A patient has turned up in coma who had some deep brain waves from his hippocampus, which is deeply located in the brain. He was flat-lined from his cortex. One cat study under anesthesis mimicked this. I've followed this story for abouta week and finally found one reasonable commentary. With drugs involved the significance in minimal. Flat-lined is still flat-lined:-http://www.scientificamerican.com/article.cfm?id=peculiar-brain-signals-found-in-flat-lined-patient