Predicting Cognitive Resilience Against Sleep Loss

• Differences in the medial prefrontal cortex (MPFC) as measured by fMRI, DTI, and MRS [ Time Frame: Session 2 of study (1 week after enrollment) ] [ Designated as safety issue: No ]
  It is hypothesized that, relative to vulnerable individuals, those who are highly resistant to the adverse effects of sleep loss on cognition will show: 1) increased gray matter volume in the MPFC, 2) greater white matter integrity as indicated by the Diffusion Tensor Imaging measure of fractional anisotropy (FA) values in the MPFC, 3) greater functional activation in MPFC during cognitively demanding tasks, 4) greater functional connectivity between MPFC and alerting regions of the midbrain and thalamus; and 5) different ratios of GABA and glutamate within the MPFC.
  
  

• Psychomotor Vigilance Task (PVT) [ Time Frame: At sleep deprivation session (2 weeks after enrollment) ] [ Designated as safety issue: No ]
  The PVT will be administered 17 throughout the overnight sleep deprivation session. PVT performance measures participants' alertness and objective resilience to sleep deprivation. PVT performance will be used as a measure to retrospectively assign participants into sleep loss-resistant and sleep loss-vulnerable groups.
  
  

• Karolinska Sleepiness Scale (KSS) [ Time Frame: At sleep deprivation session (2 weeks after enrollment) ] [ Designated as safety issue: No ]
  The KSS will be administered 17 throughout the overnight sleep deprivation session. The KSS provides a measure of subjective sleepiness.
  
  

Resilience, the ability to cope effectively and adapt to a wide range of stressful environmental challenges, appears to be mediated extensively by the medial prefrontal cortex (MPFC). Sleep deprivation has been shown to reduce metabolic activity throughout the brain, particularly the MPFC. The ability to resist the effects of sleep loss appears to be a stable, trait-like phenomenon that is consistent across situations, suggesting that it may reflect an enduring quality of the underlying neurobiological system. The present study aims to identify the neural basis of resilience and effectively discriminate resistant from vulnerable individuals during an overnight sleep deprivation session. Specifically, the primary aims of this research are 1) to further our understanding of the role of the MPFC in resilience and 2) to develop a statistical prediction algorithm based on multimodal neuroimaging that will reliably discriminate between individuals who are resilient versus vulnerable to the cognitive impairing effects of sleep loss.