Fast cooling of objects as large as a human body, or even a human head, is essentially impossible due to the square-cube law: the thermal capacity of an object is proportional to its mass, which, for a given density, is proportional to its volume, while its capacity to transfer heat is proportional to its surface area. As size increases, surface area grows quadratically while volume grows cubically, hence their ratio decreases.
Has anyone thought about chopping brains in to slices and freezing the slices? I guess you'd have to match the slices up to each other extremely precisely to recover the brain though.
Per PZ Myers, the state of the art in neural preservation doesn't recoverably preserve usable amounts of state in zebrafish brains, which are a few hundred microns on a side. How thin slices were you thinking of? And how fast were you going to be slicing?
...I’ve worked with tiny little zebrafish brains, things a few hundred microns long on one axis, and I’ve done lots of EM work on them. You can’t fix them into a state resembling life very accurately: even with chemical perfusion with strong aldehyedes of small tissue specimens that takes hundreds of millis
http://www.strike-the-root.com/51/walker/walker12.html
Came across it pretty randomly, I found it quite intriguing. Cryonics is "routine" for human embryos, not far-fetched for humans at all. Makes the whole thing seem potentially very reasonable (and me someone who hasn't signed up and doesn't plan to).