EEG Power Densities (0.5–20 Hz) in Different Sleep–Wake Stages in Rats

Abstract

Bjorvatn, B., S. Fagerland and R. Ursin. EEG power densities (0.5–20 Hz) in different sleep–wake stages in rats. PHYSIOL BEHAV 63(3) 413–417, 1998.—Frontofrontal and frontoparietal EEG power densities (0.5–20 Hz) in waking, light and deep slow-wave sleep, transition-type sleep, and rapid-eye-movement (REM) sleep were investigated for 8 h during the light period in 16 male Wistar rats. The data indicate that as δ activity (0.5–4.5 Hz) increased from light to deep slow-wave sleep, the number of epochs per scoring epoch with high σ activity (11–16 Hz) as well as power densities in the rest of the spectrum (5–20 Hz) including σ frequencies also increased. This is in parallel with other rat studies but contrasts findings in humans, where EEG σ activity is reported to decrease as sleep deepens. During the 8-h recording period, δ activity decreased whereas σ activity increased.