"Interestingly, even when we looked at much higher temporal resolution, brain networks appear to fluctuate on a relatively slow time scale," said first author Viviana Betti, PhD, a postdoctoral researcher at Chieti. "However, when the subjects went from resting to watching a movie, the networks appeared to shift the frequency channels in which they operate, suggesting that the brain uses different frequencies for rest and task, much like a radio."
In the study, the scientists asked one group of volunteers to either rest or watch the movie during brain scans. A second group was asked to watch the movie and look for event boundaries, moments when the plot or characters or other elements of the story changed. They pushed a button when they noticed these changes.
As in previous studies, most subjects recognized similar event boundaries in the movie. The MEG scans showed that the communication between regions in the visual cortex was altered near the movie boundaries, especially in networks in the visual cortex.
"This gives us a hint of how cognitive activity dynamically changes the resting-state networks," Corbetta said. "Activity locks and unlocks in these networks depending on how the task unfolds. Future studies will need to track resting-state networks in different tasks to see how correlated activity is dynamically coordinated across the brain."
|Contact: Michael C. Purdy|
Washington University School of Medicine