TY - JOUR
T1 - Predator-induced plasticity in sleep architecture in wild-caught Norway rats (Rattus norvegicus)
AU - Lesku, John A.
AU - Bark, Rebekah J.
AU - Martinez-Gonzalez, Dolores
AU - Rattenborg, Niels C.
AU - Amlaner, Charles J.
AU - Lima, Steven L.
N1 - Funding Information:
We thank Aliyah Dastour and Kristen Ortiz for help with the rats and Christine Foulkes, Swapna Mohan, and Timothy Roth for assistance during surgeries. We thank also the Department of Ecology and Organismal Biology and the Indiana Academy of Sciences for funding, as well as the Max Planck Society for support during the analysis and writing of this manuscript.
PY - 2008/6/3
Y1 - 2008/6/3
N2 - Sleep is a prominent behaviour in the lives of animals, but the unresponsiveness that characterizes sleep makes it dangerous. Mammalian sleep is composed of two neurophysiological states: slow wave sleep (SWS) and rapid-eye-movement (REM) sleep. Given that the intensity of stimuli required to induce an arousal to wakefulness is highest during deep SWS or REM sleep, mammals may be most vulnerable during these states. If true, then animals should selectively reduce deep SWS and REM sleep following an increase in the risk of predation. To test this prediction, we simulated a predatory encounter with 10 wild-caught Norway rats (Rattus norvegicus), which are perhaps more likely to exhibit natural anti-predator responses than laboratory strains. Immediately following the encounter, rats spent more time awake and less time in SWS and REM sleep. The reduction of SWS was due to the shorter duration of SWS episodes, whereas the reduction of REM sleep was due to a lower number of REM sleep episodes. The onset of SWS and REM sleep was delayed post-encounter by about 20 and 100 min, respectively. The reduction of REM sleep was disproportionately large during the first quarter of the sleep phase, and slow wave activity (SWA) (0.5-4.5 Hz power density) was lower during the first 10 min of SWS post-encounter. An increase in SWA and REM sleep was observed later in the sleep phase, which may reflect sleep homeostasis. These results suggest that aspects of sleep architecture can be adjusted to the prevailing risk of predation.
AB - Sleep is a prominent behaviour in the lives of animals, but the unresponsiveness that characterizes sleep makes it dangerous. Mammalian sleep is composed of two neurophysiological states: slow wave sleep (SWS) and rapid-eye-movement (REM) sleep. Given that the intensity of stimuli required to induce an arousal to wakefulness is highest during deep SWS or REM sleep, mammals may be most vulnerable during these states. If true, then animals should selectively reduce deep SWS and REM sleep following an increase in the risk of predation. To test this prediction, we simulated a predatory encounter with 10 wild-caught Norway rats (Rattus norvegicus), which are perhaps more likely to exhibit natural anti-predator responses than laboratory strains. Immediately following the encounter, rats spent more time awake and less time in SWS and REM sleep. The reduction of SWS was due to the shorter duration of SWS episodes, whereas the reduction of REM sleep was due to a lower number of REM sleep episodes. The onset of SWS and REM sleep was delayed post-encounter by about 20 and 100 min, respectively. The reduction of REM sleep was disproportionately large during the first quarter of the sleep phase, and slow wave activity (SWA) (0.5-4.5 Hz power density) was lower during the first 10 min of SWS post-encounter. An increase in SWA and REM sleep was observed later in the sleep phase, which may reflect sleep homeostasis. These results suggest that aspects of sleep architecture can be adjusted to the prevailing risk of predation.
KW - Anti-predator behaviour
KW - Homeostasis
KW - Mammal
KW - Predation
KW - REM sleep
KW - SWS
KW - Spectral power density
KW - Vigilance
UR - http://www.scopus.com/inward/record.url?scp=41149117867&partnerID=8YFLogxK
U2 - 10.1016/j.bbr.2008.01.006
DO - 10.1016/j.bbr.2008.01.006
M3 - Article
C2 - 18313152
AN - SCOPUS:41149117867
SN - 0166-4328
VL - 189
SP - 298
EP - 305
JO - Behavioural Brain Research
JF - Behavioural Brain Research
IS - 2
ER -