A Research Blog

Prof Michael Chee

This article was contributed by Professor Michael Chee, Director, Centre for Cognitive Neuroscience, Duke-NUS Medical School

fMRI, a brain imaging technique, can detect spontaneous fluctuations in blood flow that are synchronized across functionally related but physically separate brain regions. More recently, it has been shown that this type of functional connectivity, evaluated by when a person simply lies down in a MRI scanner with his / her eyes open, is not static. Instead, it displays recurrent shifting patterns not unlike a restless sea. Although dynamic shifts in functional connectivity have been suspected to signify changing mental states, clear proof that the shifts have behavioral significance has been elusive.

A team led by Michael Chee and Juan Zhou of Duke-NUS Medical School, Singapore and communicated in the Aug 8th issue of the Proceedings of the National Academy of Sciences (USA) found the missing link between shifting mental gears and imaging data through sophisticated analyses anchored on the everyday observation that when we are sleepy, our eyelids tend to shut.

MD-PhD student Chen Hao Wang found that no matter how many computer-detected ‘dynamic functional connectivity states’ he derived from the ‘task-free’ fMRI data, there were always two extreme patterns that emerged.  One corresponded to a state when their eye-lids were more closed, and the other to when the eye-lids were wide open.

To forge the missing link between brain images and behavioral state, Wang applied the same analysis to data collected when participants had to detect unpredictable sounds. He found the same two extreme patterns corresponded to slower and faster responses respectively, signifying that the imaging patterns could be related to a persons’ state of vigilance. Additionally, he discovered that individuals more susceptible to dozing off when sleep deprived tended to dwell in the ‘low vigilance’ state, even when they were well rested.

Chee hopes that this finding will open the door to probing how an individual’s repertoire of dynamic functional connectivity states can inform about that person’s mental ‘capacity’, without having to use potentially taxing behavioral tests that require patient co-operation. Extension of the methodology pioneered by Chee, Zhou and others could open new vistas for the investigation of mental disorders, diminished states of consciousness, and even healthy cognitive aging. “Future tests would need to be anchored to other behavioral benchmarks, requiring creative approaches,” added Zhou, “But opening the door sure has been fun!” Chee ended with.

   

This study was supported by the National Research Foundation Singapore under its Singapore Translational Research Investigator Award (NMRC/STaR/0004/2008) and Singapore Ministry of Health (MOH)’s National Medical Research Council (NMRC) under its Singapore Translational Research Investigator Award (NMRC/STaR/0015/2013), and Far East Organisation awarded to Professor Chee.

This study was also supported by NRF Singapore under its Cooperative Basic Research Grant (CBRG) (NMRC/CBRG/0088/2015), administered by the Singapore MOH’s NMRC, and Duke-NUS Medical School Signature Research Program funded by Ministry of Health, Singapore awarded to Assistant Professor Zhou.

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