Researchers at Stanford University have determined from brain-imaging data whether
experimental subjects are recalling events of the day, singing silently to themselves, performing mental arithmetic, or merely relaxing.
In the study, subjects engaged in these mental activities at their own natural pace, rather than in a controlled, precisely timed fashion as is typically required in experiments involving fMRI. The team used uninterrupted scan periods ranging from 30 seconds to 10 minutes in length.
The team assembled images from each separate scan. Instead of comparing “on-task” images with “off-task” images to see which regions were active during a distinct brain state compared with when the brain wasn’t in that state, the researchers focused on which collections, or networks, of brain regions were active in concert with one another throughout a given state
The researchers found that distinct mental states can be distinguished based on unique patterns of activity in coordinated networks — brain regions that are synchronously communicating with one another.
The team is using this network approach to develop diagnostic tests for Alzheimer’s disease and other brain disorders in which network function is disrupted.
M. D. Greicius, et al., Decoding Subject-Driven Cognitive States with Whole-Brain Connectivity Patterns, Cerebral Cortex, 2011; DOI: 10.1093/cercor/bhr099 (in press)