Brain May Avoid Thought Traffic Jams by Communicating at Different Frequencies
Posted on May 7, 2012Researchers have found that brain networks may avoid traffic jams by communicating on different frequencies. The researchers found different brain networks (areas of the brain that regularly work together) in the human brain use different frequencies. The research was published here in Nature Neuroscience.
Maurizio Corbetta, MD, the Norman J. Stupp Professor of Neurology at Washington University, says, "Many neurological and psychiatric conditions are likely to involve problems with signaling in brain networks. Examining the temporal structure of brain activity from this perspective may be especially helpful in understanding psychiatric conditions like depression and schizophrenia, where structural markers are scarce."
Scientists usually study brain networks using magnetic resonance imaging, which tracks blood flow. The scientists assume that an increase in blood flow to part of the brain indicates increased activity in the brain cells of that region. This MRI data misses activity that occurs at frequencies greater than 0.1 hertz.
Corbetta says, "Magnetic resonance imaging is a useful tool, but it does have limitations. It only allows us to track brain cell activity indirectly, and it is unable to track activity that occurs at frequencies greater than 0.1 hertz, or once every 10 seconds. We know that some signals in the brain can cycle as high as 500 hertz, or 500 times per second."
Researchers used a technique called magnetoencephalography (MEG) to analyze brain activity in 43 healthy volunteers. MEG detects very small changes in magnetic fields in the brain that are caused by many cells being active at once. It can detect these signals at rates up to 100 hertz. The researchers found that brain networks tick at different frequencies.
Lead author Joerg Hipp, PhD, of the University Medical Center at Hamburg-Eppendorf and the University of Tübingen, both in Germany, says, "We found that different brain networks ticked at different frequencies, like clocks ticking at different speeds."
For example, networks that included the hippocampus, a brain area critical for memory formation, tended to be active at frequencies around 5 hertz. Networks constituting areas involved in the senses and movement were active between 32 hertz and 45 hertz. Many other brain networks were active at frequencies between eight and 32 hertz. The researchers say these "time-dependent" networks resemble different airline route maps, overlapping but each ticking at a different rate.