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ATLANTA – According to a study by Georgia State University, the shape and connectivity of brain networks – distinct areas of the brain that work together to perform complex cognitive tasks – can change fundamentally and recurrently over time.
The interaction and communication between neurons, called "functional connectivity", give birth to brain networks. Researchers have long badumed that these networks were spatially static and that a fixed set of brain regions contributed to each network. But in a new study published in Mapping of the human brainResearchers in the state of Georgia have found evidence that brain networks are fluid in space and functionally.
The researchers collected brain imaging data by functional magnetic resonance imaging (fMRI) to create snapshots of network activity at a granular level over several minutes, and observed rapid changes in the function, size and location of networks.
"Assuming that each brain region interacts with the rest of the brain in the same way is simplified in the long run," said Armin Iraji, researcher at the Center for Translational Research in Neuroimaging and Data Science (TReNDS) and lead author of the 39, study. Co-authors of the study include Vince Calhoun, professor of psychology at the University and director of TReNDS, and Jessica Turner, badociate professor of psychology.
The researchers discovered that the spatial properties of a given brain network evolve over time, as does its relationship with other brain networks.
"You can think of the brain as an organization in which employees work together to make the whole system work," Iraji said. "For a long time, we thought that brain networks were like departments or offices, in which the same people did the same job every day, but it turns out that they may be more like spaces. coworking, in which people come in and out. " different work done at a given moment ".
Ignoring these spatial and functional variations could lead to an incorrect and incomplete understanding of the brain, Iraji added.
"Let's say we measure the functional connectivity between two regions at different times and we see some variability," he said. "From one point of view, the strength of connectivity badociated with a specific task will change over time, but what if that region is responsible for different tasks at different times?" there are different people in these two offices on different days, that's why we see the difference in communication ".
The researchers' findings are based on the concept of chronnectome – a model of the brain in which functional connectivity patterns evolve over time, which was originally proposed by Calhoun in 2014 – in this work elucidating the "space" chronnectome.
Scientists also examined whether brain networks could differ between patients with schizophrenia and healthy controls. If they found differences between the two groups, they note that these differences are not always present. It is therefore important to capture these transient changes.
"Most previous studies have looked at average network activity over time," Iraji said. "But if you look at the average, you eliminate all these small fluctuations that could be a differentiating factor between healthy people and people with brain disorders."
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Iraji said that in the future, scientists studying these disorders should include the possibility of dynamic spatial connectivity when they are trying to model the brain.
The study was funded by the National Institutes of Health grants 2R01EB005846, R01REB020407 and P20GM103472. and grant 1539067 from the National Science Foundation (NSF) to Vince Calhoun.
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