SLEEP 2011 Abstract Supplement

A. Basic Science IX. Learning, Memory and Cognition
Regression analyses were performed between spindles characteristics
and raw scores on RAVLT.
Results: No significant correlation was found between age and spindle
characteristics or between age and RAVTL scores. Spindles density in
frontal (F3 and F4) derivations were positively correlated (p < .05) with
RAVLT learning scores (trials 1 to 5) (R > .43,) and delayed recall performance
(R > .42). In addition, spindles amplitude in F4 derivation was
positively correlated with RAVLT learning performance (R = .40,) and
delayed recall performance (R = .42).
Conclusion: Higher number and amplitude of spindles in frontal areas
are linked to better verbal learning and delayed recall performance in
older subjects. These results suggest that neuronal mechanisms underlying
the spindles generation play a role in learning and verbal long term
memory capacities in aging.
0239
SHORT NAP IMPROVES COGNITIVE PERFORMANCE FOR
SEARCHING A TARGET FROM DISTRACTIVE STIMULI
Kaida K, Tsuzuki K, Takeda Y
Human Technology Research Institute, National Institute of Advanced
Industrial Science and Technology (AIST), Tsukuba, Japan
Introduction: To investigate the effects of a short nap and light exposure
on cognitive function, visual search performance was examined.
Methods: Eleven participants (31.9 ± 7.19, range 23-43 years old, 5
males) carried out a visual search task twice a day (1200-1330h, 1430-
1600h) before and after an afternoon short nap (20 min) or rest. Subjective
sleepiness (Karolinska sleepiness scale, KSS) was scored before
and after the task.During the second task (1430-1600h), bright light
treatment (2000 lux) was applied in the two conditions. The participants
took part in a total of four experimental conditions (control, short nap,
bright light, and short nap and bright light conditions). Except during
the light treatment, participants stayed in the dim lighted environment
(< 100 lux).In the visual search task, participants searched a 90° rotated
character “T” (target) among randomly rotated and deployed characters
“L” (distracter) on the computer display. In the task, participants were
required to indicate the direction of “T” (either right or left) by pressing
a button of a gamepad with right or left forefingers as quickly as possible.
One session of the task consists of 288 trials, which takes about
20 min to be completed. The task was carried out in sequence with other
types of cognitive performance tasks (not shown here).
Results: The search time (correct reaction time) was significantly shorter
in the nap and the nap and light conditions than in the control condition
(p < .05). There was no significant difference between the bright
light and the control conditions. Subjective sleepiness (KSS) was also
significantly lower in both the nap condition and the nap and light condition
compared to the control condition (p < .05).
Conclusion: Short nap improves cognitive performance to search a target
from distractive stimuli.
0240
EFFECT OF NIGHT SHIFT SCHEDULE ON VISUAL
ENCODING IN A STIMULUS ONSET ASYNCHRONY TASK
Kuhn JW 1 , Jackson ML 1 , Whitney P 2 , Hinson JM 2 , Van Dongen H 1
1
Sleep and Performance Research Center, Washington State University,
Spokane, WA, USA, 2 Department of Psychology, Washington State
University, Pullman, WA, USA
Introduction: Distinct cognitive processes need to be disentangled to
better understand the effect of sleep and sleep loss on cognitive performance.
We distinguished semantic encoding and decision times by
varying stimulus onset asynchronies (SOAs) in a category matching
task. The task involved 200 trials in which two words were presented
either simultaneously (0ms SOA) or with delays between the first and
second word (200ms, 400ms, 600ms, or 800ms SOAs). Subjects had to
decide whether the two words belonged to the same semantic category.
Response time (RT) was measured from the onset of the second word.
The longer the SOA, the more time the person has to encode the first
word before measurement of RT began. The SOA at which there was
no further advantage to RT represented the time used to encode the first
word, uncontaminated by decision and response processes.
Methods: N=16 healthy men (ages 27.5±5.6y) participated in a 16-day
in-laboratory study with two 5-day periods of simulated night work. The
SOA task was administered at baseline (14:30) and on day 5 of each
night work period (02:30). RT stabilized consistently at a presentation
interval of 400ms; accordingly, encoding time was calculated as the difference
between RT at 0ms and at 400ms.
Results: Mixed-model ANOVA was used to examine whether there
were differences between sessions in grand mean RT and in encoding
time for correctly answered trials, distinguishing “Yes” and “No” decisions.
Grand mean RT of correct answers significantly improved across
sessions (“Yes”: F[2,30]=9.6, P