Chee_relayout_US_Neuro 16/02/2010 11:07 Page 93
Imaging
What Has Functional Magnetic Resonance Imaging Revealed Regarding the
Neurobehavioral Correlates of Sleep Deprivation?
Michael WL Chee, MBBS, MRCP(UK)
Professor, Cognitive Neuroscience Laboratory, Neuroscience and Behavioral Disorders Program, Duke-NUS Graduate Medical School Singapore
Abstract
A night of total sleep deprivation can result in performance decline in several cognitive domains. Functional magnetic resonance imaging (fMRI) has
helped to reveal the neuroanatomical correlates of such changes in attention and memory, as well as in risky decision-making. Studies of sleep
deprivation have shed light on the role of sleep in the consolidation of declarative memory, which can be observed in the form of temporally specific
changes in hippocampal and neocortical activation. Sleep deprivation can also be thought of as a cognitive ‘stress test’ that may afford testing of
cognitive enhancers.
Keywords
Sleep deprivation, functional magnetic resonance imaging (fMRI), attention, memory, decision-making
Disclosure: This work was supported by the Defense Science and Technology Agency, Singapore (POD0713897) and a STaR Investigatorship.
Received: January 5, 2009 Accepted: May 4, 2009
Correspondence: Michael WL Chee, MBBS, MRCP(UK), Neuroscience and Behavioral Disorders Program, Duke-NUS Graduate Medical School, Singapore 169857.
E: michael.chee@duke-nus.edu.sg
Total sleep deprivation (SD) for as little as 24 hours can result in common, is more difficult to study because proper experimental control
measurable decline in cognitive performance.
1
Beyond experimental is difficult and more expensive to realize.
settings, changes in attention, memory, and decision-making contribute
to increased physician errors while on shift duty,
2,3
and deficits in vigilant The best-characterized cognitive domain in the setting of SD is probably
attention can result in fatal transport accidents.
4
Despite a growing working memory.
6–14
Other facets of cognition studied include verbal
number of editorials and advisories
5
regarding the health risks of SD, self- learning,
15,16
sustained attention,
17–19
divided attention,
20
visuospatial
imposed denial of sleep has become increasingly prevalent in urban attention,
19,21
inhibitory function,
22
decision-making,
23,24
and emotional
societies. As such, what was formerly of interest primarily to the military responses to pictures
25
(see Table 1).
has become a global health and safety concern. This has motivated an
awakening of research into the mechanisms underlying SD-related Working memory involves temporary storage and manipulation of
cognitive decline. Additionally, it has become of interest to identify information. Tasks designed to evaluate working memory have
individuals susceptible to the effects of SD and to ascertain the consistently recruited lateral prefrontal
26
and parietal cortices.
27
Most of
appropriateness of countermeasures deployed to reduce functional these studies show that SD tends to reduce task-related activation in
deficits where SD is unavoidable. Functional magnetic resonance imaging these regions, with additional involvement of the ventral visual cortex.
(fMRI) has attracted considerable interest as a tool in these research However, the manner in which SD influences the functional anatomy of
areas because it complements observing behavior, provides a clearer working memory has differed somewhat across studies, possibly as a
spatial localization of cognitive effects than electroencephalography result of cognitive subtask differences, task difficulty, duration of SD,
(EEG), and can be performed repeatedly without significant safety analytical methods used, and inter-subject variation.
concerns. The fMRI studies reviewed here pertain to studies examining
task-related activation in sleep-deprived individuals and to reports on the Given the variation in findings, one might ask whether fMRI is capable
delayed effects of sleep or SD on neural activation. The latter set of of yielding reproducible results in the setting of SD. This concern was
studies were performed primarily to characterize memory consolidation. addressed in a study in which healthy volunteers were studied four
times: twice under conditions of SD and twice following a normal
Imaging Task-related Activation night of sleep. The study found that parietal activation decline
During Sleep Deprivation reproducibly correlated with behavioral decline across state
14
and
Several cognitive domains have been evaluated in the context of 24, 35, concurred with behavioral studies that suggest vulnerability to SD to
and 48 hours of total SD (see Table 1). Chronic partial SD, while more be trait-like.
28,29
© TOUCH BRIEFINGS 2009
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