SLEEP 2011 Abstract Supplement

A. Basic Science IV. Neurobiology
Conclusion: Individuals with high vulnerability showed increased information
processing around sleep onset. There is a trend that when
under stress, individuals with high vulnerability may have enhanced attention
and reduced inhibitory process around sleep onset. The findings
need to be confirmed with increased number of subjects.
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REGIONAL DIFFERENCES IN THE CORTICAL EEG
ASYMMETRY DURING SLOW WAVE SLEEP IN THE FUR
SEAL
Pavlova I 1 , Lyamin O 1,2,3 , Kosenko P 4 , Mukhametov L 1,3 , Siegel J 2
1
Utrish Dolphinarium Ltd., , Moscow, Russian Federation, 2 UCLA and
VA GLAHS Sepulveda, , North Hills, CA, USA, 3 Severtsov Institute of
Ecology and Evolution, , Moscow, Russian Federation, 4 South Federal
University, , Rostov-on-Don, Russian Federation
Introduction: Slow wave sleep (SWS) in the fur seal (Callorhinus ursinus)
is frequently characterized by a highly expressed interhemispheric
EEG asymmetry called the asymmetrical SWS (ASWS). The aim of this
study was to examine spatial-temporal aspects of cortical EEG asymmetry
during SWS in this species.
Methods: Three seals were implanted with 10 EEG electrodes, positioned
bilaterally (5 in each hemisphere) over the frontal, occipital and
parietal cortex. The degree of interhemispheric EEG asymmetry in the
range of 1.2-4 Hz for each pair of symmetrical monopolar recordings
was estimated based on the asymmetry index [AI = (L-R)/(L+R), where
L and R are the spectral powers in the left and right hemispheres, respectively;
calculated in 20-sec epochs], and the percentage of epochs with
an absolute AI>0.3. Each animal was recorded for 2 nights.
Results: The average AI in 5 symmetrical monopolar derivations ranged
between -0.30 and -0.57 in episodes of right ASWS, between +0.25 and
+0.42 in episodes of left ASWS. In contrast, AI at the same derivations
for episodes of high voltage bilateral SWS were between -0.02
and +0.03. The percent of 20-sec epochs with an absolute AI>0.3 varied
between 40 and 71% of all SWS epochs in episodes of left ASWS, between
38 and 75% in episodes of right ASWS and between 0 and 7% in
episodes of bilateral SWS. In 2 out of 3 seals during ASWS both the AI
and number of epochs with an absolute AI>0.3 in the frontal derivations
were significantly smaller than the corresponding values in the parietal
and occipital derivations (one-way Anova, p