The question whether
decapitation is a humane method of
euthanasia in awake animals is being debated. To gather arguments in this debate, obsolete rats were decapitated while recording the EEG, both of awake rats and of anesthetized rats. Following
decapitation a fast and global loss of power of the EEG was observed; the power in the 13-100 Hz frequency band, expressing cognitive activity, decreased according to an exponential decay function to half the initial value within 4 seconds. Whereas the pre-
decapitation EEG of the anesthetized animals showed a burst suppression pattern quite different from the awake animals, the power in the postdecapitation EEG did not differ between the two groups. This might indicate that either the power of the EEG does not correlate well with consciousness or that consciousness is briefly regained in the anesthetized group after
decapitation. Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following
decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning
ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference. Two conclusions were drawn from this experiment. It is likely that consciousness vanishes within seconds after
decapitation, implying that
decapitation is a quick and not an inhumane method of
euthanasia. It seems that the massive wave which can be recorded approximately one minute after
decapitation reflects the ultimate border between life and death. This observation might have implications in the discussions on the appropriate time for organ donation.