Characterization of the bout durations of sleep and wakefulness.
OBJECTIVE
(a) Develop a new statistical approach to describe the microarchitecture of wakefulness and sleep in mice; (b) evaluate differences among inbred strains in this microarchitecture; (c) compare results when data are scored in 4-s versus 10-s epochs.


METHODS
Studies in male mice of four inbred strains: AJ, C57BL/6, DBA and PWD. EEG/EMG were recorded for 24h and scored independently in 4-s and 10-s epochs.


RESULTS
Distribution of bout durations of wakefulness, NREM and REM sleep in mice has two distinct components, i.e., short and longer bouts. This is described as a spike (short bouts) and slab (longer bouts) distribution, a particular type of mixture model. The distribution in any state depends on the state the mouse is transitioning from and can be characterized by three parameters: the number of such bouts conditional on the previous state, the size of the spike, and the average length of the slab. While conventional statistics such as time spent in state, average bout duration, and number of bouts show some differences between inbred strains, this new statistical approach reveals more major differences. The major difference between strains is their ability to sustain long bouts of NREM sleep or wakefulness. Scoring mouse sleep/wake in 4-s epochs offered little new information when using conventional metrics but did when evaluating the microarchitecture based on this new approach.


CONCLUSIONS
Standard statistical approaches do not adequately characterize the microarchitecture of mouse behavioral state. Approaches based on a spike-and-slab provide a quantitative description.
McShane
Blakeley B
BB
Kellogg School of Management, Northwestern University, Evanston, IL, USA.
Galante
Raymond J
RJ
Jensen
Shane T
ST
Naidoo
Nirinjini
N
Pack
Allan I
AI
Wyner
Abraham
A
D000818:Animals; D001522:Behavior, Animal; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D004576:Electromyography / Q000379:methods; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008954:Models, Biological; D012890:Sleep / Q000502:physiology*; D013045:Species Specificity; D013223:Statistics as Topic; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*
J Neurophysiol. 2008 Jun;99(6):3090-103
18417630
Nature. 2005 Oct 27;437(7063):1257-63
16251950
Proc Natl Acad Sci U S A. 2004 Dec 14;101(50):17545-8
15583127
J Neurophysiol. 2007 Jun;97(6):3828-40
17409167
Behav Brain Res. 2009 Jan 23;196(2):228-36
18835301
Sleep. 1999 Mar 15;22(2):155-69
10201060
Proc Natl Acad Sci U S A. 2005 Oct 11;102(41):14860-4
16192355
Exp Neurol. 2009 May;217(1):46-54
19416673
Eur J Neurosci. 2006 Mar;23(6):1567-74
16553620
Eur J Neurosci. 2007 Jan;25(2):512-8
17284193
J Neurosci. 2001 Apr 15;21(8):2610-21
11306614
Cell. 1999 Aug 20;98(4):437-51
10481909
Proc Natl Acad Sci U S A. 2006 May 2;103(18):7118-23
16636276
Physiol Genomics. 2007 Jan 17;28(2):232-8
16985007