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There is a widely published meme that you keep thinking after you die:

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After you die, it is believed that you have 7 minutes of brain activity left inside you

Obviously it doesn't hold true if one is shot to the head, but if one has a heart attack or is decapitated with the brain remaining intact is it true?

(I have also heard that while active in these final moments, the brain releases dmt (N,N-Dimethyltryptamine) which causes one's life to flash before his eyes.)

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    Pretty sure that's going to be a "define alive" situation... – RBarryYoung Jun 29 '15 at 15:24
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    second part of the question is covered here – bummi Jun 29 '15 at 15:26
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RBarryYoung said

Pretty sure that's going to be a "define alive" situation...

He hit the nail on the head.

The definition of death has changed throughout history. In the United States, the declaration of legal death is generally influenced by the Uniform Determination of Death Act (1980) (a short summary of it and related laws can be found here). The UDDA was needed to get rid of the discrepancy between clinical death and brain death. The former was historically based on the stoppage of cardiorespiratory activity, while the latter (a newer approach) is based on brain function. The UDDA elaborates on this conflict:

The medical profession, also, has developed techniques for determining loss of brain functions while cardiorespiratory support is administered. At the same time, the common law definition of death cannot assure recognition of these techniques. The common law standard for determining death is the cessation of all vital functions, traditionally demonstrated by an “absence of spontaneous respiratory and cardiac functions.” There is, then, a potential disparity between current and accepted biomedical practice and the common law.

The UDDA gives two possible scenarios to determine death:

  1. [Determination of Death]. An individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards.

As mentioned in the summarizing source, the UDDA does not define death. Either definition may be used. The New York Times, seven years later, also mentions that some states (40 total, at the time) had enacted similar measures on a state level.

A state related to brain death is brain stem death, which must not be confused. The two are treated different legally as well as medically. From the same New York Times article (giving a state-specific example):

The new definition would not apply, for example, to patients who have lost higher brain function, but who retain brain-stem, or autonomic lower-brain activity, such as the late Karen Anne Quinlan in New Jersey. Such patients can maintain heart and respiratory function with or without mechanical assistance and would be considered alive under the new regulations Under Study in New Jersey.

So, according to federal law, if a doctor applies the brain death option of the UDDA, then the claim is absolutely false, by definition. It gets more complicated if you use the other definition, related to cardiorespiratory activity.

If the brain receives no oxygen, it succumbs to cerebral hypoxia. Brain damage can begin within about four minutes, and brain death can occur at about four to six minutes. I think this might have influenced the claim. How Stuff Works, by the way, sets a figure of six minutes.

So, to answer the question:

Does your brain keep thinking for seven minutes after you die?

  • No, if you define death as the permanent cessation of all brain functions.
  • Possibly, if you define death as the permanent cessation of cardiorespiratory activity.
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    For those who have been knocked out, imagine you wouldn't wake up - that how it's like to die. – Matas Vaitkevicius Jul 2 '15 at 8:45
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    @Matas Vaitkevicius: Now just how do you know that? I mean, you clearly had to have woken up in order to type that comment :-) – jamesqf Jul 8 '15 at 20:07
  • There's perhaps a philosophical gap in this argument: how do we know that you can't continue to think after brain death? We assume that the subjective experience of "thought" requires measurable brain activity, but I don't know how you would prove that, or if it's even provable. – Nate Eldredge Jul 9 '15 at 3:18
  • @jamesqf You are in the right place mate :) – Matas Vaitkevicius Jul 9 '15 at 6:03

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