researchers noted that smarter people have increased connectivity between some areas of the brain, while interaction is dampened between other regions.
Distinct brain module connectivity patterns
The team analyzed the brain scans of 309 participants (110 men and 199 women), all of whom were aged between 18 and 60 years. Their scores on the Full Scale Intelligence Quotient were assessed with the Wechsler Abbreviated Scale of Intelligence.
Hilger and colleagues based their study on the notion that the human brain is "split" into modules, where regions communicate with each other "preferentially," so that some areas interact more intensely than others. Basten explains this through an analogy with social networks.
"This is similar to a social network which consists of multiple subnetworks (e.g., families or circles of friends)," she says. "Within these subnetworks or modules, the members of one family are more strongly interconnected than they are with people from other families or circles of friends."
"Our brain is functionally organized in a very similar way," Basten explains. "There are subnetworks of brain regions — modules — that are more strongly interconnected among themselves while they have weaker connections to brain regions from other modules."
In the new study, the researchers found that people with higher IQs have stronger connectivity between certain brain regions. More specifically, the authors noted that clusters of network nodes in the frontal and parietal cortex, and in cortical and subcortical areas, were more strongly interconnected and more intensely active.
At the same time, the team observed that certain brain regions — such as the superior frontal gyrus temporoparietal junction — are "segregated," meaning that they communicate much less with other brain areas.
Where does causality lie?
This may suggest that brain module intra- and interconnectivity in more intelligent people are primed to discard irrelevant or distracting information.
"We assume that network properties we have found in more intelligent persons help us to focus mentally and to ignore or suppress irrelevant, potentially distracting inputs," Basten says.
However, the researchers note that it is hard to say where causation lies in these findings.
It may be, she says, that people with higher IQs are naturally wired differently, yet it may also be that these patterns of connectivity are caused by engaging in habitually demanding intellectual work. This is a conundrum that is due to be solved by future research.
"It is possible that due to their biological predispositions, some individuals develop brain networks that favor intelligent behaviors or more challenging cognitive tasks. However, it is equally as likely that the frequent use of the brain for cognitively challenging tasks may positively influence the development of brain networks."
"Given what we currently know about intelligence," she concludes, "an interplay of both processes seems most likely."