Figure 2

Fentanyl induces distinct electrocortical changes associated with sedation. (A) Electrocortical power spectral density and power bands were calculated for each epoch. (B) Epochs were then categorized as wakefulness, non-REM sleep, REM sleep, or sedation (following fentanyl 100 µg · kg⁻¹). Spectrograms of electrocortical activity, i.e. the distribution of electrocortical powers from 0 to 50 Hz, show that fentanyl increased electrocortical power between 0 and 10 Hz and decreased power between 20–50 Hz compared to wakefulness. (C) Mean data showed that fentanyl increased significantly δ power but decreased significantly β₂ power compared to wakefulness (n = 7). During non-REM sleep, δ power was higher than in wakefulness (n = 7), whereas β₂ was lower (n = 7). There was no significant difference in the amplitude of neck muscle activity between states. EMG, electromyogram. *Indicate mean data significantly different with P < 0.05. Data are presented as mean ± SEM.