Changes in EEG activity and hypothalamic temperature as indices for non-REM sleep to REM sleep transitions.
A shift of physiological regulations from a homeostatic to a non-homeostatic modality characterizes the passage from non-NREM sleep (NREMS) to REM sleep (REMS). In the rat, an EEG index which allows the automatic scoring of transitions from NREMS to REMS has been proposed: the NREMS to REMS transition indicator value, NIV [J.H. Benington et al., Sleep 17 (1994) 28-36]. However, such transitions are not always followed by a REMS episode, but are often followed by an awakening. In the present study, the relationship between changes in EEG activity and hypothalamic temperature (Thy), taken as an index of autonomic activity, was studied within a window consisting of the 60s which precedes a state change from a consolidated NREMS episode. Furthermore, the probability that a transition would lead to REMS or wake was analysed. The results showed that, within this time window, both a modified NIV (NIV(60)) and the difference between Thy at the limits of the window (Thy(D)) were related to the probability of REMS onset. Both the relationship between the indices and the probability of REMS onset was sigmoid, the latter of which saturated at a probability level around 50-60%. The efficacy for the prediction of successful transitions from NREMS to REMS found using Thy(D) as an index supports the view that such a transition is a dynamic process where the physiological risk to enter REMS is weighted at a central level.
Capitani
Paolo
P
Department of Electronics, Computer Science and Systems, Alma Mater Studiorum-University of Bologna, Italy.
Cerri
Matteo
M
Amici
Roberto
R
Baracchi
Francesca
F
Jones
Christine Ann
CA
Luppi
Marco
M
Perez
Emanuele
E
Parmeggiani
Pier Luigi
PL
Zamboni
Giovanni
G
D000204:Activity Cycles / Q000502:physiology*; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D004569:Electroencephalography; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D017286:Polysomnography / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D012895:Sleep, REM / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness