The research opens fascinating possibilities for future basic and applied studies to investigate the dynamics of brain states, particularly in cases of dysfunction -- such as schizophrenia, Alzheimer's disease and chronic pain -- without requiring external markers.
Dante R. Chialvo, research associate professor of physiology at Northwestern University Feinberg School of Medicine, led the study, which appeared in the Dec. 31 online issue of the journal Physical Review Letters. The research group included scientists from the IBM T.J. Watson Research Center, Yorktown Heights, N.Y., and the University of Islas Baleares, Mallorca, Spain.
Chialvo and colleagues described how fMRIs from healthy individuals showed that tens of thousands of discrete brain regions form a network that has the same qualitative features as other complex networks, such as the Internet (technological), friendships (social) and metabolic (biochemical) networks.
The fMRI technology provided, in each recording session, hundreds of consecutive images of brain activity discretized in thousands of tiny cubes (voxels). The image intensity at each cube usually indicates the amount of brain activity at that site.
The investigators then calculated the degree of correlation between the activities among the tens of thousands of brain regions. Through their computations, the group discovered which brain regions were momentarily "linked" in a "network."
When they further analyzed the structure of these networks, they saw a familiar picture: Brain networks share the features of other complex networks, such as the Internet -- very few "jumps" were necessary for connecting any two nodes.