US Patent 7725174 Distinguishing different drug effects from the electroencephalogram

This disclosure provides a method of indicating a subject's reaction to different agents administered to induce anesthesia. In particular, the subject's reaction can be assessed by receiving electrical signals from first and second electrodes spatially distributed on different regions of a subject's head, and by processing the electrical signals from the electrodes to provide a first indicator of the subject's reaction to a first of the agents and a second indicator of the subject's reaction to a second agent.