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Name: Ethan
Status: other
Grade: other
Location: GA
Country: USA
Date: Summer 2011


Question:
Greetings, I was wondering how long a human brain can retain its information after death. If an individual dies, by the definition of brain death, how long can the cells retain most information before they begin to deteriorate. If the brain is preserved in embalming fluid, can it still retain the same synaptic connections and memories? If in the future, we posses the technology to completely rebuild bodies or rejuvenate dead cells, even ones that have been preserved, I was curious if the same information stored in the brain could also be brought back. From a biological standpoint, not a medical one, would the cells be damaged beyond repair only hours after cell death? Or would the embalming fluid cause damage and loss of information?



Replies:
Ethan

If you are thinking of a brain like you would think of a computer hard drive, (just plug it in and you can read the data) the answer is no.

Here is the definition of brain death from Wikipedia at:
http://en.wikipedia.org/wiki/Brain_death

as:

"Brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of brain oxygenation. It should not be confused with a persistent vegetative state.

Brain death, either of the whole brain or the brain stem, is used as a legal indicator of death in many jurisdictions."

Plus, data in the human brain is not stored in the same way that it is stored in a computer memory. Rather than a 1 or a 0 at a specific location in the memory brain data seems to exist in the form of patterns of neuron connections and brain death is defined as necrosis, and necrosis is defined at:

http://dictionary.reference.com/browse/necrosis

as

"death of a circumscribed portion of animal or plant tissue"

Feel free to explore these URLs for more information.

Sincere regards,
Mike Stewart


Interesting question! Human memory is comparatively volatile, somewhat like computer RAM. RAM needs a steady flow of energy to maintain its memory. When the power is cut, the contents are wiped. Similarly, when the brain is deprived of oxygen (for what seems to otherwise be a fairly inconsequential period of time) significant and irretrievable damage occurs.

Preservation techniques are something of a misnomer. Embalming fluid would be very disruptive, probably impact cell permeability, and also denature macromolecules associated with memory encoding. Even with the addition of cryoprotectants, cryopreservation would also be highly disruptive to signal transduction within the neural networks that facilitate memory.

As for memories being salvageable and transferable, there is no known process by which we can do so. This hasn’t stopped the idea from being popularized in sci-fi media, where it seems downright routine. In this very hypothetical and fanciful scenario, scientists take memory snapshots, called engrams, digitize them (convert neurochemical/biochemical patterns into binary data), and upload to a computer for storage. This data could then be downloaded to a blank slate (a new host body – perhaps a clone, and “rebooted”), or an individual’s consciousness could reside on a mainframe, immortalized.

Dr. Tim Durham
Instructor, Office of Curriculum and Instruction University Colloquium Department of Biological Sciences Florida
Gulf Coast University


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