Experimental setting for electrocorticographic recordings in the ferret under different concentrations of isoflurane. (A) A custom-made 64-channel electrode array was used to record the electrocorticogramm. (B) Array in situ. The ECoG-array was designed to cover the temporo-parieto-occipital cortex. (C) During the course of the experiment, isoflurane concentration was varied in 13 steps across 7 levels. Each level was kept for 20 min, of which the last 4 min was chosen for analysis. Data acquisition started at least 5 h after the initial anesthesia with ketamine/meditomidine. (D) Average power (normalized to the maximum per frequency) during the course of the experiment for all 6 animals. While frequencies below around 30 Hz showed a relative increase with higher isoflurane concentrations, higher frequencies displayed the opposite effect.