A study led by Ryan V. Raut, an instructor in WashU Medicine Mallinckrodt Institute of Radiology, has shown that it is possible to predict continuously evolving brain-wide states such as changing neural activity, oxygen levels or metabolic activity from variations in pupil dilation.
The result supports the idea that small-scale neuronal activities - such as a reaction to a specific stimulus - are not only subject to the dynamics of their own circuit or region of the brain, but exist within a brain-wide or even organism-wide system of synchronized activity.
The study was published in Nature.
Using a technique called wide-field optical imaging, in which a camera observes large sections of the brain's cortex, the surface layer of the brain, the researchers observed the activity of thousands of neurons in an awake mouse. They showed that fluctuations in the animal's pupil size correlated with complex patterns of brain activity, including in brain regions with no direct connection to eye function. Their model was able to accurately predict patterns of brain activity, validating the theory that individual neurocircuits and the rest of the brain's activities are deeply intertwined.
The results could inform better models of how brain activity is modulated, which may also facilitate improvements in interpreting neuroimaging data to diagnose and treat complex neurological conditions and cognitive disorders.
