Figure 2.

Frontal cortex EEG recordings showing changes seen at the three anesthetic endpoints (depths) tested: LORR–loss of righting reflex, LOPP—loss of paw pinch, and LOTC—loss of tail clamp. The dominant effect at loss of consciousness (LORR) was a slowing of the EEG resulting in a high power delta signal that resembled slow wave sleep patterns. At surgical levels of anesthesia (LOTC) burst suppression activity was seen. Note a reverse pattern of changes was seen on recovery as isoflurane concentrations decreased and responses returned (ROTC, ROPP, and RORR). Calibration = 500 μV and 1.0 s.