If a non-mammal is starved of oxygen for some time, how long would it take the animal's neurons to die?
Medically, recovery of brain function after 3 minutes of oxygen deprivation at body temperature is rare.  

Further down here in 1 it indicates that at lower temperatures the time can be much longer.  At 13C, the record is 80 minutes for people.  Animals cooled to 0C have a record of recovery of three hours!  Not sure how much like themselves they feel after that though...