Brain Death in Frogs: Is it True?

[Ivan Seeking]

I just heard a scientist say that when frozen, frogs have NO brain activity, but that they can still be revived. Is this true? I knew that frogs could be frozen and revived, but I had never heard the claim about brain activity. If this is true, then when is a frog brain dead, and what is the difference between stasis and brain death; cell death?

Is this why people think we could be frozen and later revived with our consciousness intact?

 

[Mike H]

http://www.pbs.org/wgbh/nova/sciencenow/3209/05-ask.html" .

Given the statement that anaerobic glycolysis still occurs to meet the greatly reduced demand for energy, I'd suggest that significantly reduced metabolic activity indicates a state of stasis. Lack of metabolic activity would suggest (immanent) death.

I'm not very familiar with the human cryogenics issue, but aren't they freezing at temperatures well below the -5 degrees Celsius mentioned for frogs? Some minimal level of cellular metabolism is still possible in frogs, it seems, under those conditions. Being frozen at -100 deg. Celsius is a whole different manner, even with lots of cryoprotectant.

 

[Ivan Seeking]

Does "metabolic activity" imply "brain activity" such as we might measure with an EEG, or does this relate only to the supply of nutrients for the cells?

 

[Mike H]

I would not imagine there to be any electrical activity as measurable by an EEG to be present, simply just a very low baseline activity of biochemical reactions("metabolic activity"). There's no circulation, no sense in propagating nerve signals as the frog is otherwise frozen, just a very slow turnover over the nutrients that are already present in the frog's cells.

Of course, this is just my speculation as, like the scientist on the NOVA page notes, there are no definitive published accounts regarding brain activity in frozen frogs. I would imagine that one would need to monitor the frozen frog for the entire period of its low-temperature hibernation - maybe there's very, very low-frequency behavior going on that otherwise goes undetected.

 

[Ivan Seeking]

Of course, this is just my speculation as, like the scientist on the NOVA page notes, there are no definitive published accounts regarding brain activity in frozen frogs. I would imagine that one would need to monitor the frozen frog for the entire period of its low-temperature hibernation - maybe there's very, very low-frequency behavior going on that otherwise goes undetected.

Yes, whether or not there are very low levels of electrical activity would seem to have profound implications; that is to say, if indeed there is no electrical activity.