Sleep Deprivation Brain Activation Case Study

This case study examines the effects of sleep deprivation (SD) on brain activation and cognitive performance, focusing on lapses in attention. The study used fMRI to compare brain activity during a visual task in rested wakefulness (RW) and SD states. Results showed that SD led to slower and less accurate responses, with reduced task-related activity in several brain regions. Lapses during SD were associated with reduced extrastriate signals, indicating a decline in visual sensory function, and increased thalamic activation, suggesting compensatory mechanisms. The study highlights the complex interplay between top-down control deficits, visual cortex contributions, and neurotransmitter involvement in SD-related cognitive lapses.

Notes for paper: Lapsing during Sleep Deprivation Is Associated with Distributed Changes
in Brain Activation (Chee et al., 2008).
Aim(s):
 To identify the association between lapses occurring during SD and task related brain
activation changes.
Participant:
 n= 24 (mean age 22.5 +/- 1.6 years).
 13 females, 11 males; all right handed individuals.
Study Design:
 Participants had at least 6.5 hours of sleeping every night since a month before the
study.
 Morningness-eveningness score less than 22.
 Without any sleep disorder.
 Without any psychiatric disorder.
Protocol:
 Vigorous activity, smoking or consuming alcohol was prevented.
 Actigraph was presented in the first visit to monitor sleep patterns.
 fMRI imaging was done on the next two visits.
 SD and RW sessions were separated by a week.
 Participants took part in non-strenuous activity during SD session.
Measures:
 Local and global letters task stimuli

 3 T Allegra system (Siemens) for imaging
 Brain Voyager QX version 1.8.6 for image processing
 Voxel for task related activation
 Trial-by-trial analysis and direct comparison
Results:
 SD responses were slower and less accurate than RW.
 Correct trial response distribution had a pronounced long right tail
 Incongruent trials had slower response than congruent trials.
 Significant reduction in task related activity in SD compared to RW.
 Lapse related cortical responses showed peristimulus signal reduction.
 No difference in this reduction between RW and SD states.
 Association observed between increased peak signals and lapses in regions that
control cognition.
 More pronounced signal elevation in RW.
 SD lapses associated with reduced extrastriate signals.
 Greater task related thalamic activation in SD.
Interpretation:
 Reduction in task-related extrastriate activation during SD lapses proves that low
visual sensory function is a contributory factor.
 Top-down control deficits are associated with lapses during SD.
 Neuronal loss and lowering in time during SD recruits the frontoparietal neurons can
to compensate for attention lapses.
 Wake state instability is visible while considering trial-by-trial fluctuations in
response time, during SD state.

 Lapses in RW and SD state differ in several ways. The most relevant difference is in
extrastriate activation attenuation that precedes a widespread close down of external
environment responsiveness.
 A thorough understanding of SD lapses will benefit from teasing out reduction in top-
down attention control, attenuated visual cortex contributions and neurotransmitters
involved in rapid transition from putative microsleep to wakeful alertness.