WESTCHESTER, Ill.—Functional magnetic resonance imaging (fMRI) may be a practical method of assessing the efficacy of interventions against the detrimental effects of sleep deprivation. Although further work needs to be done to measure its true effectiveness, the repeatability and reliability of fMRI is a hopeful sign for its usefulness in future studies of this nature, according to a study published in the January 1 issue of the journal SLEEP.
The study, conducted by Michael W. L. Chee, MBBS, and colleagues of the Singhealth Research Laboratories in Singapore, focused on 19 healthy, right-handed subjects, who all underwent two sessions (pairs of fMRI scans) at rested wakefulness and after sleep deprivation. Brain activation was highly correlated across sessions in a frontoparietal network previously implicated in working memory function. The magnitude of decline in this activation after sleep deprivation was preserved in bilateral parietal regions.
Among several behavioural metrics investigated, the most robust marker of vulnerability to sleep deprivation was the change in the intra-individual variability of reaction times. This was shown to be both stable over time and correlated with the drop in left parietal activation from rested wakefulness to sleep deprivation in both experimental sessions.
“This study is significant from several viewpoints. The first relates to the supposed trait like quality of responses to sleep deprivation,” said Chee. “While it stands to reason that the brain should similarly manifest trait-like behavior in response to sleep deprivation, we are the first group to actually demonstrate that fMRI can be used to track this.”
The other advantage of having an imaging marker, said Chee, is that depending on the area that is highlighted, clues are provided as to which systems underpin vulnerability to sleep deprivation.
“The parietal lobe has, to me anyway, been the perennial bridesmaid to the frontal lobes,” said Chee. “We almost worship our ability to muster executive control over decisions — a key role of the frontal lobes, but less weight has been given to the parietal lobes that are responsible for sensory integration and various aspects of attention. ‘Garbage in, garbage out’, say computer scientists. Well, if the signal(s) and information the frontal lobe is fed are degraded, memory will ultimately be affected. So while behavioral tests show failure of short term memory, the real problem may be more fundamental and relate to degraded data input to brain regions that act on that information.”
SLEEP is the official journal of the Associated Professional Sleep Societies, LLC, a joint venture of the American Academy of Sleep Medicine (AASM) and the Sleep Research Society.
SleepEducation.com, a Web site maintained by the AASM, provides information about the various sleep disorders that exist, the forms of treatment available, recent news on the topic of sleep, sleep studies that have been conducted and a listing of sleep facilities.
For a copy of this study, entitled, “Reproducibility of Changes in Behaviour and fMRI Activation Associated with Sleep Deprivation in a Working Memory Task”, or to arrange an interview with an AASM spokesperson regarding this study, please contact Jim Arcuri, public relations coordinator, at (708)492-0930, ext. 9317, or email@example.com.