drummon, s. p. a., brown, g. g., gillin, j. c., stricker, j. l., wong, e. c., buxton, r. b....
TRANSCRIPT
Drummon, S. P. A., Brown, G. G., Drummon, S. P. A., Brown, G. G., Gillin, J. C., Stricker, J. L., Wong, Gillin, J. C., Stricker, J. L., Wong,
E. C., Buxton, R. B.E. C., Buxton, R. B.
Lecturer: Katie YanLecturer: Katie Yan
Introduction Sleep Deprivation (SD) = lack of sleep
Study specifies ~35 hours awake
One night’s sleep deprivation impairs performance on many cognitive tasksEspecially verbal learning & tasks dependent
upon Pre-Frontal Cortex (PFC) involvement
Associated with impairments in the cerebral systems that form the neural substrates of these functions
Effects are poorly understood
Variables
Dependent Independent
Performance on verbal learning tasks
Brain areas activated
Rested State Sleep-Deprived State
Hypothesis
Sleep Deprivation will significantly impair free recall.
On the basis of previous studies, they predicted that PFC would be less responsive to cognitive demands following SD.
Methods
Participants: 13 normal healthy young adults
Relatively normal sleeping patterns
During SD:Monitored in a hospital from 22:00 until time
of scan around 16:30-18:00 the next day○ 34.7 ± 1.2 hours without sleep
Not allowed stimulants of any kind
Methods
Design: Five baseline & four experimental blocks
alternatingEach block 40s; total trial 360s
Methods Baseline
Five words were presented & instructed to not memorize but to determine whether UPPER or lower-case letters.
ExperimentalInstructed to memorized the five words for later
testingTested ~10min after the end of functional scans
MethodsProcedures:
The order of rested and SD conditions was counterbalanced:
Four separate cognitive tasks during fMRI scans in both states
Serial subtraction for analysis○ 20 sagittally oriented slices covering whole brain○ Identified regions that were significantly more
activated during one state than the other
Results
Subjects performed significantly less well on free recall when they were sleep-deprived.
ResultsSubjects did not perform significantly differently between Rested state and SD state in recognition tasks.
Results
The PFC was more responsive after one night of sleep deprivation than after normal sleep, contrary to the hypothesis.Increased subjective sleepiness in sleep-
deprived subjects correlated significantly with activation of the PFC.
Temporal lobes were significantly more activated during rested state than during SD.
The bilateral parietal lobes and two additional frontal regions were more activated after SD than rested state.
Results
Although sleep deprivation significantly impaired free recall compared with the rested state, better free recall in sleep-deprived subjects was associated with greater parietal lobe activation.○ Measured through haemodynamic responses
DiscussionRegarding the Parietal Lobe:
Following SD, activation within the parietal lobes was related to preservation of near-normal verbal learning
Neurophysiological substrate of the initial compensation for SD
Underlie partially successful behaviour adaptation to SD during verbal learning
Restricted to certain cognitive functions
DiscussionRegarding the Temporal Lobe:
Behavioural compensation for SD was not complete, and some of the changes in cerebral activation that followed SD may have contributed to poorer recall performance.
Reduced response of the left temporal lobe to verbal learning Lowered free recall scores?
Personal Opinions...
Considered that simple repetition of verbal learning task might alter BOLD response through practice effects or habituation.Used t-test to compare 1st & 2nd nights of
activation to look for significant alterations of BOLD response
No overlap!
Strengths:
Personal Opinions...
Only had 13 subjectsGender was also not specified
Tasks consisted of only five wordsToo little?
Relatively short duration of sleep deprivationMay have only measured period of time when
brain is still able to compensate for SD and maintain relatively intact performance
Limitations
Personal Opinions...
If they achieved longer sleep deprivation, they may have observed a smaller compensatory response, or even something novel.Try it!
Decreased temporal activity in Alzheimer’sAlzheimer patients as subjects!
Future Possibilities:
Take Home Message:
Only pull all-nighters for multiple choice final exams, don’t bother for short answer exams...
You will probably fail.You will probably fail.
Les Questions?