SLEEP 2011 Abstract Supplement

A. Basic Science IX. Learning, Memory and Cognition
0245
EFFECT OF SLEEP DEPRIVATION ON ITEM AND SOURCE
MEMORY
Kubin ZJ 1 , Mehalick ML 1,2 , 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: In this pilot study, we investigated the effect of sleep deprivation
on source memory as contracted with item memory. Source
memory, which involves remembering the source (as opposed to the
content) of an item of information, has been shown to involve frontal
brain areas, whereas item memory utilizes predominantly temporal and
parietal brain areas. We employed a source memory task, during which
a list of 96 words was read to the subjects, twice, through headphones
using male and female voices. A series of words from the list mixed
with new words was then visually presented to the subjects, and they
were asked whether or not they had heard the word (item memory); and
whether the source was a male or female voice (source memory).
Methods: Out of a total of N=19 subjects (ages 20-55y, 9f), the first
ten subjects completed an overnight laboratory sleep deprivation experiment,
during which the source memory test was administered at 21:30,
00:45 and 04:00. The other nine subjects were studied afterwards in a
control experiment for which they entered the laboratory to perform the
source memory test at 09:30, 12:45 and 16:00 (12 hours out of phase
with the first group). The number of items recognized correctly (hits)
and incorrectly (false alarms), and the number of items of which the
source was identified correctly were compared between sleep-deprived
subjects and controls using mixed-effects ANOVA.
Results: Sleep deprivation resulted in significantly more false alarms
for item memory (F[1,34]=4.59, P=0.040), but there was no difference
with controls for item hits (F[1,34]=2.30, P=0.14). No significant difference
was found between groups for source memory (F[1,34]=0.07,
P=0.79). There were no significant effects of test session for item and
source memory outcomes (F[2,34]≤1.53, P≥0.23), and no significant interactions
(F[2,34]≤0.86, P≥0.43).
Conclusion: This pilot study suggested that although one night of sleep
deprivation increased the number of false alarms for item memory, this
duration of sleep deprivation may not impair source memory.
Support (If Any): CDMRP award W81XWH-05-1-0099 and DURIP
grant FA9550-06-1-0281
0246
ENHANCEMENT EFFECT OF SLEEP ON NOVEL WORD
ASSOCIATION: AN EVENT-RELATED POTENTIAL STUDY
Lin C 1,2 , Yang C 1,2
1
Department of Psychology, National Cheng-Chi University, Taipei,
Taiwan, 2 Research Center for Mind, Brain and Learning, National
Cheng-Chi University, Taipei, Taiwan
Introduction: The effect of sleep on declarative memory remains contradictory.
Prior studies showed that learning of related word pairs benefited
from sleep consistently, learning of unrelated word pairs however
showed mixed results. It is possible that the behavioral measures used in
previous studies are not sensitive enough to reveal subtle effects of sleep
on new association. N400, an event-related potential (ERP) component
reflecting relatedness among words in semantic memory, was used in the
present study to investigate effect of sleep on the physiological process
underlying new association of unrelated word pairs.
Methods: Eleven subjects (4 males, mean age=22.9) participated in the
study. They were randomly assigned to either Sleep group or Wakefulness
group. In the learning phase, participants were asked to memorize
80 visually presented unrelated word-pairs, and followed by a pre-test
phase with a recognition task. The participants then underwent either
nocturnal sleep (Sleep group) or sleep deprivation (Wakefulness group),
and a post-test was conducted after subjects had one night of recovery
sleep. During both pre-test and post-test sessions, primes and target
words were presented successively for the subjects to judge whether
they are among the original pairs or new pairs. ERPs were recorded during
both test phases.
Results: The behavioral data showed that improvement of recognition
from pre-test to post-test were not different between Sleep and Wakefulness
groups (t=1.61, p=0.14). Decrease in reaction time however was
greater following sleep compared to wakefulness (t=2.80, p