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.