A combined research team, formed by scientists from the School of Medicine, from the Washington University, in the United States, and from the Institute of Technology and Advanced Biomedical Imaging, from the University of Chieti, in Italy, has managed to use faster brain scans in order to map the brain activity of volunteers either at rest or while watching a movie. The study has been recently published in the online journal Neuron.
According to the senior author of the study, Dr Maurizio Corbetta, the activity of the brain consists of waves that repeat themselves as slow as once ever 10 or more seconds, or as fast as one every 50 milliseconds. Corbetta reports that this is the first attempt of the research team to scan the waves that repeat themselves every 50 milliseconds, whilst also mapping the wave fluctuations of the slower waves. Their analysis is similar to that made through the use of an fMRI (functional magnetic resonance imaging). The research team analyzed the brain activity of subjects while they were resting or watching a movie. The results show interesting information about the configuration of the brain networks and the differences in conformation during rest and activity. Corbetta also said that understanding how the brain networks function is very important for better future diagnosis and treatment of brain injuries and disorders.
Precedent studies have revealed several networks of the brain that are used during the rest-state. These brain networks are groups of brain regions whose level of activity either rise or fall in synchronization when the brain is resting. The research team used the technology called fMRI in order to locate and investigate the respective brain networks. However, the fact that the fMRI technique is rather slow, they were only capable of investigating waves that changed every 10 seconds or more.
Furthermore, the research team used a newer, faster technology, called MEG (magnetoencephalography). This technique is capable of detecting waves that are active for less than 50 milliseconds, thus allowing the research team to investigate the waves that have between 1 and more than 50 activity cycles per second. The first author of the study, professor Viviana Betti, said that the brain activity appears to be fluctuation on a slow time scale. However, when the subjects stopped resting and started watching a movie, the brain networks also shifted their frequency channels. This lead Viviana to conclude that the brain uses various frequencies for completing tasks and resting. She compared the brain to a radio.
The subjects that participated in the study were asked to either watch a movie or rest, activities during which the research team scanned the activity of their brains. Another group of subjects were asked to pay attention to events occurring in the movies, such as plot twists. The subjects in the second group were asked to press a button whenever they observed a new event in the ongoing movie. Just as previous studies have shown, the majority of test subjects managed to identify the same events during the movie. The MEG results showed that the communications between different regions of the visual cortex changed during the events of the movies.
Corbetta concludes that the results of the study reveal that there are dynamic changes happening to the rest-state networks during cognitive activities. He believes that future studies are needed in order to track the network activity during different tasks, and to see the level of correlation and dynamic coordination across the regions of the brain.