Intelligence – It’s all about connectivity


Image: dr Kirsten Hilger
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Photo credits: Gunnar Bartsch / University of Würzburg

You’re taking a nap on the sofa when your son shows up and asks you to help him with his math homework. This transition from sleep to work is quite a challenge for the brain. Depending on the type of task, a specific neural network must be activated. Depending on the complexity of the task, different networks must interact. All this requires energy and strength.

A new study recently published in the journal cerebral cortex suggests that the higher a person’s intelligence score, the easier it is for them to transition between idle and different task states. This ability is based on certain neural networks and their communication structures. “The functional brain network architecture of individuals with higher resting-state test intelligence scores more closely resembles the architecture required for various cognitive tasks,” says Dr. Kirsten Hilger.

Examine the brain foundations of human intelligence

Kirsten Hilger is head of the research group “Networks of Behavior and Cognition” at the Institute of Psychology I at the University of Würzburg. Understanding the neural basis of human intelligence is a focus of her research. Her main interest is the relationship between functional and structural brain networks and their importance for individual differences in intelligence. Together with doctoral student Jonas A. Thiele and a team from Indiana University, Bloomington (USA), she carried out the project funded by the German Research Foundation (DFG).

Functional and structural brain networks – to explain this difference, the neuroscientist uses a simple image: If you imagine the exchange of information between different brain regions as a transport of goods from London to Chicago, the freeway would represent the structural brain connections – the better the freeway infrastructure, the faster traffic can flow. In contrast, traffic would correspond to the functional context of the brain. These functional relationships were the subject of the current study.

A study of more than 800 adults

To do this, the team used data from multi-center projects involving more than 800 adults, which were made available to researchers as part of international data-sharing initiatives. The participants in the study either rested or had to do various tasks. During this time, their brain activity was monitored using functional magnetic resonance imaging (fMRI).

Seven types of tasks had to be completed – each representing a different cognitive process. For example, in order to activate their working memory, the participants had to decide whether the last image in a long series of images was identical to a previously shown image. To study language processing, they were told a story; then they had to choose between two alternatives to decide what the subject of the story was. To test social cognition, they watched video clips of moving geometric objects. They were then asked to decide whether or not these objects interacted with each other.

Each task triggers brain adaptations

“Magnetic resonance imaging allowed us to test our hypothesis that higher levels of general intelligence are associated with less reconfiguration of brain networks,” explains Hilger. Reconfiguration: This concept can also be illustrated with the metaphor of road traffic.

“When we are at rest, we measure the basic traffic, which is always flowing, so to speak,” explains Hilger. An external cognitive demand is then comparable to rush hour or a holiday weekend – task-specific traffic comes on top of the basic traffic, and depending on the task, different adjustments – or reconfigurations – are necessary.

Highly intelligent people need fewer adjustments

Hilger and her team analyzed processes both in the whole brain and in various functional brain networks known to be associated with specific brain functions. The results suggest that the functional networks of people with higher intelligence scores require fewer adjustments when switching between different cognitive states—their network architecture is designed to require less reconfiguration from sleep to work mode. Or, figuratively speaking, their basic traffic flows in a way that makes these adjustments less complex and doesn’t create congestion.

This effect occurred regardless of the type of task to be completed – i.e. regardless of the different cognitive demands to be processed. Their relative contribution to the observed effect was almost identical. According to the scientists, this result allows the conclusion that intelligence is a property of a widespread “multitask brain network” or, to put it another way: “Intelligence is a phenomenon of the adaptation of the entire brain to different requirements,” says Hilger. The more intelligent an individual is, the better suited their brain’s network architecture is to performing various cognitive tasks.

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