I was talking with a cousin about animal models (he does work involving rat's brains), and asphyxiation. He was talking about CO2 (for asphyxiation high concentrations of CO2 are used) causes a lot of problems in brains (I forget what it does exactly, something about turning on parts of the brain that are not normally on, turning other parts off). It also creates carbonic acid. I asked about nitrogen, and if that would cause problems too - as it would not form an acid - he said he did not know. Does anyone know anything about this?