Regional differences in the dynamics of the cortical EEG in the rat after sleep deprivation

Objective: To investigate regional changes of the cortical sleep EEG in the rat, recordings were obtained from a frontal and an occipital derivation, on a baseline day (n = 14 male rats, Sprague-Dawley strain) and after 24 h sleep deprivation (SD, n = 7). Methods: Spectral analysis of the vigilance states revealed state and frequency specific differences in EEG power by two-way ANOVA and post-hoc t tests. Results: In the theta band (6.25-9.0 Hz) occipital power was larger than frontal power in waking and REM sleep, whereas frontal power was larger in the frequency range between 10.25-16.0 Hz in non-REM sleep and REM sleep. After SD frontal power in the 2-4 Hz band in non-REM sleep was increased more than occipital power and frontal power in the 10.25-16.0 Hz range was more attenuated. In REM sleep frontal power in the theta band and in the 10.25-16.0 Hz range was more increased than occipital power. Power in the waking EEG did not differ between the two derivations after SD. Conclusions: The differential responses to SD may reflect regional use-dependent aspects of sleep regulation. These observations support the notion that sleep is not only a global phenomenon but has also local, use-dependent features. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.